Nuclear magnetic resonance apparatus and method of use

Abstract

The present invention relates to providing a nuclear magnetic resonance (NMR) apparatus suitable for measuring nuclear magnetic resonance (NMR) signals within a subject's body part. The present invention provides a lightweight and portable nuclear magnetic resonance (NMR) apparatus. The apparatus is suitable for measuring nuclear magnetic resonance (NMR) signals by using a plurality of magnets arranged in an array to generate a first heterogeneous magnetic field B0 having a static magnetic field gradient B0. A plurality of radio frequency coils are arranged to generate individual heterogeneous magnetic fields B1 substantially orthogonal to the first heterogeneous magnetic field B0. The plurality of radio frequency coils are configured to generate a plurality of different radio frequencies and bandwidths. Acquisition means process the magnetic resonance signal data and provide spatial localization by acquiring nuclear magnetic resonance (NMR) signal data from different bandwidths within the gradients of B0 and B1. A method for acquiring nuclear magnetic resonance (NMR) data and a method for diagnosing brain injury are also provided.

Description

Technical Field

[0001] The present invention relates to providing a nuclear magnetic resonance (NMR) apparatus suitable for measuring nuclear magnetic resonance (NMR: Nuclear Magnetic Resonance) signals within a body part of a subject.

Background Art

[0002] Conventional nuclear magnetic resonance imaging diagnostic apparatuses (MRI: also referred to as Magnetic Resonance Imaging devices) are large and expensive, and are installed in specialized hospitals or diagnostic imaging facilities. Since these conventional apparatuses require trained technical staff, a subject in need of diagnostic imaging must travel to the location where the apparatus is installed to undergo the diagnostic imaging.

Prior Art Documents

Non-Patent Literature

[0003]

Non-Patent Literature 1

Non-Patent Literature 2

Summary of the Invention

Problem to be Solved by the Invention

[0004] If the subject is immobile or has experienced a medical event such as a stroke, moving the subject may not be safe. These limitations often lead to the subject not being diagnosed quickly enough, potentially delaying treatment.

[0005] The object of the present invention is to overcome some of these limitations, or at least to provide an alternative that is useful to the public. [Means for solving the problem]

[0006] In one aspect, the present invention provides a nuclear magnetic resonance (NMR) apparatus suitable for measuring nuclear magnetic resonance NMR signals in a target region within a body part of a subject. The apparatus comprises the following: (a) A plurality of magnets arranged in an array, the magnet array configured to receive a body part of a subject, the magnet array configured to generate a first inhomogenetic magnetic field B0 having a static magnetic field gradient B0 within the body part of the subject being examined, wherein the magnet array comprises a plurality of magnet rings arranged at intervals from each other, each magnet ring configured to extend around the body part, and the plurality of magnets, (b) A plurality of radio frequency coils arranged in an array, wherein the radio frequency coils are configured to be positioned between the magnet array and the periphery of the body part when in use, and each of the radio frequency coils is configured to generate an individual non-uniform magnetic field B1 substantially orthogonal to a first non-uniform magnetic field B0, and the plurality of radio frequency coils are configured to generate a plurality of different radio frequencies and bandwidths over the entire volume of the body part of the subject, and (c) Acquisition means for obtaining nuclear magnetic resonance NMR signal data from different bandwidths within the gradients of B0 and B1, and processing the magnetic resonance signal data to provide spatial localization over the volume of a body part, It is equipped with, (d) The configuration of the magnet array and the radio frequency coil array shall ensure that the magnetic fields of B0 and B1 provide coverage over substantially the entire area of ​​the target region in the body part within the device.

[0007] In one example, the magnet array comprises a plurality of yokes arranged at intervals from each other. Each yoke supports at least one pair of spaced-apart magnets. The yokes and magnets are arranged in an array. The magnets thus define a ring. The ring defines a bore within the device.

[0008] In one example, the spaced yokes are linear. Each yoke can support at least one pair of magnets. In one example, the spaced yokes may be substantially curved around the magnet array to form a magnet ring.

[0009] In one example, the device may have three or more magnetic rings. In one example, a radio frequency coil array comprises a magnet array and a number of coils positioned to extend between the periphery of a body part. The radio frequency coil array is configured to provide spatial information over the volume of a target area.

[0010] In one example, each radio frequency coil is sensitive to spins within a specific sector of the bore. In one example, the radio frequency coil array is configured to provide a transmit-only coil and a plurality of receive-only coils.

[0011] In one example, the radio frequency coil array is configured to provide a plurality of radio frequency coils capable of transmitting and receiving. In one example, multiple radio frequency coils are configured to transmit simultaneously.

[0012] In one example, multiple radio frequency coils are configured to receive simultaneously. In one example, the cross-section of the bore defined by the magnetic ring may be substantially elliptical.

[0013] In one example, the side profile of each magnetic ring may be non-planar. In one example, the magnets in the array may be arranged at irregular intervals.

[0014] In one example, the magnet array may be configured to provide a controlled first non-uniform magnetic field B0 having a magnetic field strength of about 80 mT to about 120 mT, preferably about 100 mT, within the bore.

[0015] In one example, the magnet array may be configured to provide a magnetic field gradient of approximately 15 mT to approximately 20 mT across the target region. In one example, the device is made portable. In one example, the weight of the portable device may be less than approximately 30 kg, preferably less than approximately 25 kg.

[0016] In one example, the body part may be the subject's head. In another example, the subject may be a human being. In another aspect, a method for acquiring nuclear magnetic resonance NMR data using the apparatus provided above is provided, the method comprising the following steps: (a) A process of applying a controlled non-uniform magnetic field B0 over the volume of a target region of the subject's body part, and generating a series of acquisition bands having different resonance frequencies from each other, (b) exciting nuclear spins within each of said set of acquisition bands that collectively cover a target region of a body part by generating and transmitting radio frequency pulses from a plurality of radio frequency coils, such that said nuclear spins generate a plurality of unique radio frequency signals; (c) receiving said plurality of unique radio frequency signals emitted by the nuclear spins from the acquisition bands that collectively provide spatial information over the target region by using the unique spatial sensitivity of each radio frequency coil; and (d) processing the received radio frequency signals to provide data representative of one or more magnetic resonance properties of the target region.

[0017] In another aspect, there is provided a method of diagnosing brain injury using the device as defined above, the method comprising the steps of: (a) applying a controlled inhomogeneous magnetic field B0 over the volume of the head of a subject to generate a series of mutually different acquisition bands each having a different resonance frequency; (b) exciting nuclear spins within each of said set of acquisition bands that collectively cover the head by generating and transmitting radio frequency pulses from a plurality of radio frequency coils, such that said nuclear spins generate a plurality of unique radio frequency signals; (c) receiving said plurality of unique radio frequency signals emitted by the nuclear spins from the acquisition bands that collectively provide spatial information over the head by using the unique spatial sensitivity of each radio frequency coil; (d) processing the received radio frequency signals to provide data representative of one or more magnetic resonance properties of the target region; and (e) interpreting the data to diagnose the presence or absence of brain injury.

[0018] In one example, the brain injury can be an ischemic stroke. In one example, the brain injury can be a hemorrhagic stroke. In one example, the brain injury can be neonatal hydrocephalus.

[0019] In the method defined above, as an example, in step (d), the data representing one or more magnetic resonance characteristics of the target region can be further processed into an image. In the method defined above, as an example, steps (a) to (d) can be performed in less than about 20 minutes, or less than 15 minutes, or less than about 10 minutes.

[0020] In the method defined above, as an example, independent signals can be received by simultaneously using at least a plurality of radio frequency coils. In the method defined above, as an example, the radio frequency pulse generated in step (b) can have an excitation bandwidth of about 40 kHz to about 60 kHz.

[0021] In the method defined above, as an example, the series of acquisition regions generated in step (a) can include at least 5 acquisition regions. In the method defined above, as an example, the magnetic resonance characteristic of the target region can be diffusion.

[0022] In the method defined above, the magnetic resonance characteristic of the target region can be perfusion. In the method defined above, the magnetic resonance characteristic of the target region can be T2.

[0023] In the method defined above, the body part can be the head of a subject. In the method defined above, the subject can be a human.

[0024] In the method defined above, as an example, the method may be carried out in an environment away from the hospital (setting remote from hospital). This disclosure will be described below with reference to specific examples. However, other examples not described above are equally possible within the scope of this disclosure. Methods, processes, hardware, or software that perform the methods different from those described may be provided within the scope of this disclosure. The various features and processes of this disclosure may be combined in combinations different from those described.

[0025] Further aspects of this disclosure will become apparent from the following disclosures. Where references in this specification to external sources comprising patent specifications and other documents are made, these are generally for the purpose of providing context for the description of the features described. Unless otherwise stated, references to such sources should not be construed in any jurisdiction as an admission that such sources constitute prior art or form part of the general common knowledge of the art.

[0026] <Definition> As used herein, the term “bore” means “volume within a device” in relation to a device, and more specifically “volume for receiving a body part.”

[0027] As used herein, the term "about" in relation to a referenced numerical value means the referenced numerical value within a range of up to ±10% of that referenced numerical value. For example, the expression "about 30 kg" encompasses a range of "from 33 kg to 27 kg".

[0028] As used herein, the terms “and / or” mean both “and” and “or.” As used herein, “(s)” following a noun means the plural and / or singular form of the noun. As used herein, the term “comprising” means “including” or “consisting at least in part of.” When interpreting any description containing the terms herein, all features preceded by the terms must be present in each description, but other features may also be present. Related terms, such as “comprise” and “comprised,” should be interpreted similarly. All entire disclosures of applications, patents, and publications cited above and below (if any) are incorporated herein by reference.

[0029] In this specification, the terms “comprises,” “comprising,” “includes,” and “including” should be interpreted as non-exclusive, inclusive, and open-ended. Specifically, as used herein (with claims), “comprises,” “comprising,” “includes,” and “including,” and their variations, mean that the specified features, processes, or components are included. These terms should not be interpreted as excluding the existence of other features, processes, or components.

[0030] As used herein, the terms "approximately" or "approximate" mean "near" or "close," or "about" or "near." Alternatively, "approximately" or "approximate" can mean "estimated" or "inaccurate."

[0031] As used herein, the term “substantially” means “in most of the case,” “almost,” “essentially,” or “to a considerable or significant degree.”

[0032] One or more examples of the present disclosure are described below with reference to the accompanying drawings. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic perspective view of a nuclear magnetic resonance NMR spectrometer, showing the subject's head positioned inside the bore. [Figure 2] This is another perspective view of a nuclear magnetic resonance NMR apparatus, showing a notch for the magnet, and schematically illustrating the position and proximity of the radio frequency coil to the magnet, as well as the head of the subject located inside the bore. [Figure 3] This is a schematic diagram showing that a series of spaced-out magnet rings form a magnet array as a whole. [Figure 4] Figure 4(a) shows a plan view of a magnet ring array having an elliptical arrangement. Figure 4(b) shows a side view of a magnet ring array having a planar arrangement. Figure 4(c) shows a magnet ring array having a non-planar arrangement. [Figure 5] Figures 5(a) and 5(b) show cross-sectional views of a pair of magnets spaced apart at each end of the yoke, showing that the magnets together provide a magnetic field indicated by B0, and that the radio frequency coil provides a substantially orthogonal field B1. [Figure 6] Figures 6(a) to 6(e) show plots of magnetic field strength in different planes. Figure 6(a) shows the magnetic field strength in the XZ plane. Figure 6(b) shows the magnetic field strength in the YZ plane. Figures 6(c), 6(d), and 6(e) show the magnetic field strength in the XY plane and at different heights. [Figure 7] The magnetic field strength along the X-axis is shown for five different magnet ring radii ranging from 110mm to 130mm. [Figure 8] Figure 8(a) shows a three-dimensional view of a radio frequency array having multiple radio frequency coils. Figure 8(b) shows a two-dimensional plan view of a radio frequency array having multiple radio frequency coils. Figures 8(c) to 8(f) all show plots of radio frequency intensity from individual coils across the entire bore and different planes. [Figure 9] Figures 9(a) to 9(d) show plots in different planes indicating regions prone to ischemic stroke. [Figure 10] Figures 10(a) and 10(c) show a pair of acquisition bandwidths generated by the magnetic array, and Figures 10(b) and 10(d) show the respective target region coverages of the corresponding pair of heatmap slices. [Figure 11] This shows a series of acquired bandwidths obtained from multiple radio frequency coils across different sectors of the target region / brain. [Figure 12] For patients with ischemic areas, a plot of the simulated diffusion-weighted signal difference between the left and right hemispheres is shown. [Figure 13] A rendering of a portable nuclear magnetic resonance NMR apparatus, equipped with the magnet array and radio frequency coil described herein, is shown. [Modes for carrying out the invention]

[0034] Figure 1 shows a magnet array 1 suitable for a nuclear magnetic resonance (NMR) system. The magnet array 1 is configured and shown to receive a subject's skull 2. The magnet array 1 includes a framework configured to define a bore in which a body part, such as the subject's skull 2, will be placed during use. The framework includes one or more rings 3 and 4 spaced apart from each other. These rings 3 and 4 support a plurality of magnets 5 within an array composed of two or more concentric rings (shown in Figure 3). Each ring 3, 4 is spaced apart from each other and is fixed by a plurality of yokes 6 that position the concentric rings 3, 4 in a spaced manner. Each yoke 6 supports one or more magnets to form the magnet array 1.

[0035] The magnet array 1, when combined with a series of radio frequency (RF) coils 7 pre-positioned between the magnet array 1 and the skull 2 ​​during use, forms a nuclear magnetic resonance (NMR) system. The radio frequency coils 7 are best illustrated in Figure 2.

[0036] Referring to Figure 3, another example is shown in which the magnet array consists of three magnet rings 8, 9, and 10 spaced apart from each other. Each magnet ring 8, 9, and 10 is shown to have magnets 5 spaced apart from each other. The distance between each magnet ring 8, 9, and 10 is known as the z-spacing distance. This example of magnet rings 8, 9, and 10 differs from the examples of magnet arrays shown in Figures 1 and 2 in that it includes an inner magnet ring 9.

[0037] Referring to Figure 4, the magnet array is configured in an elliptical shape (see Figure 4(a)) and has planar sides (see Figure 4(b)). However, it should be understood that any shape surrounding the target area can be used, and that non-planar sides (see Figure 4(c)) may also be appropriate depending on the shape of the target area.

[0038] In this example, the nuclear magnetic resonance NMR system uses a constant magnetic field B0 provided by a magnet array, but also relies on a weaker oscillating magnetic field B1. This oscillating magnetic field B1 is provided by a series of radio frequency coils, such as coil 7 of the magnet array, and is used to excite spins by generating the B1 magnetic field and to detect signals from the spins.

[0039] In conventional nuclear magnetic resonance (NMS) and magnetic resonance imaging (MRI) systems, homogeneous B0 and B1 fields (combined with pulse gradients) enable the excitation, detection, and spatial localization of NMS signals from nuclear spins within the NMS system. In contrast, the NMS system configured as described herein performs measurements in an inhomogeneous field generated by its B0 magnet array. Spins enter an on-resonance state when their B0-dependent resonance frequency at their location falls within the excitation frequency bandwidth of the B1 field. Off-resonance spins are substantially insensitive to excitation from the B1 field. Therefore, measurements in an inhomogeneous B0 field are limited by the B1 excitation frequency and bandwidth, thereby limiting the coverage region, i.e., the region in which signals can be excited and detected. However, the spatial sensitivity of the described nuclear magnetic resonance NMR spectrometer is achieved through the design of the magnet array and RF coil array, thereby ensuring that the B0 and B1 fields can still cover substantially the entire area of ​​the target region within the spectrometer.

[0040] Furthermore, the apparatus is configured to minimize mass and improve the efficiency of the magnet array, i.e., the in-bore magnetic field strength per unit weight of the magnet array. Since the intensity of the nuclear magnetic resonance NMR signal depends on the magnetic field strength, it is important to maximize the intensity of the B0 field by configuring the magnet array. However, the weight of the apparatus is an important consideration, especially for portability in pre-hospital or in-field environments. Reducing weight is desirable as it facilitates the transport and use of the apparatus. The design and optimization of the number, size, and position of magnets in the magnet array (discussed in Example 1 below) improves the efficiency of the design while maintaining coverage across the target region.

[0041] Referring to Figures 5(a) and 5(b), a cross-sectional view of one pair of magnets 11 already positioned on the yoke 12 is shown, along with an arbitrary inner magnet 13. The curve 15 shows contour lines of the B0 magnetic field strength extending between the magnets, with the direction of the magnetic field indicated by the arrow B0. The magnetic field strength decreases as the line moves away from the magnets, thus forming a static magnetic field gradient. The B0 magnetic field extends across the target region, i.e., across the central shaded area 16. Figure 5(b) shows the effect of an additional magnet ring 17. The additional magnet ring 17 is configured to straighten the contour lines 15 of the B0 magnetic field strength across the target region. The magnet array and RF coil assembly, as a whole, provide a multitude of these arrangements. In the example shown in Figure 1, there are 18 pairs of magnets, each generating its own magnetic field. The RF coil 14 is shown positioned between the magnets (11, 13, 17) and spaced apart from the magnets (11, 13, 17) and the yoke 12. The oscillating magnetic field B1 is generated by the current flowing through the RF coil 14 and is substantially orthogonal to B0. This arrangement is determined to be substantially optimized. Each RF coil 14 is positioned independently of the magnet pair 11. Figure 5 should be understood as a simplification of the entire apparatus.

[0042] Magnetic field coverage depends on the heterogeneous B0 and B1 fields generated by the magnet array and RF coils. The heterogeneous B0 field forms a controlled gradient across the bore, and spins located at different positions are subject to a range of B0 field intensity, which corresponds to a range of resonance frequencies. By performing multiple nuclear magnetic resonance NMR measurements across a range of B1 frequencies and bandwidths corresponding to different positions across the bore, the instrument can excite and detect signals from multiple different regions across the heterogeneous B0 field, thereby increasing coverage. This controlled gradient, i.e., the controlled heterogeneous magnetic field B0, is necessary to achieve the functionality of the nuclear magnetic resonance NMR system.

[0043] In addition to the magnet array and RF coil array, additional hardware is required to acquire nuclear magnetic resonance NMR signals from spins in the bore. This includes a spectrometer (e.g., supplied by Resonint, Wellington, New Zealand) for executing nuclear magnetic resonance NMR pulse sequences and RF amplifiers for transmitting and receiving (e.g., supplied by TOMCO, Stepney, South Australia, Australia). This hardware is similar to the electronics used in other low-field nuclear magnetic resonance NMR instruments. The spectrometer handles the timing within the pulse sequence, generating RF pulses with varying frequency, power, and duration to acquire the nuclear magnetic resonance NMR signal. The spectrometer can operate in multi-channel mode, acquiring RF signals from all RF coils simultaneously, or in multiplexed mode, acquiring signals from only a subset of the RF coils simultaneously.

[0044] Referring to Figure 13, an example of a hypothetical commercial nuclear magnetic resonance NMR spectrometer is shown. The spectrometer is housed in a housing equipped with hand grips to facilitate portability. The spectrometer may also include one or two windows that allow the user to see outside the spectrometer, for greater comfort and to reduce any feelings of claustrophobia.

[0045] <Example 1 - Simulation example of a magnet array> The B0 magnetic field generated by the magnet array described above defines the spatial sensitivity and coverage of the system. To understand the efficiency and gradient generated by different types of magnet array designs, a range of magnet assembly designs were fabricated, and the magnetic fields they generated were simulated. For each design, a range of parameters such as the number of magnets, magnet size, ring diameter, eccentricity, and z-spacing were tested to understand how they affect the magnetic field strength and gradient. These parameters were used to create a list of magnet positions and magnetization directions, which were used as input for the simulation process.

[0046] The full geometry of the magnet array, including the shapes of the magnet blocks and yoke pieces, has been generated using the selected finite element method (FEM). The simulation was performed using the open-source gmsh / GetDP software. This generated the three-dimensional volume of the magnetic field, from which its magnitude, B0 magnetic field, has been calculated.

[0047] The geometry was meshed using the software gmsh, and the coercivity, remanent magnetization, and permeability of the magnet and yoke regions were set according to the material properties. The field was solved using the scalar magnetic potential method with the software package GetDP.

[0048] This method was used to simplify the analysis while capturing the effect of changes in material permeability. The magnetic field has been calculated and then interpolated onto a regular grid, generating a two-dimensional map of the magnetic field across the bore, or a three-dimensional volume.

[0049] The most efficient design with the found axial field was determined to be the in-out ring or Aubert ring design, modified to include a yoke connecting the main rings. This design generates a radial magnetic field gradient, with the field being weakest along the bore axis at r=0 and increasing with increasing r within the bore. The magnetic field strength results for this design are shown in a series of contour plots in Figure 6.

[0050] The magnet array is based on two magnet rings (8,10) that define the bore, and an additional magnet ring (9) can be placed between them to further modify the magnetic field as desired. One of the main rings (8) has a block that is positioned so that the magnetization is directed radially outward from the bore axis, while the other (10) has a block that is directed toward the bore axis, as shown in Figure 3. These magnet rings generated a magnetic field within the array that was oriented along the bore axis z, as shown in Figure 3.

[0051] Between the in-out magnet rings, one or two additional magnet rings may be present to further control the magnetic field gradient within the bore. The magnets in the additional magnet rings (9) were magnetized to face the "-z" direction to enhance the magnetic field strength within the bore. The size of the magnets may be varied depending on the desired magnetic field gradient. Preferably, to avoid a reduction in bore dimensions, the magnets were the same size as the in-out ring magnets or smaller.

[0052] Furthermore, a yoke bar made of a high-permeability metal such as steel is connected to the in-out ring, forming a yoke that reorients and concentrates the magnetic field inward within the bore. This increases the magnetic field strength within the bore, improving the efficiency of the magnet array and further reducing stray magnetic fields outside the device. It also provides mechanical support for the in-out ring.

[0053] In in-out magnet ring designs, various simulated designs observed a decrease in magnetic field strength within the bore as the diameter increased (for the same number of magnets). This trend was expected because the magnetic field generated by the same volume of magnets spreads over a larger volume. This suggested that smaller bore volumes would have offered higher efficiency, although the body parts being measured still limited the minimum bore size.

[0054] Furthermore, it was determined that stretching the magnetic ring along the y-axis into an elliptical shape helps maintain field intensity and coverage, as well as minimizing the diameter in the x-axis direction and the enclosed bore volume. This is desirable because the skull is a preferred body part to be considered within the bore volume, and the length of the skull is usually longer than its width, i.e., the anterior-posterior length is longer than its lateral width. To fit the skull into the bore, larger dimensions limit the minimum size of the device. Surprisingly, it was found that stretching the magnetic ring along the y-axis helps maintain field intensity and coverage, as well as minimizing the diameter in the x-axis direction and the enclosed bore volume.

[0055] It was also found that the z-spacing of the rings affects the magnetic field strength and gradient. For a pair of in-out magnet rings, the maximum magnetic field strength and efficiency were obtained when the z-spacing was substantially equal to the diameter of the magnet rings. However, this also significantly increased the radial gradient, limiting the magnetic field coverage. When the z-spacing was larger than the diameter, the radial gradient decreased at the expense of field strength. This parameter was determined to be important for controlling the system's coverage.

[0056] Another parameter of interest was the shape of the ring along the y-axis. This could be a flat plane with a constant z-position along the y-axis, as shown in Figure 4(b). On the other hand, the effect of distorting the z-position of the magnet along the anterior-posterior axis to follow the contour of the target region was also investigated. This contour may be obtained by averaging the shape of the target region, or, for example, y=cz*z for y<0. 2 The position of the magnetic ring may be distorted by mathematical representations such as the following. This describes a plane that has a curved region toward the rear of the magnetic ring, improving coverage of the target region.

[0057] Further optimization of the magnet array may include changing the spacing of the magnets around the ring, for example, increasing the spacing between adjacent magnets within the ring, or removing one or more magnets from specific locations within the ring. This may allow for further weight reduction and improved patient comfort by reducing claustrophobia.

[0058] Depending on the z-spacing of the magnetic rings, the magnetic field exhibits an ellipse with a maximum value of B0. A saddle point where the magnetic field gradient is substantially zero was observed (see dashed line 19 in Figure 6(d)). It was determined that the saddle point and beyond must be located outside the bore volume or any region of interest in order to ensure a consistent magnetic field gradient covers the bore volume and target region.

[0059] Because the z-spacing of the rings was large relative to the magnet size, it was also considered to add an inner magnet ring ("9" in Figure 3) in the space between the in-out rings ("8" and "10" in Figure 3). These are magnetized along the z-axis to increase the magnetic field strength within the array. In designs with a yoke, the inner ring is constrained to be smaller than the main in-out ring. The number of rings and their positions could be freely varied. It was observed that adding one or two smaller magnet rings in the middle of the outer magnet rings provided a method for controlling the field gradient, particularly at the edge of the target region / bore. By controlling the radius of the inner magnet ring, the gradient across the target region could be made more constant, thereby eliminating any influence from the maximum field strength ring mentioned above.

[0060] Another consideration in the magnet array design was the shape of the magnetic field contours and gradients. As discussed in Example 3 below, the inhomogeneity of the B0 field was used to select spins from different radial depths within the bore. This technique made it possible to localize the nuclear magnetic resonance NMR signal to different radii by changing the B1 excitation frequency. The B0 magnetic field intensity contours indicated by "15" in Figures 5(a) and 5(b) reflect the volume of spins excited at each excitation frequency that form the acquisition band, as shown, for example, in Figure 6.

[0061] In addition to maintaining coverage across the target region (labeled "16" in Figures 5(a) and 5(b)), it was important to control the shape of these contours in each acquisition band. This was because strongly curved acquisition bands made it more difficult to radially localize the detected nuclear magnetic resonance NMR signal. In curved acquisition bands, the radius of the acquisition band can depend on z, making it difficult to localize the signal to a single radius. It was preferable to design the magnet array so that the field contours across the target region were substantially straight. This could be achieved by adding an additional magnet ring above the upper end of the magnet array, enclosing one side, as shown in "17" in Figure 5(b). The additional magnet ring 17 appeared to straighten the magnetic field contours across the target region because it enhanced the field in the upper half of the bore.

[0062] <Example 2 - Coil Simulation Example> In another example, the contribution of a heterogeneous B1 field generated by an array of RF coils to the instrument coverage was simulated. Each coil has a sensitivity pattern that reflects its sensitivity to spins located at different positions due to the heterogeneous B1 it generates.

[0063] The B1 fields generated by these coils were simulated using the Biot-Savart law (see Griffiths). Since the B1 is of a low radio frequency, the coil currents can be treated as quasi-static. The RF coil array was parametrically defined to control the position and size of the RF coils. As a result, a series of elliptical wire paths along the surface of an elliptical cylinder fitting around the bore rim was determined to be optimal, as shown in Figures 8(a) and 8(b).

[0064] Similar to the B0 design, the radio frequency fields generated by each coil were calculated on a grid to simulate a three-dimensional image of the B1 field generated by each RF coil when a current of 1 ampere is passed through each RF coil. Slices of the three-dimensional image are shown in Figures 8(c) and 8(d). The magnitude of the B1 field on the XY plane was used. This is to control the spatial sensitivity of the RF coils to the nuclear magnetic resonance NMR signal. The magnitude of the B1 field was selected within a specific range, which corresponds to the region where RF pulses that produce 180-degree excitation relative to the B0 bandwidth are permitted. In these simulations, a B1 magnitude of 1.5–6 microtesla was selected as the "detectable" region and is shaded in gray in the slices shown in Figures 8(c) and 8(d).

[0065] The detectable region of B1 maps a series of sectors across the bore volume, aligned with the RF coil. Since the angular size of the sectors is controlled by the width of the RF coil, the attenuation of B1 with respect to the distance from the RF coil also depended on the width and dimensions of the RF coil.

[0066] In one embodiment, the coil array was configured as a plurality of RF coils that both transmit and receive RF pulses within the bore volume. In this configuration, the pulse from each RF coil excited one sector of the bore because the B1 field generated by the coil was non-uniform. The plurality of RF coils were used to detect signals from the excited sectors. In this embodiment, it was found that this arrangement provided good spatial resolution because the non-uniformity of B1 controlled both the excitation and detection regions.

[0067] In another embodiment, the coil array was configured as an array of RF-receiving coils with a separate volumetric transmitting coil. The transmitting coil was configured to excite the entire acquisition band in a single experiment, effectively exciting a ring. The array of receiving coils still provides spatial information for different sectors due to the B1 non-uniformity of each receiving coil. This provides the advantage of faster acquisition across the target region, as it eliminates the need to repeat nuclear magnetic resonance NMR measurements for each individual coil and frequency combination. It also reduces the requirement for high-power switching between different coils. The transmitting coil can follow designs used in conventional magnetic resonance imaging (MRI) and nuclear magnetic resonance NMR systems, for example, birdcage or saddle coil designs that generate transverse B1 across the volume.

[0068] In practical applications, the power and / or duration of the RF pulse passing through the RF coil of B1 will need to be varied depending on the intended area within the bore. Furthermore, the sensitivity across the detectable area will also vary depending on the distance from the RF coil.

[0069] <Example 3 - Acquisition Method, Target Region Identification, and Coverage> Since the coverage of the instrument depends on the spatial distribution of the B0 and B1 fields, it is desirable to ensure that the target region for a particular indication is located within the coverage region and within the bore volume. Heterogeneous B0 and B1 fields hinder the use of conventional magnetic resonance imaging (MRI) imaging techniques and pulse sequences to acquire and localize nuclear magnetic resonance NMR signals across the bore. Conventional nuclear magnetic resonance NMR experiments do not provide coverage of the target region because they only detect signals from small areas of the bore.

[0070] To address this, the Magnetic Resonance Imaging in static gradient method was introduced. The heterogeneous B0 field was divided into a series of bands with different magnetic field strengths along the gradient, resulting in a series of resonance frequencies. The different bands reflect different radial depths within the bore. The thickness of these bands in space is determined by the bandwidth of the RF excitation pulses generated by the spectrometer. A series of nuclear magnetic resonance NMR measurements were performed, with the excitation frequency set to the resonance frequency of each individual band, thereby obtaining signals from each band. Combining the results from different bands increased coverage across the bore.

[0071] Further spatial localization is provided by the RF coil array. As described in Example 2 above, each coil has a sensitivity pattern due to the non-uniform B1 field it generates. By performing a series of measurements using different RF coils in the array, it became possible to localize the signal to a specific sector of the bore.

[0072] Spatial localization techniques can be combined with various pulse sequences to enable the acquisition of conventional magnetic resonance imaging (MRI) contrast. These include T1-weighted, T2-weighted, and diffusion-weighted images. Measurements from different coil and bandwidth combinations allow for comparison of signal intensities from different locations within a body part, providing information about the location and size of potential lesions.

[0073] To simulate the coverage of spatial localization techniques, the B0 magnetic field image simulated for the magnet described in Example 6 below was used for the coverage study. The B0 field image was sliced ​​into a series of 16 frequency bands, each defined by a series of center frequencies (in the range of 4.1–4.9 MHz) and an excitation bandwidth for each band (assuming 50 kHz). The bandwidths and number of bands were selected to match the limitations of the spectrometer hardware. The spectrometer hardware has a limited frequency range in which it can tune and acquire signals. Each simulated acquired band reflects the volume in the magnetic field excited at a specific B1 frequency and bandwidth, and overall system coverage was obtained by combining the volumes of bands with different excitation frequencies. In actual applications, the number, frequency, and bandwidth of acquired bands are expected to be set based on the limitations of the specific spectrometer and RF acquisition hardware, as well as the specific magnetic field strength and gradient generated by the magnet array in each band, and the desired resolution.

[0074] Because the coverage area and resolution generated by spatial localization techniques differ from those of conventional magnetic resonance imaging (MRI) images, it was crucial to design the magnet array and RF coil array so that the device's B0 and B1 fields would enable coverage to cover the most important areas of a body part for a specific injury. While the device can be used for numerous indications or injuries, ischemic stroke is a particularly interesting area, and the inventors conducted research on ischemic stroke to identify target areas. As background, since ischemic stroke is caused by occlusion of the vascular system, statistically, it is more likely to occur in certain locations than others due to vascular anatomy (see Bonkhoff et al.). In contrast, some areas may have a lower risk of ischemia. Statistical heatmaps have been generated using images from the Stroke Neuroimaging Study (Titan Neuroscience, Australia). Patient images were normalized to the standard MNI (Montreal Institute of Neurology) space, and stroke lesions were segmented to indicate brain regions affected by stroke. By integrating the lesions and averaging across all patients, statistical heatmaps were obtained, shown in Figure 9(a) (displayed in the XY plane) and Figure 9(b) (displayed in the XZ plane), which show the brain regions most susceptible to stroke. The values ​​in the 3D images correspond to the probability that the voxel was affected by stroke in patients within the dataset.

[0075] The heatmap showed that ischemic stroke was most common in the middle cerebral artery (MCA) region, and as a result, other lesion types were not adequately reflected in the final heatmap. To address this issue, the weighting of clinically important stroke types was increased, which artificially added more "heat" to the stroke-affected areas outside the middle cerebral artery (MCA) region, proportionally reducing the "heat" in the rest of the brain. This additional weighting generated a second heatmap, which was used for system optimization and design (see heatmaps in Figure 9(c): XY plane and Figure 9(d): XZ plane).

[0076] The heatmap was thresholded to identify voxels with a significant probability of containing stroke lesions. Voxels exceeding the threshold were combined to define the target region. This process allowed for the identification and quantification of the target region for ischemic stroke within the bore volume, although this method may be applicable to other conditions as well.

[0077] To evaluate the potential performance of a nuclear magnetic resonance NMR spectrometer, the target region and frequency band described above were combined. The acquisition band was superimposed on the target region along with a matching grid, and the number of target region voxels present within the acquisition band was counted. This yielded a geometric coverage score that can be used to design and optimize the magnetic array.

[0078] As an example of this method, Figure 10 shows the plane for calculating the coverage score for the magnets described in Example 6. Figure 10(a) shows the XY plane passing through the center of the magnet array (z=0mm), with contour lines indicating frequency bands. Figure 10(b) shows the plane of the target region aligned and superimposed from the weighted heatmap described above, indicating that the entire target region in this slice was within the acquisition band. A second XY plane from further below the bore (z="-32" mm) is shown in Figures 10(c) and 10(d), showing the target region and coverage. The result of this process is the coverage score, which was 88% for the weighted heatmap and the magnet array. The coverage score for the magnet array and the unweighted heatmap was 93%. These coverage scores provided confidence that the B0 field distribution generated by the magnet array has the potential to detect signals from a large portion of the region where strokes occur.

[0079] <Example 4 - Measurement simulation using stroke patient data with diffusion-weighted imaging> One of the objectives of this device is to provide a means of rapidly diagnosing whether or not a subject has been affected by a stroke. To understand the sensitivity of the nuclear magnetic resonance NMR spectrometer to stroke, we simulated the signals acquired by the device in sets of individual magnetic resonance imaging MRI images from stroke patients using the Australian TITAN Neuroscience stroke imaging database. The results obtained provided guidance on the potential performance of the device based on actual, true stroke data.

[0080] The simulation was achieved using diffusion-weighted imaging (DWI). Diffusion-weighted imaging (DWI) contrast has very high sensitivity to microstructural changes in ischemic stroke and is often used clinically to diagnose stroke. Reduced diffusion during stroke results in lesions with increased signal intensity on magnetic resonance imaging (MRI) images. The selected device design for use in this example is described in Example 6 below.

[0081] The system simulates the signals acquired, and a series of 3D acquisition bands are created by combining B0 and B1 magnetic field maps to estimate the signal patterns of different injuries. Each combination of coil and B0 band generates what is referred to herein as the “acquisition band”. The acquisition bands are superimposed and aligned on existing 3D magnetic resonance imaging (MRI) image data for each individual subject. The sum of the intensities of the MRI image voxels within each acquisition band yields the simulated signal for measurement in each band. The simulation focused on diffusion-weighted DWI, but other signals that could be investigated may include T2, T2_Flair, diffusion-weighted DWI, etc., which may be known to those skilled in MRI imaging. A series of examples of acquisition bands are shown in Figure 11 (superimposed as an anatomical reference on the heatmap described above). The bands for the left and right hemispheres are shown as bands in the slices in the left and right columns, respectively. Furthermore, the two lower slices show the acquisition bandwidths corresponding to the posterior left and posterior right coils, which makes it possible to detect signals from the indicated brain sectors.

[0082] This study uses data obtained from stroke subjects with lesions, with b = 1000 s / μm 2 The study begins with diffusion-weighted images, which were acquired on a conventional clinical magnetic resonance imaging (MRI) system. The images were normalized to a standard MNI (Montreal Institute of Neurology) space, and brain volume was extracted. Lesions within the brain were manually annotated to test the crossover between a series of acquired bandwidths. The bandwidths were then crossed over the brain volume images, and the diffusion-weighted DWI intensities of voxels within each bandwidth were summed. This simulated the acquisition of the device's diffusion-weighted signal for each bandwidth.

[0083] The simulation signals were input into a simplified classifier to identify the degree of ischemia and the hemisphere affected in the brain. By comparing diffusion-weighted imaging (DWI) signals from the acquisition band in different hemispheres of the brain, the hemisphere with ischemic lesions could be identified by a higher diffusion-weighted signal. The unaffected hemisphere effectively served as a control. Ischemia could be identified by using the signal difference from the two hemispheres, depending on the changes in volume and diffusion rate of the ischemic lesions.

[0084] This process was performed across 120 stroke images, and the resulting data is shown in Figure 12. Figure 12 clearly demonstrates that the difference in diffusion-weighted DWI signals between two hemispheres correlates with the size of the ischemic lesion, and that the device and measurement simulations predict the detection and diagnosis of stroke.

[0085] <Example 5 - Signal localization for image output> As discussed in Example 3 above, the heterogeneous B0 and B1 fields generated by the apparatus can be used to localize the nuclear magnetic resonance NMR signals acquired by the apparatus. Since it is advantageous to display this in an intuitive manner for clinicians, the inventors proposed a method for generating images from the nuclear magnetic resonance NMR signals measured by the apparatus. This method relies on prior knowledge of the B0 and B1 fields designed in Examples 1 and 2. To generate images in real space, the spin contribution at each position in the bore must be known for each coil and band combination. This was found using the simulation methods described in Examples 1 and 2, but may also be measured directly by mapping the magnetic field in space using a Gauss meter or by measuring known calibration samples. To generate output images, the measured nuclear magnetic resonance NMR signals for each band from each coil were processed to generate weighted values ​​that reflect the desired signal contrast for each band from each coil. This included common magnetic resonance imaging MRI contrasts such as T1-weighted, T2-weighted, or diffusion-weighted contrast. The bandwidth values ​​were used to set the image intensity of each pixel within the bandwidth. The image intensity for overlapping bandwidths was set using a weighted average of the sensitivity maps for each pixel. This generated an image that is a projection passing through the target region and convolved with the shape of the acquired bandwidth as an effective point-spread function. The image contrast may be modified by applying further image post-processing techniques common in conventional magnetic resonance imaging (MRI) to the image output.

[0086] <Example 6 - Construction of a Nuclear Magnetic Resonance NMR Spectrometer> An example of the device is shown in Figure 1. The device comprises a magnet array designed using the method described above, and includes an inwardly magnetized ring, an outwardly magnetized ring, and one additional ring in the center. This was stretched 1.1 times along the y-axis, and the rings were curved to follow the plane of the target region. This generated a magnetic field of 96–115 mT within the brain volume. The weight, including the mild steel yoke, was approximately 30 kg. It had sufficient clearance for the widest side (99th percentile) of an adult head. This was combined with 12 RF coils in an array of coils pre-arranged at equal intervals around the head.

[0087] Each ring consisted of 18 magnet blocks, preferably 1.5 Tesla (T) neodymium iron boron (NIB)-grade N42, with block dimensions of 35mm × 35mm × 50mm. The blocks were magnetized along the 35mm axis and had a residual magnetic field of 1.3T. They were sourced from Shanghai Jin_Magnet. The yoke pieces were machined from 8mm thick mild steel plates with dimensions of 300mm × 35mm. Mild steel was selected for its high permeability to concentrate the magnetic field within the array. The magnets and yokes were mounted on an aluminum frame using stainless steel fasteners. The radio frequency coil was formed from multiple turns of enameled copper wire with a diameter of approximately 150mm. The magnet array was housed within a plastic shell (not shown in the figure), with the RF coil positioned inside the shell, near the bore and the body part to be measured. The final weight of this magnet array was approximately 32kg, more preferably less than approximately 25kg.

[0088] <Advantages> This nuclear magnetic resonance NMR system offers numerous advantages over existing technologies through its integrated design of magnet arrays, RF coil arrays, nuclear magnetic resonance NMR acquisition methods, and applications. Conventional nuclear magnetic resonance NMR and magnetic resonance imaging (MRI) systems rely on a strong (>1.5T) and uniform B0 field. In contrast, this system does not require a uniform field; instead, it uses a heterogeneous field designed to provide coverage and localization across brain volume. The magnet array for generating the heterogeneous B0 field is significantly simpler and lighter than the magnets used to generate the B0 field in conventional systems. Furthermore, because the magnetic field is designed to be primarily within the target region, less magnetic material is required within the array, resulting in lower costs.

[0089] The low magnetic field (<120mT) generated by this device poses less risk and is safer to use than the high magnetic fields (>1.5T) used in conventional magnetic resonance imaging (MRI) systems. The low field reduces the force exerted on nearby ferromagnetic objects. The magnet design with a yoke also reduces leakage magnetic fields outside the device. Furthermore, at this magnetic field strength, the B1 excitation frequency is lower, resulting in less RF power deposition and heating in body parts.

[0090] Static magnetic field gradient technology eliminates the need for additional hardware such as gradient coils and amplifiers used in conventional scanners. This reduces the power required to operate the system, allowing it to be powered by a portable battery or plug-in power supply. This makes the device significantly smaller, lighter, and more portable.

[0091] Inexpensive, lightweight, quiet, and portable devices would enable new applications, for example, in ambulances or remote locations. For the specific indication of ischemic stroke, portable devices for diagnosing stroke could improve patient outcomes by accelerating the diagnostic process.

[0092] While the apparatus and methods of this disclosure have been described in terms of embodiments included herein, it will be apparent to those skilled in the art that modifications can be applied to the features or elements (integers) of the apparatus and / or methods described herein without departing from the concepts, spirit, and scope of this disclosure. All such similar substitutions and modifications, which are apparent to those skilled in the art, are deemed to fall within the scope and concepts of this disclosure as defined by the appended claims.

Claims

1. A device as a nuclear magnetic resonance NMR apparatus suitable for measuring nuclear magnetic resonance NMR signals within a target region of a subject's body part, wherein the device is (a) A plurality of magnets arranged in an array, wherein the magnet array is configured to receive the body part of the subject, and the magnet array is positioned within the body part of the subject being examined, B ０ First heterogeneous magnetic field B having a static magnetic field gradient ０ The magnet array is configured to generate a plurality of magnets, and the magnet array comprises a plurality of magnet rings that are spaced apart from each other, and each of the magnet rings is configured to extend around the body part, (b) A plurality of radio frequency coils arranged in an array, wherein the radio frequency coils are configured to be positioned between the magnet array and the area around the subject's body part when in use, and each of the radio frequency coils is connected to the first non-uniform magnetic field B ０ Individual non-uniform magnetic fields B that are substantially orthogonal to the given field. １ A plurality of radio frequency coils are configured to generate a plurality of different radio frequencies and bandwidths over the entire volume of the subject's body part, and (c) B ０ and B １ An acquisition means for obtaining nuclear magnetic resonance NMR signal data from mutually different bandwidths within the gradient, and processing the nuclear magnetic resonance NMR signal data to provide spatial localization over the volume of the body part, It is equipped with, (d) The configuration of the magnet array and the radio frequency coil array is B ０ and B １ The magnetic field is such that it ensures coverage over substantially the entire area of ​​the target region in the body part within the device. Device.

2. The aforementioned magnet array comprises a plurality of yokes that are spaced apart from each other. Each of the yokes supports at least one pair of the magnets that are spaced apart, The yoke and the magnets are arranged in an array, so that the magnets define the magnet ring, and the magnet ring defines a bore within the device. The apparatus according to claim 1.

3. The yokes, which are already spaced apart, are in a straight line. Each of the yokes supports at least one pair of the magnets. The apparatus according to claim 2.

4. The spaced-apart yokes are substantially curved around the magnet array to form the magnet ring. The apparatus according to claim 2.

5. The device has three or more of the aforementioned magnetic rings. The apparatus according to any one of claims 1 to 4.

6. The array of radio frequency coils is configured to include a plurality of radio frequency coils arranged to extend between the magnet array and the periphery of the body part, The array of radio frequency coils is configured to provide spatial information over the volume of the target region. The apparatus according to any one of claims 1 to 5.

7. Each of the aforementioned radio frequency coils is sensitive to nuclear spins in a specific sector of the bore. The apparatus according to claim 6.

8. The array of radio frequency coils is configured to provide a transmit-only coil and a plurality of receive-only coils. The apparatus according to claim 6.

9. The array of radio frequency coils is configured to provide a plurality of radio frequency coils capable of transmitting and receiving. The apparatus according to claim 6.

10. Multiple radio frequency coils are configured to transmit simultaneously. The apparatus according to claim 6.

11. Multiple radio frequency coils are configured to receive simultaneously. The apparatus according to claim 6.

12. The cross-section of the bore defined by the magnetic ring is substantially elliptical. The apparatus according to any one of claims 1 to 11.

13. The side profile of each of the aforementioned magnet rings is non-planar. The apparatus according to any one of claims 1 to 12.

14. The magnets within the aforementioned magnet array are arranged at irregular intervals. The apparatus according to any one of claims 1 to 13.

15. Said magnet array has a controlled first non-uniform magnetic field B having a magnetic field strength of from about 80 mT to about 120 mT, preferably about 100 mT, in the bore ０ which is configured to provide The apparatus according to any one of claims 1 to 14.

16. The magnet array generates a magnetic field B of approximately 15 mT to approximately 20 mT across the target region. ０ It is configured to provide a gradient. The apparatus according to any one of claims 1 to 15.

17. The aforementioned magnetic field B ０ The gradient is mainly radial across the target region. The apparatus according to claim 15.

18. The magnetic array has a magnetic field B that is substantially linear across the target region. ０ It is configured to generate contour lines. The apparatus according to claim 16.

19. The device is portable. The apparatus according to any one of claims 1 to 18.

20. The weight of the portable device is less than approximately 30 kg, preferably less than approximately 25 kg. The apparatus according to any one of claims 1 to 19.

21. The aforementioned body part is the head of the subject. The apparatus according to any one of claims 1 to 20.

22. The subject is a human being. The apparatus according to any one of claims 1 to 21.

23. A method for acquiring nuclear magnetic resonance NMR data using the apparatus described in any one of claims 1 to 22, wherein the method is: (a) A controlled heterogeneous magnetic field B over the volume of the target area of ​​the subject's body part. ０ The process involves applying a certain force to generate a series of acquired bandwidths that have different resonance frequencies from each other, (b) A step of generating and transmitting radio frequency pulses from one or more radio frequency coils to excite nuclear spins within each of the acquisition bands of a set of acquisition bands that collectively cover the target region of the body part, so that the nuclear spins generate a plurality of intrinsic radio frequency signals, (c) A step of receiving a plurality of the characteristic radio frequency signals that have been emitted by the nuclear spin from an acquisition band that collectively provides spatial information over the target region by using the characteristic spatial sensitivity of each of the radio frequency coils, and (d) A step of processing the received radio frequency signal to provide data representing one or more magnetic resonance characteristics of the target region, A method that includes [the following features].

24. In step (d), the data representing one or more of the magnetic resonance characteristics of the target region is further processed into an image. The method according to claim 23.

25. Steps (a) to (d) are to be completed in less than approximately 20 minutes. The method according to claim 23 or claim 24.

26. Steps (a) to (d) are to be completed in less than approximately 15 minutes. The method according to any one of claims 23 to 25.

27. Steps (a) to (d) are to be completed in less than approximately 10 minutes. The method according to any one of claims 23 to 26.

28. The independent signal is received by using at least multiple radio frequency coils simultaneously. The method according to any one of claims 23 to 27.

29. The radio frequency pulse generated in step (b) has an excitation bandwidth of approximately 40 kHz to approximately 60 kHz. The method according to any one of claims 23 to 28.

30. The series of acquired bandwidths generated in step (a) comprises at least five acquired bandwidths. The method according to any one of claims 23 to 29.

31. The magnetic resonance characteristics of the target region are diffusion. The method according to any one of claims 23 to 30.

32. The magnetic resonance characteristics of the target region are perfusion. The method according to any one of claims 23 to 31.

33. The magnetic resonance characteristic of the target region is T2. The method according to any one of claims 23 to 32.

34. The aforementioned body part is the head of the subject. The method according to any one of claims 23 to 33.

35. The subject is a human being. The method according to any one of claims 23 to 34.

36. The aforementioned subject is in an environment away from the hospital. The method according to any one of claims 23 to 35.

37. The aforementioned data is processed into an image in real space by combining the signals from each of the radio frequency coils using the sensitivity map of each radio frequency coil in real space. The method according to claim 24.

38. The aforementioned image is presented as a projection passing through the target region. The method according to claim 24.

39. A method for diagnosing brain injury using the apparatus described in any one of claims 1 to 22, wherein the method is: (a) A controlled heterogeneous magnetic field B across the volume of the subject's head. ０ The process involves applying a certain force to generate a series of acquired bandwidths that have different resonance frequencies from each other, (b) A step of generating and transmitting radio frequency pulses from one or more radio frequency coils to excite nuclear spins within each of the acquisition bands of a set of acquisition bands that collectively cover the head, so that the nuclear spins generate a plurality of intrinsic radio frequency signals, (c) A step of receiving a plurality of the characteristic radio frequency signals that have been emitted by the nuclear spin from the acquisition bands that collectively provide spatial information across the head by using the characteristic spatial sensitivity of each of the radio frequency coils, (d) A step of processing the received characteristic radio frequency signal to provide data representing one or more magnetic resonance characteristics of the target region, and (e) A step of diagnosing the presence or absence of the brain injury by interpreting the data, A method that includes [the following features].

40. In step (d), the data representing one or more of the magnetic resonance characteristics of the target region is further processed into an image. The method according to claim 39.

41. Steps (a) to (d) are to be completed in less than approximately 20 minutes. The method according to claim 39 or claim 40.

42. Steps (a) to (d) are to be completed in less than approximately 15 minutes. The method according to any one of claims 39 to 41.

43. Steps (a) to (d) are to be completed in less than approximately 10 minutes. The method according to any one of claims 39 to 42.

44. The independent signal is received by using at least multiple radio frequency coils simultaneously. The method according to any one of claims 39 to 43.

45. The radio frequency pulse generated in step (b) has an excitation bandwidth of approximately 40 kHz to approximately 60 kHz. The method according to any one of claims 39 to 44.

46. The series of acquisition bandwidths generated in step (a) comprises at least five acquisition bandwidths. The method according to any one of claims 39 to 45.

47. The magnetic resonance characteristics of the head are diffusive. The method according to any one of claims 39 to 46.

48. The magnetic resonance characteristics of the head are perfusion. The method according to any one of claims 39 to 47.

49. The magnetic resonance characteristic of the head is T2. The method according to any one of claims 39 to 48.

50. The subject is a human being. The method according to any one of claims 39 to 49.

51. The aforementioned subject is in an environment away from the hospital. The method according to any one of claims 39 to 50.

52. The aforementioned brain injury is an ischemic stroke. The method according to any one of claims 39 to 51.

53. The aforementioned brain injury is a hemorrhagic stroke. The method according to any one of claims 39 to 52.

54. The aforementioned brain injury is neonatal hydrocephalus. The method according to any one of claims 39 to 53.

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