System and method for generating hyperpolarized compounds using parahydrogen

Abstract

Systems and methods for increasing nuclear spin polarization in a target compound are disclosed. The nuclear spin polarization can be increased by obtaining a target compound or a precursor of the target compound. The target compound or precursor can include a first proton and a second proton that share singlet spin order, and a third proton bound to at least one of the first proton or the second proton. The target atom can be bound to at least the third proton. The precursor can be placed within an average magnetic field strength of less than 500 mT. A magnetic resonance (MR) pulse sequence can be applied to the precursor, the MR pulse sequence configured to transfer a population from the first and second protons to the target atom, thereby imparting at least 1%, 2%, 5%, 10%, or 20% non-equilibrium nuclear spin polarization to the target atom.

Description

[Technical Field]

[0001] Cross-references to related applications This application claims the interests of U.S. Provisional Patent Application No. 63 / 201,151, filed April 15, 2021. This application claims the interests of U.S. Provisional Patent Application No. 63 / 122,006, filed December 7, 2020. This application claims the interests of International Application PCT / IB2021 / 000493, filed July 23, 2021, which in turn claims the interests of U.S. Provisional Patent Application No. 63 / 055,367, filed July 23, 2020. International Application PCT / IB2021 / 000493 also claims the interests of U.S. Provisional Patent Application No. 63 / 076,411, filed September 10, 2020. Each of the above applications is incorporated herein by reference in its entirety.

[0002] The disclosed embodiments generally relate to the production of hyperpolarized materials for use in nuclear magnetic resonance, magnetic resonance imaging, or similar applications. [Background technology]

[0003] Para-hydrogen-induced polarization (PHIP) is a low-cost, high-throughput method for polarizing metabolites for hyperpolarized (HP) magnetic resonance imaging (MRI). Para-hydrogen-induced polarization (PHIP), para-hydrogen-induced polarization by side-chain hydrogenation (PHIP-SAH), and signal amplification by reversible exchange (SABRE) can be used to polarize metabolites (e.g., fumarate or pyruvate). However, existing polarization approaches may not be suitable for preclinical or clinical hyperpolarized MRI applications because such approaches may not achieve sufficient sample volume, purity, polarization, or concentration. [Overview of the project]

[0004] The disclosed systems and methods relate to the generation of hyperpolarized target compounds using at least one of PHIP, PHIP-SAH, or SABRE. The generation of hyperpolarized materials may involve the application of a sequence of microwave pulses or the modulation of a magnetic field. In some embodiments, the target compound may be hyperpolarized in solution and then induced to precipitate from the solution. The precipitate may be redissolved in a specified volume of solvent to form a solution having a desired concentration of the hyperpolarized target compound. Polarization may be transitioned from two hydrogen atoms to the spin state of the target atom using a mediating atom and a mediating atom that forms a quantum three-body system.

[0005] The disclosed embodiments include a system for generating hyperpolarized molecules. The system may include a hydrogenation device, a polarization device, an RF waveform generator, and a purification system. The hydrogenation device may be configured to produce a parahydrogenated solution by mixing a solvent, a parahydrogen gas, and a precursor of hyperpolarized molecules, the precursor comprising unsaturated chemical bonds. The polarization device may be configured to produce a polarization solution containing hyperpolarized molecules using the parahydrogenated solution. The polarization device may include a polarization chamber, one or more radio frequency (RF) coils, and a magnetic field source. The polarization chamber may be configured to receive the parahydrogenated solution. The polarization chamber may include a polarization region having a volume of at least 10 milliliters (mL). One or more radio frequency (RF) coils may be arranged around the polarization region of the polarization chamber. The magnetic field source may be arranged around the polarization region of the polarization chamber and may be configured to provide an average magnetic field strength of up to 200 millitesla (mT). An RF waveform generator may be coupled to one or more RF coils of the polarization device. The RF waveform generator may be configured to apply an RF waveform to one or more RF coils. The purification system may be configured to separate the purified fraction from the polarized solution.

[0006] The disclosed embodiments include a method for increasing nuclear spin polarization in a target compound. The method may include: obtaining a target compound or a parahydrogenation precursor of a target compound; placing the target compound or parahydrogenation precursor within an average magnetic field strength of less than 500 mT; and applying a magnetic resonance (MR) pulse sequence to the target compound or parahydrogenation precursor. The obtained target compound or parahydrogenation precursor may include: (i) a first proton; (ii) a second proton coupled to at least one of the first protons by a first J coupling constant, wherein the first and second protons have singlet spin order; (iii) a third proton coupled to at least one of the first or second protons by a second J coupling constant; and (iv) a target atom coupled to at least the third proton by a third J coupling constant. The first and second protons can be separated from the target atom by at least four chemical bonds. The MR pulse sequence may be configured to transfer a group of protons from the first and second protons to the target atom, thereby imparting at least 1%, 2%, 5%, 10%, or 20% of non-equilibrium nuclear spin polarization to the target atom.

[0007] The disclosed embodiments further include a method for generating a hyperpolarized molecule. The method may include: obtaining a precursor of the molecule; carrying out a parahydrogen-induced polarization (PHIP) reaction between parahydrogen and the precursor; placing the molecule within an average magnetic field strength of 0 to 500 mT; applying a magnetic resonance (MR) pulse sequence to the molecule; cleaving a side chain from the precursor to thereby generate a hyperpolarized molecule and the cleaved side chain; purifying the hyperpolarized molecule from the cleaved side chain; administering the hyperpolarized molecule to a subject; and performing a hyperpolarized magnetic resonance imaging (MRI) procedure on the subject. The precursor may include a molecule and a side chain bonded to the molecule, the molecule including a target atom, and the side chain including at least one unsaturated chemical bond separated from the target atom by at least three intervening chemical bonds. Carrying out the parahydrogen-induced polarization (PHIP) reaction may add a first proton and a second proton across at least one unsaturated bond to form the molecule. The MR pulse sequence may be configured to transfer a collection of protons from the first and second protons to a target atom. The MR pulse sequence may thereby impart at least 1%, 2%, 5%, 10%, or 20% of non-equilibrium nuclear spin polarization to the target atom.

[0008] Both the above general description and the following detailed description are illustrative and descriptive only and do not limit the embodiments of this disclosure as defined in the claims. [Brief explanation of the drawing]

[0009] The accompanying drawings, including portions thereof, illustrate several embodiments and, together with this specification, serve to illustrate the principles and features of the disclosed embodiments. In the drawings:

[0010] [Figure 1] Exemplary processes for PHIP or PHIP-SAH polarization, consistent with the disclosed embodiments, are illustrated. [Figure 2A] A quantum mechanical four-body system suitable for polarity transition using mediating protons, consistent with the disclosed embodiments, is illustrated. [Figure 2B]We disclose an approximate energy structure of the quantum mechanical three-body system of protons, as illustrated in Figure 2A, which is consistent with the embodiments disclosed. [Figure 3] The simulation and calculation of the PulsePol transfer efficiency of the spin system in Figure 2A, consistent with the disclosed embodiments, are illustrated. [Figure 4] An exemplary schematic diagram of a polarizer for obtaining a high-concentration biocompatible solution containing a hyperpolarized target compound is shown. [Figure 5A] An exemplary schematic diagram of a system including a polarizer and a separation system for obtaining a high-concentration biocompatible solution containing a hyperpolarized target compound is shown. [Figure 5B] An exemplary schematic diagram of a system including a polarizer and a separation system for obtaining a high-concentration biocompatible solution containing a hyperpolarized target compound is shown. [Figure 5C] An exemplary schematic diagram of a system including a polarizer and a separation system for obtaining a high-concentration biocompatible solution containing a hyperpolarized target compound is shown. [Figure 6A] An exemplary schematic diagram of a system for generating a hyperpolarized target compound, consistent with the disclosed embodiments, is shown. [Figure 6B] The frequency and amplitude characteristics of a high-frequency sweep suitable for polarization transition using mediating protons, consistent with the disclosed embodiments, are illustrated. [Figure 6C] The frequency and amplitude characteristics of a high-frequency sweep suitable for polarization transition using mediating protons, consistent with the disclosed embodiments, are illustrated. [Figure 6D] The frequency and amplitude characteristics of a high-frequency sweep suitable for polarization transition using mediating protons, consistent with the disclosed embodiments, are illustrated. [Figure 6E] Figures 6B to 6D illustrate the 13C polarization in a plane parallel to the static magnetic field during the application of high-frequency sweep, consistent with the disclosed embodiments. [Figure 7A] The simulation and experimental results of polarized transfer using protonated and deuterated pyruvate cinnamyl molecules according to the disclosed embodiments are illustrated. [Figure 7B] The simulation and experimental results of polarized transfer using protonated and deuterated pyruvate cinnamyl molecules according to the disclosed embodiments are illustrated. [Figure 7C] The polarizations achieved for DAMD-d6, DMAD, fumarate, CP 1-13C d1, and CP according to the disclosed embodiments are illustrated. [Figure 8] A polarized 25 ml sample of 1-13C cinnamyl pyruvate prepared according to the disclosed embodiments is shown. [Figure 9] Figure 8 shows the 13C NMR spectrum of polarized 13C-enriched cinnamyl pyruvate, measured with a 60 MHz SpinSolve spectrometer. [Modes for carrying out the invention]

[0011] Hereinafter, exemplary embodiments discussed with respect to the attached drawings will be given in detail. In some cases, the same reference numerals will be used throughout the drawings and the following description to refer to the same or similar parts. Unless otherwise defined, technical or scientific terms have the meanings generally understood by those skilled in the art. The disclosed embodiments are described in sufficient detail to enable those skilled in the art to carry out the disclosed embodiments. It should be understood that other embodiments may be available and that modifications may be made without departing from the scope of the disclosed embodiments. Accordingly, the materials, methods and examples are illustrative and not necessarily intended to be limiting.

[0012] Recent research in the fields of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) has demonstrated that NMR and MRI signals associated with various bio-relevant imaging agents can be dramatically enhanced using various so-called hyperpolarization techniques. Such dramatic signal enhancements enable spectroscopic analysis of bio-relevant imaging agents as they are metabolized by various tissues at different locations within the body. Analysis of metabolic information determined by such spectroscopic imaging can enable non-invasive determination of the health status of tissues within the body. For example, abnormal metabolism of bio-relevant imaging agents may indicate diseases such as cancer at several locations within the body.

[0013] Existing techniques for hyperpolarized bio-imaging agents include dissolution-dynamic nuclear polarization (DNP), para-hydrogen-induced polarization (PHIP), PHIP-SAH side-chain hydrogenation (PHIP-SAH), and reversible exchange-based signal amplification (SABRE). However, with the exception of DNP, existing techniques cannot produce clinically meaningful volumes and concentrations of bio-imaging agents with sufficient polarization and purity. DNP has several drawbacks, including costly instrumentation and the long time required for polarization accumulation.

[0014] PHIP-SAH technology has expanded the usefulness of PHIP-based polarization methods in the preparation of bio-relevant imaging agents. In PHIP-SAH, a precursor molecule is hydrogenated and then cleaved. The precursor molecule generally contains a side chain with an unsaturated chemical bond (such as a carbon-carbon double or carbon-carbon triple bond), which is chemically linked to the bio-relevant imaging agent. For example, the side chain may be positioned on one side of the carboxyl group so that the side chain and the bio-relevant imaging agent combine to form an ester precursor. The side chain is then reacted with a parahydrogen, which positions a proton with a high level of spin order across the unsaturated bond. This spin order is then transferred to a target nucleus located within the bio-relevant imaging agent (such as the nucleus of a 13C target atom). The side chain is then cleaved and removed, allowing for the formation of a solution containing the bio-relevant imaging agent with a hyperpolarized target nucleus.

[0015] Unfortunately, previous PHIP-SAH techniques typically require unsaturated chemical bonds located two or fewer chemical bonds away from the target atom, resulting in at least one para-hydrogen proton terminating within three chemical bonds of the target atom for a sufficiently strong bond. This limitation imposes significant constraints on precursors and reduces the usefulness of the PHIP-SAH method. Such previous approaches generally require a trade-off between the chemical stability of the precursor and the ease with which para-hydrogens can be added across unsaturated chemical bonds.

[0016] Therefore, there is a need for hyperpolarization methods and systems that utilize PHIP-SAH precursor molecules having unsaturated bonds located at least three chemical bonds away from the target atom, resulting in each parahydrogen proton ending at at least four chemical bonds away from the target atom, enabling the generation of clinically significant amounts of hyperpolarized bio-related imaging agents.

[0017] The disclosed embodiments include systems and methods for generating target compounds (also called target molecules), such as bio-relevant imaging agents, with clinically significant polarization, concentration, volume, and purity. The disclosed embodiments provide technical improvements to polarized target compounds in solution. These technical improvements support increases in target compound concentration, degree of target compound polarization, and increased solution volume.

[0018] The systems and methods described herein are located on target atoms or nuclei (on bio-related imaging molecules). 13The PHIP-SAH precursor molecule was utilized, containing an unsaturated chemical bond located at least three chemical bonds away from the target nucleus (e.g., a 1C target nucleus). Parahydrogen is added across the unsaturated chemical bond such that two parahydrogen protons are each located at least four chemical bonds away from the target atom or nucleus. The mediating proton located between the parahydrogen proton and the target nucleus forms a quantum mechanical spin network that is manipulated to transfer spin order from the parahydrogen proton to the target nucleus, resulting in hyperpolarization of the target nucleus. Radio frequency (RF) excitation, with a magnetic field readily generated between 0 and 500 mT, is used to drive this transformation of the parahydrogen spin order to the target nucleus polarization. Manipulating with this regimen may allow for scaling up of polarization transfer to clinically significant volumes. Because the unsaturated chemical bond is located further away from the target nucleus, the precursor molecule is less sensitive to trade-offs between different optimization parameters such as chemical stability and the ease with which parahydrogen is added across the unsaturated chemical bond. Therefore, precursor molecules can be better optimized to enable the generation of clinically significant volumes of hyperpolarized bio-related imaging agents, such as pyruvate, acetates, other carboxylates, and other clinically significant target compounds, which utilize unsaturated side chains for para-hydrogen-based polarization.

[0019] Electromagnets with or without ferromagnetic cores may be used to generate such low magnetic fields at large volumes (e.g., clinically significant volumes). Magnetic shielding may be added to enhance homogeneity over large volumes. Thus, larger volumes (e.g., clinically significant volumes) of more highly polarized target compounds can be generated.

[0020] The disclosed embodiments may be used together or separately. For example, the disclosed technical improvements in polarized target compounds may be used in conjunction with the disclosed improved separation method or other separation methods. Similarly, the disclosed technical improvements in separation target compounds may be used in conjunction with the disclosed improved polarization method or other polarization methods.

[0021] Parahydrogen can be used as a polarization source, consistent with the disclosed embodiments. Parahydrogen is a form of molecular hydrogen in which two proton spins are in a singlet state, as described herein. The disclosed embodiments are not limited to a specific method of producing parahydrogen. Parahydrogen can be formed in gaseous or liquid form. Parahydrogen can be produced in gaseous form by flowing hydrogen gas at a low temperature (e.g., cryogenic temperatures such as between the boiling point of liquid helium and the boiling point of liquid nitrogen) through a chamber having a catalyst (e.g., iron oxide or another suitable catalyst). The hydrogen gas may contain both parahydrogen and orthohydrogen. The low temperature can cause the hydrogen gas to reach thermodynamic equilibrium in the chamber and increase the population of parahydrogen. The disclosed embodiments are not limited to a specific parahydrogen production location. Parahydrogen can be produced at a first location and then transported to a second location for use. In some embodiments, the first location may be a chamber, which may be part of a container, bottle, holder, or other area capable of holding gas or liquid. Such a chamber may be maintained at a suitable pressure or temperature. In some embodiments, the first location may refer to a physical location such as a room, a laboratory, a specific warehouse, a hospital, or any other location where parahydrogen may be produced. The disclosed embodiments are not limited to any particular method of parahydrogen transport. The produced parahydrogen may be transported in a chamber that may be different from the chamber in which the parahydrogen was produced. The chamber in which the parahydrogen gas is transported may be maintained at a suitable pressure or temperature that can be transported by vehicle or by person. Transporting parahydrogen may involve moving parahydrogen from one container to a different container. Transporting parahydrogen may involve moving parahydrogen within the same location, such as from one part of a room to another part of a room. Transporting parahydrogen may involve moving parahydrogen from one room in a building to a different room in the same building, or to a nearby building. Transporting parahydrogen may involve moving parahydrogen to a different location in a different part of the same city, or to a different city. Transporting parahydrogen may involve transporting parahydrogen near a polarizer or NMR / MRI device. Transporting parahydrogen may involve packaging or transporting parahydrogen in suitable containers.

[0022] The collective difference between spin states may be the difference between two sets of spin states divided by the total set of spin states. The collective difference may be expressed as a fractional collective difference or a percentageal collective difference. In certain embodiments, the fractional collective difference is at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In certain embodiments, the fractional collective difference is at most about 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. In certain embodiments, the fractional collective difference is within the range defined by any two of the preceding values.

[0023] Hydrogen gas can exhibit a collective difference between proton spin states that far exceeds the collective difference between proton spin states in thermal equilibrium. Parahydrogen can have a large collective difference between either the singlet spin state or the triplet spin state. For example, I achieved by hydrogenation in a high magnetic field. z1 I z2 In the case of order, a large collective difference exists between the spin states |↑>|↓> and |↑>|↑>. The collective difference of proton spin states can be greater than approximately 0.1 (for example, a 10% difference in spin states - 55% of parahydrogen molecules in the sample are in the singlet state and 45% are in the triplet state), and greater than or equal to 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or less than or equal to approximately 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1.

[0024] The target compound may include a material suitable for use in NMR or MRI operations (e.g., "NMR material"). In some embodiments, such NMR material may increase the NMR / MRI signal and signal-to-noise ratio (SNR). In some embodiments, the NMR material may be suitable for use in solution NMR spectroscopy. In some embodiments, the NMR material may be a metabolite (e.g., biorelevant molecules such as amino acids, sugars, and their derivatives) suitable for use in NMR metabolomics applications. In some embodiments, the NMR material may be suitable for in vitro probing of the metabolism of cell cultures or other biological tissues. In some embodiments, the NMR material may be used in NMR probes to investigate transient effects requiring high signal enhancement due to hyperpolarization, such as proton exchange between water and biomolecules. In some embodiments, the NMR material may be a small molecule or metabolite suitable for injection into cells, tissues, or organisms for detection in MRI scans. In some embodiments, the NMR material may be introduced into a chamber for further analysis by NMR or MRI operations. In some embodiments, the NMR material may be enriched with 13C atoms. In some embodiments, the NMR material may be a biocompatible material that does not necessarily possess metabolic functions.

[0025] In accordance with the disclosed embodiments, the target compound is pyruvate, lactate, bicarbonate, fumarate, urea, alpha-ketoglutarate, dehydroascorbate, glutamate, glutamine, acetate, dihydroxyacetone, acetoacetate, glucose, ascorbate, zymonate, imidazole, nicotinamide, nitroimidazole, pyrazinamide, isoniazid, any of the above conjugate acids, natural and unnatural amino acids, their esters, or any of the above. 13 C or 15 This could be a modified example of N-enriched tissue.

[0026] In accordance with the disclosed embodiments, the target compound may be produced from a “precursor” of the target compound. Such production may involve one or more chemical reactions. In some embodiments, the target compound may be produced from the precursor by hydrogenation of one or more unsaturated bonds (e.g., unsaturated carbon-carbon bonds) of the precursor. For example, when the target compound is a fumarate, one or more unsaturated bonds of acetylenedicarboxylic acid may be hydrogenated to produce fumaric acid. In some embodiments, the target compound may be produced from the precursor by cleaving a side chain from the precursor to obtain the target compound. In some embodiments, the precursor may be an ester having the general formula -COOR. Thus, in such embodiments, the term “side chain” may refer to the R portion of the ester. In some embodiments, the side chain may include substituents and functional groups directly bonded to the ester oxygen, which is bonded by carbons on both sides. For example, the precursor may be an enol or inol ester of the target compound, and the specific enol or inol may be referred to as the side chain. As a further example, the target compound may be a pyruvate. When the precursor is vinyl pyruvate, the side chain is a vinyl functional group. When the precursor is cinnamyl pyruvate, the side chain is a phenylallyl functional group. When the precursor is allyl pyruvate, the side chain is an allyl functional group. When the precursor is propargyl pyruvate, the side chain is a propargyl functional group. In some embodiments, the target compound can be produced from the precursor by hydrogenation and cleavage of the side chain. For example, the precursor may be hydrogenated, and then the side chain may be cleaved to obtain the target compound. Hydrogenation may occur at a position on the side chain or on the target compound.

[0027] In accordance with the disclosed embodiments, hydrogenation may be carried out using parahydrogenation (e.g., parahydrogenation). Such parahydrogenation can create a collective difference in proton spins in the parahydrogenation precursor. In accordance with the disclosed embodiments, the collective difference in proton spins can be transferred to the polarization of the target nuclear spin of the parahydrogenation precursor, thereby creating a hyperpolarized parahydrogenation precursor. When the target compound is produced from the precursor by hydrogenation, the hyperpolarized parahydrogenation precursor may be a hyperpolarized target compound. When the target compound is produced from the precursor by hydrogenation and its side chains are cleaved, the hyperpolarized parahydrogenation precursor can be cleaved to obtain a hyperpolarized target compound.

[0028] Various embodiments of this disclosure disclose methods for preparing hyperpolarized target compounds. In some embodiments, the target compound may be produced from a precursor via parahydrogenation and polarization using PHIP or SABRE, while in other embodiments, the target compound may be produced from a precursor via parahydrogenation and polarization using PHIP-SAH, followed by cleavage of the side chain.

[0029] Figure 1 illustrates an exemplary process 100 for PHIP or PHIP-SAH polarization, consistent with the disclosed embodiments. Process 100 may be used for large-scale PHIP polarization to generate target compounds for in vitro or in vivo MRI. A similar process may be used for SABRE polarization, in which the hydrogenation in step 105 is replaced with an exchangeable bond of the target compound and para-hydrogen to the polarization catalyst. This illustration of process 100 is not intended to limit it. The assumed embodiments may include additional or fewer steps, or the steps may be combined or separated. For example, process 100 may be initiated in step 105 using previously generated or obtained para-hydrogen. As an additional example, process 100 may be terminated in step 109 with the purification or separation of the target compound. Similarly, the transport in steps 103 and 111 may be optional. Furthermore, although illustrated for use in MRI, the target compounds are not necessarily limited to such use.

[0030] An optional step 101 of process 100 illustrates the production of parahydrogen, consistent with the disclosed embodiments. Parahydrogen can be produced by flowing low-temperature hydrogen gas through a chamber having a catalyst such as iron oxide, allowing parahydrogen and orthohydrogen to reach their thermodynamic equilibrium. In some embodiments, at low temperatures, parahydrogen may become increasingly dense. In some alternative embodiments, liquid parahydrogen may be prepared similarly. Parahydrogen can be produced in advance or as needed, consistent with the disclosed embodiments.

[0031] An optional step 103 of process 100 illustrates the transport of pressurized parahydrogen containers, e.g., gas bottles, consistent with the disclosed embodiments. These parahydrogen containers can be filled and transported near the MRI scanner. In some alternative embodiments, the pressurized parahydrogen may also be liquid parahydrogen bottles, which can also be filled and shipped. In alternative embodiments, the parahydrogen generator is connected to a PHIP polarizer, thus eliminating the need for parahydrogen gas containers.

[0032] Step 105 of process 100 illustrates the parahydrogenation of the precursor, consistent with the disclosed embodiments. In some embodiments, the parahydrogen gas is combined with the precursor (e.g., in a solution or mixture) to hydrogenate the precursor. z1 I z2 This can create lower energy states between |↑>|↓> and |↓>|↑>, or singlet spin order on two hydrogen spins.

[0033] Step 107 illustrates, consistently with the disclosed embodiments, the transition of the collective difference in the parahydrogenated proton spin state to polarization on the target nuclear spin of the parahydrogenation precursor. Such a transition can be achieved, consistently with the embodiments of the present disclosure, by using at least one of the following: modulation of a magnetic field applied to a solution containing the parahydrogenation precursor, or application of a sequence of high-frequency pulses. Such a transition can generate a hyperpolarized precursor. In some embodiments, the hydrogenation and hyperpolarized precursors may include side chains (for example, the precursor may be an ester of the target compound). The hydrogenation reaction may occur within the side chain, and the spin order may be transitioned to polarization on the target nuclear spin at a location within the target compound.

[0034] Step 109 illustrates the purification or separation of the hyperpolarization precursor (or the hyperpolarization target compound generated from the hyperpolarization precursor) from the original solution, consistent with the disclosed embodiments. In some embodiments using PHIP-SAH, the purification or separation may include cleaving the hyperpolarization precursor to produce the hyperpolarization target compound. In embodiments using PHIP or SABRE, the hyperpolarization precursor may include the hyperpolarization target compound. The purification or separation may include inducing a precipitate of the hyperpolarization precursor or hyperpolarization target compound from the original solution.

[0035] Optional step 111 illustrates the transport of the precipitate, consistent with the disclosed embodiments. The precipitate may be transported in a transport device having a magnetic field and optionally a coolant.

[0036] An optional step 113 illustrates the use of the target compound, consistent with the disclosed embodiments. In some embodiments, the hyperpolarized target compound may be injected into the patient for use in MRI imaging (e.g., hyperpolarized MRI experiment or other preferred imaging procedure) upon redissolution of the precipitated particles (and optionally after adjustment of temperature and pH, cleavage of precursors, and separation of the target compound, or any additional chemical reaction).

[0037] target compound In some embodiments, the target compound can be selected such that following hydrogenation and other potential chemical reactions, one of the products is a hyperpolarized target compound, such as a hyperpolarized bio-related imaging agent, that can be used for HP MRI applications. In some embodiments, the hyperpolarized target compound can be generated through additional chemical reactions. Such additional chemical reactions can include adding a side chain containing an unsaturated moiety for hydrogenation and polarization to transfer the polarization to the target compound and then cleaving the side chain, for example, by hydrolysis. For example, an ester of the target compound can be used for polarization using the PHIP-SAH method. In the PHIP-SAH method, hydrogenation with parahydrogen is carried out on a precursor that is a chemical derivative of the target compound, such as a bio-related imaging agent. The chemical derivative generally includes an ester containing the bio-related imaging agent and a side chain containing an unsaturated carbon-carbon bond. Parahydrogen is used to hydrogenate the unsaturated carbon-carbon bond and transfer the spin order from parahydrogen to the target compound. After hydrogenation and polarization transfer, the ester can be cleaved to generate the hyperpolarized target compound. In some embodiments, various precursors and esters of the target compound can be used. In some embodiments, the ester is an enol or inol ester of a carboxylic acid, and in other embodiments, they are esters such as allyl and propargyl esters. Various embodiments of the present disclosure disclose transferring spin order from the 1 H spin of the side chain to the nuclear spin of the side chain or the target compound itself. In some embodiments, the polarization can be hyperpolarization (HP) that refers to an excess population in one or more nuclear spin states compared to the thermal equilibrium nuclear spin state distribution in a given magnetic field. Such a thermal equilibrium distribution can be described by the Boltzmann distribution.

[0038] In some embodiments, the spin order can first be transferred from the spin order on parahydrogen to the spin order or polarization on the first nuclear spin in the side chain and then from there to the second nuclear spin in the target compound. For example, the first nuclear spin can be the 1 H nuclear spin in the side chain, the second nuclear spin can be the 13 C nuclear spin in the target compound, or alternatively the13 C or 15 It may also be an N spin, and thereafter in the target compound 13 C or 15 It can transition to an N-spin. In some embodiments, 13 C- 13 The CJ bond can still be larger than 1 Hz even with a bond distance of 3, and in a preferred embodiment, further in the target compound 13 The spin of a 1C nuclear can become hyperpolarized. For example, this can occur within a side chain. 13 This enables polarization of [2-13C]pyruvate by transfer from the C spin.

[0039] Various embodiments of this disclosure disclose the use of parahydrogen to hydrogenate the side chains of a target compound.

[0040] In some embodiments, the precursor may be selected such that, following hydrogenation and other potential chemical reactions, one of the products is a target compound usable for HP MRI applications. In some embodiments, the target compound may be produced through an additional chemical reaction following hydrogenation. Such an additional chemical reaction may involve hydrogenation and the addition of a side chain containing an unsaturated moiety for polarization, and then cleaving the side chain of the target compound, for example, by hydrolysis, in order to transfer the polarization to the target compound. For example, an ester of the target compound may be used for polarization using the PHIP-SAH method. After hydrogenation and polarization transfer, the ester may be hydrogenated to produce a hyperpolarized target compound.

[0041] As used herein, hydrolysis is defined as the cleavage of a molecule via a nucleophilic substitution reaction involving the addition of the element water. It may also be carried out under anhydrous conditions in the presence of hydroxide ions.

[0042] In some embodiments, a carboxylic acid having the following general formula (I) can be used as the target compound. [ka] During the ceremony -C* This indicates a carboxylic acid carbon atom that undergoes 13C hyperpolarization. -R is optionally carbonyl (C=O), hydroxyl (C-OH), or amino (NR). 1 R 2 ) A linear, branched, or cyclic alkyl chain that is interrupted or substituted with one or more groups selected from halogen atoms and haloalkyl groups, or interrupted by a carbocyclic aliphatic or aromatic ring and then optionally substituted with one or more functional groups.

[0043] In certain embodiments, the precursor of the target compound may be an unsaturated ester of the target compound. In some embodiments, the unsaturated bond in the target compound may be detached from the target spin by at least three bonds. In certain embodiments, the target spin is C of formula (I). * It is an atomic molecule. In certain embodiments after hydrogenation, the para-hydrogenated proton is at least four bond-away from the target atom.

[0044] Using parahydrogenated protons that are at least four bonds away from the target atom can mitigate the trade-offs that may arise when using parahydrogenated protons separated by fewer bonds from the target atom. For example, using pyruvate side chains limited to three or fewer chemical bonds between the parahydrogenated proton and the target nucleus results in a trade-off between precursor stability, hydrogenatability, and synthesizability. For instance, when limited to three or fewer bonds, a more stable precursor that is more difficult to hydrogenate may be formulated, or a less stable precursor that is more easily hydrogenated may be formulated. In both cases, the synthesis of the precursor may be difficult. Increasing the number of bonds between the parahydrogenated proton and the target atom can mitigate these trade-offs because the formulation of the precursor is less restricted. Thus, precursors that are easily hydrogenated and easily synthesized can be formulated. However, the transition of polarization between the parahydrogenated proton and the target atom may become more difficult. Polarization transitions can be particularly difficult when using RF pulses and magnetic fields with amplitudes of 0 to 500 mT, because proton resonance frequencies can be difficult to distinguish at such magnetic field amplitudes (i.e., J-bonds between protons can be larger than their Larmor frequency difference). The disclosed embodiments address this technical problem by using mediating protons to form a quantum three-body system with parahydride protons. Spin order can be transferred from the parahydride protons to the target atoms in the target compound through the mediating protons. Thus, an acceptable level of polarization transition can be obtained, and the advantage of greater separation between the parahydride protons and the target compound is realized.

[0045] In certain embodiments, the precursor molecular structure is given by formula (II) or formula (III). Formula (II) shows the general structure of the propargyl ester of the target carboxylic acid compound, and formula (III) shows the allyl ester, where the unsaturated bond is three bond-away from the target spin. After hydrogenation of the unsaturated bond with a parahydrogen, the parahydrogenated proton is four and five bond-away from the target spin. In certain embodiments, the mediating proton may be used to create polarized transitions having a polarized transition waveform at the 13C enriched position.

[0046] [ka] During the ceremony -C * This exhibits a naturally occurring 13C-enriched or optionally 13C-labeled carboxylic acid carbon atom that undergoes hyperpolarization of 13C. -R is defined above with respect to equation (I). -R 3 H(isotopes) are optionally blocked or substituted with one or more functional groups, halogen atoms, and haloalkyl groups, or blocked by carbocyclic aliphatic or aromatic rings, and then optionally substituted with one or more functional groups or similarly substituted heteroatoms (e.g., N, O, Si, P, S, halogens, ...). 1 H and 2 It is either a linear, branched, or cyclic hydrocarbon chain (containing H). -R 4 H(isotopes) are optionally blocked or substituted with one or more functional groups, halogen atoms, and haloalkyl groups, or blocked by carbocyclic aliphatic or aromatic rings, and then optionally substituted with one or more functional groups or similarly substituted heteroatoms (e.g., N, O, Si, P, S, halogens, ...). 1 H and 2 It is either a linear, branched, or cyclic hydrocarbon chain (containing H). -R 5 H(isotopes) are optionally blocked or substituted with one or more functional groups, halogen atoms, and haloalkyl groups, or blocked by carbocyclic aliphatic or aromatic rings, and then optionally substituted with one or more functional groups or similarly substituted heteroatoms (e.g., N, O, Si, P, S, halogens, ...). 1 H and 2 It is either a linear, branched, or cyclic hydrocarbon chain (containing H). -R 6H(isotopes) are optionally blocked or substituted with one or more functional groups, halogen atoms, and haloalkyl groups, or blocked by carbocyclic aliphatic or aromatic rings, and then optionally substituted with one or more functional groups or similarly substituted heteroatoms (e.g., N, O, Si, P, S, halogens, ...). 1 H and 2 It is either a linear, branched, or cyclic hydrocarbon chain (containing H). -R 7 H(isotopes) are optionally blocked or substituted with one or more functional groups, halogen atoms, and haloalkyl groups, or blocked by carbocyclic aliphatic or aromatic rings, and then optionally substituted with one or more functional groups or similarly substituted heteroatoms (e.g., N, O, Si, P, S, halogens, ...). 1 H and 2 It is either a linear, branched, or cyclic hydrocarbon chain (containing H).

[0047] Parahydrogenation In accordance with the disclosed embodiments, a precursor for a target compound can be parahydrogenated by combining the precursor, parahydrogen, and a hydrogenation catalyst. The disclosed embodiments are not limited to a specific method for producing a parahydrogenated precursor. In some embodiments, the precursor may be added to a mixture containing parahydrogen. In some embodiments, parahydrogen gas may be added to a solution containing the precursor (for example, the parahydrogen gas may be bubbled in such a solution). In the hydrogenation of the precursor, the parahydrogen is formed by the two hydrogen spins in the precursor, I z1 I z2 This can produce order, a preferred set of lower energy states between |↑>|↓> and |↓>|↑>, or singlet spin order on two hydrogen spins in the precursor.

[0048] The precursor may have unsaturated bonds that can be hydrogenated by parahydrogen gas. Following the combination of the precursor and parahydrogen, more than 50%, more than 60%, more than 70%, more than 80%, more than 90%, or nearly all of the precursor may be hydrogenated. Similarly, less than 90%, less than 80%, less than 70%, less than 60%, less than 50%, or less of the precursor may be hydrogenated. Alternatively, the percentage of hydrogenation may fall within the range defined by any two of the preceding values.

[0049] In some embodiments, the parahydrogenation precursor may have a collective difference of at least 10%, 20%, or 40% in the parahydrogenation proton spin states. In some embodiments, the collective difference is between the spin state containing the parahydrogenation proton and the spin state containing other nuclear spins, e.g., additional protons on the compound. In some embodiments, the parahydrogenation precursor may include side chains, and the parahydrogenation spins may be located on the side chains.

[0050] In some embodiments, the concentration of the hydrogenation catalyst during hydrogenation is at most approximately 50 mM, 40 mM, 30 mM, 20 mM, 10 mM, 9 mM, 8 mM, 7 mM, 6 mM, 5 mM, 4 mM, 3 mM, 2 mM, 1 mM, 0.9 mM, 0.8 mM, 0.7 mM, 0.6 mM, 0.5 mM, 0.4 mM, 0.3 mM, 0.2 mM, 0.1 mM, and at least It may be approximately 0.1mM, 0.2mM, 0.3mM, 0.4mM, 0.5mM, 0.6mM, 0.7mM, 0.8mM, 0.9mM, 1mM, 2mM, 3mM, 4mM, 5mM, 6mM, 7mM, 8mM, 9mM, 10mM, 20mM, 30mM, 40mM, 50mM or more, or within the range defined by any two of the preceding values.

[0051] The disclosed embodiments may include methods implemented by the disclosed system for generating hyperpolarized target compounds. The disclosed methods may include mixing a solution comprising a precursor and a hydrogenation catalyst for the target compound using a mixing mechanism. The mixing mechanism may be a device for introducing, holding, and facilitating a blend, mixture, or solution of two or more materials. In some embodiments, the mixing mechanism may be located within a chamber, and the mixing may occur within the chamber. In some embodiments, the solution may be mixed at a location away from the chamber. The solution may be in a volume of at least approximately 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 6 ml, 7 ml, 8 ml, 9 ml, 10 ml, 20 ml, 30 ml, 40 ml, 50 ml, 60 ml, 70 ml, 80 ml, 90 ml, or 100 ml or more, or in a volume of at most 100 ml, 90 ml, 80 ml, 70 ml, 60 ml, 50 ml, 40 ml, 30 ml, 20 ml, 10 ml, 9 ml, 8 ml, 7 ml, 6 ml, 5 ml, 4 ml, 3 ml, 2 ml, or 1 ml, or within a volume range defined by any two of the preceding values.

[0052] In some embodiments, the mixing mechanism may be a gas-liquid exchange mechanism. For example, the gas-liquid exchange mechanism may be a bubbler or a diffusion system. In some embodiments, the mixing mechanism may include a membrane adapted to allow the diffusion of molecular hydrogen. In some embodiments, mixing may be carried out using a spray chamber, in which the solution is sprayed into a chamber filled with pressurized parahydrogen.

[0053] In some embodiments, the catalyst may be any molecule, complex, or particle system that catalyzes hydrogenation. In some embodiments, a homogeneous metal catalyst, such as a rhodium complex or a ruthenium complex, may be provided. The rhodium complex may be used for the preparation and activation of precursor molecules and parahydrogen. In some embodiments, a heterogeneous metal catalyst attached to nanoparticles may be used.

[0054] Various embodiments of this disclosure disclose introducing a solution into a chamber configured to hold the solution during polarization transition. In some embodiments, the solution may be mixed within the chamber. In some embodiments, the solution may be hydrogenated within the chamber. In some embodiments, the chamber may be located within a magnetic shield (e.g., a mu-metal shield). The magnetic shield can reduce the effects of the Earth's magnetic field (or other external magnetic fields). Therefore, placing the solution within a chamber may include placing the solution within a magnetic shield. In some embodiments, for example, an electromagnet or permanent magnet magnetic field generator may be configured to generate a magnetic field within the chamber. An RF coil may be configured to generate RF irradiation within the chamber to induce polarization transition.

[0055] As described herein, in some embodiments, parahydrogenation may occur before polarization transition (e.g., before application of RF irradiation to the solution). In various embodiments, parahydrogenation may occur during polarization transition. For example, parahydrogen may be combined with the solution during modulation of the magnetic field amplitude (e.g., flowed through the solution or bubbled).

[0056] In certain embodiments, parahydrogen gas may be combined with a solution in a hydrogenation chamber under pressure. The pressure may be at least about 10 bar, 15 bar, 20 bar, 30 bar, or 50 bar or more, and may be at most about 50 bar, 30 bar, 20 bar, 15 bar, or 10 bar or less, or may be within the range defined by any two of the preceding values. In such embodiments, parahydrogen may be combined with a solution in a metal chamber that can withstand the pressure. Parahydrogen may be combined with the solution over a time interval (or the dissolution of parahydrogen may occur in less than a time interval). The time interval may be less than about 90 seconds, 60 seconds, 30 seconds, 20 seconds, 10 seconds, 5 seconds, or 3 seconds or less, and may be greater than about 3 seconds, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 60 seconds, or 90 seconds or more, or may be within the range defined by any two of the preceding values.

[0057] The proposed systems and methods may be used in conjunction with any suitable polarization transfer scheme that uses parahydrogen to induce polarization (e.g., PHIP, PHIP-SAH, SABRE, or any other suitable polarization transfer method).

[0058] When used with SABRE, both parahydrogen molecules and target compounds can be bound to the polarization transition catalyst. Then, while the parahydrogen and target compound are bound, polarization transition can occur, at least partially. In some embodiments, the parahydrogen gas is dissolved in a first solution containing the target compound and the polarization transition catalyst. The first solution can be an aqueous solution or an organic solvent, such as deuterated chloroform, deuterated acetone, deuterated ethanol, or deuterated methanol, whichever solvent allows SABRE polarization.

[0059] In such embodiments, the polarized migration catalyst can reversibly bond a target compound (e.g., pyridine or another preferred target compound) and parahydrogens, enabling spin-ordered or polarized migration to the target compound. After such migration, the mean polarization of the compound is within a range defined by at least about 1%, 10%, 30%, 50%, and at most about 90%, 50%, 30%, 10%, or 1%, or any two of the preceding values. The polarized nuclide is, 15 N, 13 C, 1 H, 31 P, 19 It could be 1F, or other nuclides that can be polarized by SABRE.

[0060] In some embodiments, the polarized migration catalyst may be or include a metal complex, for example, an iridium organometallic complex (e.g., iridium organometallic complex [IrCl(COD)(1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene)]). In some embodiments, the polarized migration catalyst may be or include a heterometallic catalyst connected to nanoparticles. Polarization transition

[0061] In certain embodiments, the concentration of the precursor (in embodiments using PHIP-SAH) or target compound (in embodiments using PHIP or SABRE) in the solution before polarization transition may be approximately 10 mM, 20 mM, 30 mM, 40 mM, 50 mM, 60 mM, 70 mM, 80 mM, 90 mM, 100 mM, 250 mM, 400 mM, 600 mM, or 1000 mM or less. In certain embodiments, the concentration of the precursor may be approximately 1000 mM, 600 mM, 400 mM, 250 mM, 100 mM, 90 mM, 80 mM, 70 mM, 60 mM, 50 mM, 40 mM, 30 mM, 20 mM, or 10 mM or less. The volume of the solution may be greater than approximately 1 ml, 2 ml, 3 ml, 5 ml, 10 ml, 20 ml, 30 ml, 50 ml, 100 ml, 200 ml, 300 ml, 500 ml, 1000 ml, or 2000 ml, or less than 2000 ml, 1000 ml, 500 ml, 300 ml, 200 ml, 100 ml, 50 ml, 30 ml, 20 ml, 10 ml, 5 ml, 3 ml, 2 ml, or 1 ml, or within the range defined by any two of the preceding values.

[0062] Polarization transition using high-frequency waveforms Various embodiments of this disclosure disclose the application of polarized transitional magnetic perturbations aimed at generating a magnetic field around a solution. In some embodiments, the magnetic field is at least about 0G, 0.01G, 0.02G, 0.03G, 0.04G, 0.05G, 0.06G, 0.07G, 0.08G, 0.09G, 0.1G, 0.2G, 0.3G, 0.4G, 0.5G, 0.6G, 0.7G, 0.8G, 0.9G, 1G, 2G, 3G, 4G, 5G, 6G, 7G, 8G, 9G, 10G, 20G, 30G, 40G, 50G, 60G, 70G, 80G, 90G, 100G, 200G, 300G, 400G, 500G, 600G, 700G, The magnetic field has an intensity of 800G, 900G, 1,000G, 2,000G, 3,000G or more, or at most about 3,000G, 2,000G, 1,000G, 900G, 800G, 700G, 600G, 500G, 400G, 300G, 200G, 100G, 90G, 80G, 70G, 60G, 50G, 40G, 30G, 20G, 10G, 9G, 8G, 7G, 6G, 5G, 4G, 3G, 2G, 1G, 0.9G, 0.8G, 0.7G, 0.6G, 0.5G, 0.4G, 0.3G, 0.2G, or 0.1G or less. In some embodiments, the magnetic field has an intensity within a range defined by any two of the preceding values. For example, in some embodiments, the magnetic field has an intensity of 0.1 G to 3,000 G around the solution. In some embodiments, the magnetic field has an intensity of 0 G to 0.1 G. Magnetic perturbations can be generated by magnetic shields, electric coils, electromagnets, or permanent magnets, or a combination of the above. The magnetic field can be applied to the sample in pulse or continuous wave (CW) form. Magnetic perturbations may be static or vary over time.

[0063] The signal generator may be configured to generate one or more radio frequency (RF) waveforms that can be applied to a sample to shift its polarization. The signal generator may include another computing unit, processor, controller, associated memory, PC, computer service, or any device that can perform computational operations using inputs and generate outputs. In some embodiments, the RF coil may emit or "apply" an RF irradiation or pulse sequence containing a first RF waveform. In some embodiments, the RF coil may have one or more channels. The channels may be paths for the RF signal. At least one channel may be provided for each different type of NMR spectroscopy. In some embodiments, 1 For H, at least one channel, and 13 For C, at least one channel may exist. The first RF waveform is generated by one or more high-frequency coils (RF coils) arranged around the sample. 1 This can be applied to H channels. In some embodiments, the second RF waveform is the RF coil 13 It can be applied to C channels. In some embodiments, 13 The RF waveform on the C channel may be configured to apply a polarization transition sequence such as gS2hm, S2hM, SLIC, ADAPT, or PulsePol.

[0064] In some embodiments, the pulse sequence is equivalent when the chemical shift difference is smaller than the J bond between them. 1 It may be configured to transition spin order from H hydrogen spin. Examples of such sequences may be Goldman sequences (M. Goldman, H. Johannesson, CRPhys. 2005, 6, 575-581; this reference is incorporated herein by reference in its entirety for all purposes), singlet-to-heteronuclear magnetization (S2hM) sequences, pulse polarization (PulsePol) sequences, or other sequences used in singlet NMR (e.g., ADAPT, SLIC, etc.). Equivalent 1Hydrogen spin (for example, when the chemical shift difference is smaller than the J bond between them) can occur for hydrogenated protons in symmetric molecules independent of the magnetic field, or in many molecular esters in various magnetic fields. For example, equivalent 1 Hydrogen spins are at least 0.01mT, 0.1mT, 0.2mT, 0.3mT, 0.4mT, 0.5mT, 0.6mT, 0.7mT, 0.8mT, 0.9mT, 1mT, 2mT, 3mT, 4mT, 5mT, 6mT, 7mT, 8mT, 9mT, 10mT, 20mT, 30mT, 40mT, 50mT, 60mT, 70mT, 80mT, 90mT, 100mT or more, with a maximum of 100mT and 90mT. It may exist in a magnetic field within the range defined by any two of the following values: mT, 80mT, 70mT, 60mT, 50mT, 40mT, 30mT, 20mT, 10mT, 9mT, 8mT, 7mT, 6mT, 5mT, 4mT, 3mT, 2mT, 1mT, 0.9mT, 0.8mT, 0.7mT, 0.6mT, 0.5mT, 0.4mT, 0.3mT, 0.2mT, 0.1mT or less, or any two of the preceding values.

[0065] In some embodiments, the RF amplitude is 1 Hz to 100 kHz relative to the 13C spin precession in the rotating frame. In some embodiments, the RF frequency is 20 Hz to 200 kHz, or 1 Hz to 1 MHz.

[0066] In some embodiments, the magnetic field has an intensity of 0G to 0.1G. In certain embodiments, within this magnetic field range, the applied RF magnetic field amplitude is greater than the static magnetic field amplitude. The Hamiltonian can be expressed in a coordinate system that rotates with the RF magnetic field frequency. The resulting Hamiltonian is given by the equation

number

[0067] In some embodiments, the magnetic shield may be configured to maintain magnetic field homogeneity or to generate a magnetic field below the Earth's magnetic field (which is approximately 0.25 G to 0.65 G, depending on the location). The magnetic shield may maintain the magnetic field strength within the polarization chamber during the application of a polarization waveform to one or more high-frequency coils.

[0068] In accordance with the disclosed embodiments, when performing PHIP or PHIP-SAH polarization, the RF waveform may be applied to a solution containing a parahydrogenation precursor or a parahydrogenation target compound. When performing SABRE polarization, the RF waveform may be applied to a solution containing a target compound, parahydrogen, and a polarization transition catalyst. The concentrations of the target compound, parahydrogen, and polarization transition catalyst may be given herein.

[0069] The polarization waveform can generate an RF magnetic field across or within the volume of the polarization transition chamber 402. This volume may be greater than approximately 1 ml, 2 ml, 3 ml, 5 ml, 10 ml, 20 ml, 30 ml, 50 ml, 100 ml, 200 ml, 300 ml, 500 ml, 1000 ml, or 2000 ml or less, or less than 2000 ml, 1000 ml, 500 ml, 300 ml, 200 ml, 100 ml, 50 ml, 30 ml, 20 ml, 10 ml, 5 ml, 3 ml, 2 ml, or 1 ml, or within the range defined by any two of the preceding values. RF magnetic field modulation may be performed for a certain duration. The duration may be greater than approximately 100 milliseconds, 200 milliseconds, 300 milliseconds, 500 milliseconds, 1000 milliseconds, 2000 milliseconds, 3000 milliseconds, 5000 milliseconds, 10000 milliseconds, 20000 milliseconds, or less than approximately 30000 milliseconds, 20000 milliseconds, 10000 milliseconds, 5000 milliseconds, 3000 milliseconds, 2000 milliseconds, 1000 milliseconds, 500 milliseconds, 300 milliseconds, 200 milliseconds, or 100 milliseconds, or within the range defined by any two of the preceding values. In certain embodiments, the RF amplitude is adiabatically swept through a resonant state with the frequency either resonant or non-resonant at the target spinlarmor frequency.

[0070] In certain embodiments, after the polarization transition step, the non-hydrogen nuclear spins of the bio-related imaging agent have nuclear spin polarizations greater than approximately 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 50%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 1%, or 1%, or within the range defined by any two of the preceding values. In some embodiments, this polarization is achieved for volumes greater than at least about 5 ml, 10 ml, 20 ml, 30 ml, 40 ml, 50 ml, 60 ml, 70 ml, 80 ml, 90 ml, 100 ml, 200 ml, 300 ml, 400 ml, 500 ml, 600 ml, 700 ml, 800 ml, 900 ml, or 1000 ml or more, or within the range defined by 1000 ml, 900 ml, 800 ml, 700 ml, 600 ml, 500 ml, 400 ml, 30 ml, 200 ml, 100 ml, 90 ml, 80 ml, 70 ml, 60 ml, 50 ml, 40 ml, 30 ml, 20 ml, 10 ml, 5 ml or less, or any two of the preceding values.

[0071] In certain embodiments, a specific precursor molecule 1 The H spin is deuterated (i.e., 1 H spin is 2 (Substituted by H spins). In the low magnetic field regimes in which the polarization transitions described herein occur, 2 The presence of H spins leads to parahydrogenation. 1 Either by coupling to the H spin, or by the ZZ interaction resulting from the difference in Larmor frequencies. 1 It only mediates the H spin and therefore does not have a significant effect on polarization transition.

[0072] In certain embodiments, the precursor molecule is an ester of the target compound polarized via the PHIP-SAH approach. Often, having an unsaturated bond at least four bond-away from the target nucleus allows for a more robust and stable precursor molecule. In certain embodiments, the two parahydrogenated protons on the side chain are both at least four bond-away from the target nucleus. In certain embodiments, the polarization transfer from the parahydrogenated proton to the target nucleus spin is performed using RF irradiation in an equivalent regime. In certain embodiments, the direct coupling between the parahydrogenated proton and the target nucleus spin is less than 0.5 Hz, 0.3 Hz, 0.1 Hz, or 0.05 Hz, and mediating proton spin is used to generate a larger effective coupling.

[0073] Compared to high-field regimes where the chemical shifts of protons allow for spectral distinction of protons with different chemical shifts (i.e., regimes where the chemical shift is greater than the J bond between parahydrogenated protons), using mediating proton spins in the equivalent regime is difficult due to several problems: (1) Protons cannot be addressed individually; (2) Due to the indistinguishability of proton spins, in the equivalent regime, the initial singlet state is distributed between coupled proton spins and not localized on parahydrogenated spins, unlike in the high-field regime; (3) The coupling between intermediate spins and parahydrogenated spins is a complete long-term coupling compared to the zz coupling in the high-field regime. For these reasons, the sequence that initially transitions polarization to mediating spins is not very practical.

[0074] In some embodiments, the mediating proton spin in the equivalent regime targets the polarization (e.g., 13 C, 15 Used to transfer to nuclear spin (such as N).

[0075] In certain embodiments, several parahydrogenated precursor molecules or target compounds are present. 1 H nuclear spin is deuterated (i.e., several 1 The H nuclear spin is, 2(Substituted by H nuclear spin). In the low magnetic field regimes in which the polarization transition described herein occurs, 2 The presence of H spins leads to parahydrogenation. 1 Either by coupling to the H spin, or by the ZZ interaction resulting from the difference in Larmor frequencies. 1 It only mediates the H spin and therefore does not have a significant effect on polarization transition.

[0076] Polarization transitions using mediating spin in equivalent regimes In some embodiments, polarization is achieved using RF pulse sequences, CW irradiation, or modulation of magnetic field amplitude or frequency. 1 The H para-hydrogenation spin can be transferred to the target atom's spin. The mediating atomic spin is the spin of the para-hydrogenation proton (e.g., located on the side chain of the para-hydrogenation precursor) and the spin of the target atom (e.g., located in the target compound). 13 When the J bond between a C atom and another atom is too weak to undergo direct polarization transition, it can be used to induce polarization transition.

[0077] The effectiveness of polarization transitions using mediating nuclear spins may depend on the ambient magnetic field strength at which the transition occurs. The chemical shift difference between spins may increase with increasing electric field strength. Therefore, in "equivalent regimes" of low magnetic and electric field strengths, the J coupling and the chemical shift difference between spins may be of similar magnitude. In such equivalent regimes, protons may not be individually addressable. Furthermore, the initial singlet state may be distributed among coupled proton spins rather than localized on the para-hydrogenated spin (e.g., due to the indistinguishability of proton spins). In addition, the coupling between the mediating spin and the para-hydrogenated spin may be a complete long-term coupling (e.g., compared to only zz coupling in high-field regimes). Such properties may lead to impractical polarization transitions using mediating nuclear spins.

[0078] The upper limit of the equivalent regime may depend on the compound in which polarization transition occurs. For example, when polarization transition involves the para-hydrogenated side chain of an ester (e.g., the esters described herein), the upper limit can be 0 mT to 500 mT. For symmetric molecules such as fumarates and succinates, where there is a minimal chemical shift difference between the hydrogenated proton spins, the upper limit may be even higher (e.g., >500 mT). Therefore, a considerable magnetic field may be required to avoid operation in the equivalent regime.

[0079] The disclosed embodiments include a method for inducing polarization transitions using mediating nuclear spin in an equivalent regime. Such a method involves an RF pulse sequence (e.g., PulsePol, S2hM, etc.) or CW irradiation (e.g., target combined with amplitude sweep). 13 Using C-spin SLIC or resonance frequency irradiation, the target (e.g., 13 C, 15 N, 19 F, or 31 P) Polarization transition to nuclear spin can be achieved. Since such methods operate within an equivalent regime, they do not require the substantial magnetic field required by methods that do not operate within an equivalent regime. Therefore, such methods can be more easily implemented in clinical practice and on a clinical scale.

[0080] In some embodiments, RF sweeping (e.g., magnetic resonance pulse sequences) can be applied to a compound (e.g., a solution containing a parahydrogenation precursor to a target compound). The RF sweeping may be configured to transfer a population of first and second protons to the target atom, thereby imparting at least 1%, 2%, 5%, 10%, or 20% non-equilibrium nuclear spin polarization to the target atom.

[0081] Figures 6B–6D illustrate frequency and amplitude characteristics of a radio frequency sweep suitable for polarity transition using mediating protons, consistent with the disclosed embodiments. As illustrated in Figures 6B–6D, the RF sweep may comprise two phases. During the first phase, the RF amplitude may increase linearly from zero, as illustrated in Figure 6B, while the frequency may increase to a target frequency (e.g., the frequency of the target atom), as illustrated in Figure 6C. 13 It is maintained at the C Larmor frequency. In some embodiments, the amplitude increase may be substantially linear (e.g., the increase may include transient pauses, stepwise increases, or follow a trajectory that deviates from a linear increase at any given point by less than 5% or less than 10% of the full-scale increase). In some embodiments, the amplitude increase may be substantially monotonic (e.g., the increase may include transient decreases, but follow a trajectory that deviates from a monotonic increase at any given point by less than 5% or less than 10% of the full-scale increase). In some embodiments, the amplitude trajectory may be optimized using a neural optimizer such as GRAPE or CRAB.

[0082] During the second phase, the RF amplitude may decrease linearly to zero, while the frequency of the RF magnetic field increases linearly. In some embodiments, the frequency increase may be substantially linear (e.g., the increase may include transient pauses, stepwise increases, or follow a trajectory that deviates from a linear increase at any given point by less than 5% or 10% of the full-scale increase). In some embodiments, the frequency increase may be substantially monotonic (e.g., the increase may include transient decreases, but follow a trajectory that deviates from a monotonic increase at any given point by less than 5% or 10% of the full-scale increase).

[0083] Figure 6E shows a plane parallel to the static magnetic field during the application of the high-frequency sweep shown in Figures 6B-6D, consistent with the disclosed embodiments. 13The C polarization is illustrated. As shown in Figure 6E, during the first phase (e.g., the first phase 681), the polarization (e.g., spin order) is introduced from parahydrogenated protons (e.g., added across the double bonds of the unsaturated precursor) through the mediating proton spin network. 13 It can transition to a C nucleus. This process accumulates in a plane that crosses a static magnetic field (e.g., along the x-axis, y-axis, or other points in the xy-plane), as illustrated by trace 685. 13 This can result in the accumulation of C polarization. During the second phase (e.g., second phase 687), the polarization may be adiabatically transitioned from the xy-plane to the z-axis (as illustrated by trace 685). In some embodiments, 13 Ensuring that the C polarization is parallel to the static magnetic field (for example, along the z-axis) can facilitate the transport of the polarization precursor (or polarization target compound).

[0084] RF sweeping can be performed while a magnetic field is applied to the compound. In some embodiments, the average magnetic field strength is at least 0.01mT, 0.02mT, 0.05mT, 0.1mT, 0.2mT, 0.5mT, 1mT, 2mT, 5mT, 10mT, 20mT, 50mT, 100mT, 200mT, 500mT, 1,000mT, 2,000mT, 5,000mT or more, and at most about 5,000mT. The average magnetic field strength may be within the range defined by any two of the following values: 2,000mT, 1,000mT, 500mT, 200mT, 100mT, 50mT, 20mT, 10mT, 5mT, 2mT, 1mT, 0.5mT, 0.2mT, 0.1mT, 0.05mT, 0.02mT, 0.01mT or less, or the range defined by any two of the preceding values.

[0085] In some embodiments, a first para-hydrogenated proton among para-hydrogenated protons may have a first Larmor frequency determined by an average magnetic field strength, a second para-hydrogenated proton among para-hydrogenated protons may have a second Larmor frequency determined by the average magnetic field strength, and a mediating proton may have a third Larmor frequency determined by the average magnetic field strength. These three Larmor frequencies may be different. In some embodiments, a first difference between the first and second Larmor frequencies, a second difference between the first and third Larmor frequencies, or a third difference between the second and third Larmor frequencies is less than twice a first J-coupling (J 12 ), less than twice a second J-coupling (J 23 ), or less than twice a third J-coupling (J 3c ). In some embodiments, at least one of the first difference, the second difference, or the third difference is less than 20 Hz.

[0086] In some embodiments, a magnetic field sweep may be used to transfer polarization. The magnetic field sweep may include first, second, and third phases. In the first phase, a constant magnetic field is applied. In the second phase, the strength of the magnetic field may be reduced to a low value. In the third phase, the strength of the magnetic field may be increased. The increase can be incremental or linear.

[0087] FIG. 2A illustrates a quantum mechanical four-system suitable for transferring polarization using a mediating proton, consistent with the disclosed embodiments. This system includes two para-hydrogenated spins (spin 1 and 2 having a J-coupling J 12 ), one mediating proton spin (spin 3, assuming negligible coupling to spin 1 and J-coupling J 23 to spin 2), and a target 13 C nuclear spin (spin C). Spin couplings that lead only to minor corrections in the eigenenergy (e.g., the coupling of spin 3 to spin 1, the coupling of spin 1 to spin C, etc.) are omitted. The general arrangement of FIG. 2A may include three 1 H atoms and one 13 C atom of a para-hydrogenated precursor molecule. The three 1 H atoms are two1 Mediated by three atomic bonds from one of the H atoms 1 May contain H atoms and two 1 The H atoms are the result of the hydrogenation of unsaturated bonds by parahydrogen molecules.

[0088] In some embodiments, two 1 [[ID=I1]]The H atoms are each, respectively, 12 Covalently bonded to a C atom. Each 12 C atom may be covalently bonded to each other by two. In some embodiments, two 1 The H atoms can be separated from one 13 C atom by at least four chemical bonds. For example, when the cinnamyl pyruvate precursor is parahydrogenated across a double bond, the parahydrogen proton is 13 Incorporated four and five bonds away from the C target atom. In some embodiments, 13 A C atom (or other target atom) is covalently bonded to a mediating 1 H atom. In some arrangements, the atoms forming the quantum mechanical three-body system are part of pyruvate, a precursor of pyruvate containing at least one unsaturated bond, fumarate, a precursor of fumarate containing at least one unsaturated bond, succinate, or a precursor of succinate containing at least one unsaturated bond.

[0089] [[ID=2S]] Figure 2B discloses an approximate energy structure of the quantum mechanical three-body system illustrated by the protons of Figure 2A, consistent with the disclosed embodiments. The system of three proton spins exhibits the eigenstates and energy splittings shown in Figure 2B, with a = J 23 / J 12 ,

Number

[0090] J 12 >J 23 In this case, states 7 and 8 can be highly clustered (for example, having a population greater than 0.7 to 0.9 in some embodiments, or greater than the application-dependent threshold in various embodiments). For example, J 12 =11.4Hz, J 23 =4.9Hz, J 3C Assuming =3.15Hz, P(7,8)=0.928. Therefore, the quantum mechanical three-body system includes high-density energy eigenstates (e.g., states 7 and 8) and low-density energy eigenstates, allowing more than 90% of the collective difference between states to be transitioned. Equivalent regime-operable pulse sequences (e.g., S2hM, PulsePol, or another suitable pulse sequence) teeth,

number

[0091] Figure 3 illustrates the simulation and calculation of the PulsePol transfer efficiency of the spin system in Figure 2A, consistent with the disclosed embodiments. The simulation and calculation of the PulsePol transfer efficiency are performed using coupled J 12 =11.4Hz, J 23 =4.9Hz, J 3C The test was performed using =3.15Hz. Trace 301 is the resonance condition.

number

[0092] Polarization transition using magnetic field modulation In some embodiments, polarized transition magnetic perturbations may be carried out within a magnetic shield (e.g., a muon shield) to achieve a homogeneous low magnetic field. The magnetic shield operates in a μT magnetic field below the Earth's magnetic field. 13 This enables the performance of polarization transition to the C nucleus spin. Low magnetic fields are approximately 0mG, 0.1mG, 0.2mG, 0.3mG, 0.4mG, 0.5mG, 0.6mG, 0.7mG, 0.8mG, 0.9mG, 1.0mG, 2.0mG, 3.0mG, 4.0mG, 5.0mG, 6.0mG, 7.0mG, 8.0mG, 9.0mG, 10mG, 20mG, 30mG, 40mG, 50mG, 60mG, 70mG, 80mG, 90mG, 100mG or more, or approximately 10 The magnetic fields may be less than 0mG, 90mG, 80mG, 70mG, 60mG, 50mG, 40mG, 30mG, 20mG, 10mG, 9mG, 8mG, 7mG, 6mG, 5mG, 4mG, 3mG, 2mG, 1mG, 0.9mG, 0.8mG, 0.7mG, 0.6mG, 0.5mG, 0.4mG, 0.3mG, 0.2mG, 0.1mG, or within the range defined by any two of the preceding values. In these magnetic fields, the polarization is determined by the proton spin and, 13 C, 15 N, 19 F, 31The transition is achieved by utilizing level pseudocrossing (LAC) between P and other spin species of interest. In some embodiments, the magnetic field can be adjusted to a specific magnetic field strength relative to the LAC. In various embodiments, the magnetic field strength can be adjusted over time to enable robust polarization transition in larger volume samples. For example, the magnetic field strength can be swept through the LAC conditions. Alternatively or additionally, the sample may be physically moved within the magnetic field. Such modulation can relax constraints on magnetic field homogeneity and magnetic field offset. Thus, robust polarization transition can be achieved in larger volumes with greater efficiency. Furthermore, relaxing constraints on magnetic field homogeneity and magnetic field offset can enable the use of less complex, more precise, or more expensive polarization systems.

[0093] The lower limit of magnetic field modulation is approximately -10μT, -9μT, -8μT, -7μT, -6μT, -5μT, -4μT, -3μT, -2μT, -1μT, -0.9μT, -0.8μT, -0.7μT, -0.6μT, -0.5μT, -0.4μT, -0.3μT, -0.2μT, -0.1μT or higher, or approximately -0.1μT, -0.2μT. T may be less than or equal to -0.3μT, -0.4μT, -0.5μT, -0.6μT, -0.7μT, -0.8μT, -0.9μT, -1μT, -2μT, -3μT, -4μT, -5μT, -6μT, -7μT, -8μT, -9μT, -10μT, or within the range defined by any two of the preceding values. The upper limit of the modulation may be greater than approximately 0.1 μT, 0.2 μT, 0.3 μT, 0.4 μT, 0.5 μT, 0.6 μT, 0.7 μT, 0.8 μT, 0.9 μT, 1 μT, 2 μT, 3 μT, 4 μT, 5 μT, 6 μT, 7 μT, 8 μT, 9 μT, 10 μT or less, or less than approximately 10 μT, 9 μT, 8 μT, 7 μT, 6 μT, 5 μT, 4 μT, 3 μT, 2 μT, 1 μT, 0.9 μT, 0.8 μT, 0.7 μT, 0.6 μT, 0.5 μT, 0.4 μT, 0.3 μT, 0.2 μT, 0.1 μT or less, or within the range defined by any two of the preceding values. The magnetic field may have an amplitude across or including the volume of the polarization transition chamber 402. This volume may be greater than approximately 1 ml, 2 ml, 3 ml, 5 ml, 10 ml, 20 ml, 30 ml, 50 ml, 100 ml, 200 ml, 300 ml, 500 ml, 1000 ml, or 2000 ml, or less than 2000 ml, 1000 ml, 500 ml, 300 ml, 200 ml, 100 ml, 50 ml, 30 ml, 20 ml, 10 ml, 5 ml, 3 ml, 2 ml, or 1 ml, or within the range defined by any two of the preceding values. Modulation may be performed over a certain duration.The duration may be approximately 100 milliseconds, 200 milliseconds, 300 milliseconds, 500 milliseconds, 1000 milliseconds, 2000 milliseconds, 3000 milliseconds, 5000 milliseconds, 10000 milliseconds, 20000 milliseconds, or more than 30000 milliseconds, or less than approximately 30000 milliseconds, 20000 milliseconds, 10000 milliseconds, 5000 milliseconds, 3000 milliseconds, 2000 milliseconds, 1000 milliseconds, 500 milliseconds, 300 milliseconds, 200 milliseconds, or 100 milliseconds, or within the range defined by any two of the preceding values. Therefore, the rate of change of the magnetic field amplitude may be approximately 0.05 μT, 0.1 μT, 0.5 μT, or 1 μT or more. The upper limit of the rate of change of the magnetic field amplitude may be determined by the capabilities of the equipment used to perform the sweep. In some embodiments, when the magnetic field is within the upper and lower limits disclosed above, the spatial deviation of the magnetic field across the modulated volume may be less than about half (or a quarter, or an eighth, or a tenth) of the amplitude of the magnetic field. For example, when the magnetic field strength is less than 2 μT (or greater than -2 μT), the spatial deviation of the magnetic field across the modulated volume may be less than 1 uT (or less than 0.5 μT, 0.25 μT, or 0.2 μT). As an additional example, when the magnetic field strength is less than 10 μT (or greater than -10 μT), the spatial deviation of the magnetic field across the modulated volume may be less than 5 uT (or less than 2.5 μT, 1.25 μT, or 1.0 μT). The spatial deviation may be measured, for example, by taking at least 10, 30, 50, 100, or 500 spatially randomly sampled or spatially equally distributed measurements of the magnetic field in the volume and calculating the standard deviation of the sampled magnetic field measurements. Such homogeneity can be achieved within a large homogeneous magnetic shield, for example, by having a large puncture solenoid through the magnetic shield, or by using a large Helmholtz coil with a large homogeneous region for generating magnetic field amplitude modulation. In certain embodiments, the modulation is a sweep of the magnetic field. In some embodiments, the magnetic field amplitude modulation includes non-adiabatic jumps, monotonic amplitude changes, or a combination thereof.

[0094] In certain embodiments, after the polarization transition step, the non-hydrogen nuclear spin of the bio-related imaging agent has a nuclear spin polarization that is greater than 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, or less than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or 1%, or within the range defined by any two of the preceding values. In some embodiments, this polarization is achieved for solution volumes greater than approximately 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 6 ml, 7 ml, 8 ml, 9 ml, 10 ml, 20 ml, 30 ml, 40 ml, 50 ml, 60 ml, 70 ml, 80 ml, 90 ml, 100 ml, 200 ml, 300 ml, 400 ml, 500 ml or more, or less than approximately 500 ml, 400 ml, 300 ml, 200 ml, 100 ml, 90 ml, 80 ml, 70 ml, 60 ml, 50 ml, 40 ml, 30 ml, 20 ml, 10 ml, 9 ml, 8 ml, 7 ml, 6 ml, 5 ml, 4 ml, 3 ml, 2 ml, 1 ml or less, or within the range defined by any two of the preceding values. In various embodiments, after the polarization transition, a portion of the collective difference in the parahydrogenated proton spin state is applied to the target of the bio-related imaging agent (e.g., 13 C) Transition to nuclear spin polarization. This portion may be greater than 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, or less than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or 1%, or within the range defined by any two of the preceding values.

[0095] In certain embodiments, magnetic field modulation includes non-adiabatic jumps in the magnetic field, defined as changes in the magnetic field faster than 1 μT, 5 μT, or 10 μT / second. Non-adiabatic jumps can be performed for magnetic fields where level pseudocrossing occurs, involving proton and aproton spins. Considering J coupling between nuclear spins in the system, this value can be analytically calculated or identified by plotting the energy levels of the Hamiltonian for different magnetic fields and identifying the LAC. In some embodiments, the duration for which the magnetic field amplitude is in the LAC condition is less than 2 seconds, less than 1 second, or less than 0.5 seconds.

[0096] In certain embodiments, modulation of the magnetic field amplitude may involve monotonically changing the magnetic field amplitude (or monotonically over each of a limited number of intervals, such as increasing intervals of 1 to 10 and / or decreasing intervals of 1 to 10). In various embodiments, modulation of the magnetic field amplitude may involve linearly changing the magnetic field amplitude. The initial magnetic field amplitude of the sweep, the final magnetic field amplitude, and the total duration of the sweep may be optimized for the target compound. In some embodiments, the magnetic field amplitude during the sweep is within lower and upper limits. The lower limit may be greater than approximately -2μT, -1μT, -0.9μT, -0.8μT, -0.7μT, -0.6μT, -0.5μT, -0.4μT, -0.3μT, -0.2μT, or -0.1μT, or less than approximately -0.1μT, -0.2μT, -0.3μT, -0.4μT, -0.5μT, -0.6μT, -0.7μT, -0.8μT, -0.9μT, -1μT, or -2μT, or within the range defined by any two of the preceding values. The upper limit may be greater than approximately 0.1 μT, 0.2 μT, 0.3 μT, 0.4 μT, 0.5 μT, 0.6 μT, 0.7 μT, 0.8 μT, 0.9 μT, 1 μT, or 2 μT, or less than approximately 2 μT, 1 μT, 0.9 μT, 0.8 μT, 0.7 μT, 0.6 μT, 0.5 μT, 0.4 μT, 0.3 μT, 0.2 μT, or 0.1 μT, or within the range defined by any two of the preceding values. In some embodiments, the modulation duration may be greater than approximately 100 milliseconds, 200 milliseconds, 300 milliseconds, 500 milliseconds, 1000 milliseconds, 2000 milliseconds, 3000 milliseconds, 5000 milliseconds, or less than approximately 10000 milliseconds, 5000 milliseconds, 3000 milliseconds, 2000 milliseconds, 1000 milliseconds, 500 milliseconds, 300 milliseconds, 200 milliseconds, or 100 milliseconds, or within a range defined by any two of the preceding values. In some embodiments, the amplitude rate of change varies along the amplitude profile. In some embodiments, a constant adiabatic sweep is calculated by selecting a specific subgroup of level pseudocrossings in the spin system. In certain embodiments, magnetic amplitude modulation includes a combination of non-adiabatic jumps, monotonic amplitude modulation, and rate of change sign inversion.

[0097] In some embodiments, specific magnetic field amplitudes can support spontaneous spin-order transitions between parahydrogen and target compounds when both are coupled to a polarized catalyst. For example, SABRE-SHEATH can support such spin-order transitions for 15N or 13C polarizations using magnetic fields defined by approximately 100nT, 200nT, 300nT, 400nT, 500nT, 600nT, 700nT, 800nT, 900nT, or above 1mT, or approximately 1mT, 900nT, 800nT, 700nT, 600nT, 500nT, 400nT, 300nT, 200nT, or below 100nT, or any two of the preceding values. As an additional example, SABRE-SHEATH can support such spin-order transitions for 1H polarizations using magnetic fields above 0.1mT and below 100mT. The spin order of parahydrogen atoms can be transitioned to polarization on the target compound, or to spin order on the target compound. In some embodiments using SABRE, the magnetic field value varies between two or more fixed values, producing mean dynamics that lead to polarization transition.

[0098] In alternative embodiments, polarization transition occurs in magnetic fields higher than 0.1 G and below 200,000 G by applying a transition waveform using an RF continuous wave or pulse to transition the spin order from the coupled parahydrogen to the polarization on the nuclear spins in the catalyst-bound target compound. SLIC-SABRE, SABRE-INEPT, or ADAPT sequences may be used, for example, in high-field SABRE transitions.

[0099] In another embodiment, the polarization of a 1H nucleus on a SABRE-polarized molecule, polarized either directly or by polarization transfer from another nucleus on the same molecule, is transferred to a target compound by chemical exchange, for example, using the SABRE-RELAY method.

[0100] Purification and separation In some embodiments, the precursor may be selected such that, following hydrogenation and other potential chemical reactions, one of the products is a bio-relevant imaging agent usable for HP MRI applications. In some embodiments, the bio-relevant imaging agent may be produced through additional chemical reactions following hydrogenation. Such additional chemical reactions may include, for example, cleavage of the molecular side chains by hydrolysis. For example, an ester of the bio-relevant imaging agent may be used for polarization using the PHIP-SAH method. After hydrogenation and polarization transition, the ester may be cleaved to produce a hyperpolarized bio-relevant imaging agent.

[0101] The volume of the solution containing the target compound after cleavage (and the concentration of the target compound produced) may depend on the volume of the solution used for polarization transfer and the concentration of the precursor in that solution. Exemplary ranges of solution volume and precursor concentration are described herein. As further specific examples, at least 1 ml of solution containing at least 10 mM of the target compound may be produced. Alternatively, at least 5 ml of solution containing at least 50 mM of the target compound may be produced. Alternatively, at least 10 ml of solution containing at least 100 mM of the target compound may be produced.

[0102] Consistent with the disclosed embodiments, after polarization migration (and, in the PHIP-SAH embodiments, cleavage of the precursor to generate the hyperpolarized target compound), the properties of the solution containing the hyperpolarized target compound may be modified to induce precipitation of the hyperpolarized target compound.

[0103] Such precipitates may allow for the separation of the hyperpolarized target compound (or hyperpolarized precursor) from other substances in the solution (e.g., side chain fragments in embodiments using PHIP-SAH, hydrogenation catalysts in embodiments using SABRE, hyperpolarized catalysts, etc.). The precipitate may form crystals, amorphous solid particles, polycrystalline materials, etc. After precipitation, at least a fraction of the solid hyperpolarized target compound (or hyperpolarized precursor) can be separated from the solution and other substances in the solution. For example, a mixture of precipitate and solution may be filtered to remove particles. The filtered precipitate may be washed with a second solvent. The second solvent may be selected to remove the original solvent and other substance residues in the solution without completely dissolving the filtered precipitate. In some embodiments, the washing step occurs for less than approximately 300 seconds, 200 seconds, 100 seconds, 90 seconds, 80 seconds, 70 seconds, 60 seconds, 50 seconds, 30 seconds, 20 seconds, or 10 seconds, or more than approximately 10 seconds, 20 seconds, 30 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 200 seconds, or 300 seconds, or within a range defined by any two of the preceding values. The precipitate consists of acetic acid, acetone, acetonitrile, benzene, 1-butanol, 2-butanol, 2-butanone, t-butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, 1,2-dichloroethane, diethylene glycol, diethyl ether, digleam (diethylene glycol dimethyl ether), 1,2-dimethoxyethane (gleam, DME), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), 1,4-dioxane, ethanol, ethyl acetate, ethylene glycol, and glycerin. The process may be carried out using aqueous solutions or solutions containing organic solvents such as n, heptane, hexamethylphosphoramide (HMPA), hexamethylphosphoric triamide (HMPT), hexane, methanol, methyl t-butyl ether (MTBE), methylene chloride, N-methyl-2-pyrrolidone (NMP), nitromethane, pentane, petroleum ether (ligroin), 1-propanol, 2-propanol, pyridine, tetrahydrofuran (THF), toluene, triethylamine, water, heavy water, o-xylene, m-xylene, and p-xylene. In some embodiments, the organic solvent is used in the polarization and precipitation steps.For example, parahydrogens may be more soluble in organic solvents than in aqueous solutions. Therefore, hydrogenation may occur more efficiently in such solvents. Thus, in some embodiments using PHIP or PHIP-SAH, parahydrogen-induced polarization may occur in a solution formed with an organic solvent. In various embodiments, an aqueous solution is used for hydrogenation and polarization transfer. In some embodiments, this aqueous solution may be mixed with a miscible organic solvent before precipitation of the hyperpolarized target compound.

[0104] In some embodiments, precipitation of the target compound can be induced by changing the pH of the solvent. In organic solvents, certain bio-related imaging agents (e.g., carboxylic acids, pyridines, etc.) may be soluble at concentrations suitable for polarization using PHIP, PHIP-SAH, or SABRE. However, salts of these bio-related imaging agents may be highly insoluble. For example, such salts may be insoluble at concentrations below about 10 mM, 1 mM, 0.1 mM, or 0.01 mM or less, or above about 0.01 mM, 0.1 mM, 1 mM, or 10 mM or more, or within the range defined by any two of the preceding values. The organic solution may contain a bio-related imaging agent at a concentration suitable for hyperpolarization using PHIP, PHIP-SAH, or SABRE. After polarization, the pH of the organic solution may be changed to induce precipitation of the bio-related imaging agent salt. In aqueous solutions, salts of certain bio-related imaging agents (e.g., fumarates, glutamates, etc.) are more soluble than their acidic forms. Therefore, aqueous solutions may contain bio-related imaging agents at concentrations suitable for hyperpolarization using PHIP, PHIP-SAH, or SABRE. After polarization, the pH of the aqueous solution may be lowered to induce precipitation of the acidic form of the bio-related imaging agent.

[0105] In line with the disclosed embodiments, a pH change can be induced by the addition of an acidic or basic molecule to a solution, such as sodium chloride or sodium hydroxide. In some embodiments, a pH change can be induced by mixing the solution with another solution having a substantially different pH. In some embodiments, precipitation resulting from a pH change occurs within a range defined by either about 100 seconds, 90 seconds, 80 seconds, 70 seconds, 60 seconds, 50 seconds, 40 seconds, 30 seconds, 20 seconds, 10 seconds, 9 seconds, 8 seconds, 7 seconds, 6 seconds, 5 seconds, 4 seconds, 3 seconds, 2 seconds, or 1 second or less, or about 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, or 100 seconds or more, or within a range defined by any two of the preceding values.

[0106] In some embodiments, precipitation of the target compound can be induced without changing the pH of the solution that induces a change in the hyperpolarized target compound between salt and acid forms.

[0107] In some embodiments, hydrogenation and polarized migration may occur in a first solution having a first solvent. The target compound may have high solubility in the first solvent. Precipitation may be induced by mixing the first solution with a second solvent to form a second solution. The second solvent may be selected such that the solubility of the target compound in the second solution is low enough to initiate precipitation.

[0108] In some embodiments, the temperature of the solution is changed, thereby reducing the solubility of the hyperpolarized molecules and initiating precipitation. In most solvents, solubility decreases as the temperature decreases. The change in temperature to a desired temperature with lower solubility is preferably carried out within a time of less than about 100 seconds, 50 seconds, 30 seconds, 20 seconds, 10 seconds, 5 seconds, 3 seconds, 2 seconds, or 1 second, or within a time of more than about 1 second, 2 seconds, 3 seconds, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 50 seconds, or 100 seconds, or within a range defined by any two of the preceding values. For example, the maximum molar fraction of acetic acid in n-heptane is 0.935 at 14.8°C and only 0.02 at -29.2°C, and even lower at lower temperatures. The temperature selected for precipitation may be selected as a temperature above the freezing point of the solvent.

[0109] In some embodiments, the surface area of ​​the solution may be increased to induce nucleation of the precipitate. This can be achieved, for example, by spraying the solution through a nozzle to create very small droplets with a high surface area. In certain embodiments, microcrystalline seeds (which may be the target compound or another biocompatible compound) may be added to the solution to induce precipitation.

[0110] In some embodiments, the pressure of the solution changes, thereby reducing the solubility of the hyperpolarized compound and initiating precipitation.

[0111] In some embodiments, the concentration of the hyperpolarized target compound increases beyond its solubility limit, thereby inducing precipitation without reducing the solubility level of the compound in the solvent. This can be achieved, for example, by adding non-polarized molecules of the target compound or by evaporating a specific volume of the solvent, thereby increasing the concentration of the target compound beyond its solubility limit.

[0112] In some embodiments, the polarization parameters of PHIP, PHIP-SAH, or SABRE may be optimized to exceed the solubility limit of the target compound in its acid or salt form, preferably at the expense of achieving lower polarization, for high concentrations. This can be achieved, for example, in PHIP or PHIP-SAH, by starting with a high concentration of precursor for hydrogenation and selecting a long hydrogenation time that allows polarization to decrease due to relaxation, in order to achieve high concentrations of the target compound. In SABRE, this can be achieved by increasing the concentration of the target compound at the expense of the polarization transition from para-hydrogen impairing efficiency.

[0113] In some embodiments, precipitation can be accelerated by the addition of mechanical energy or by improved mixing of the mixture over a certain duration. This can be done, for example, by applying ultrasound to the mixture through an ultrasonic solicitor, or by mechanical or magnetic mixing of the sample. In certain embodiments, the additional mixing or introduction of mechanical energy is carried out within a range defined by any two of the preceding values, such as more than about 0.1 seconds, 1 second, 5 seconds, or 10 seconds or less, or less than about 10 seconds, 5 seconds, 1 second, or 0.1 seconds.

[0114] In some embodiments, precipitation can be induced by a chemical reaction involving a hyperpolarized target compound. The hyperpolarized target compound may react with another compound or in response to an external stimulus such as electromagnetic radiation (e.g., UV irradiation). The product of this reaction has reduced solubility compared to the hyperpolarized target compound, thereby inducing precipitation. For example, the external stimulus may modify the structure of the hyperpolarized target compound, thereby reducing its solubility. Following the redissolution of the precipitate, additional reactions may be carried out to produce the desired final product (e.g., a bio-related imaging agent, NMR material, etc.).

[0115] In some embodiments, hydrolysis of the precursor can induce precipitation. For example, in some embodiments using PHIP-SAH, the solvent may be selected such that the precursor is more soluble than the target compound. The concentration of the precursor in the solution may be selected so that the target compound precipitates from the solution after cleavage of the side chain and formation of the target compound. In some such embodiments, cleavage may be initiated by changing the pH of the solution. For example, cleavage may be initiated by adding a base (e.g., sodium hydroxide or another suitable base). In some embodiments, the solution may be formed using an organic solvent, and cleavage may be carried out under basic conditions. After cleavage, the less soluble target compound undergoes rapid precipitation while retaining its polarization. The same solution may be used for hydrogenation, polarization transfer, and precipitation, or a different solvent may be mixed with the solution used for hydrogenation and polarization transfer.

[0116] In some embodiments using PHIP-SAH, precursor precipitation may occur before cleavage. Such embodiments may be preferred when the precursor is more stable than the target compound. Precipitation of the precursor may be induced by modifying the pH of the solution so that the solubility of the precursor is reduced, or by mixing the precursor in a solution or compound that reduces its solubility. In such embodiments, cleavage of the precursor may be carried out after the precursor is redissolved in the solvent. The precursor may be filtered and washed as described herein to remove other substances present in the original solution, such as a hydrogenation catalyst. The precursor may then be reacted to form the target compound (e.g., by cleaving the side chains). The target compound may be separated from other reaction products by liquid-liquid extraction or by an additional precipitation step, consistent with the precipitation methods described herein. In some embodiments using PHIP-SAH, precipitation may occur after the formation of the target compound from the precursor. Such precipitation may be carried out according to the methods described herein.

[0117] In some embodiments, the conversion of spin order to polarization occurs before the compound solidifies and precipitates. In other embodiments, this conversion occurs after the redissolution of the crystal with the target compound.

[0118] In some embodiments, several steps of precipitation, washing, and redissolution are performed. This may be advantageous in further purifying the target compound, increasing the relaxation time of the precipitate, or further separating the polarization and cleavage steps. For example, the first precipitate may be used to wash the catalyst, while the second precipitate is a crystalline form with a longer relaxation time and may be used for transport. In another embodiment, the first precipitate is an ester of the target compound after hydrogenation and polarization transition, and the second precipitate is performed after cleavage.

[0119] In line with the disclosed embodiments, the precipitation (and optionally washing) step may separate the hyperpolarized target compound (or hyperpolarized precursor) from other substances in the original solution (e.g., catalyst, original solvent, reaction product, etc.). For example, the majority of the hydrogenation catalyst present in the original solution may be retained in the original solution after precipitation of the target compound. In some embodiments, the precipitate (after optionally washing) may retain less than about 1%, 0.1%, 0.01%, 0.001% of the hydrogenation catalyst, or more than about 0.001%, 0.01%, 0.1%, 1% or more of the hydrogenation catalyst. Similarly, in embodiments using PHIP-SAH and cleavage of the precursor molecule before precipitation, the precipitate may retain cleavage byproducts (e.g., side chains or other cleaved residues) in amounts less than approximately 1%, 0.1%, 0.01%, or 0.001%, or retain cleavage byproducts greater than approximately 0.001%, 0.01%, 0.1%, or 1%, or retain an amount of cleavage byproducts within the range defined by any two of the preceding values.

[0120] In some embodiments, the amount of hyperpolarized particles in the precipitate accumulates over several iterations of hydrogenation, polarization migration, and precipitation of additional target compounds.

[0121] Micrometer-sized hyperpolarized solid particles, in particular, can be a valuable resource in several applications. Some applications include, for example, using microparticles as NMR / MRI tracers when insoluble in aqueous solutions. In some embodiments, solid hyperpolarized compounds obtained using precipitation of PHIP, PHIP-SAH, or SABRE hyperpolarized solutions are dissolved in a solvent and used as hyperpolarizers in hyperpolarized NMR or MRI.

[0122] In some embodiments, after precipitation and separation from the original solvent (and potential transport of the hyperpolarized precipitate), the precipitate can be redissolved in the solvent (e.g., for use as a drug in hyperpolarized MRI). Preferably, the solvent is a biocompatible solvent, preferably an aqueous solution. In some embodiments, redissolution is carried out within a range defined by about 60 seconds, 30 seconds, 20 seconds, 10 seconds, or less than 5 seconds, or about 5 seconds, 10 seconds, 20 seconds, 30 seconds, or more than 60 seconds, or any two of the preceding values.

[0123] In some embodiments, after redissolution, the target compound may be present at a higher concentration than that used during PHIP, PHIP-SAH, or SABRE polarization. In some embodiments, the concentration of the hyperpolarized target compound after redissolution is greater than about 100 mM, 150 mM, 200 mM, 250 mM, 300 mM, 350 mM, 400 mM, 450 mM, or 500 mM or less, or less than about 500 mM, 450 mM, 400 mM, 350 mM, 300 mM, 250 mM, 200 mM, 150 mM, or 100 mM, or within the range defined by any two of the preceding values. Thus, the concentration of the precursor or target compound during polarization may be independent of the concentration of molecules in the injection solution. The concentration of the precursor or target compound during polarization may be selected for efficient polarization transition. In some embodiments, this polarization concentration may be less than the concentration of the hyperpolarized target compound after redissolution. For example, the polarization concentration may be less than or equal to approximately 300 mM, 200 mM, 150 mM, 140 mM, 130 mM, 120 mM, 110 mM, 100 mM, 90 mM, 80 mM, 70 mM, 60 mM, 50 mM, 40 mM, 30 mM, 20 mM, or 10 mM, or greater than or equal to approximately 10 mM, 20 mM, 30 mM, 40 mM, 50 mM, 60 mM, 70 mM, 80 mM, 90 mM, 100 mM, 110 mM, 120 mM, 130 mM, 140 mM, 150 mM, 200 mM, or 300 mM, or within a range defined by any two of the preceding values. In some embodiments, the precipitate sample may exhibit polarization greater than approximately 30%, 20%, 10%, 5%, and 1%, or polarization less than approximately 1%, 5%, 10%, 20%, and 30%.After the particles are redissolved, the concentrations of the catalyst, precursor, or cleavage byproducts are less than or equal to 1 μM, 900 nM, 800 nM, 700 nM, 600 nM, 500 nM, 400 nM, 300 nM, 200 nM, 100 nM, 90 nM, 80 nM, 70 nM, 60 nM, 50 nM, 40 nM, 30 nM, 20 nM, 10 nM, 9 nM, 8 nM, 7 nM, 6 nM, 5 nM, 4 nM, 3 nM, 2 nM, and 1 nM, respectively. The purity may be greater than M, 2nM, 3nM, 4nM, 5nM, 6nM, 7nM, 8nM, 9nM, 10nM, 20nM, 30nM, 40nM, 50nM, 60nM, 70nM, 80nM, 90nM, 100nM, 200nM, 300nM, 400nM, 500nM, 600nM, 700nM, 800nM, 900nM, or 1 μM, or within the range defined by any two of the preceding values. In some embodiments, the purity of the hyperpolarized target compound after redissolution may be greater than 90%, 92%, 95%, 98%, or 99%, or less than 99%, 98%, 95%, 92%, or 90%, or within the range defined by any two of the preceding values. In various embodiments, at least the fraction of the hyperpolarized compound can be separated from cleaved side chains, or other reaction by-products, if present.

[0124] Figure 4 illustrates an exemplary schematic diagram of a polarizer 400 for obtaining a high-concentration biocompatible solution containing a hyperpolarized target compound. Polarizer 400 can be used in conjunction with PHIP, PHIP-SAH, or SABRE polarization methods. Parahydrogen can be dissolved in a solution containing the catalyst and target compound in a parahydrogenation chamber 401. The chamber 401 can be of various designs known in the art to dissolve a large amount of parahydrogen in the solution and achieve high efficiency of hydrogenation or polarization transfer. In some embodiments, the chamber 401 may include an inlet for introducing parahydrogen into the solution under high pressure. In various embodiments, the chamber 401 may be or include a flow chamber in which a membrane separates the solution from the flowing parahydrogen gas, allowing the parahydrogen to dissolve in a solution having a high surface area. In another embodiment, the chamber 401 may be a parahydrogen chamber in which the solution is sprayed into the chamber in small droplets, thereby establishing a large surface area for the dissolution of parahydrogen.

[0125] The transfer of spin order on para-hydrogen molecules to polarization on a target compound can be carried out in a polarization transfer chamber 402. For example, for PHIP or PHIP-SAH polarization, the polarization can be transferred by crossing a specific low magnetic field, typically less than 1 μT, either during or after the dissolution of hydrogen. In another embodiment, the magnetic field sweep includes at least some range of -10 μT to 10 μT. In another embodiment, a magnetic field of 0.1 G or higher may be used, and the polarization transfer is induced by a sequence of RF irradiations. In SABRE polarization, in a particular embodiment, the polarization transfer occurs by dissolving hydrogen in a specific magnetic field. This magnetic field may be lower than the Earth's magnetic field and therefore require magnetic shielding, as used in SABRE-SHEATH, or it may be higher than the Earth's magnetic field, as used in 1H polarization via SABRE. In another embodiment, a magnetic field greater than 0.1 G is used, and the polarization transfer is induced by a sequence of RF irradiations.

[0126] The precipitation chamber 403 may be used to induce precipitation of a hyperpolarized target compound. In some embodiments, the chamber 403 may include an inlet (e.g., a reagent port) for introducing a powder or solution (e.g., a precipitant) to be mixed with a solution containing the hyperpolarized target compound and to induce precipitation. In some embodiments, the chamber 403 may include a stimulation port for introducing electromagnetic radiation (e.g., ultraviolet radiation) into the chamber 403. As described herein, electromagnetic radiation can cause a solubility reduction change in the structure of the hyperpolarized target compound (e.g., thereby inducing precipitation of the hyperpolarized target compound). In some embodiments, the added powder or solution may include a base or acid such as sodium hydroxide, potassium hydroxide, hydrogen chloride, or sulfuric acid. In some embodiments, the added powder or solution may induce hydrolysis of the hyperpolarized compound.

[0127] In some embodiments, the chamber 403 may include a separation component for separating the precipitated compound from the solution. In some embodiments, this component may be a filter that allows the solvent to pass through but not the fine particles. An exemplary filter is a commercially available sterile filter. In another embodiment, the separation component may include a centrifuge configured to centrifuge the precipitate from the solution (or separate precipitates of different particle sizes). In another embodiment, the precipitated crystals are given sufficient time to settle to the bottom of the separation component, preferably in a designed well, which allows the solution to be washed or diluted with little effect on the precipitated particles. In another embodiment, the separation component may include a heating element for thermally evaporating the solution and preserving the precipitated particles. In another embodiment, the separation component may include a temperature and pressure controller that allows the sample to be separated by a freeze-drying method, which includes freezing the sample and sublimating the mixture, excluding the precipitated particles.

[0128] In certain embodiments, the chamber 403 may include an inlet for introducing a solution for the washing step, and the solvent containing the catalyst is either washed away or significantly diluted with the washing solution. In some embodiments, the washing solution is biocompatible. For example, if the separation component includes a filter, the washing solution may flow through the filter and wash the precipitated particles away from the original solvent.

[0129] The magnetic field generated by the permanent magnet or electromagnet 404 may be applied to at least a portion of the sedimentation chamber. In one embodiment, the magnetic field is applied to most or all of the sedimentation chamber. The magnetic field may be configured such that some of the sedimented particles are subjected to a magnetic field greater than about 1 mT, 10 mT, 100 mT, 100 mT, 2 T or more, or less than 2 T, 1 T, 100 mT, 10 mT, 1 mT or less.

[0130] In some embodiments, large amounts of precipitated hyperpolarized particles can be accumulated by repeated iterations of parahydrogen dissolution, hyperpolarization target compound, and precipitation. This can be carried out in a continuous flow, discrete batch, or a mixture of continuous flow and discrete batch. In some embodiments, some of the steps are carried out at once in several batches, while other steps are carried out sequentially in each batch. This may be, for example, when one step is carried out in a larger volume than others. For example, in some embodiments, parahydrogen dissolution may be carried out in solution volumes greater than approximately 5 ml, 20 ml, 50 ml, 100 ml or more (or less than approximately 100 ml, 50 ml, 20 ml, 5 ml), while polarization transfer may be carried out in smaller volumes. In some embodiments, parahydrogen dissolution will be carried out on larger volumes of solution, while polarization transfer will be carried out sequentially on smaller batches. In this embodiment, precipitation may be carried out on each batch after polarization transfer, or alternatively, sequentially on larger batches after the accumulation of larger volumes of the hyperpolarized target compound after polarization transfer.

[0131] The particles are then dissolved in a dissolution or extraction chamber 405, and the particles are redissolved and extracted for detection in hyperpolarized NMR or MRI. In some embodiments, redissolution may be carried out in a biocompatible solvent. In a preferred embodiment, the solvent is an aqueous solution. In a preferred embodiment, the dissolution chamber includes an inlet for introducing the solvent. In a preferred embodiment, the dissolution chamber includes an outlet. In another embodiment, the dissolved particles are injected directly into the patient from the dissolution chamber using an HP MRI scanner. In a preferred embodiment, a magnetic field, either permanent or generated by an electromagnet, is applied to the dissolution chamber. The magnetic field in the region of the precipitated particles before dissolution may be greater than about 1 mT, 10 mT, 100 mT, 1 T, or 2 T or less, or less than 2 T, 1 T, 100 mT, 10 mT, or 1 mT, or within the range defined by any two of the preceding values.

[0132] In some embodiments, chambers 203 and 205 may be the same chamber. This chamber may be selectively transported to different locations between precipitation and dissolution. In some embodiments, chambers 201 and 203 may be the same chamber.

[0133] transportation In line with the disclosed embodiments, the polarization migration and use of the target compound may occur at different locations. In various embodiments, the precursor (in the solution used for polarization migration, or as a precipitate) may be transported to another location after precipitation. In various embodiments, the target compound (in the solution used for polarization migration, as a precipitate, or redissolved) may be transported to another location. The disclosed embodiments are not necessarily limited to any particular transport distance or duration. Instead, the maximum distance or duration may be determined based on the target compound, its initial degree or polarization, the desired final degree of polarization, and the transport conditions. In some embodiments, the precipitate may be transported at least 1 meter in a suitable transport device.

[0134] In accordance with the disclosed embodiments, the transport device may be configured to transport samples of a precursor or target compound. The transport device may be arranged and configured to transport one or more samples simultaneously. The transport device may include a transport chamber configured to receive one or more samples. The transport device may be configured to maintain the transport chamber within a predetermined temperature range and a predetermined magnetic field strength. The transport device may be configured to maintain one or more samples within a magnetic field greater than about 10 G, 100 G, 1000 G or more, or less than 1000 G, 100 G, 10 G or less.

[0135] Permanent magnets or electromagnets included in the transport device may provide a magnetic field. Furthermore, in some embodiments, the permanent magnets or electromagnets may be shielded to reduce the strength of the magnetic field outside the transport device. The transport device may also include a cooling system. The cooling system may be configured to maintain the sample at a predetermined temperature or within a predetermined temperature range during transport. For example, the cooling system may be configured to maintain the sample at a temperature below 270K, below 80K, or below 4K. In some embodiments, the transport device may be configured to maintain the sample at approximately liquid nitrogen temperature. The transport device may include insulation between the cooling system and the outside of the transport device to minimize heat exchange with the external environment. In some embodiments, the cooling system may be configured to maintain the sample temperature using a low-temperature gas flow. In various embodiments, the cooling system may be configured to maintain the sample temperature using a coolant. In various embodiments, the transport device may include a dewar to provide cooling for the sample. To distribute hyperpolarized samples over long distances, containers may be transported, preferably by standard transport vehicles such as airplanes, trains, trucks, cars, and ships.

[0136] In some embodiments, the hyperpolarized precipitate particles are transported within a transport device. In some embodiments, the relaxation time of the hyperpolarized precipitate particles in the transport device is longer than about 1 minute, 10 minutes, 30 minutes, 1 hour, 3 hours, or 10 hours or more, or shorter than about 10 hours, 3 hours, 1 hour, 30 minutes, 10 minutes, or 1 minute or less.

[0137] Exemplary System Figures 5A, 5B, and 5C illustrate exemplary schematic diagrams of systems and separation systems including polarizers for obtaining high-concentration biocompatible solutions containing hyperpolarized target compounds, respectively. Such systems may be used in conjunction with PHIP, PHIP-SAH, or SABRE polarization methods. Figure 5A illustrates an exemplary polarizer 500 consistent with the disclosed embodiments. In the PHIP or PHIP-SAH embodiments, the polarizer 500 may include a hydrogenation device configured to produce a solution of a parahydrogenation precursor relative to a target compound (e.g., a parahydrogenation precursor solution). The hydrogenation device may produce a parahydrogenation precursor solution by mixing a solvent, parahydrogen gas, and the precursor of the target compound. In some embodiments, the hydrogenation device may mix a solution containing the precursor dissolved in a solvent (e.g., a precursor solution). In some embodiments, the precursor may contain unsaturated chemical bonds. The parahydrogen gas may react with the precursor at unsaturated chemical bonds to form a parahydrogenation precursor. In some embodiments, the precursor may be a pyruvate precursor containing at least one unsaturated bond, a fumarate precursor containing at least one unsaturated bond, or a succinate precursor containing at least one unsaturated bond. In SABRE's embodiment, the hydrogenation device may combine a solution containing the target compound and a polarization catalyst with parahydrogen. The hydrogenation catalyst may bring the parahydrogen close to the target compound to enable polarization transfer.

[0138] In accordance with the disclosed embodiments, the hydrogenation device may include a parahydrogenation chamber 501. The chamber 501 may be designed and configured to accommodate a combination of parahydrogen and a solvent (or precursor solution). The chamber 501 may be designed and configured to achieve high hydrogenation efficiency. Parahydrogen may be combined with the solvent (or precursor solution) over a time interval (or the dissolution of parahydrogen may occur in less than a time interval). The time interval may be less than about 90 seconds, 60 seconds, 30 seconds, 20 seconds, 10 seconds, or 5 seconds or less, or greater than about 5 seconds, 10 seconds, 20 seconds, 30 seconds, 60 seconds, or 90 seconds or more, or within the range defined by any two of the preceding values. In certain embodiments, a precursor is hydrogenated within a range defined by any two of the following values: above approximately 30 mM, 50 mM, 100 mM, 250 mM, 400 mM, 600 mM, or 1000 mM or less, or below approximately 1000 mM, 600 mM, 400 mM, 250 mM, 100 mM, 50 mM, or 30 mM.

[0139] In some embodiments, the chamber 501 may include a bubbler configured to introduce parahydrogen gas into a solvent (or precursor solution). For example, the chamber 501 may include an inlet for introducing pressurized parahydrogen into the solvent (or precursor solution). In certain embodiments, the parahydrogen is introduced into the solvent (or precursor solution) in the hydrogenation chamber at a pressure within the range defined by at least about 10 bar, 15 bar, 20 bar, 25 bar, 30 bar, 35 bar, 40 bar, 45 bar, 50 bar or more, and at most about 50 bar, 45 bar, 40 bar, 35 bar, 30 bar, 25 bar, 20 bar, 15 bar, 10 bar or less, or any two of the preceding values. In certain such embodiments, the high-pressure dissolution of parahydrogen into the solvent (or precursor solution) occurs in a metal chamber capable of withstanding the pressure into which the parahydrogen is introduced. In other embodiments, the chamber is made of a plastic material. In certain embodiments, the bubbler includes a nozzle head for introducing parahydrogen into the solvent (or precursor solution) in microbubbles for a larger surface area.

[0140] In various embodiments, the chamber 501 may be a flow chamber. In such embodiments, a membrane may separate the solvent (or precursor solution) from the flowing parahydrogen gas. The membrane may be positioned within the flow chamber to have a high surface area, allowing the parahydrogen to dissolve in the solvent (or precursor solution).

[0141] In various embodiments, the chamber 501 may include a chamber filled with parahydrogen gas. The aerozoizer of the chamber 501 may be configured to spray a solvent (or precursor solution) into the chamber in small droplets, thereby establishing a large surface area for the dissolution of parahydrogen.

[0142] In some embodiments, the heating coil 505 may be located around or inside the chamber 501. Such a coil may be energized to control the temperature of the solution in the chamber 501.

[0143] Consistent with the disclosed embodiments, the polarization device may include a polarization chamber 502. The polarization chamber 502 may be configured to receive a parahydrogen precursor solution from the hydrogenation device. The polarization chamber 502 may include a polarization region having volume. The volume may be at least about 10 mL, 20 mL, 30 mL, 40 mL, 50 mL, 60 mL, 70 mL, 80 mL, 90 mL, 100 mL, 200 mL, 300 mL, 400 mL, 500 mL, 600 mL, 700 mL, 800 mL, 900 mL, or 1000 mL or more, or 1000 mL, 900 mL, 800 mL, 700 mL, 600 mL, 500 mL, 400 mL, 300 mL, 200 mL, 100 mL, 90 mL, 80 mL, 70 mL, 60 mL, 50 mL, 40 mL, 30 mL, 20 mL, or 10 mL or less, or within the range defined by any two of the preceding values.

[0144] The polarizer 500 may include a polarization device configured to produce a solution of a polarized parahydrogenation precursor relative to a target compound (e.g., a polarized parahydrogenation precursor solution). Consistent with the disclosed embodiments, the polarization device may include a magnetic field generator 507 that can set the magnetic field amplitude in the polarization chamber 502 (or polarization region) to a specific value (or set the magnetic field to follow a specific time-dependent amplitude trajectory).

[0145] In accordance with the disclosed embodiments, the magnetic field generator 507 can adjust the magnetic field over a specified range of -10 μT to 10 μT within the polarization chamber 502 (or polarization region). In some embodiments, the magnetic field generator 507 can adjust the magnetic field over a specified range. In certain embodiments, when the amplitude of the modulated magnetic field is less than 10 μT, the spatial deviation of the modulated magnetic field is less than half (or a quarter, or an eighth, or a tenth) of the amplitude of the magnetic field. In some embodiments, such homogeneity can be achieved by having a large puncture solenoid through a magnetic shield, or by using a large Helmholtz coil with a large homogeneous region for generating magnetic field amplitude modulation (e.g., within a large homogeneous magnetic shield).

[0146] Modulation may be performed over a certain duration. In some embodiments, the duration may be about 100 milliseconds to 30,000 milliseconds (as described herein, for example). In certain embodiments, modulation may be a sweep of the magnetic field. In some embodiments, the magnetic field coil may be controlled by an external waveform generator. The external waveform generator may be configured to generate a fluctuating magnetic field within the magnetic shield to efficiently shift the polarization. In certain embodiments, for example, in SABRE polarization, the magnetic field in the polarization chamber 502 is a constant value less than approximately 1 μT, 2 μT, 3 μT, 4 μT, 5 μT, 6 μT, 7 μT, 8 μT, 9 μT, 10 μT, 20 μT, 30 μT, 40 μT, 50 μT, 60 μT, 70 μT, 80 μT, 90 μT, 100 μT, 200 μT, 300 μT, 400 μT, 500 μT, 600 μT, 700 μT, 800 μT, 900 μT, 1000 μT or more. The range may be kept within a certain value or range exceeding approximately 1000 μT, 900 μT, 800 μT, 700 μT, 600 μT, 500 μT, 400 μT, 300 μT, 200 μT, 100 μT, 90 μT, 80 μT, 70 μT, 60 μT, 50 μT, 40 μT, 30 μT, 20 μT, 10 μT, 9 μT, 8 μT, 7 μT, 6 μT, 5 μT, 4 μT, 3 μT, 2 μT, or 1 μT, or within a range defined by any two of the preceding values. The magnetic field in the polarization chamber 302 can be maintained within a range defined by any two of the following constant values ​​or ranges, or preceding values, for at least about 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds or more, and at most about 60 seconds, 50 seconds, 40 seconds, 30 seconds, 20 seconds, 10 seconds, 9 seconds, 8 seconds, 7 seconds, 6 seconds, 5 seconds, 4 seconds, 3 seconds, 2 seconds, 1 second or less.

[0147] In certain embodiments, magnetic field modulation may be performed by flowing a solution through an area within the magnetic shield 503 having a constant magnetic field profile.

[0148] In certain embodiments, a single solenoid may be used to control the magnetic field gradient in and out of the magnetic shield 503, as well as to modulate the magnetic field within the shield.

[0149] Consistent with the disclosed embodiments, the polarization device may include a polarization shield 503. In some embodiments, the magnetic shield 503 may be constructed from mu-metal or another suitable shielding material. A magnetic field generator 507 may be disposed within the magnetic shield 503. The polarization region of the polarization chamber 502 may be disposed within the magnetic shield 503. The magnetic shield 503 may allow the application of a magnetic field with an amplitude less than the Earth's magnetic field to the solution in the polarization transition chamber 502. In certain embodiments, the magnetic field generator 507 may allow the magnetic field in the polarization transition chamber 502 to be set to a specific value (or to follow a specific time-dependent amplitude trajectory). In certain embodiments, the para-hydrogenation chamber 501 may be at least partially an outer magnetic shield 503, as shown in Figure 5A. Alternatively, the para-hydrogenation chamber 501 may be inside the magnetic shield 503 (for example, a single reservoir may combine the functions of the para-hydrogenation chamber 401 and the polarization transition chamber 402).

[0150] The polarizer 500 may include a high-frequency waveform generator (shown in Figure 5A). The high-frequency waveform generator may be electrically coupled to the magnetic field coil 407. The high-frequency waveform generator may be configured to apply a high-frequency waveform to one or more RF coils and thus generate an electromagnetic field within the polarization device. The high-frequency waveform generator may be configured to generate a fluctuating magnetic field amplitude within the magnetic shield to efficiently shift the polarization.

[0151] In some embodiments, the polarizer 500 may be used in conjunction with a purification system configured to separate the purified fraction from the polarization solution. In some embodiments, the purification system may include a separation system 506. After polarization, a solution containing a polarization precursor (PHIP for PHIP-SAH applications) or a polarization target compound (for SABRE applications) may be delivered to the separation system 506. The separation system 506 may be configured to receive a solution containing a polarization precursor (PHIP or PHIP-SAH applications) or a polarization target compound (for SABRE applications). In some embodiments, the separation system 506 may include connections for automatically or manually transferring the fluid from the polarizer 500 (e.g., a fluid manifold or other suitable connection). The separation system 506 may be or include a precipitation chamber, as detailed in the "Purification and Separation" section. In some embodiments, the purification system may be configured to receive a cleavage solution. The cleavage solution may cleave side chains from the hyperpolarized parahydrogenation precursor, thereby generating the hyperpolarized target compound. As described herein, the cleavage solution may induce a hydrolytic reaction that separates the target compound from the rest of the precursor molecule. In some embodiments, the cleavage solution may be configured to alter the pH of the solution containing the hyperpolarized parahydrogenation precursor. In some embodiments, the redissolution chamber detailed in the "Purification and Separation" section may be a chamber of the separation system 506. Thus, after extraction and purification of the hyperpolarized target compound, the hyperpolarized target compound may be dissolved in a biocompatible solvent, preferably an aqueous solvent. In various embodiments, liquid-liquid extraction between the organic phase and the aqueous phase may be carried out by the separation system 506. Such liquid-liquid extraction may be used to cleave the parahydrogenation precursor from the side chains to produce the target compound and to separate the target compound from catalysts used for hydrogenation or polarization transition, cleavage byproducts, or organic solvents. In some embodiments, a fluorinated phase may be used in addition to / as an alternative to the organic phase and may be combined with the aqueous phase for improved separation. In some other embodiments, the purification step may include catalytic removal.Such catalytic removal involves adding a binding material that preferentially binds to the catalyst, which is then separated by filtration, centrifugation, or other mechanical means. In some embodiments, the hyperpolarized molecules may be cleaved to produce a target compound inside the separation system 506. In some embodiments, the pH level and temperature of the sample may be monitored and controlled in the separation system 506 to meet the conditions for injection into a patient. Alternatively, a quality control system (similar to quality control system 613) may be used to monitor the characteristics of the sample. The sample may be injected into an animal or human patient for hyperpolarized MRI scanning in an MRI scanner (e.g., one in MRI system 612).

[0152] The disclosed embodiments are not limited to embodiments that include a magnetic shield 503. In some embodiments (for example, embodiments in which a suitable polarization transition may occur in an ambient magnetic field), the polarizer 500 may omit the magnetic shield 503.

[0153] Figure 5B illustrates a polarizer 510 consistent with the disclosed embodiments. The polarizer 510 may include a hydrogenation device, a polarization device, a high-frequency waveform generator, and a purification system similar in design and function to those described above with respect to Figure 5A.

[0154] In accordance with the disclosed embodiments, the polarizer 510 may include a hydrogenation device similar to that of the polarizer 500. In some embodiments, the hydrogenation device of the polarizer 510 may include a para-hydrogenation chamber 511 similar to that of the para-hydrogenation chamber 501. In some embodiments, the hydrogenation device of the polarizer 510 may optionally include a heater coil 515 similar to that of the heater coil 505.

[0155] In accordance with the disclosed embodiments, the polarizer 510 may include a polarization device similar to the polarization device of the polarizer 510. In some embodiments, the polarization device of the polarizer 510 may include a polarization chamber 512 similar to the polarization chamber 502. The polarization chamber 512 may have a volume, configuration, etc., similar to that described with respect to the polarization chamber 502.

[0156] In accordance with the disclosed embodiments, the polarization device of the polarizer 510 may include a magnetic field generator 517 similar to the magnetic field generator 507. The magnetic field generator 517 can adjust the magnetic field over a specified range of 0 to 500 mT within the polarization chamber 512 (or its polarization region). In some embodiments, the magnetic field generator 517 may provide a constant magnetic field. In some embodiments, the magnetic field generator 517 may adjust the magnetic field.

[0157] In various embodiments, the magnetic field generator 517 can generate magnetic fields exceeding 0.1mT, 0.2mT, 0.3mT, 0.4mT, 0.5mT, 0.6mT, 0.7mT, 0.8mT, 0.9mT, 1.0mT, 2.0mT, 3.0mT, 4.0mT, 5.0mT, 6.0mT, 7.0mT, 8.0mT, 9.0mT, 10mT, 20mT, 30mT, 40mT, 50mT, 60mT, 70mT, 80mT, 90mT, 100mT, 200mT, 300mT, and 500mT. Or, it may include electromagnets or permanent magnets capable of generating magnetic fields of less than or equal to approximately 500mT, 300mT, 200mT, 100mT, 90mT, 80mT, 70mT, 60mT, 50mT, 40mT, 30mT, 20mT, 10mT, 9mT, 8mT, 7mT, 6mT, 5mT, 4mT, 3mT, 2mT, 1mT, 0.9mT, 0.8mT, 0.7mT, 0.6mT, 0.5mT, 0.4mT, 0.3mT, 0.2mT, or 0.1mT. The magnetic field may be applied to a sample in the polarization chamber 512.

[0158] In some embodiments, the polarization device of the polarizer 510 may include a magnetic shield 513 similar to the magnetic shield 503. Similar to the magnetic shield 503, the magnetic shield 513 may be constructed from mu-metal or another suitable shielding material. A magnetic field generator 517 may be disposed within the magnetic shield 513. The polarization region of the polarization chamber 512 may be disposed within the magnetic shield 513. The magnetic shield 513 may allow the application of a magnetic field with an amplitude less than the Earth's magnetic field to the solution in the polarization transition chamber 512.

[0159] In some embodiments, the RF coil 514 may be configured to generate a high-frequency waveform on the sample in the chamber for polarization transition. As used herein, the high-frequency waveform further includes an audio frequency waveform. Thus, the high-frequency waveform may be 20 Hz to 200 kHz, or 1 Hz to 1 MHz. In various embodiments, the waveform is configured to be a polarization transition waveform relevant for transitioning the polarization on the sample. The polarization transition waveform may be selected depending on the type of compound, the magnetic field, and whether the compound is polarized by the PHIP, PHIP-SAH, or SABRE method, as described herein. In various embodiments (not shown in Figure 5B), the RF coil 514 may be the same coil, or may include the same coil used in the magnetic field generator 517 to generate a static magnetic field. In various embodiments, the magnetic field generator 517 may be a solenoid, and the RF coil 514 may be arranged as a saddle coil around the solenoid (not shown in Figure 5B). In various embodiments, the RF coil 514 may generate an oscillating electromagnetic field in which the magnetic field has components perpendicular to the static magnetic field. In various embodiments, the RF coil 514 may be configured to generate a circularly polarized magnetic field using, for example, two sets of orthogonal coils. In some embodiments, while the polarization waveform is applied by the RF coil 514, the magnetic shield 513 may be configured to maintain a magnetic field strength within the polarization chamber within a range defined by at least about 10mT, 20mT, 40mT, 80mT, 160mT, 200mT, 250mT, 500mT, 1000mT or more, 1000mT, 500mT, 250mT, 200mT, 160mT, 80mT, 40mT, 20mT, 10mT or less, or any two of the preceding values.

[0160] The polarizer 510 may include a high-frequency waveform generator similar to the RF waveform generator of the polarizer 510. The high-frequency waveform generator may be configured to apply one or more high-frequency waveforms over a predetermined period (e.g., 0.5 to 30 seconds, or another preferred period). The high-frequency waveforms may include waveforms with a frequency that is substantially constant over the period, waveforms with a frequency that changes substantially linearly (or substantially monotonically) over the period, waveforms with an amplitude that is substantially constant over the period, and waveforms with an amplitude that changes substantially linearly (or substantially monotonically) over the period. One or more channels of the high-frequency waveform generator may be electrically coupled to the magnetic field generator 517, and the high-frequency waveforms may be applied to the magnetic field generator 517. One or more channels of the high-frequency waveform generator may be electrically coupled to the RF coil 514. In various embodiments, one or more channels connected to the RF coil 514 are configured to generate high-frequency waveforms during polarization transition.

[0161] The high-frequency electromagnetic field generated by the RF coil 514 can be used to perform polarization transfer to target nuclear spins within the polarization chamber 512 of a sample volume defined by at least approximately 10 mL, 20 mL, 30 mL, 40 mL, 50 mL, 60 mL, 70 mL, 80 mL, 90 mL, 100 mL, 200 mL, 300 mL, 400 mL, 500 mL, 600 mL, 700 mL, 800 mL, 900 mL, 1000 mL or more, or 1000 mL, 900 mL, 800 mL, 700 mL, 600 mL, 500 mL, 400 mL, 30 mL, 20 mL, 10 mL or less, or any two of the preceding values.

[0162] In a particular embodiment where the para-hydrogenation chamber 511 is a polarized chamber 512, continuous wave irradiation or pulses convert the para-hydrogenated protons into deuterium or 13 Decoupling from the C-spin can be generated by the RF coil 514 during hydrogenation.

[0163] In certain embodiments, the high-frequency waveform may include pulses, frequency sweeps, or amplitude sweeps to perform polarization transitions, as described in the “Polarization Transitions” section. In certain embodiments, for example, in SABRE polarization, the high-frequency waveform in the polarization chamber 402 may be a constant value less than approximately 1 μT, 2 μT, 3 μT, 4 μT, 5 μT, 6 μT, 7 μT, 8 μT, 9 μT, 10 μT, 20 μT, 30 μT, 40 μT, 50 μT, 60 μT, 70 μT, 80 μT, 90 μT, 100 μT, 200 μT, 300 μT, 400 μT, 500 μT, 600 μT, 700 μT, 800 μT, 900 μT, 1000 μT or more. The value may be kept within a range defined by any two of the following values: a certain value or range exceeding approximately 1000 μT, 900 μT, 800 μT, 700 μT, 600 μT, 500 μT, 400 μT, 300 μT, 200 μT, 100 μT, 90 μT, 80 μT, 70 μT, 60 μT, 50 μT, 40 μT, 30 μT, 20 μT, 10 μT, 9 μT, 8 μT, 7 μT, 6 μT, 5 μT, 4 μT, 3 μT, 2 μT, or 1 μT. The amplification of the high-frequency waveform in the polarization chamber 402 can be maintained within a range defined by any two of the following constant or range values, or preceding values, between at least approximately 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, and 60 seconds, and at most approximately 60 seconds, 50 seconds, 40 seconds, 30 seconds, 20 seconds, 10 seconds, 9 seconds, 8 seconds, 7 seconds, 6 seconds, 5 seconds, 4 seconds, 3 seconds, 2 seconds, and 1 second.

[0164] Polarizer 510 may include a purification system similar to the purification system of polarizer 500. In some embodiments, the purification system may include a separation system similar to the separation system 506 of polarizer 500. The separation system may be or include a precipitation chamber 516. After polarization, a solution containing a polarization precursor (for PHIP or PHIP-SAH applications) or a polarization target compound (for SABRE applications) may be delivered to the separation system 516. The separation system 516 may be configured to receive a solution containing a polarization precursor (for PHIP or PHIP-SAH applications) or a polarization target compound (for SABRE applications). In some embodiments, the separation system 506 may include a connection (e.g., a fluid manifold or other suitable connection) for automatically or manually transferring fluid from polarizer 500. In some embodiments, the purification system may be configured to receive a cutting solution, similar to the purification system of polarizer 500. In some embodiments, the redissolution chamber is a chamber in the separation system 516 similar to the separation system 506 of polarizer 500. In various embodiments, liquid-liquid extraction between the organic phase and the aqueous phase may be carried out by a separation system 516 similar to the separation system 506 of the polarizer 500. In some embodiments, a fluorinated phase may be used in addition to / as an alternative to the organic phase and may be combined with the aqueous phase for improved separation. In some other embodiments, the purification step may include catalytic removal. In some embodiments, hyperpolarized molecules may be cleaved to produce a target compound inside the separation system 516. In some embodiments, the pH level and temperature of the sample may be monitored and controlled in the separation system 516 to meet the conditions for injection into a patient. Alternatively, a quality control system (similar to the quality control system 613) may be used to monitor the characteristics of the sample. The sample may be injected into an animal or human patient for hyperpolarized MRI scanning in an MRI scanner (e.g., one in MRI system 612).

[0165] The disclosed embodiments are not limited to embodiments that include a magnetic shield 513. In some embodiments (for example, embodiments in which a suitable polarization transition may occur in an ambient magnetic field), the polarizer 510 may omit the magnetic shield 513.

[0166] Figure 5C illustrates a polarizer 520 consistent with the disclosed embodiments. The polarizer 520 may include a magnetic shield 561. The magnetic shield 561 may be constructed from mu-metal or another suitable shielding material. Similar to the magnetic shield 503, the magnetic shield 561 may allow the magnetic field within the magnetic shield 561 to be set to a specific value or orbit. The polarizer 520 may include a polarization chamber 541. As shown in Figure 5C, the polarization chamber may penetrate the magnetic shield 561, allowing an NMR tube 551 (or a larger volume container) containing a sample 553 to be placed within the magnetic shield 561. In embodiments using the polarization device 530, polarization may occur in the region of the polarization chamber located within the shield, solenoid, and saddle coil (e.g., the region containing the sample in the NMR tube or a larger volume container). In embodiments of PHIP or PHIP-SAH, the sample 553 may be a solution containing a precursor (before parahydrogenation) or a parahydrogenation precursor. In SABRE's embodiments, sample 553 may be a solution containing a target compound (and optionally a hydrogenation catalyst). The solenoid valve 543 may be wound around the polarization chamber 541. The solenoid valve 543 may penetrate the magnetic shield 561. The electromagnetic 543 may be conductive (e.g., copper) and may be energized to provide a magnetic field along the z-axis of the polarizer 530. A saddle coil 571 may be disposed within the magnetic shield 561 and around the solenoid 541. The saddle coil 571 may be conductive (e.g., copper) and may be energized to provide a magnetic field (e.g., in the xy-plane) that crosses the magnetic field generated by the solenoid 543. Consistent with the disclosed embodiments, the solenoid 543 may be electrically connected to a high-frequency waveform generator (not shown). When driven by the high-frequency waveform generator, the solenoid 543 may be a magnetic field generator similar to the magnetic field generator 507 or magnetic field generator 517. In accordance with the disclosed embodiments, the saddle coil 571 may be electrically connected to a high-frequency waveform generator (or another high-frequency generator). When driven by the high-frequency waveform generator, the saddle coil 571 may be a high-frequency magnetic field generator similar to the RF coil 514.

[0167] In some embodiments, the polarizer 520 may be used in conjunction with a purification system configured to separate the purified fraction from the polarization solution. In some embodiments, the purification system may include a separation system, as well as a separation system 506 or 516.

[0168] Figure 6A illustrates an exemplary schematic diagram of a system for generating a hyperpolarized target compound, consistent with the disclosed embodiments. The system may include a polarizer 600, a precipitation chamber 606, a transport device 610, a redissolution system 611, an MRI system 612, and a quality control system 613. In some embodiments, at least one of the transport device 610 and the quality control system 613 may be omitted.

[0169] Polarizer 600 may be one of polarizers 500, 510, and 520, or similar to them. Polarizer 600 may be used in conjunction with a purification system including a precipitation chamber 606 and a magnetic field generator 608. The precipitation chamber 606 may be similar to the precipitation chamber 403 discussed with respect to Figure 4. The magnetic field generator 608, which may be a permanent magnet or electromagnet, may apply a magnetic field greater than about 1 mT, 10 mT, 100 mT, 1000 mT or more, or less than about 1000 mT, 100 mT, 10 mT, or 1 mT to at least a portion of the precipitate in the precipitation chamber 606.

[0170] In some embodiments, after precipitation, the precipitate may be transported to different locations in the transport device 610, which may include a magnetic field generator and a cooling system as described herein. The magnetic field generator includes a permanent or electromagnet configured to apply a magnetic field of about 1 mT, 10 mT, 100 mT, 1000 mT or more, or less than about 1000 mT, 100 mT, 10 mT, or 1 mT to at least some of the precipitated particles in the transport device 610. The hyperpolarized particles may be transported to a redissolution system 611 as detailed herein, and the precipitate may be redissolved in a biocompatible solvent, preferably an aqueous solvent. In some embodiments, the redissolution system may be part of a purification system. For example, after purification, the polarization precursor or polarization target compound may be redissolved (e.g., from the precipitate) before being transported in the transport device 610. In various embodiments, the purified polarization precursor may be redissolved and then cleaved to form the polarization target compound. The polarized target compound can then be separated and transported within the transport device 610.

[0171] After extraction and purification, the solution properties can be monitored by the quality control system 613. In a preferred embodiment, the quality control system monitors the pH and temperature of the solution (e.g., a redissolved solution produced by the redissolution system 611 containing the hyperpolarized target compound). In some embodiments, the quality control system 613 may additionally monitor the solution containing trace amounts of the original solvent in which the parahydrogen was dissolved. Such monitoring can be performed, for example, by a UV / VIS spectrometer. The solution containing the hyperpolarized target compound can be injected into an animal or human patient for hyperpolarized MRI scanning using the MRI system 612.

[0172] Exemplary polarized transfer in cinnamyl parahydrogenpyruvate By applying the systems and methods described herein, parahydrogen protons can be converted 13 Polarization was shifted to the 1C-labeled cinnamyl pyruvate precursor. The cinnamyl pyruvate precursor is 13It is characterized by a carbon-carbon triple bond located three bonds away from the target atom. Therefore, when the pyruvate cinnamyl precursor is para-hydrogenated across the triple bond, the para-hydrogen proton is, 13 The C target atom was incorporated four and five bonds away. The following demonstrates the usefulness of the systems and methods presented herein for transferring polarization to target nuclei located at least four chemical bonds away from a parahydrogen proton.

[0173] From the parahydrogen proton after hydrogenation 13 We developed an RF sweep-based method for transferring singlet spin order to polarization on C nuclei and compared it with an ultra-low magnetic field sweep-based method. Both RF sweeps and magnetic field sweeps are effective in determining the initial population imbalance after hydrogenation. 13 The process relies on adiabatic passage through level countercrossings (LACs) to result in C polarization.

[0174] 13 The physical mechanism involved in C polarization is the adiabatic evolution of the system when the magnetic field or RF amplitude is swept sufficiently slowly. The eigenvalue of interest is the largest J bond in the system, J 12 As described above with respect to Figures 2A and 2B, the lowest energy state is the one that is overcrowded after hydrogenation (when the swept parameters, e.g., amplification for the RF pulse or magnetic field for the magnetic field sweep, are 0). During the sweep, when the swept parameters, e.g., amplitude of the RF pulse or magnetic field for the field sweep, become large enough to cross the LAC conditions, the low energy state is, 13 This corresponds to a state where the C polarization is aligned with the magnetic field. Therefore, at the end of the sweep, the overcrowded state is the target. 13 C spin is polarized, total 13 This state leads to C polarization.

[0175] In particular, with respect to RF sweep, the sweep parameter is the RF amplitude Ω. After hydrogenation, the eigenstates of the system are occupied according to their overlap with the singlet state of parahydrogen protons. J 12Since is the largest J bond in the system, the most densely packed eigenstate is the lowest energy eigenstate. If Ω is sufficiently large, for example significantly higher than the value of the LAC condition detailed in the "Transfer of Polarization Using Mediating Spins" section, then at the end of the sweep, the carbon polarization determines the lowest energy eigenstate. Thus, if the RF amplitude is swept sufficiently slowly, and as a result the dynamics are adiabatic, the eigenstates of the overcrowded state have the same carbon polarization. In some embodiments, it is only necessary for the RF amplitude to be swept slowly near the level anticrossing (LAC) and for the state ensemble to transition.

[0176] method The low static magnetic field used in the described experiment was generated using a double-layer solenoid that penetrated a mu-metal magnetic shield (MS-2, twinleaf, USA) along the Z direction. This configuration allowed for the generation of a magnetic field up to 100 μT. The homogeneity of the magnetic field was measured to be 10 nT across the sample volume using a Fluxgate magnetometer (Stefan Mayer Instruments, Germany). The coil was powered using a common laboratory power supply, and the output was attenuated with a 1 kHz high-power resistor. The RF excitation magnetic field was generated using a built-in shim coil in the MS-2 shield perpendicular to the static magnetic field. The RF signal was generated by an NI card (National Instruments 6363-USB) and amplified using an audio amplifier. The amplitude of the RF magnetic field was measured using the same Fluxgate sensor (Stefan Mayer Instruments, Germany).

[0177] A catalyst solution containing 3 mg / ml of Rh(dppb)(COD) catalyst precursor was prepared. This solution was then mixed with a solution containing the precursor of the target compound to form the desired PHIP or PHIP-SAH molecule. For the experiment to obtain cinnamyl pyruvate, 25 mM 1- 13 A solution of the cinnamylpropagylpyruvic acid precursor C was prepared.

[0178] The samples were bubbling at room temperature for 60 seconds under a 2.5 bar para-hydrogen atmosphere. Hydrogenation was carried out under a laboratory magnetic field (approximately 50 μT) and at high temperatures (55°C for solutions using acetone-d6 as the solvent, and 90°C for solutions using D2O as the solvent).

[0179] Next, an RF sweep or magnetic field sweep was performed. As can be understood, other methods for shifting polarization using adiabatic and non-adiabatic RFS are possible, as described herein.

[0180] In accordance with the disclosed embodiments, the RF sweep was performed as shown in Figures 6B–6D. The RF frequency was initially increased from zero to approximately 20 Hz to ensure that the spin system ensemble passed through the relevant level anticrossing (LAC). Then, during the first phase of the RF sweep, the RF frequency was increased linearly while the RF amplitude was increased in a magnetic field of 100 μT. 13 The frequency of C was maintained in resonance with the Larmor frequency. Unless otherwise specified, the duration of the first phase was 8 seconds. In the second phase of the RF sweep, the RF frequency was linearly increased to 70 Hz higher than the Larmor frequency of 13C, and the RF amplitude was linearly reduced to zero. The duration of the second phase was 2 seconds.

[0181] In accordance with the disclosed embodiments, the magnetic field sweep comprised first, second, and third phases. In the first phase, the sample was held in a static magnetic field of 10 μT or inserted into a polarizer at 10 μT. In the second phase, the magnetic field was adiabatically reduced to 50 nT. In the third phase, the magnetic field was linearly increased to 1 μT. Unless otherwise specified, the duration of the third phase was 8 seconds.

[0182] After performing RF or magnetic field sweeps, the sample was transferred to a benchtop NMR spectrometer (Fourier 80, Bruker, USA) to acquire the 13C NMR spectrum. To estimate polarization, the proton thermal signal was measured using a wide-field spectrometer (Bruker 400 MHz), and the sample concentration was calculated using an external reference. Polarization was then calculated using the reference sample (1- 13The thermal signal and signal of 14C methanol (99.4 percent labeled) were determined by comparing them. This approach to polarization estimation was used with the calculated polarization and the highly enriched solution used in this study. 13 Fully relaxed C-labeled molecule 13 This was verified by comparing it with the polarization obtained in relation to the acquisition of the C spectrum.

[0183] result Figures 7A and 7B illustrate the simulation and experimental results of polarized transfer using protonated and deuterated pyruvate cinnamyl molecules. Figure 7A shows carboxylic acid 13 The polarization transfer to cinnamyl pyruvate using a mediating proton spin that connects a C spin to a parahydrogen proton is illustrated. For this spin system, RF sweeping and MFC function equally well. Increasing the duration of the first phase of RF sweeping increases the amount of polarization transferred, which then stabilizes, reaching approximately 60% polarization transfer efficiency at a first phase duration of 15 seconds. Similar experimental results were achieved for magnetic field sweeping. Simulations of these experiments show excellent agreement with the experimental results, explaining both the increase in polarization and the eventual stabilization.

[0184] Figure 7B shows a carboxylic acid. 13 Polarized transfer to cinnamyl pyruvate d1 using a mediating deuteron spin that connects the C spin to a parahydrogen proton is illustrated. Polarized transfer efficiency using RF sweep is increased by approximately 40% compared to the protonated molecule. RF sweep achieved steady-state polarized transfer efficiency at approximately 90%. Simulations of RF sweep experiments (with relaxation effects omitted) showed good agreement with experimental results. Relaxation did not appear to be a problem at the timescale investigated, but would likely limit transport efficiency at longer timescales. Magnetic sweep did not achieve the same degree of polarization as RF sweep. As the duration of magnetic sweep increased, the polarization achieved decreased. These results suggest that rapid deuterium relaxation is a target. 13This follows the prediction that the polarization transfer to the C atom will be inhibited. When RF sweeping was used, the polarization was not transferred to deuterium, and a second type of scalar relaxation was effectively avoided. These effects, combined, allow for significantly higher polarization. The theoretical efficiency of sweeping the deuterated molecule is almost 1.5 times higher than that of protonation, since all states are accessible. This higher theoretical efficiency was achieved in an experiment where the polarization of deuterated cinnamyl pyruvate reached 8.25%, compared to 6.0% protonated cinnamyl pyruvate, resulting in a 1.375-fold increase. The transfer rate required to ensure that the transfer was adiabatic was similar to the rate of magnetic field sweeping, and the relaxation rate was also similar.

[0185] Figure 7C illustrates the polarization achieved for DAMD-d6, DMAD, fumarate, CP 1-13C d1, and CP according to the disclosed embodiments. For all molecules investigated, RF sweeps produced polarization at a level equivalent to or exceeding that of magnetic field sweeps. Here, hydrogenation was carried out in a water bath heated to 60°C (heated to 90°C except for the fumarate). The laboratory magnetic field during hydrogenation was approximately 50 μT.

[0186] Exemplary polarization shifts in large volumes: A 2 ml solution of acetone-d6 containing 100 mM starting material and 5 mM catalyst was heated in an ETFE-coated aluminum reaction vessel. After reaching a temperature of 55°C, the sample was exposed to a parahydrogen atmosphere consisting of 10 bars and bubbled with parahydrogen for 30 seconds. The solution was then transferred to a container located inside a polarization transfer device and diluted with 23 ml of acetone. A static magnetic field of 0.1 mT was used as a guide magnetic field for sample transport and subsequent polarization transfer. Subsequently, the amplitude of the RF magnetic field on resonance with the 13C NMR resonance frequency was increased from 0 to 4 uT within 5 seconds. Following the amplitude increase, a 2-second adiabatic 90-degree point-to-point rotation was performed to orient the generated hyperpolarized magnetization parallel to the static magnetic field. The adiabatic rotation was performed by a homogeneous amplitude decrease and RF frequency increase, as described in the experiment above. Subsequently, 0.6 ml of the sample solution was extracted and the 13C signal was measured by a 60 MHz tabletop spectrometer.

[0187] Figure 8 shows a 1- 13 A polarized 25 ml sample of cinnamyl C pyruvate is shown. Figure 9 shows the polarized sample shown in Figure 8. 13 C-enriched cinnamyl pyruvate was measured using a 60 MHz SpinSolve spectrometer. 13 The 13C NMR spectrum is shown in the figure.

[0188] The above description is provided for illustrative purposes only. It is not exhaustive and is not limited to the exact form or embodiment disclosed. Modifications and adaptations of embodiments will become apparent from the specification and implementation review of the disclosed embodiments. For example, while the described implementations include hardware, systems and methods consistent with this disclosure may be implemented using hardware and software. In addition, while certain components are described as being coupled together, such components may be integrated with each other or distributed in any preferred manner.

[0189] Embodiments of this specification include systems, methods, and tangible non-temporary computer-readable media. A method may be performed, for example, by at least one processor receiving instructions from a tangible non-temporary computer-readable storage medium, at least partially. Similarly, a system consistent with this disclosure may include at least one processor and memory, the memory of which may be a tangible non-temporary computer-readable storage medium. As used herein, tangible non-temporary computer-readable storage medium refers to any type of physical memory on which information or data readable by at least one processor can be stored. Examples include random-access memory (RAM), read-only memory (ROM), volatile memory, non-volatile memory, hard drives, CD-ROMs, DVDs, flash drives, disks, registers, caches, and any other known physical storage media. Singular terms such as “memory” and “computer-readable storage medium” may further refer to multiple structures, such as multiple memories or computer-readable storage media. As used herein, “memory” may include any type of computer-readable storage medium unless otherwise specified. A computer-readable storage medium may store instructions for execution by at least one processor, including instructions for causing a processor to perform steps or stages consistent with the embodiments herein. In addition, one or more computer-readable storage media may be used in implementing a computer implementation method. The term “non-transient computer-readable storage medium” should be understood to include tangible articles, excluding carrier waves and transient signals.

[0190] Furthermore, while exemplary embodiments are described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., aspects across various embodiments), adaptations, or variations based on this disclosure. The elements of the claims should be interpreted broadly on the basis of the language used in the claims, and not limited to the examples described herein or during the examination of the application, and such examples should be interpreted as non-exclusive. Furthermore, the steps of the methods of this disclosure may be modified in any way, including changing the order of the steps, or inserting or deleting steps.

[0191] The features and advantages of this disclosure are evident from the detailed specification, and therefore the attached claims are intended to cover all systems and methods that fall within the true spirit and scope of this disclosure. As used herein, the indefinite articles "a" and "an" mean "one or more." Similarly, the use of plural terms does not necessarily mean plural unless made clear in a given context. Furthermore, since numerous modifications and variations readily arise from the study of this disclosure, it is undesirable to limit this disclosure to the exact structures and operations illustrated and described, and therefore all suitable modifications and equivalents may be sought to fall within the scope of this disclosure. This disclosure includes the following embodiments of the invention: <Document Name> Claims <Aspect 1> A system for generating hyperpolarized molecules, A hydrogenation device configured to produce a parahydrogenated solution by mixing a solvent, parahydrogen gas, and a precursor of the hyperpolarized molecule, wherein the precursor contains an unsaturated chemical bond, A polarization device configured to generate a polarization solution containing the superpolarized molecules using the parahydrogenated solution, wherein the polarization device is (a) A polarization chamber configured to receive the parahydrogenated solution, wherein the polarization chamber includes a polarization region having a volume of at least 10 milliliters (mL), (b) One or more radio frequency (RF) coils disposed around the polarization region of the polarization chamber, and (c) A polarization device including a magnetic field source disposed around the polarization region of the polarization chamber and configured to provide an average magnetic field strength of up to 200 millitesla (mT), An RF waveform generator coupled to one or more RF coils of the polarization device, wherein the RF waveform generator is configurable to apply an RF waveform to the one or more RF coils, A system comprising: a purification system configured to separate a purified fraction from the polarized solution. <Aspect 2> The system according to embodiment 1, further comprising a dissolution chamber configured to contain the purified fraction and to receive a second solvent for dissolving the purified fraction. <Aspect 3> The system according to embodiment 1, wherein the polarization device comprises a magnetic shield, and the magnetic shield is disposed around the polarization region of the polarization chamber. <Aspect 4> The system according to embodiment 1, wherein the magnetic shield is configured to maintain the magnetic field strength in the polarization chamber below 200 mT while the polarization waveform is applied to one or more RF coils. <Aspect 5> The system according to embodiment 1, wherein the hydrogenation device comprises a bubbler configured to introduce the parahydrogen gas into the solvent, a membrane configured to allow the diffusion of the parahydrogen gas into the solvent, or an aerozoizer configured to spray droplets of the solvent into a parahydrogen chamber configured to receive the parahydrogen gas. <Aspect 6> The system according to embodiment 1, wherein the precursor of the target compound comprises the target compound chemically bonded to a side chain containing the unsaturated chemical bond. <Aspect 7> The system according to embodiment 6, wherein the precursor of the target compound comprises an ester of the target compound. <Aspect 8> The system according to embodiment 6, wherein the purification system is configured to receive a cleavage solution configured to cleave the side chain from the precursor of the target compound, thereby producing the target compound. <Pattern 9> The system according to embodiment 1, wherein the purification system includes a separation system, the purified fraction of the polarization solution includes a precipitated fraction of the polarization solution, and the separation system is configured to separate the precipitated fraction of the hyperpolarized molecules from the polarization solution. <Aspect 10> The system according to embodiment 9, wherein the dissolution chamber is configured to contain the precipitated fraction and to receive a second solvent for dissolving the precipitated fraction. <Aspect 11> The RF waveform generator can be configured to apply the RF waveform over a predetermined period of time, and the RF waveform is The frequency that remains substantially constant during the aforementioned period, The frequency changes substantially linearly during the aforementioned period. An amplitude that is substantially constant during the aforementioned period, or The system according to embodiment 1, comprising at least one of an amplitude that changes substantially linearly over the aforementioned period. <Aspect 12> A method for increasing nuclear spin polarization in a target compound, (a) To obtain a target compound or a parahydrogenated precursor of the target compound, wherein the target compound or the parahydrogenated precursor of the target compound is at least (i) The first proton and (ii) A second proton coupled to at least the first proton by a first J coupling constant, wherein the first and second protons have singlet spin order, (iii) A third proton bonded to at least one of the first protons or the second protons by a second J bond constant, (iv) A target atom bonded to at least the third proton by a third J bond constant, The first and second protons are separated from the target atom by at least four chemical bonds, and obtained. (b) Placing the target compound or parahydrogenation precursor within an average magnetic field strength of less than 500 mT, (c) A method comprising applying a magnetic resonance (MR) pulse sequence to the target compound or parahydrogenation precursor, wherein the MR pulse sequence is configured to transfer a collection of first and second protons to the target atom, thereby imparting at least 1%, 2%, 5%, 10%, or 20% non-equilibrium nuclear spin polarization to the target atom. <Aspect 13> The method according to embodiment 12, wherein the first, second, and third protons form a quantum mechanical three-body system having high-density energy eigenstates and low-density energy eigenstates. <Aspect 14> The method according to embodiment 13, wherein multiple eigenstates are highly densely clustered. <Aspect 15> The method according to embodiment 13, wherein the MR pulse sequence is configured to collectively transition from the high-density energy eigenstate to the low-density energy eigenstate, thereby imparting at least 1%, 2%, 5%, 10%, or 20% of non-equilibrium nuclear spin polarization to the target atom. <Aspect 16> The method according to embodiment 13, wherein, prior to (b), the high-density energy eigenstates have a total population of at least 50%, 60%, 70%, 80%, or 90%. <Aspect 17> The method according to embodiment 12, further comprising imparting the singlet spin order to the first and second protons prior to (a). <Aspect 18> The method according to embodiment 17, wherein imparting the singlet spin order to the first and second protons involves carrying out a parahydrogen-induced polarization (PHIP) reaction between the parahydrogen and the precursor, thereby adding the first and second protons across the unsaturated bonds of the precursor to form the parahydrogenated precursor. <Aspect 19> The method according to embodiment 18, wherein the precursor of the compound comprises a side chain containing at least one unsaturated bond and at least the third proton, so that, following the PHIP reaction, the side chain contains at least the first proton, the second proton, and the third proton. <Aspect 20> The method according to embodiment 19, further comprising cleaving the side chain from the precursor to form the target compound. <Aspect 21> The method according to embodiment 20, wherein imparting the singlet spin order to the first and second protons involves carrying out a signal amplification (SABRE) reaction by reversible exchange between parahydrogen molecules and the target compound, thereby transferring polarization from the parahydrogen molecules to the nuclei on the target compound. <Aspect 22> The first J bond constant is J 12 This is shown, and the second J bond constant is J 23 As shown, the MR pulse sequence is approximately

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Number

[0192] Embodiments may be further described using the following sections. Section 1. A system for generating hyperpolarized molecules, comprising a hydrogenation device configured to generate a parahydrogenated solution by mixing a solvent, a parahydrogen gas, and a precursor of hyperpolarized molecules, wherein the precursor comprises an unsaturated chemical bond, and a polarization device configured to generate a polarization solution containing hyperpolarized molecules using the parahydrogenated solution, wherein the polarization device comprises (a) a polarization chamber configured to receive the parahydrogenated solution, the polarization chamber comprising a polarization region having a volume of at least 10 milliliters (mL), A polarization device comprising: (b) a polarization chamber, (c) one or more radio frequency (RF) coils disposed around the polarization region of the polarization chamber, and (d) a magnetic field source disposed around the polarization region of the polarization chamber and configured to provide an average magnetic field strength of up to 200 millitesla (mT); an RF waveform generator coupled to one or more RF coils of the polarization device, wherein the RF waveform generator is configurable to apply an RF waveform to one or more RF coils; and a purification system configured to separate a purified fraction from a polarization solution. The system according to paragraph 1, further comprising a dissolution chamber configured to contain a purified fraction and to receive a second solvent for dissolving the purified fraction. Section 3. The system according to Section 1 or 2, wherein the polarization device comprises a magnetic shield, the magnetic shield being disposed around the polarization region of the polarization chamber. Section 4. The system according to any one of sections 1 to 3, wherein the magnetic shield is configured to maintain the magnetic field strength in the polarization chamber below 200 mT while a polarization waveform is applied to one or more RF coils. Section 5. The system according to any one of sections 1 to 4, wherein the hydrogenation device comprises a bubbler configured to introduce parahydrogen gas into a solvent, a membrane configured to allow diffusion of parahydrogen gas into a solvent, or an aerozoizer configured to spray droplets of solvent into a parahydrogen chamber configured to receive parahydrogen gas. Section 6. The system according to any one of sections 1 to 5, wherein the precursor of the target compound comprises a target compound chemically bonded to a side chain containing an unsaturated chemical bond. Section 7. The system according to Section 6, wherein the precursor of the target compound comprises an ester of the target compound. Section 8. The system according to Section 6 or 7, wherein the purification system is configured to receive a cleavage solution configured to cleave a side chain from a precursor of a target compound, thereby producing the target compound. Section 9. The system according to any one of sections 1 to 8, wherein the purification system comprises a separation system, the purified fraction of the polarized solution comprises a precipitated fraction of the polarized solution, and the separation system is configured to separate the precipitated fraction of hyperpolarized molecules from the polarized solution. Section 10. The system according to Section 9, wherein the dissolution chamber is configured to contain a precipitated fraction and to receive a second solvent for dissolving the precipitated fraction. Paragraph 11. The system according to any one of paragraphs 1 to 10, wherein the RF waveform generator can be configured to apply an RF waveform over a predetermined period of time, and the RF waveform includes at least one of a frequency that is substantially constant over the period, a frequency that changes substantially linearly over the period, an amplitude that is substantially constant over the period, or an amplitude that changes substantially linearly over the period. Section 12. A method for increasing nuclear spin polarization in a target compound, comprising: (a) obtaining the target compound or a parahydrogenation precursor of the target compound, wherein the target compound or the parahydrogenation precursor of the target compound comprises at least (i) a first proton, (ii) a second proton coupled to at least the first proton by a first J coupling constant, wherein the first and second protons have singlet spin order, (iii) a third proton coupled to at least one of the first or second protons by a second J coupling constant, and (iv) at least a third by a third J coupling constant A method comprising: (b) obtaining a target atom bonded to protons, wherein the first and second protons are separated from the target atom by at least four chemical bonds; (b) placing the target compound or parahydrogenation precursor within an average magnetic field strength of less than 500 mT; and (c) applying a magnetic resonance (MR) pulse sequence to the target compound or parahydrogenation precursor, wherein the MR pulse sequence is configured to transfer a group of protons from the first and second protons to the target atom, thereby imparting at least 1%, 2%, 5%, 10%, or 20% non-equilibrium nuclear spin polarization to the target atom. Article 13. The method according to Article 12, wherein the first, second, and third protons form a quantum mechanical three-body system having high-density energy eigenstates and low-density energy eigenstates. Paragraph 14. The method described in Paragraph 13, wherein multiple eigenstates are densely clustered. The method according to paragraph 13 or 14, wherein the MR pulse sequence is configured to collectively transition from a high-density energy eigenstate to a low-density energy eigenstate, thereby imparting at least 1%, 2%, 5%, 10%, or 20% non-equilibrium nuclear spin polarization to a target atom. The method according to any one of paragraphs 13 to 15, wherein, prior to paragraph 16(b), the dense energy eigenstates have a total population of at least 50%, 60%, 70%, 80%, or 90%. The method according to any one of paragraphs 12 to 16, further comprising conferring singlet spin order to the first and second protons before paragraph 17(a). The method according to paragraph 17, comprising adding a first proton and a second proton across the unsaturated bond of a precursor to impart singlet spin order to a first and second proton, thereby carrying out a parahydrogen-induced polarization (PHIP) reaction between a parahydrogen and a precursor, and thereby forming a parahydrogenated precursor. Item 19. The method according to item 18, wherein the precursor of the compound comprises a side chain containing at least one unsaturated bond and at least a third proton, thereby, following a PHIP reaction, the side chain contains at least a first proton, a second proton, and a third proton. Section 20. The method according to Section 19, further comprising cleaving a side chain from a precursor to form a target compound. The method according to paragraph 20, wherein conferring singlet spin order to the first and second protons carries out a signal amplification (SABRE) reaction by reversible exchange between parahydrogen molecules and a target compound, thereby transferring polarization from the parahydrogen molecules to the nuclei on the target compound. Section 22. The first J bond constant is J 12 This is shown, and the second J bond constant is J 23 As shown, the MR pulse sequence is approximately

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Claims

1. A system for generating hyperpolarized target compounds, A hydrogenation device configured to produce a parahydrogenated solution by mixing a solvent, parahydrogen gas, and a precursor of the target compound, wherein the precursor contains an unsaturated chemical bond, A polarization device configured to generate a polarization solution containing the superpolarized target compound using the parahydrogenated solution, wherein the polarization device is (a) A polarization chamber configured to receive the parahydrogenated solution, wherein the polarization chamber includes a polarization region having a volume of at least 10 milliliters (mL), (b) One or more radio frequency (RF) coils disposed around the polarization region of the polarization chamber, and (c) A polarization device including a magnetic field source disposed around the polarization region of the polarization chamber and configured to provide an average magnetic field strength of up to 200 millitesla (mT), An RF waveform generator coupled to one or more RF coils of the polarization device, wherein the RF waveform generator is configured to apply a polarization transition waveform to the one or more RF coils over a predetermined period of time, The system comprises a purification system configured to separate the purified fraction from the polarized solution, The polarization transition waveform is The frequency that remains substantially constant during the aforementioned period, The frequency changes substantially linearly during the aforementioned period. An amplitude that is substantially constant during the aforementioned period, or Amplitude that changes substantially linearly over the aforementioned period Including at least one of the following: system.

2. The system according to claim 1, further comprising a dissolution chamber configured to contain the purified fraction and to receive a second solvent for dissolving the purified fraction.

3. The system according to claim 1, wherein the polarization device comprises a magnetic shield, and the magnetic shield is disposed around the polarization region of the polarization chamber.

4. The system according to claim 3, wherein the magnetic shield is configured to maintain the magnetic field strength in the polarization chamber below 200 mT while the polarization transition waveform is applied to one or more RF coils.

5. The system according to claim 1, wherein the hydrogenation device comprises a bubbler configured to introduce the parahydrogen gas into the solvent, a membrane configured to allow the diffusion of the parahydrogen gas into the solvent, or an aerozoizer configured to spray droplets of the solvent into a parahydrogen chamber configured to receive the parahydrogen gas.

6. The system according to claim 1, wherein the precursor of the target compound comprises the target compound chemically bonded to a side chain containing the unsaturated chemical bond.

7. The system according to claim 6, wherein the precursor of the target compound comprises an ester of the target compound.

8. The system according to claim 6, wherein the purification system is configured to receive a cleavage solution configured to cleave the side chain from the precursor of the target compound, thereby producing the hyperpolarized target compound.

9. The system according to claim 1, wherein the purification system includes a separation system, the purified fraction of the polarized solution includes a precipitated fraction of the polarized solution, and the separation system is configured to separate the precipitated fraction of the hyperpolarized target compound from the polarized solution.

10. The system according to claim 9, further comprising a dissolution chamber, the dissolution chamber being configured to contain the precipitate fraction and to receive a second solvent for dissolving the precipitate fraction.

11. A method for generating a hyperpolarized target compound, comprising the following: Using a hydrogenation device, a parahydrogen solution is produced by mixing a solvent, parahydrogen gas, and a precursor of the target compound, wherein the precursor contains unsaturated chemical bonds; Using a polarization device, a polarization solution containing a hyperpolarized target compound is generated using a parahydrogenated solution, where the polarization device is (a) A polarization chamber configured to receive a parahydrogenated solution, wherein the polarization chamber includes a polarization region having a volume of at least 10 milliliters (mL), (b) One or more radio frequency (RF) coils arranged around the polarization region of the polarization chamber, and (c) A magnetic field source, disposed around the polarization region of the polarization chamber and configured to provide an average magnetic field strength of up to 200 millitesla (mT), including; Applying a polarization transition waveform to one or more RF coils over a predetermined period of time using an RF waveform generator coupled to one or more RF coils of a polarization device, wherein the polarization transition waveform is The frequency that remains substantially constant during the aforementioned period, The frequency changes substantially linearly during the aforementioned period. An amplitude that is substantially constant during the aforementioned period, or Amplitude that changes substantially linearly over the aforementioned period Includes at least one of the following; Separating the purified fraction from the polarized solution using a purification system.

12. The method according to claim 11, further comprising using a dissolution chamber to contain the purified fraction and to receive a second solvent for dissolving the purified fraction.

13. The method according to claim 11, wherein the polarization device comprises a magnetic shield, the magnetic shield is disposed around the polarization region of the polarization chamber.

14. The method according to claim 11, further comprising using a magnetic shield to maintain the magnetic field strength in the polarization chamber below 200 mT while applying a polarization transition waveform to one or more RF coils.

15. The hydrogenation device has a bubbler, a membrane, or an elarosolyzer. The method according to claim 11, further comprising: introducing parahydrogen gas into a solvent using a bubbler; enabling the diffusion of parahydrogen gas into the solvent using a membrane; or spraying droplets of the solvent into a parahydrogen chamber configured to receive parahydrogen gas using an aerozoizer.

16. The method according to claim 11, wherein the precursor of the target compound comprises a target compound chemically bonded to a side chain containing an unsaturated chemical bond.

17. The method according to claim 11, wherein the precursor of the target compound comprises an ester of the target compound.

18. The method according to claim 17, further comprising receiving a cleavage solution using a purification system, thereby cleaving a side chain from a precursor of a target compound, thereby generating a hyperpolarized target compound.

19. The method according to claim 11, wherein the purification system comprises a separation system, the purified fraction of the polarized solution comprises a precipitated fraction of the polarized solution, and the method further comprises separating the precipitated fraction of the hyperpolarized target compound from the polarized solution using the separation system.

20. The method according to claim 19, further comprising using a dissolution chamber to contain the precipitated fraction and to receive a second solvent for dissolving the precipitated fraction.

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