Cyclen-based compounds and their Gd(III) complexes for use as multimodal PET / MRI contrast agents

Abstract

The present invention relates to the use of cyclen compounds of general formula (I) for the preparation of multimodal PET / MRI contrast agents: [Formula 1] TIFF2025540211000059.tif39169 In the above formula, R is NO2 or F; A is independently -CH2COOH; -CH(CH3)COOH; -CH((CH2) n -CH3)COOH (wherein n is an integer ranging from 1 to 3); and -CH2P(=O)(OH)Ph; Z is H or A. The present invention also relates to a Gd(III) complex of a compound of general formula (I) (wherein R is 18 F).

Description

Detailed Description of the Invention

[0001] [Technical Field] The present invention provides a method for producing a complex comprising the steps of: 18 F and Gd 3+ The present invention relates to cyclen-based compounds, their Gd(III) complexes, and their use as multimodal PET / MRI contrast agents.

[0002] [Background technology] Magnetic resonance imaging (MRI) and positron emission tomography (PET) are among the most powerful tools in clinical imaging. The information provided by these techniques is, to a large extent, complementary. State-of-the-art equipment combines the advantages of both techniques into a single hybrid PET / MRI technique.

[0003] MRI is valued for providing excellent anatomical images of soft tissues at high resolution. MRI can measure the movement of the body's water molecules, which make up approximately 60-70% of body weight. 1 It is based on the magnetic resonance signal of the H nucleus. In MRI, organs can be easily distinguished by differences in water content or relaxation rate of the magnetic resonance (MR) signal. When intrinsic contrast is insufficient, exogenous contrast agents can be administered intravenously. These are mainly based on gadolinium(III) chelates and are known as gadolinium-based contrast agents (GBCAs). Typical examples are chelates of the macrocyclic ligand DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and the open-chain ligand DTPA (diethylenetriaminepentaacetic acid). The purpose of the paramagnetic Gd(III) ion is to detect the presence of ions in the vicinity of water. 1The primary function of GBCAs is to induce relaxation of the H nucleus, and the ligand serves to mask the toxicity of this metal ion. In general, macrocyclic DOTA-like chelators are known to provide Gd(III) chelators with much higher kinetic inertness than acyclic DTPA-like chelators. High kinetic inertness is desirable for in vivo applications because it prevents toxic Gd(III) ions from detaching from the chelate. Therefore, macrocyclic chelators are preferred. Currently used GBCAs are nonspecific compounds, i.e., they do not bind to specific molecular targets. However, they provide important diagnostic information based on differences in tissue diffusion and perfusion properties. These differences are often associated with pathological changes. The resulting differences in GBCA biodistribution can be visualized by MRI, revealing pathological conditions.

[0004] PET is valued for its exceptional sensitivity in providing specific information about molecular targets. The technique relies on the administration of a tracer molecule labeled with a positron-emitting radionuclide. When the radionuclide decays, the emitted positron annihilates with a nearby electron, generating two gamma photons traveling in opposite directions (180 degrees apart). An external detector array registers both photons and reveals their origins, allowing for the construction of an image of the tracer molecule within the body. This photon-counting principle makes PET a highly sensitive and quantitative technique. Because only very small amounts of tracer molecule are required for detection, it is possible to target and image low-abundance molecular targets. A drawback is the lack of anatomical imaging. For this reason, PET is often combined with computed tomography (CT) or, more recently, MRI, both of which can provide anatomical reference images. 11 C. 13 N, 18 F, 64 Cu, 68 Ga, 89 Many PET tracers using various PET nuclides, including Zr, have been clinically approved or are under development. 18 F is 18It is the most widely used because it can be prepared in large quantities cost-effectively by cyclotron irradiation of O-enriched water. 18 F has a moderate half-life of 110 minutes, making it suitable for the synthesis of a wide range of small organic tracer molecules, and is the most common clinical PET tracer. 18 F]FDG (fluorodeoxyglucose).

[0005] PET / MRI combination systems offer significant advantages over separate PET and MRI and other imaging techniques. Primarily, PET / MRI examinations reduce patient radiation burden compared with PET / CT and provide excellent anatomical images of soft tissues. Simultaneous acquisition of temporally and spatially coincident images from both modalities offers improved diagnostic accuracy, speed, and the opportunity for the discovery of new diagnostic imaging markers. However, current PET / MRI practice relies on the separate administration of two contrast agents: a radiotracer for PET and a GBCA for MRI. These have completely independent pharmacokinetic behaviors and provide independent diagnostic information. There are no clinically approved agents that simultaneously provide PET signal and MRI contrast from a single compound. In fact, only a few such compounds have been reported in the literature to date. Combining a Gd(III) chelate and a PET radionuclide into a single, stable, and well-defined molecule presents significant synthetic challenges and has hindered progress. One of the earliest examples [Frullano, L. et al., Angew. Chem. Int. Ed. 2010, 49 (13), 2382-2384] was via a click reaction. 18 reported a pH-responsive PET / MRI contrast agent based on a Gd(III) chelate with a F-bearing prosthetic group, with an overall yield of only 0.6% using a multi-step synthesis. The same group then partially dechelated one of the four Gd(III) chelates, followed by 64A PET / MRI version of the fibrin-targeting MRI drug EP-2104R was prepared by complexing it with Cu(II) [Uppal, R. et al., Radiology 2011, 258 (3), 812-820]. However, the lack of control over the decomplexation / complexation strategy resulted in a mixture of positional isomers rather than a single well-defined compound. 68 Some researchers have attempted to create dendrimer-like polymetallic structures by decorating Ga(III) chelates with multiple Gd(III) chelates, resulting in fairly large and complex molecules [Kumar, A. et al., Bioconjugate Chem. 2015, 26 (3), 549-558; Notni, J. et al., Chem. Eur. J. 2013, 19 (38), 12602-12606]. However, the translation of such complex molecules into clinical practice is usually hindered by poor synthetic reproducibility.

[0006] Another challenge faced when preparing a combined PET / MRI contrast agent is that the amount of radionuclide required for PET signal is approximately 9–10 orders of magnitude less than the Gd(III) chelate required for MRI contrast. To meet these conflicting demands, a mixture of two isotopically distinct versions of the agent can be prepared. The agent containing the active PET isotope is present in only trace amounts necessary to obtain a PET signal, while the majority of the agent is a chemically identical molecule containing a stable (non-radioactive) isotope. A larger amount of this non-radioactive version is required to obtain the desired MRI contrast. Because the two versions are chemically identical (different only by isotope), they have the same pharmacokinetic properties. However, if the agent utilizes a metal PET radionuclide, this implies the coadministration of a relatively large amount of non-radioactive exogenous metal, which poses a significant risk of metal-induced toxicity. From this perspective, 18 The use of F has advantages over metallic PET nuclides. 18 Not only is F a widely available and inexpensive isotope, but it also forms a stable covalent bond, CF, and fluorinated compounds are generally well tolerated.

[0007] 18 Despite the advantageous properties of the F isotope, challenges remain to achieve its rapid and efficient incorporation into PET / MRI agents, especially regarding the stability of Gd(III) chelates as MRI contrast sources due to radioactive decay. 18 To limit the loss of the F isotope, it is ideally conjugated to the molecule at the final stage of synthesis. While methods have been developed to achieve this for pure organic PET tracers, the presence of a Gd(III) chelate in a PET / MRI agent is incompatible with many synthesis and purification conditions. For example, Gd(III) chelates are commonly 18 They have poor solubility in the water-free organic solvents required for F-labeling chemistry. Additionally, Gd(III) chelates are unstable under the acidic conditions required for chromatographic or ion-exchange purification of the final product. Therefore, the conditions developed for the synthesis of pure organic PET tracers cannot be directly applied to Gd(III) chelate chemistry.

[0008] Thus, it will provide access to well-defined small molecule PET / MRI agents similar to MRI contrast agents currently in clinical use. 18 The background art is lacking compounds and methods for the rapid and efficient labeling of Gd(III) chelates with F radionuclides.

[0009] DISCLOSURE OF THE INVENTION In the background art, a moderate number of bimodal PET / MRI agents have been prepared, based on fairly complex bimetallic compounds or multi-step syntheses to achieve labeling with PET isotopes. These examples have failed to provide simple and easily synthetically achievable molecular PET / MRI agents similar to nonspecific MRI contrast agents currently in clinical use. In contrast, we demonstrate that macrocyclic Gd(III) chelates bearing pyridine arms equipped with suitable leaving groups are capable of inhibiting neutrophil attack. 18We have found that macrocyclic chelator molecules can be conveniently labeled with F-fluoride anions. This one-step reaction is fast and proceeds directly on the preformed Gd(III) chelate, thus eliminating the need for an additional complexation step. The macrocyclic chelator molecule is structurally closely related to DOTA, which, in its Gd(III) chelate form, has a long track record of safe clinical use as an MRI contrast agent. Surprisingly, we have found that 18 F labeling also allows the identification of the Gd(III) chelate in the pyridine moiety. 19 From F 18 We found that isotope exchange to F was also possible, but this reaction did not occur at all or proceeded in very low yields when performed with the free macrocyclic chelator. This is because the Gd(III) chelate was preferentially labeled, leaving Gd(III) and 18 This ensures that cleaner, desired products containing both fluorine and fluorine are obtained, acting as multimodal PET / MRI agents. Furthermore, this synthetic approach allows for the adjustment of the molar ratio of the PET-active (radiolabeled) and non-radioactive versions of the agent, allowing for the desired PET signal and MRI contrast to be tailored to specific PET / MRI devices and applications. Thus, these compounds and their radiolabeling methods overcome the problems of the background art discussed above.

[0010] The object of the present invention is the use of cyclen compounds of general formula (I) in pharmacy, preferably for preparing multimodal PET / MRI contrast agents.

[0011] [ka] In the above formula, R is NO2 or F; A is independently -CH2COOH; -CH(CH3)COOH; -CH((CH2) n -CH3)COOH (wherein n is an integer ranging from 1 to 3); -CH2P(=O)(OH)Ph; Z is H or A.

[0012] The compounds of general formula (I) can be synthesized from nitro-pyridine or fluoro-pyridine intermediates of general formula (II).

[0013] [ka] In the above formula, R is NO2 or F; and X is a halogen, preferably Cl or Br.

[0014] The intermediate of general formula (II) is reacted with a cyclen-based intermediate of general formula (III).

[0015] [ka] In the above formula, A' is A (as defined above) in which the OH group is protected, preferably a methoxy group, an ethoxy group or a tert-butoxy group; and Z' is hydrogen or A'.

[0016] The resulting precursor of general formula (IV) is then deprotected (removing the protection of the OH group), preferably using trifluoroacetic acid, to give the compound of general formula (I) as defined above.

[0017] [ka] In the above formula, Z' and A' are as defined above.

[0018] In one preferred embodiment of the cyclen-based compounds of general formula (I), A and Z are the same and are preferably selected from -CH2P(=O)(OH)Ph; and -CH(CH3)COOH.

[0019] In one preferred embodiment of the cyclen-based compounds of general formula (I), A is the same and is preferably selected from -CH2P(=O)(OH)Ph; and -CH(CH3)COOH; and Z is hydrogen.

[0020] In one preferred embodiment, R is located para to the nitrogen atom of the pyridyl pendant arm. More preferably, R is F.

[0021] In one embodiment, the cyclen-based compound of general formula (I) is selected from the group consisting of: 2,2',2''-(10-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L 1 ) 2,2',2''-(10-((6-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L 2 ) 2,2',2''-(10-((3-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L 3 ) 2,2',2''-(10-((4-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L 4 ) 2,2',2''-(10-((5-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L 5 ) 2,2',2''-(10-((6-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L 6 ) 2,2'-(4-((4-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,7-diyl)diacetic acid (L 7 ) (2S,2'S,2''S)-2,2',2''-(10-((3-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)tripropionic acid (L 8 ) ((4-((3-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(methylene))bis(phenylphosphinic acid)(L 9 ) 2,2'-(4-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,7-diyl)diacetic acid (L 10 ) (2S,2'S,2''S)-2,2',2''-(10-((4-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)tripropionic acid (L 11 ) (2S,2'S,2''S)-2,2',2''-(10-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)tripropionic acid (L 12 ).

[0022] The subject of the present invention are also compounds of general formula (Ia):

[0023] [ka] In the above formula, R is NO or F, preferably R is F; A is independently -CH(CH3)COOH; -CH((CH2) n and Z is H or A, preferably Z is A.

[0024] Preferably, the R substituent is located para to the nitrogen atom of the pyridyl pendant arm. More preferably, A is —CH(CH 3 )COOH.

[0025] In the most preferred embodiment, the compounds according to the invention have the following formula (Va, Vb), in which all -C*H(CH3)COOH groups have the same configuration (all have the S configuration or all have the R configuration):

[0026] [ka] Preferably, the R substituent in the compound of formula (Va) or (Vb) is located para to the nitrogen atom of the pyridyl pendant arm. More preferably, R is F.

[0027] A further object of the present invention is a coordination compound of Gd(III) ions with a cyclen-based compound of general formula (I) or (Ia) as defined above, and its use in medicine for preparing a multimodal PET / MRI contrast agent. The coordination compound is a cyclen-based compound of general formula (I) or (Ia) with Gd(III) ions. 3+ The compounds of formula (I) or (Ia) can be prepared by reacting them with a salt (e.g., GdCl) to form a Gd(III) chelate of the compound of formula (I) or (Ia). Such Gd(III) chelates are suitable contrast agents for MRI imaging due to their high thermodynamic stability, kinetic inertness, and favorable relaxivity properties.

[0028] Multimodal PET / MRI contrast agents contain Gd(III) chelates. 18 The above-described coordination compounds of Gd(III) ions and cyclen compounds of general formula (I) or (Ia) can be prepared by radiolabeling with F. Radiolabeling can be performed by radiolabeling the pyridine moiety of the Gd(III) chelate where R is F. 19 From F 18 Use isotopic exchange to F or use nitro groups where R is NO218 For Gd(III) chelates containing R as NO2, both radiolabeling methods can be used in combination, in this case the nitro group 19 Aromatic nucleophilic substitution with F followed by 19 From F 18 In both cases, the radiolabeling is performed on the Gd(III) chelate, not on the ligand itself. Therefore, the product is Gd(III) and 18 F, making it suitable to act as a multimodal PET / MRI agent. Preferably, the radioisotope label is a cyclotron-generated 18 F - and mixed with the Gd(III) chelate at 90° C., preferably for at least 5 minutes.

[0029] Therefore, another object of the present invention is a multimodal PET / MRI contrast agent of general formula (VI):

[0030] [ka] In the formula, A is independently selected from the group consisting of -CH2COOH; -CH(CH3)COOH; -CH((CH2) n -CH3)COOH (wherein n is an integer ranging from 1 to 3); and -CH2P(=O)(OH)Ph; Z is H or A.

[0031] Preferably, 18 F is para to the nitrogen atom of the pyridyl pendant arm.

[0032] In one embodiment, the multimodal PET / MRI contrast agent has the general formula (VIa):

[0033] [ka] In the formula, A is independently selected from the group consisting of -CH2COOH; -CH(CH3)COOH; -CH((CH2) n and —CHP(═O)(OH)Ph; preferably, A is —CH(CH)COOH or —CHP(═O)(OH)Ph.

[0034] Preferably, 18 When F is in the para position relative to the nitrogen atom of the pyridyl pendant arm, then A is not -CH2COOH.

[0035] In one preferred embodiment, Z is A, more preferably A is -CH(CH3)COOH, and even more preferably all A(-C*H(CH3)COOH) have the same configuration (all A have S configuration or all A have R configuration). Most preferably, all A have the same configuration, 18 F is para to the nitrogen atom of the pyridyl pendant arm.

[0036] In one embodiment, the multimodal PET / MRI contrast agent has the general formula (VIb):

[0037] [ka] In the formula, A is independently selected from the group consisting of -CH2COOH; -CH(CH3)COOH; -CH((CH2) n and -CHP(=O)(OH)Ph; preferably, A is -CH(CH)COOH or -CHP(=O)(OH)Ph. More preferably, A is -CH(CH)COOH, and even more preferably, the configuration of both A(-C*H(CH)COOH) is the same.

[0038] In a most preferred embodiment, the multimodal PET / MRI contrast agent has the general formula (VI), (VIa) or (VIb), wherein: 18 F is in the para position relative to the nitrogen atom of the pyridyl pendant arm.

[0039] The object of the present invention is also a method for preparing a multimodal PET / MRI contrast agent of said general formula (VI) as defined above, said method comprising the following steps: a) providing a cyclen-based compound of general formula (I) as defined above; b) forming a Gd(III) chelate of the compound of general formula (I); c) reacting the Gd(III) chelate with 18 Radiolabeled with F.

[0040] In one embodiment, step b) comprises reacting the cyclen compound of general formula (I) with Gd 3+ This is achieved by reacting the compound with Gd(III) ions, thereby forming a Gd(III) chelate of the compound of general formula (I). Preferably, the conditions for the chelation reaction are as follows: Gd in the form of salts (e.g., chloride, bromide, sulfate, nitrate, methanesulfonate, trifluoromethanesulfonate, formate, acetate, lactate, malate, citrate, 2-hydroxyisobutyrate, mandelate, diglycolate, tartrate) 3+ The solution containing the ions and the solution of the compound of general formula (I) are preferably mixed. 3+The ions and the compound of general formula (I) are mixed in a molar ratio of 1:0.5 to 1:100, preferably 1:0.7 to 1:50, and even more preferably 1:0.9 to 1:10. The concentration of the soluble component can be selected from a range allowed by the solubility of such compounds in a given solvent at a given temperature, preferably in the range of 0.000001 to 0.5 mol / L. The solvent may be water, a water-miscible organic solvent (e.g., methanol, ethanol, propanol, isopropanol, acetone, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran), or a mixture thereof. To compensate for the protons released during complex formation, an organic or inorganic base, such as LiOH, NaOH, KOH, aqueous NH3, triethylamine, N,N-diisopropylethylamine, or pyridine, is added to the reaction mixture, and the complex formation is carried out in the solution. Preferably, 1 to 10 molar equivalents of base are added per molecule of the compound of formula (I). Finally, the reaction can be carried out in a buffer solution. In this case, it is not necessary to add an organic or inorganic base to the reaction mixture. Stirring or shaking the mixture at room temperature or an elevated temperature for up to 24 hours results in complete complex formation. Preferably, the mixture is stirred or shaken at 40°C for 15 minutes. A moderate excess of the compound of formula (I) can be used to promote complex formation and shift the equilibrium toward chelate formation. The resulting Gd(III) chelate of the compound of formula (I) can optionally be desalted and purified from the excess compound of formula (I) and other impurities. The purification can be achieved, for example, by column chromatography or high-performance liquid chromatography (HPLC). Preferably, chromatographic separation is achieved using HPLC on a C8, C18, or phenyl-hexyl reversed phase. The mobile phase used for chromatographic purification can contain water and 3 to 40% by volume of methanol, ethanol, or acetonitrile. Optionally, a 0.01-0.1 mol / L buffer is used in the mobile phase, where the buffer comprises ammonium formate pH=7.0 or ammonium acetate pH=7.0.Fractions containing the desired metal chelate are collected and evaporated or lyophilized.

[0041] In one embodiment, the Gd(III) chelate from step b) 18 The step c) of radiolabeling with F comprises the step of: 19 From F 18 or by isotopic exchange to F in the pyridine moiety of the Gd(III) chelate (where R is a nitro group). 18 This is achieved by using aromatic nucleophilic substitution of the nitro group by F.

[0042] Preferably, step c) is carried out under the following conditions: The Gd(III) chelate from step b) is preferably dissolved in a solvent selected from the group consisting of acetone, acetonitrile, dichloromethane, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), dimethylpropyleneurea (DMPU), dimethyl sulfoxide (DMSO), sulfolane, ethyl acetate, hexamethylphosphoramide (HMPA), pyridine, tetrahydrofuran (THF), methanol, ethanol, propanol, isopropanol, butanol, tert-butanol, N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone, tert-amyl alcohol, water, or a mixture thereof. Preferably, the final concentration of Gd(III) chelate in the solvent or solvent mixture is less than 10 -12 The range is 10 M to 2 M. -12 Non-radioactive F to achieve concentrations in the range of 1 M to 2 M - An ion source is added. - The ion source may be, for example: tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, tetrabutylammonium fluoride, tetrahexylammonium fluoride, NaF, KF, RbF, CsF, [Na(15-crown-5) + ]F- , [K(18-crown-6) + ]F - , [Cs(21-crown-7) + ]F - , [Na(cryptand[2.2.1]) + ]F - , [K(cryptand[2.2.2]) + ]F - or [Cs(cryptand [3.2.2]) + ]F - . 19 To achieve nucleophilic aromatic substitution of the NO group with F, non-radioactive F - If the Gd(III) chelate from step b) does not contain any NO groups, then non-radioactive F - The addition of an ion source can be omitted.

[0043] Similarly, radioactive 18 F - The ion source is added in an amount corresponding to the desired activity. In terms of molar equivalents, this is the amount of Gd(III) chelate and / or non-radioactive F - This corresponds to a small fraction of the amount of ions. 18 F - The amount (activity) of the ion will be known to those skilled in the art without any inventive activity. 18 F - The ion source is the non-radioactive F - Similar to an ion source (e.g., [ 18 F]tetramethylammonium fluoride, [ 18 F]tetraethylammonium fluoride, [ 18 F]tetrapropylammonium fluoride, [ 18 F]tetrabutylammonium fluoride, [ 18 F]Tetrahexylammonium fluoride, Na 18 F, K 18 F, Rb 18 F, Cs 18 F, [Na(15-crown-5) + ] 18 F - , [K(18-crown-6)+ ] 18 F - , [Cs(21-crown-7) + ] 18 F - , [Na(cryptand[2.2.1]) + ] 18 F - , [K(cryptand[2.2.2]) + ] 18 F - or [Cs(cryptand [3.2.2]) + ] 18 F - The reaction mixture is then stirred at a temperature in the range of -50°C to 250°C, preferably in the range of 5°C to 200°C, for at least 0.1 seconds, preferably for up to 8 hours.

[0044] In a more preferred embodiment, step c) is carried out in a solvent selected from acetonitrile, DMF, DMAC, DMPU, DMSO, sulfolane, HMPA, THF, tert-butanol, NMP, 1,3-dimethyl-2-imidazolidinone, tert-amyl alcohol, water or a mixture thereof. The final concentration of Gd(III) chelate in said solvent or solvent mixture is 10 -6 M to 0.5M. Optionally, non-radioactive F - Add an ion source and -6 Achieve concentrations ranging from 0.5M to 0.5M. Non-radioactive F - The ion source is preferably tetramethylammonium fluoride, tetrabutylammonium fluoride, NaF, KF, CsF, [Na(15-crown-5) + ]F - , [K(18-crown-6) + ]F - , [Na(cryptand[2.2.1]) + ]F - and [K(cryptand [2.2.2]) + ]F - is selected from.

[0045] radioactive 18 F -The ion source is added in an amount corresponding to the desired activity. 18 F - The ion source is the non-radioactive F - Similar to an ion source (e.g., [ 18 F]tetramethylammonium fluoride, [ 18 F]Tetrabutylammonium fluoride, Na 18 F, K 18 F, Cs 18 F, [Na(15-crown-5) + ] 18 F - , [K(18-crown-6) + ] 18 F - , [Na(cryptand[2.2.1]) + ] 18 F - or [K(cryptand[2.2.2]) + ] 18 F - The reaction mixture is then stirred at a temperature ranging from 25° C. to 200° C. for at least 1 minute, preferably up to 2 hours.

[0046] Most preferably, the solvent is selected from acetonitrile, DMF, DMSO, or a mixture thereof. The final concentration of the Gd(III) chelate ranges from 0.1 mM to 100 mM. Optionally, non-radioactive F - Add the ion source to achieve a concentration ranging from 1 mM to 300 mM. - The ion source is preferably tetrabutylammonium fluoride or [K(cryptand [2.2.2]) + ]F - Radioactive 18 F - The ion source is added in an amount corresponding to the desired activity. 18 F - Source: [ 18 F]tetrabutylammonium fluoride and [K(cryptand[2.2.2]) + ] 18 F -The reaction mixture is then stirred at a temperature ranging from 25°C to 150°C for at least 1 minute, preferably up to 100 minutes.

[0047] An object of the present invention is also a method of imaging a region of interest in a patient using multimodal PET / MRI imaging, said method comprising: - administering to a patient a pharmaceutical formulation comprising a multimodal PET / MRI contrast agent of general formula (VI), (VIa) or (VIb); - detecting the arrival of a multimodal PET / MRI contrast agent present in the pharmaceutical formulation in the region of interest by comparing the PET signal and / or the MRI signal in the region of interest during or after administration of the pharmaceutical formulation; - acquiring PET and MRI image data of the region of interest; and - constructing a multimodal PET / MRI image of the region of interest using the PET and MRI image data, the region of interest being displayed distinct from background tissue.

[0048] Pharmaceutical formulations containing the multimodal PET / MRI contrast agent of general formula (VI), (VIa) or (VIb) may further contain conventionally used pharmaceutically acceptable auxiliary substances. The dosage form of the pharmaceutical formulation is a form for administration by injection, most often as a bolus or as an infusion, preferably intravenously. Suitable pharmaceutically acceptable auxiliary substances are preferably selected from the group consisting of solvents (especially aqueous solutions or saline), buffers (especially phosphate buffers, HEPES = 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid), ionizing additives, antioxidants, and antibacterial additives. A person skilled in the art would be able to determine which auxiliary substances to select without performing any inventive activity.

[0049] In one embodiment, the pharmaceutical formulation further comprises a coordination compound of Gd(III) ions with a cyclen-based compound of general formula (I) or (Ia), as defined above. Gd(III) and19 The presence of the coordination compound containing F provides an MRI signal, while 18 The presence of a multimodal PET / MRI contrast agent of general formula (VI), (VIa) or (VIb) having F provides PET and MRI signals. 18 Since the amount of F radionuclide is about 9-10 orders of magnitude lower than the amount of Gd(III) chelate required for MRI imaging, the MRI imaging of the pharmaceutical formulations can be enhanced by the presence of a non-radioactive Gd(III) chelate of a compound of general formula (I) or (Ia) as defined above. When the radioactive and non-radioactive Gd(III) chelates differ only in the fluorine isotope (the coordination compounds are structurally identical, 19 F isotope or 18 The concentration of the non-radioactive Gd(III) chelate should be sufficient to achieve MRI imaging, and the concentration of the PET / MRI contrast agent should be sufficient to achieve PET imaging. The concentration of the Gd(III) chelate to achieve MRI imaging and the concentration of the PET / MRI contrast agent to achieve PET imaging are preferably selected. 18 The concentration of the F radionuclide will be known to those skilled in the art. Generally, the molar ratio of the non-radioactive Gd(III) chelate of the compound of general formula (I) or (Ia) to the PET / MRI contrast agent of general formula (VI), (VIa) or (VIb) is preferably about 1:10. -10 ~about 1:10 -8 It should be.

[0050] An object of the present invention is also a multimodal PET / MRI contrast agent of general formula (VI), (VIa) or (VIb) and / or a pharmaceutical formulation comprising same, for use in medicine, preferably for use in combined PET / MRI diagnostic methods.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: [Gd(L)] as precursor 1Chromatogram of the radiolabeling experiment from Example 4 using ). The product corresponds to the peak at 7.431 minutes in the UV detector. The product corresponds to the peak at 7.767 minutes in the gamma detector.

[0052] Figure 2: [Gd(L)] as precursor 4 Chromatogram of the radiolabeling experiment from Example 4 using ). The product corresponds to the peak at 7.343 minutes in the UV detector. The product corresponds to the peak at 7.700 minutes in the gamma detector.

[0053] Figure 3: L as precursor 4 Chromatogram of the radiolabeling experiment of Example 4 using 100 mg of 10 ... 18 F - The main peak in the UV detector corresponds to the unlabeled starting material L 4 is equivalent to

[0054] Figure 4: [Gd(L 4 )] and [Gd(L 7 )] at 37°C and 0.47T, determining the relaxation rate by linear regression of concentration versus longitudinal relaxation rate.

[0055] Figure 5: Relaxation rate measurements in a relaxometer reveal the acid-assisted decomplexation of [Gd(L)] in 0.1 M HCl at 37 °C. 4 )], [Gd(L 7 Comparison of the kinetic inactivity of ) and Magnevist. The upper graph shows data from 4 hours after the start of the experiment, and the lower graph shows data from 24 hours after the start of the experiment. 1p The values ​​should be the same for all measured complexes after thermodynamic equilibrium has been reached, but elemental analysis confirmed that slight differences in the concentrations of the samples (pipetting errors) explain this difference. Data for unchelated GdCl3 solutions of the same molar concentration are shown for reference. The curves illustrate the differences in kinetic inertness of the metal chelates. Magnevist, which is used clinically, is degraded almost immediately (<5 min), whereas [Gd(L7 )] takes longer to reach complete decomplexation. Finally, the [Gd(L 4 ) chelate is the most inactive, and even after 24 hours under these conditions the curve is far from reaching thermodynamic equilibrium, indicating that the majority of the chelate remains intact.

[0056] Figure 6: Radiolabeled [Gd(L 4 (A) In vitro simultaneous PET / MRI imaging of different concentrations of radioisotope labeled [Gd(L)]. 4 (B) T1-weighted MRI and PET images acquired simultaneously in an array of vials containing [Gd(L)], different concentrations of Magnevist as a reference, and two samples of pure HO and PBS (phosphate-buffered saline). Numbers indicate the concentration of the contrast agent in mM. (C) The concentration of [Gd(L)] in the samples from panel A quantified by ICP-OES (gadolinium content) and gamma counting (radioactivity). 4 Quantification of the PET signal from panel A also shows excellent linear correlation with the MRI signal (C) derived from T1-weighted images and the relaxation rate (D) derived from the T1 map.

[0057] Figure 7: PET / MRI of radiolabeled [Gd(L)] in mice (N=3) showing rapid uptake and clearance from the kidney. 4 Pharmacokinetics of )]. (A) Pharmacokinetic curve derived from MRI T1 maps, expressed as % change in 1 / T1. (B) Pharmacokinetic curve derived from PET images, expressed as % injected volume per mL. The right axis relates to bladder data.

[0058] Figure 8: Radiolabeling of [Gd(L)] in mice (N=6) 4 Biodistribution of ). (A) Biodistribution based on measurement of radioactivity (gamma counter) expressed as % injected dose per gram of wet tissue. (B) Biodistribution based on measurement of gadolinium (ICP-OES) expressed as % injected dose per gram of wet tissue.

[0059] Figure 9: Radiolabeling of [Gd(L) 4 Simultaneous in vivo PET / MRI imaging of )]. From left to right, images represent multiple time points: pre-injection image, injection, 10 minutes post-injection, and 60 minutes post-injection. Top row: T1-weighted dynamic contrast-enhanced (DCE) MRI. Middle row: PET image. Bottom row: Merged MRI and PET image. The PET image shows a notable hot spot in the kidney, while the MRI shows the same area as the kidney, appearing dark due to oversaturation.

[0060] [Example] Example 1: Synthesis of intermediates [ka] Synthesis of intermediate (1): In a 250 mL round-bottom glass flask, 2-methyl-4-nitropyridine N-oxide (5.15 g, 33.4 mmol, 1.0 equiv.) was dissolved in DCM (200 mL). A solution of TFAA (14 mL, 101 mmol, 3.0 equiv.) in DCM (35 mL) was added dropwise, and the resulting suspension was stirred at room temperature for 96 h. A saturated aqueous solution of KCO (40 mL) was added in four portions over 1 h, and the reaction mixture was stirred until bubbling ceased. The aqueous phase was extracted with DCM (2 × 200 mL), and the solvent was evaporated on a rotary evaporator. The residue was purified by preparative HPLC (C18, MeCN / HO gradient with 0.1% FA in the mobile phase). The product-containing fractions were combined and lyophilized. The resulting white solid was dissolved in DCM (340 mL), and DMF (46 μL, 0.60 mmol, 0.02 equiv.) and SOCl (5.5 mL, 75.1 mmol, 2.25 equiv.) were added dropwise. After stirring at room temperature for 6 h, the reaction mixture was placed on an ice bath and quenched by careful addition of saturated aqueous NaHCO (200 mL). The phases were separated, and the aqueous phase was extracted with DCM (200 mL). The organic phase was dried over NaSO, filtered, and the liquid was evaporated on a rotary evaporator. The residue was purified by column chromatography (SiO, 100% DCM to 10% MeOH in DCM). Fractions containing the product were pooled and evaporated to dryness to give the product as a yellow oil. Yield: 2.2 g (38%; two steps; based on 2-methyl-4-nitropyridine N-oxide). NMR (CDCl): 1 Hδ H 4.80 (CH2-arom, s, 2H); 7.98 (arom, dd, 3 J HH =5, 4 J HH = 2, 1H); 8.24 (arom, d, 4 J HH =2, 1H); 8.87 (arom, d, 3 J HH =5, 1H); 13 C{ 1 H} δ C45.8 (CH2-arom, s); 115.6 (arom, s); 115.8 (arom, s); 151.8 (arom, s); 154.8 (arom, s); 160.2 (arom, s).EI-HRMS: 172.0033 [M] + (Theoretical value [C6H5O2N2Cl1] + = 172.0034).

[0061] [ka] Synthesis of intermediate (2): In a 50 mL pear-shaped glass flask, 2-methyl-6-nitropyridine (224 mg, 1.62 mmol, 1.0 equiv.), NBS (577 mg, 3.24 mmol, 2.0 equiv.), and AIBN (42 mg, 0.26 mmol, 0.16 equiv.) were dissolved in CCl4 (6 mL). The reaction mixture was heated under reflux for 19 h. The solvent was evaporated on a rotary evaporator. The residue was purified by preparative HPLC (C18, MeCN / HO gradient with 0.1% FA in the mobile phase). Fractions containing the product were pooled, and DCM was added until phase separation occurred. The organic phase was separated and washed with saturated aqueous NaHCO3. The organic phase was concentrated on a rotary evaporator to give the product as a colorless solid. Yield: 79 mg (23%, based on one step, 2-methyl-6-nitropyridine). NMR (CDCl3): 1 Hδ H 4.63 (CH2-arom, s, 2H); 7.87 (arom, dd, 2 J HH =7.6, 3 J HH = 0.9, 1H); 8.07 (arom, t, 2 J HH =7.8, 1H); 8.19 (arom, dd, 2 J HH =8.0, 3 J HH = 0.8, 1H); 13 C{ 1 H} δ C31.7 (CH2-arom, s); 117.3 (arom, s); 129.3 (arom, s); 141.1 (arom, s); 156.2 (arom, s); 157.5 (arom, s).CI-HRMS: 216.9605 [M+H] + (Theoretical value [C6H6O2Br1N2] + = 216.9607).

[0062]

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[0063] [ka] Synthesis of intermediate (4): In a 50 mL round-bottom glass flask, (4-fluoropyridin-2-yl)methanol (227 mg, 1.79 mmol, 1.0 equiv.) was dissolved in DCM (35 mL) and DMF (4 μL, 0.05 mmol, 0.01 equiv.) was added. The reaction mixture was placed in an ice bath. After 20 min on the ice bath, thionyl chloride (400 μL, 5.36 mmol, 3.0 equiv.) was added dropwise, and the reaction mixture was stirred on the ice bath. After 15 min, the reaction mixture was allowed to warm to room temperature. After stirring at room temperature for 1 h, the reaction mixture was placed in an ice bath and quenched by the careful addition of saturated aqueous NaHCO3 (10 mL). The phases were separated, and the aqueous phase was extracted with DCM (2 × 40 mL). The organic phase was dried over Na2SO4, filtered, and the liquid was evaporated on a rotary evaporator to give the product as a colorless oil. Yield: 217 mg (83%; 1 step; based on (4-fluoropyridin-2-yl)methanol) NMR (CDCl3): 1 H (400.1 MHz, T = 300 K) δ H 4.69 (CH2-arom, s, 2H); 7.00 (arom., ddd, J = 8, 6, 2 Hz 1H); 7.24- 7.30 (arom., m, 1H); 8.55 (arom., dd, J = 8, 6 Hz H).13 C{ 1 H} (100.6 MHz, T = 300 K) δ C 70.8 (CH2 - arom, d, 4 J CF = 3 Hz); 110.9 (arom, d, 2 J CF = 18 Hz); 111.2 (arom, d, 2 J​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Synthesis of intermediate (5): A pear-shaped glass flask (100 mL) was charged with l-benzyl lactate (900 mg; 4.99 mmol; 1.00 equiv.) and a magnetic stirrer and briefly protected with argon three times. Then, under a constant stream of argon, dry DCM (20 mL) was added through the septum. The mixture was cooled in an ice bath (5 °C), followed by the dropwise addition of anhydrous triflic acid (0.88 mL; 5.23 mmol; 1.05 equiv.), immediately followed by the dropwise addition of dry pyridine (0.42 mL; 5.25 mmol; 1.05 equiv.). The resulting mixture was stirred at 5 °C for 30 min. The resulting suspension was then directly purified by column chromatography (30 g SiO2, DCM). The combined product-containing fractions were evaporated to dryness and briefly dried under high vacuum to give the product in free base form as a nearly colorless oil. Yield: 1.12 g (77%; 1 step; based on l-benzyl lactate). NMR (DMSO-d6): 1 Hδ H 1.53 (CH3, d, 3H, 3 J HH = 7); 5.27 (CH2, s, 2H); 5.34 (CH, q, 1H, 3 J HH = 7); 7.17-7.65 (Ph, m, 5H). 19 F{ 1 H} δ F -77.7 (s). ESI-HRMS: 335.0175 [M+Na] + (Theoretical value [C 11 H 11 O5F3S1Na1] + = 335.0172).

[0065] [ka] Synthesis of intermediate (6): In a glass vial (20 mL), cyclen (free base; 100 mg; 580 μmol; 1.0 equiv.) and K2CO3 (160 mg; 1.16 mmol; 2.0 equiv.) were suspended in dry MeCN (6 mL), followed by the addition of 5 (362 mg; 1.16 mmol; 2.0 equiv.) in dry MeCN (4 mL). The resulting mixture was stirred at 40 °C for 1 h. The solids were removed by filtration using a syringe microfilter (PTFE), and the filtrate was evaporated to dryness. The residue was purified by preparative HPLC (C18; HO-MeCN gradient with TFA addition). The product-containing fractions were combined and lyophilized to give the product in the form of a TFA salt as a brown honey. Yield: 106 mg (25%, 1 step, based on cyclen). NMR (CD3CN): 1 Hδ H 1.20 (CH3, d, 3H, 3 J HH = 7 Hz); 1.26 (CH3, d, 6H, 3 J HH = 7 Hz); 2.30-2.96 (mc, m, 16H); 3.59 (CHCH3-COOBn, q, 2H, 3 J HH = 7 Hz); 3.77 (CHCH3-COOBn, q, 1H, 3 J HH = 7 Hz); 5.09 (CH2-arom, s, 2H); 5.10 (CH2-arom, s, 4H); 7.29-7.41 (arom, m, 15H). ESI-HRMS: 659.3797 [M+H] + (Theoretical value [C 38 H 51 N4O6] + = 659.3803). EA (C 38 H 50 N4O6·0.3TFA·2.0H2O, M R = 729.0): C 63.6 (63.0); H 7.5 (6.9); N 7.7 (7.4); F 2.4 (2.2).

[0066] [ka] Synthesis of intermediate (7): In a glass vial (20 mL), Cbz2-cyclen (free base; 242 mg; 549 μmol; 1.0 equiv.) was dissolved in MeCN (12 mL), followed by solid (CHO). n PhP(OMe) (50 mg; 1.67 mmol; 3.0 equiv.) and PhP(OMe) (350 μL; 2.2 mmol; 4.0 equiv.) were added. The resulting suspension was stirred at 80 °C for 24 h. The reaction mixture was then filtered through a syringe microfilter (PTFE), and the filtrate was evaporated to dryness. The residue was purified by preparative HPLC (C18; HO-MeCN gradient with TFA addition). The product-containing fractions were combined, neutralized with diluted aqueous NaHCO and evaporated to dryness. The residue was dissolved in DCM (75 mL) and HO (75 mL) and transferred to a separatory funnel. After shaking, the bottom phase was separated. The aqueous phase was further extracted with DCM (3 × 25 mL). The combined organic layers were dried over anhydrous NaSO, filtered through a glass frit (S3), and evaporated to dryness. The residue was further dried overnight under high vacuum to give the product in free base form as a nearly colorless oil. Yield: 259 mg (61%; 1 step; based on Cbz2 cyclen). NMR (CD3CN): 1 Hδ H 2.30-3.38 (mc, CH2-P, m, 16+4H); 3.47 (CH3, d, 6H, 3 J HP = 11); 5.00-5.12 (CH2-Ph, m, 4H); 7.27-7.40 (Ph, m, 10H); 7.40-7.51 (Ph, m, 4H); 7.51-7.60 (Ph, m, 2H); 7.60-7.82 (Ph, m, 4H). 31 P δ P 42.8 (m). ESI-HRMS: 777.3178 [M+H] + (Theoretical value [C 40 H 51 N4O8P2] + = 777.3177).

[0067] [ka] Synthesis of intermediate (8): A pear-shaped glass flask (50 mL) was charged with 7 (250 mg; 322 μmol) and a magnetic stirrer, and the flask was protected with argon three times. Solid Pd@C (50 mg) was then added, and the flask was further protected with argon three times. MeOH (25 mL) was then added through a septum under a constant flow of argon. The argon flow was then removed, and H2 gas (from a balloon) was bubbled through the mixture at room temperature for 2 hours. The catalyst was then filtered off using a syringe microfilter (PTFE; the filter was further washed with MeOH). The filtrate was evaporated to dryness and coevaporated once with DCM. The residue was further dried overnight under high vacuum to give the product in the form of the free base as a nearly colorless oil. Yield: 161 mg (98%; based on one step; 8). NMR (CD3CN): 1 Hδ H 2.28-3.14 (mc, CH2-P, m, 16+4H); 3.53 (CH3, d, 3H, 3 J HP = 11); 3.54 (CH3, d, 3H, 3 J HP = 11); 7.46-7.63 (Ph, m, 6H); 7.71-7.83 (Ph, m, 4H). 31 P δ P 43.3 (m). ESI-HRMS: 509.2438 [M+H] + (Theoretical value [C 24 H 39 N4O4P2] + = 509.2441).

[0068] [ka] Synthesis of intermediate (9): In a 50 mL round-bottom glass flask, methyl 4-fluoropicolinate (250 mg, 1.61 mmol, 1.0 equiv.) was dissolved in MeOH (16 mL) and NaBH (180 mg, 4.78 mmol, ~3.0 equiv.) was added with stirring. After adding HO (1 mL), the reaction was stirred at room temperature for 3 h. The liquid was evaporated on a rotary evaporator, and the residue was suspended in a saturated aqueous solution of KCO (25 mL). The aqueous phase was extracted with DCM (2 × 25 mL), and the solvent was evaporated on a rotary evaporator. The residue was dissolved in DCM (11 mL), and EtN (280 μL, 2.02 mmol, 1.3 equiv.) was added. The reaction mixture was placed in an ice bath. After 20 min on an ice bath, methanesulfonyl chloride (146 μL, 1.88 mmol, 1.23 equiv) was added and the reaction mixture was stirred on an ice bath. After 15 min, the reaction mixture was warmed to room temperature and stirred for 1 h. The reaction mixture was diluted with DCM (40 mL) and washed with HO (2×40 mL) and brine (40 mL). The organic phase was dried over NaSO, filtered, and the liquid was rotary evaporated to give the product as a dark orange oil. Yield: 240 mg (77%; two steps; based on methyl 4-fluoropicolinate) NMR (CDCl): 1 Hδ H 3.12 (CH3, s, 3H); 5.33 (CH2-arom, s, 2H); 7.04 (arom.,ddd, J = 8, 6, 3 Hz 1H); 7.24 (arom., dd, J = 9, 3 Hz, 1H); 8.58 (arom., dd, J = 8, 6 Hz, 1H); 13 C{ 1 H} δ C 38.2 (CH3, s); 70.4 (CH2-arom, s);110.5 (arom, d, 2 J CF = 18 Hz); 111.7 (arom, d, 2 J CF = 17 Hz); 152 (arom, d, 3 J CF = 7 Hz); 157.2 (arom, d, 3 J CF= 7 Hz); 169.5 (arom, d, 1 J CF = 265 Hz). 19 F{ 1 H} δ F -99.3 (s). CI-HRMS: 206.0281 [M+H] + (Theoretical value [C7H9O3N1F1S1] + = 206.0282).

[0069] [ka] Synthesis of intermediate (10): In a 50 mL round-bottom glass flask, (5-fluoropyridin-2-yl)methanol (173 mg, 1.36 mmol, 1.0 equiv.) was dissolved in DCM (10 mL) and EtN (250 μL, 1.80 mmol, 1.3 equiv.) was added. The reaction mixture was placed in an ice bath. After 20 min on the ice bath, methanesulfonyl chloride (142 μL, 1.84 mmol, 1.35 equiv.) was added and the reaction mixture was stirred on the ice bath. After 15 min, the reaction mixture was allowed to warm to room temperature and stirred for an additional 1 h. The reaction mixture was diluted with DCM (40 mL) and washed with HO (2 × 40 mL) and brine (40 mL). The organic phase was dried over NaSO, filtered, and the liquid was evaporated on a rotary evaporator to give the product as an orange solid. Yield: 219 mg (78%; 1 step; based on (5-fluoropyridin-2-yl)methanol) NMR (CDCl3): 1 Hδ H 3.08 (CH3, s, 3H); 5.31 (CH2-arom, s, 2H); 7.42 - 7.53 (arom.,m, 2H); 8.47 (arom., dd, J = 3, 1 Hz, 1H); 13 C{ 1 H} δ C 38.2 (CH3, s); 70.8 (CH2-arom, s);124.1 (arom, d, 3 J CF = 3 Hz); 124.2 (arom, d, 2 J CF= 11 Hz); 138 (arom, d, 2 J CF = 24 Hz); 149.6 (arom, d, 4 J CF = 4 Hz); 159.4 (arom, d, 1 J CF = 258 Hz). 19 F{ 1 H} δ F -125.8 (s). CI-HRMS: 206.0284 [M+H] + (Theoretical value [C7H9O3N1F1S1] + = 206.0282).

[0070] [ka] Synthesis of intermediate (11): A pear-shaped glass flask (500 mL) was charged with ethyl L-lactate (6.70 g; 56.7 mmol; 1.00 equiv.) and a magnetic stirrer and briefly protected with argon three times. Next, dry DCM (200 mL) was added through the septum under a constant stream of argon. The mixture was cooled in an ice bath (5 °C), and then anhydrous triflic acid (10.0 mL; 59.4 mmol; 1.05 equiv.) was added dropwise, followed immediately by dry pyridine (4.80 mL; 59.6 mmol; 1.05 equiv.). The ice bath was then removed, and the mixture was further stirred at room temperature for 1 h. The resulting suspension was then directly purified by column chromatography (250 g SiO2, DCM). The combined product-containing fractions were evaporated to dryness and briefly dried under high vacuum to give the product as a pale brown oil. Yield: 12.02 g (85%; 1 step; based on ethyl L-lactate). NMR (DMSO-d6): 1 Hδ H 1.26 (CH3-CH2, t, 3H, 3 J HH = 7); 1.51 (CH3-CH, d, 3H, 3 J HH = 7); 4.19-4.31 (CH2, m, 2H); 5.27 (CH, q, 1H, 3 JHH = 7). 19 F{ 1 H} δ F -77.7 (s). CI-HRMS: 251.0193 [M+H] + (Theoretical value [C6H 10 O5S1F3] + = 251.0196).

[0071] [ka] Synthesis of intermediate (12): In a pear-shaped glass flask (25 mL), cyclen (free base; 200 mg; 1160 μmol; 1.0 equiv.) was dissolved in dry DCM (12 mL), followed by the dropwise addition of tert-butyl 4-nitrophenyl carbonate (278 mg; 1.16 mmol; 1.0 equiv.) in dry DCM (4 mL). The resulting mixture was stirred at room temperature for 30 minutes. The liquid was evaporated, and the residue was purified by preparative HPLC (C18; HO-MeCN gradient with TFA addition). The product-containing fractions were combined and lyophilized to give the product in the form of the TFA salt as a clear solid. Yield: 245 mg (42%, based on cyclen in one step, assuming 12·2 TFA). NMR (CD3CN): 1 Hδ H 1.44 (CH3, s, 9H); 3.01-3.08 (mc, m, 4H); 3.11-3.18 (mc, m, 4H); 3.23-3.29 (mc, m, 4H); 3.39-3.48 (mc, m, 4H). 13 C{ 1 155.66 (CO, s). ESI-HRMS: 273.2284 [M+H] + (Theoretical value [C 13 H 29 N4O2] + = 273.2285).

[0072] [ka] Synthesis of intermediate (13): In a glass vial (20 mL), intermediates 12 (100 mg; 200 μmol; 1.0 equiv.) and 11 (367 mg; 1.47 mmol; 7.4 equiv.) were dissolved in dry MeCN (15 mL), followed by the addition of K2CO3 (254 mg; 1.84 mmol; 9.2 equiv.). The resulting mixture was stirred at room temperature for 15 h. The solids were removed by filtration using a syringe microfilter (PTFE), and the filtrate was evaporated to dryness. The residue was purified by preparative HPLC (C18; HO-MeCN gradient with FA addition). Fractions containing the pure product in the form of the ethyl ester were pooled and evaporated to dryness. The residue was dissolved in neat TFA (3 mL) and stirred at room temperature for 15 h. The volatiles were removed on a rotary evaporator, and the residue was purified by preparative HPLC (C18, MeCN / HO gradient with 0.1% FA in the mobile phase). The product-containing fractions were combined and lyophilized to give the product as a clear honey. Yield: 21 mg (20%, 2 steps, based on 12 assuming 13 FA). NMR (DMSO-d): 1 Hδ H 1.17-1.24 (CH3, m, 18H); 2.40 (mc, m, 2H); 2.55 (mc, m, 2H); 2.73-2.94 (mc, m, 10H); 3.21 (mc, m, 2H); 3.63 (CHCH3-COOEt, q, 2H, 3 J HH = 7 Hz); 3.74 (CHCH3-COOBn, q, 1H, 3 J HH = 7 Hz); 4.07-4.13 (O-CH2-CH3, m, 6H); 8.8 (NH, bs, 1H). 13 C{ 1 H} δ C14.1 (CH3, s); 14.22 (CH3, s); 14.24 (CH3, s); 15.2 (CH3, s); 44.8, 45.2, 46.6, 50.0 (mc); 54.8 (CCH3H-COCH2CH3, s); 57.8 (CCH3H-COCH2CH3, s); 60.0 (CCH3H-COCH2CH3, s); 60.04 (CCH3H-COCH2CH3, s); 172.5 (CO, s); 172.8 (CO, s).ESI-HRMS: 473.3329 [M+H] + (Theoretical value[C 23 H 45 N4O6] + = 473.3334).

[0073] Example 2: Synthesis of ligands

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[0084] [ka] Ligand L 12 Synthesis of (2S,2'S,2''S)-2,2',2''-(10-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)tripropionic acid): Intermediate 1 (8.2 mg, 47.6 μmol, 1.6 equiv)) was mixed with Intermediate 13 (15.0 mg, 28.9 μmol, 1.0 equiv) in tBuOH (1.3 mL), followed by the addition of DIPEA (28 μl, 158 μmol, 5.5 equiv), and the resulting solution was stirred at 80 °C for 16 h. The liquid was evaporated on a rotary evaporator, and the resulting oil was purified by preparative HPLC (C18, MeCN / HO gradient with 0.1% FA in the mobile phase). Fractions containing the pure product in the form of the ethyl ester were pooled, evaporated to dryness, and coevaporated several times with MeOH to remove MeCN. The residue was dissolved in a mixture of MeCN (500 μl) and HO (330 μl), followed by the addition of a 1 M solution of LiOH (296 μl, 296 μmol, 10 equiv.). After 47 h, the reaction mixture was quenched with FA (10 μl, 220 μmol, 7.6 equiv.), and the mixture was evaporated to dryness. The residue was purified by preparative HPLC (C18, MeCN / HO gradient with 0.1% FA in the mobile phase). The product-containing fractions were combined and lyophilized to give the product in the form of the FA salt as a yellowish solid. Yield: 6.0 mg (33%, based on 2 steps, 13). NMR (DO, ref. tBuOH): 1 Hδ H 1.24 (CH3, d, 3H, 3 J HH = 7 Hz); 1.25 (CH3, d, 3H, 3 J HH = 7 Hz); 1.59 (CH3, d, 3H, 3 J HH= 7 Hz); 2.60 - 2.64 (mc, m, 2H); 2.83 - 3.05 (mc, CHCH3COOH, m, 6H); 3.10 - 3.31 (mc, m, 5H); 3.41 - 3.55 (mc, CH2 - arom, m, 4H); 3.98 (CHCH3COOH, q, 1H, 3 J HH = 7 Hz ); 4.20 (CHCH3COOH, q, 1H, 3 J HH = 8 Hz); 4.27 (m, 1H); 4.78 (CH2 - arom, m, 1H); 8.07 (arom, dd, 1H, 3 J HH = 6 Hz, 4 J HH = 2 Hz); 8.52 (arom, d, 1H, 4 J HH = 2 Hz); 8.75 (arom, d, 1H, 3 J HH = 6 Hz); 13 C{ 1 H} δ C 8.0 (CH3, s); 10.0 (CH3, s); 10.7 (CH3, s); 43.5, 46.1, 46.9, 47.4, 47.5, 47.8, 48.1, 49.2 (mc, s); 55.7 (CCH3H - COOH, s); 58.2 (CH2 - arom, s); 60.9 (CCH3H - COOH, s); 62.1 (CCH3H - COOH, s); 117.2 (arom); 120.1 (arom); 151. (arom); 156.0 (arom, s); 160.3 (arom); 171.6 (CO, s); 174.7 (CO, s); 177.1 (CO, s). ESI - HRMS: 525.2667 [M + H] + (Theoretical value [C 23 H 37 N6O8] + = 525.2667). EA (C 23 H 36 N6O8·2.2FA·0.6H2O, M R= 627.4): C 47.5 (47.6); H 6.6 (6.7); N 13.2 (13.1).

[0085] Example 3: Synthesis of metal chelates [ka] Complex [Gd(L 1 )]: In a glass vial (25 mL), 1 1.8TFA·1.0HO (138 mg, 0.20 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 2 mL, 6 mmol, 30 equiv.), followed by the addition of aqueous GdCl (100 mM, 2.1 mL, 0.21 mmol, 1.05 equiv.), and the resulting solution was stirred for 15 min. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). Fractions containing the product were combined and lyophilized to give the product as an off-white solid. Yield: 111 mg (81%, 1 step, L 1 (based on 1.8TFA 1.0H2O). ESI-HRMS: 638.1203 [M+H] + (Theoretical value [C 20 H 28 N6O8Gd] + = 638.1204). EA (C 20 H 27 N6O8Gd·2.5H2O, M R = 687.0): C 35.0 (35.4); H 4.7 (4.4); N 12.2 (11.9); Gd 22.9 (19.4).

[0086] [ka] Complex [Gd(L 2 )]: In a glass vial (4 mL), 20.8FA 0.2HO (37.4 mg, 71.5 μmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 0.95 mL, 2.85 mmol, 40 equiv.), followed by the addition of aqueous GdCl (100 mM, 0.78 mL, 78 μmol, 1.1 equiv.), and the resulting solution was stirred at room temperature for 1 h. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a yellowish solid. Yield: 33 mg (62%, 1 step, L 2 (based on 0.8FA 0.2H2O). ESI-HRMS: 638.1201 [M+H] + (Theoretical value [C 20 H 28 N6O8Gd] + = 638.1204). EA (C 20 H 27 N6O8Gd·2.1FA·1.4H2O, M R = 758.6): C 35.0 (34.9); H 4.5 (4.4); N 11.1 (11.2); Gd 20.7 (20.8).

[0087] [ka] Complex [Gd(L 3 )]: In a glass vial (25 mL), 3 0.7TFA·1.1FA (100 mg, 0.17 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 1.7 mL, 5.1 mmol, 30 equiv.), followed by the addition of aqueous GdCl3 (100 mM, 1.9 mL, 0.19 mmol, 1.1 equiv.), and the resulting solution was stirred at room temperature for 1 h. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 98 mg (88%, 1 step, L 3 (based on 0.7TFA 1.1FA). ESI-HRMS: 611.1257 [M+H] +(Theoretical value [C 20 H 28 N5O6Gd1F1] + = 611.1259). EA (C 20 H 27 N5O6Gd1F1·2.5H2O, M R = 654.7): C 36.7 (37.2); H 4.9 (4.9); N 10.7 (10.6); Gd 24.0 (21.4); F 2.9 (2.6).

[0088] [ka] Complex [Gd(L 4 )]: In a glass vial (25 mL), 4 2.6TFA·0.3HO (156 mg, 0.21 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 1.9 mL, 5.8 mmol, 28 equiv.), followed by the addition of aqueous GdCl (100 mM, 2.16 mL, 0.22 mmol, 1.05 equiv.), and the resulting solution was stirred at room temperature for 15 min. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 82 mg (59%, 1 step, L 4 (based on 2.6TFA 0.3H2O). ESI-HRMS: 611.1275 [M+H] + (Theoretical value [C 20 H 28 N5O6Gd1F1] + = 611.1259). EA (C 20 H 27 N5O6Gd1F1·2.5H2O, M R = 654.7): C 36.7 (36.2); H 4.9 (5.0); N 10.7 (10.5); Gd 24.0 (19.8); F 2.9 (2.8).

[0089] [ka] Complex [Gd(L 5 )]: In a glass vial (25 mL), 5 0.7TFA·1.3FA (100 mg, 0.17 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 1.7 mL, 5.1 mmol, 30 equiv.), followed by the addition of aqueous GdCl3 (100 mM, 1.9 mL, 0.19 mmol, 1.1 equiv.), and the resulting solution was stirred at room temperature for 1 h. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 95 mg (82%, 1 step, L 5 (based on 0.7TFA 1.3FA). ESI-HRMS: 611.1257 [M+H] + (Theoretical value [C 20 H 28 N5O6Gd1F1] + = 611.1259). EA (C 20 H 27 N5O6Gd1F1·4H2O, M R = 681.8): C 35.2 (35.4); H 5.2 (5.0); N 10.3 (10.1); Gd 23.1 (20.8); F 2.8 (2.4).

[0090] [ka] Complex [Gd(L 6 )]: In a glass vial (25 mL), 60.5TFA·1.4FA (150 mg, 0.26 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 2.6 mL, 7.8 mmol, 30 equiv.), followed by the addition of aqueous GdCl3 (100 mM, 3.1 mL, 0.31 mmol, 1.2 equiv.), and the resulting solution was stirred at room temperature for 1 h. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 151 mg (86%, 1 step, L 6 (based on 0.5TFA 1.4FA). ESI-HRMS: 611.1256 [M+H] + (Theoretical value [C 20 H 28 N5O6Gd1F1] + = 611.1259). EA (C 20 H 27 N5O6Gd1F1·1.5H2O·0.8FA, M R = 673.5): C 37.1 (37.3); H 4.7 (4.6); N 10.4 (10.7); Gd 23.4 (23.4); F 2.8 (2.5). (C 20 H 30 N5O6F1·0.5TFA·1.4FA, M R = 576.9)

[0091] [ka] Complex [Gd(L 7 )]: In a glass vial (25 mL), 72.2TFA·0.9HO (152 mg, 0.22 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 1.64 mL, 4.9 mmol, 21 equiv.), followed by the addition of aqueous GdCl (100 mM, 2.34 mL, 0.23 mmol, 1.05 equiv.), and the resulting solution was stirred at room temperature for 15 min. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). Fractions containing the product were combined and lyophilized to give the product as a white solid. Yield: 116 mg (77%, 1 step, L 7 (based on 2.2TFA 0.9H2O). ESI-HRMS: 553.1214 [M+H] + (Theoretical value [C 18 H 26 N5O4Gd1F1] + = 553.1204). EA (C 18 H 26 N5O4Gd1F1·3.1H2O, M R = 681.2): C 33.9 (34.5); H 4.7 (4.5); N 10.3 (9.9); Gd 23.1 (19.6); F 7.8 (7.4).

[0092] [ka] Complex [Gd(L 8 )]: In a glass vial (25 mL), 8 0.1TFA 0.6H2O (4 mg, 8.1 μmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (0.5 M, pH 7.0, 1.00 mL, 0.5 mmol, 62 equiv.), followed by the addition of aqueous GdCl3 (100 mM, 97.0 μL, 9.7 μmol, 1.2 equiv.), and the resulting solution was stirred for 1 h at room temperature. The mixture was purified by preparative HPLC (C18, H2O / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 4.6 mg. ESI-HRMS: 653.1728 [M+H] + (Theoretical value [C 23 H34 N5O6Gd1F1] + = 653.1729).

[0093] [ka] Complex [Gd(L 9 )]: In a glass vial (25 mL), 9 0.1TFA 0.8HO (6 mg, 9.18 μmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (0.5 M, pH 7.0, 1.00 mL, 0.5 mmol, 51 equiv.), followed by the addition of aqueous GdCl (100 mM, 117.0 μL, 11.7 μmol, 1.2 equiv.), and the resulting solution was stirred at room temperature for 20 h. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% AcOH). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 5.4 mg. ESI-HRMS: 745.1461 [M+H] + (Theoretical value [C 28 H 36 N5O4Gd1F1P2] + = 745.1462).

[0094] [ka] Complex [Gd(L 10 )]: In a glass vial (25 mL), 10 1.7TFA·1.4H2O (129 mg, 0.20 mmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (3 M, pH 7.0, 2 mL, 8.02 mmol, 40 equiv.), then aqueous GdCl3 (100 mM, 2.2 mL, 0.22 mmol, 1.1 equiv.) was added, and the resulting solution was stirred at room temperature for 1 h. The mixture was then purified by preparative HPLC (C18, H2O / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a yellowish solid. Yield: 92 mg (64%, 1 step, L 10(based on 1.7TFA 1.4H2O). ESI-HRMS: 580.1152 [M+H] + (Theoretical value [C 18 H 26 N6O6Gd1] + = 580.1149). EA (C 18 H 26 N6O6Gd1·3FA, M R = 717.8): C 35.1 (34.9); H 4.5 (4.1); N 11.7 (12.1); Gd 21.9 (19.9).

[0095] [ka] Complex [Gd(L 11 )]: In a glass vial (4 mL), 11 0.1TFA (3.1 mg, 6.0 μmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (0.5 M, pH 7.0, 0.738 mL, 369 μmol, 62 equiv.), followed by the addition of aqueous GdCl3 (100 mM, 72.0 μL, 7.2 μmol, 1.2 equiv.), and the resulting solution was stirred at room temperature for 1 h. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 3.5 mg. ESI-HRMS: 653.1731 [M+H] + (Theoretical value [C 23 H 34 N5O6Gd1F1] + = 653.1729).

[0096] [ka] Complex [Gd(L 12 )]: In a glass vial (4 mL), 122.2FA 0.6HO (3 mg, 4.8 μmol, 1.0 equiv.) was dissolved in aqueous MOPS / NaOH buffer (0.5 M, pH 7.0, 0.706 mL, 353 μmol, 73 equiv.), followed by the addition of aqueous GdCl (100 mM, 69.0 μL, 6.9 μmol, 1.4 equiv.), and the resulting solution was stirred at room temperature for 15 min. The mixture was then purified by preparative HPLC (C18, HO / MeCN gradient with 0.1% FA). The product-containing fractions were combined and lyophilized to give the product as a white solid. Yield: 4.1 mg. ESI-HRMS: 680.1679 [M+H] + (Theoretical value [C 23 H 34 N6O8Gd1] + = 680.1674).

[0097] Radioisotope labeling experiments Example 4: 18 F - Radiolabeling with anions General Procedure Cyclotron-produced 18 F - A solution containing CO3 - The mixture was cycled through a QMA column (Sep-Pak, Waters) and eluted with 0.8 ml of elution solution (8.3 mg of TBAHCO in a mixture of 0.4 ml of HO and 0.4 ml of MeCN). The volume containing the desired activity was transferred to a 4 ml glass vial equipped with a stir bar, preheated to 120 °C, and a stream of argon was introduced. The aqueous solution was evaporated, and 300 μl of dry MeCN was introduced and evaporated again. This step was carried out twice. The material for radiolabeling ([Gd(L) 1 )], [Gd(L 4 )] or L 4 100 μl of a 15 mM solution of TBAF in THF was added, followed by 4 μl of a 1 M solution of TBAF in THF. The vial was transferred to a preheated aluminum heat block at 90 °C, and the reaction mixture was stirred for 5 min. The reaction mixture was then analyzed by HPLC equipped with gamma and UV detectors.

[0098] [Gd(L) 1 )]

[0099] [ka]

[0100] [Table 1]

[0101] The chromatogram of this radiolabeling experiment is shown in Figure 1. The radiochemical yield is defined as the amount of activity in the product expressed as a percentage of the relevant starting activity.

[0102] 18 F<-> 19 [Gd(L 4 )]

[0103] [ka]

[0104] [Table 2]

[0105] The chromatogram of this radiolabeling experiment is shown in FIG.

[0106] 18 F<-> 19 Free Ligand L via F Isotope Exchange 4 Radioisotope labeling of free ligand L 4 Experiments with are performed to demonstrate the importance of chelated metals for the radiolabeling reaction to proceed. The experiments were performed under the same conditions as other radiolabeling reactions.

[0107] [ka]

[0108] The chromatogram of this radiolabeling experiment is shown in FIG. [Table 3]

[0109] Example 5: [Gd(L 4 )] and [Gd(L 7 )] relaxation rate The relaxivity value is directly proportional to the effectiveness of the compound as an MRI contrast agent. For relaxivity measurements, [Gd(L 4 )] and [Gd(L 7 Samples of [Gd(L)] were prepared at concentrations of 0 mM, 0.2 mM, 0.5 mM, 1 mM, and 2 mM in MOPS / NaOH buffer (50 mM, pH 7.0, 150 μL). The samples prepared in this manner were used to measure the longitudinal relaxation time T1 values ​​in a relaxometer at 37 °C and 0.47 T. From these values, [Gd(L 4 )] is 3.43mM -1 s -1 and the relaxation rate of [Gd(L 7 )] is 5.33mM -1 s -1 (Table 4). The relaxivities were determined by linear regression of concentration versus longitudinal relaxivities, as seen in Figure 4. For comparison, the relaxivities of most clinically used MRI contrast agents under comparable conditions are 3-4 mM. -1 s -1(Rohrer, M.; Bauer, H.; Mintorovitch, J.; Requardt, M.; Weinmann, H.-J. Comparison of Magnetic Properties of MRI Contrast Media Solutions at Different Magnetic Field Strengths. Investigative Radiology 2005, 40 (11), 715-724. https: / / doi.org / 10.1097 / 01.rli.0000184756.66360.d3).

[0110] [Table 4]

[0111] Example 6: [Gd(L 4 )] and [Gd(L 7 )] kinetic inertness [Gd(L 4 )] and [Gd(L 7 The kinetic inertness of [(GdCl3)-3-(Diethylenetriaminepentaacetic acid)] was tested using acid-assisted decomplexation with 0.1 M hydrochloric acid. A clinically used contrast agent, Magnevist®, gadolinium-DTPA (diethylenetriaminepentaacetic acid), was used as a reference, and a solution of 1 mM GdCl3 in 0.1 M HCl was used as an example of gadolinium completely released from the chelate. All measured complexes were prepared as 1 mM solutions in a volume of 150 μL and incubated at 37°C. During decomplexation, the gadolinium ion leaves the complex and becomes fully solvated. Because solvated gadolinium shortens the T1 relaxation time more significantly than chelated gadolinium, the T1 of the sample decreases during this process. When the complex is completely decomposed and all gadolinium is solvated, the reaction reaches equilibrium. At this equilibrium, the T1 relaxation time no longer decreases. The T1 relaxation time values ​​were measured in a relaxometer at 37°C and a magnetic field strength of 0.47 T. Dynamic inertness is determined by the paramagnetic relaxation rate: R 1p =1 / T1-1 / T 1dThe longitudinal relaxation time of HCl (0.1M) was T 1d During the measurement, [Gd(L 4 In the case of [Gd(L)], a gradual increase in the T value can be observed, suggesting that the complex is slowly decomposing. 4 The T1 value of the Magnevist sample increased by 12%. The situation was different for Magnevist, where the reaction reached equilibrium already after 6 minutes (Table 5). 1p The value did not change with time, which suggests that the complex had completely decomposed. 7 )], then R 1p The increase in [Gd(L 7 This suggests that [Gd(L)] is more kinetically inactive. 4 )] and [Gd(L 7 )] was shown to be more kinetically inactive than the clinically used Magnevist and therefore suitable for in vitro applications. A graph showing the kinetic inactivity measurements is shown in the figure.

[0112] [Table 5]

[0113] Example 7: Radiolabeled [Gd(L 4 )] simultaneous PET / MRI imaging In vitro imaging of phantoms Simultaneous PET / MRI was performed on a 7T preclinical PET-MRI scanner (Bruker Clinscan, with a PET insert). 18 F-Radioisotope labeled [Gd(L 4 ) was prepared in the same manner as in Example 4. 19 F and 18 It was prepared in an automated radioactive synthesis module by isotope exchange with F. It was then dissolved in non-radioactive [(Gd(L)] in phosphate-buffered saline (PBS). 4 )] (0.5 mM stock solution) 18F-Radioisotope labeled [Gd(L 4 Phantoms (vials) were prepared by concentrating [Gd(DTPA)] in the range of 0.048 to 0.489 mM and with an activity of 0.033 to 0.490 MBq. Vials containing only an aqueous solution of Magnevist (a [Gd(DTPA)] complex) in the range of 0.1 to 0.5 mM were used as reference contrast for MR imaging. Simultaneous PET / MRI imaging was performed by acquiring T1-weighted MR images of the phantoms using a 3D FLASH sequence and a 600-second static PET scan (Figure 6, Panel A). Based on gamma counting, 18 Quantification of F activity showed excellent linear correlation with quantification of Gd by ICP-OES (Figure 6, panel B). Similarly, radioactivity measured by PET showed excellent linear correlation with the signal obtained from T1-weighted MR images (Figure 6, panel C) and the relaxivity obtained from the MRI T1 map (Figure 6, panel D). Overall, 18 F-Radioisotope labeled [Gd(L 4 )] provided a consistent signal in both imaging modalities and was therefore confirmed to be suitable for use as a bimodal contrast agent in PET / MRI.

[0114] In vitro imaging in mice 18 F-Radioisotope labeled [Gd(L 4 ) was prepared in the same manner as in Example 4. 19 F and 18 It was prepared in an automated radiosynthesis module by isotope exchange with F and prepared in saline with a molar activity of 518 MBq / µmol. [Gd(L) with an activity of 0.91 ± 0.16 MBq] was administered to anesthetized healthy C57BL / 6 mice. 4 0.09±0.03 mmol / kg of [Gd(L)] was injected (N=6). The dose was administered as a bolus at the start of the PET / MRI scan via a catheter placed in the tail vein. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and PET images were acquired simultaneously for 62 minutes to assess the effect of [Gd(L)] on both MRI and PET modalities. 4The distribution of 200 mg / kg of 2000 mg / kg of 2000 mg / kg of 2000 mg / kg of 1 ... In the renal pelvis, MRI after injection of bimodal agents produces prominent dark spots due to contrast supersaturation caused by high local concentrations of the agent in this excretory organ. These dark spots can easily be overlooked, ignored, mistaken for image artifacts, or misidentified as malignant tumors (necrosis, areas of poor perfusion, etc.). However, simultaneously acquired PET images unambiguously confirm the strong accumulation of tracer in the same areas visualized as "hot spots" on PET, thus improving diagnostic accuracy and image interpretation. [Brief explanation of the drawings]

[0115] [Figure 1] Chromatogram of the radiolabeling experiment from Example 4 using [Gd(L1)] as precursor. The product corresponds to the peak at 7.431 minutes in the UV detector. The product corresponds to the peak at 7.767 minutes in the gamma detector. [Figure 2]Chromatogram of the radiolabeling experiment from Example 4 using [Gd(L4)] as precursor. The product corresponds to the peak at 7.343 minutes in the UV detector. The product corresponds to the peak at 7.700 minutes in the gamma detector. [Figure 3] Chromatogram of the radiolabeling experiment in Example 4 using L4 as precursor. No radiolabeled product is present; the only peak in the gamma detector corresponds to free 18F. The main peak in the UV detector corresponds to the unlabeled starting material L4. [Figure 4] Determination of relaxivity by linear regression of concentration versus longitudinal relaxivity for [Gd(L4)] and [Gd(L7)] at 37 °C and 0.47 T. [Figure 5] Comparison of the kinetic inactivity of [Gd(L4)], [Gd(L7)], and Magnevist by acid-assisted decomplexation in 0.1 M HCl at 37 °C, as measured by relaxation rates in a relaxometer. The upper graph shows data from 4 hours after the start of the experiment, and the lower graph shows data from 24 hours. While R1p values ​​should be the same for all measured complexes after thermodynamic equilibrium is reached, elemental analysis confirmed that slight differences in sample concentration (pipetting error) account for this difference. Data for an unchelated GdCl3 solution of the same molar concentration are shown for reference. The curves illustrate the differences in kinetic inactivity of the metal chelates. Clinically used Magnevist decomposes almost instantly (<5 minutes), whereas [Gd(L7)] takes longer to reach complete decomplexation. Finally, the [Gd(L4)] chelate is the most inactive; even after 24 hours under these conditions, the curves are far from reaching thermodynamic equilibrium, indicating that the majority of the chelate remains intact. [Figure 6]Simultaneous in vitro PET / MRI imaging of radiolabeled [Gd(L4)] in a phantom. (A) T1-weighted MRI and PET images acquired simultaneously in an array of vials containing different concentrations of radiolabeled [Gd(L4)], different concentrations of Magnevist as a reference, and two samples of pure HO and PBS (phosphate-buffered saline). Numbers indicate the concentration of the contrast agent in mM. (B) The concentration of [Gd(L4)] in the sample from panel A, quantified by ICP-OES (gadolinium content) and gamma counting (radioactivity), shows excellent linear correlation. Quantification of the PET signal from panel A also shows excellent linear correlation with the MRI signal determined from the T1-weighted image (C) and the relaxivity determined from the T1-map (D). [Figure 7] Pharmacokinetics of radiolabeled [Gd(L4)] in mice (N=3) obtained from PET / MRI showing rapid uptake and clearance from the kidney. (A) Pharmacokinetic curve obtained from MRI T1-maps, expressed as % change in 1 / T1. (B) Pharmacokinetic curve obtained from PET images, expressed as % injected volume per mL. Right axis relates to bladder data. [Figure 8] Biodistribution of radiolabeled [Gd(L4)] in mice (N=6). (A) Biodistribution based on measurement of radioactivity (gamma counter) expressed as % injected dose per gram of wet tissue. (B) Biodistribution based on measurement of gadolinium (ICP-OES) expressed as % injected dose per gram of wet tissue. [Figure 9] In vivo PET / MRI simultaneous imaging of radiolabeled [Gd(L4)] in mice. From left to right, images represent multiple time points: pre-injection image, injection, 10 minutes post-injection, and 60 minutes post-injection. Top row: T1-weighted dynamic contrast-enhanced (DCE) MRI. Middle row: PET image. Bottom row: Merged image of MRI and PET. The PET image shows a notable hot spot in the kidney, while the MRI shows the same area as the kidney, dark due to oversaturation.

Claims

1. Use of cyclen compounds of general formula (I) in pharmacy for preparing multimodal PET / MRI contrast agents: 【Chemistry 1】 In the above formula, R is NO ２ or F; A is independently —CH ２ COOH;-CH(CH ３ )COOH;-CH((CH ２ ) ｎ CH ３ )COOH, where n is an integer ranging from 1 to 3; and —CH ２ P(═O)(OH)Ph; Z is H or A.

2. A and Z of the cyclen compound of the general formula (I) are the same, and preferably -CH ２ P(═O)(OH)Ph; and —CH(CH ３ 2. The use according to claim 1, wherein the alkyl group is selected from the group consisting of aryl, aryloxy ...

3. All A's in the cyclen-based compound of the general formula (I) are the same, and preferably -CH ２ P(═O)(OH)Ph; and —CH(CH ３ ) COOH; and Z is hydrogen; 2. The use according to claim 1.

4. 2. The use according to claim 1, wherein R of the cyclen compound of general formula (I) is located in the para position relative to the nitrogen atom of the pyridyl pendant arm.

5. 2. The use according to claim 1, wherein the cyclen-based compound of general formula (I) is selected from the group consisting of: 2,2',2''-(10-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L １ ) 2,2',2''-(10-((6-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L ２ ) 2,2',2''-(10-((3-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L ３ ) 2,2',2''-(10-((4-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L ４ ) 2,2',2''-(10-((5-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L ５ ) 2,2',2''-(10-((6-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (L ６ ) 2,2'-(4-((4-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,7-diyl)diacetic acid (L ７ ) (2S,2'S,2''S)-2,2',2''-(10-((3-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) tripropionic acid (L ８ ) ((4-((3-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(methylene))bis(phenylphosphinic acid) (L ９ ) 2,2'-(4-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,7-diyl)diacetic acid (L １０ ) (2S,2'S,2''S)-2,2',2''-(10-((4-fluoropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) tripropionic acid (L １１ ) (2S,2'S,2''S)-2,2',2''-(10-((4-nitropyridin-2-yl)methyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) tripropionic acid (L １２ ).

6. Use of a coordination compound of Gd(III) ions with a cyclen-based compound of general formula (I) according to any one of claims 1 to 5 for the preparation of a multimodal PET / MRI contrast agent.

7. Cyclen compounds of general formula (Ia): 【Chemistry 2】 In the above formula, R is NO ２ or F; preferably R is F; A is independently —CH(CH ３ )COOH;-CH((CH ２ ) ｎ CH ３ )COOH, where n is an integer ranging from 1 to 3; and —CH ２ P(═O)(OH)Ph, preferably A is —CH(CH ３ ) COOH; Z is H or A, preferably Z is A.

8. 8. A cyclen compound of general formula (Ia) according to claim 7, wherein the R substituent is located para to the nitrogen atom of the pyridyl pendant arm.

9. Z is A, and all A's are -CH(CH ３ 9. A cyclen compound of general formula (Ia) according to claim 7 or 8, wherein:

10. Multimodal PET / MRI contrast agents of general formula (VI): 【Transformation 3】 In the above formula, A is independently —CH ２ COOH;-CH(CH ３ )COOH;-CH((CH ２ ) ｎ CH ３ )COOH, where n is an integer ranging from 1 to 3; and —CH ２ P(═O)(OH)Ph; Z is H or A; Preferably, １８ F is para to the nitrogen atom of the pyridyl pendant arm.

11. A method for the synthesis of a multimodal PET / MRI contrast agent of general formula (VI) according to claim 10, comprising the steps of: a) providing a cyclen-based compound of general formula (I) as defined in claims 1 to 5; b) The cyclen compound of the general formula (I) is ３＋ ions, thereby forming a Gd(III) chelate of the compound of general formula (I); c) reacting the Gd(III) chelate of step b) with １８ It is radiolabeled with F.

12. Step c) is a reaction of the pyridine moiety of the Gd(III) chelate wherein R is F. １９ From F １８ carried out using isotopic exchange to F, The method of claim 11.

13. Step c) is the addition of a hydroxyl group to the pyridine moiety of the Gd(III) chelate. １８ carried out using aromatic nucleophilic substitution of the nitro group by F, R is a nitro group; The method of claim 11.

14. 11. A pharmaceutical formulation containing a multimodal PET / MRI contrast agent of general formula (VI) according to claim 10, further comprising at least one conventionally used pharmaceutically acceptable auxiliary substance, preferably selected from the group comprising solvents, buffers, ionizing additives, antioxidants, antimicrobial additives.

15. A multimodal PET / MRI contrast agent of general formula (VI) according to claim 10 and / or a pharmaceutical formulation according to claim 14 for use in medicine, preferably for use in multimodal PET / MRI diagnostic methods.

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