Uniform field generating coil cooling configuration and lead routing

Abstract

The invention discloses a uniform field generating coil cooling configuration and lead routing. A conductive coil assembly for a magnetic resonance imaging (MRI) system includes a substrate. The conductive coil assembly also includes a first hollow conductor coil. The conductive coil assembly also includes a second hollow conductor coil. The first hollow conductor coil and the second hollow conductor coil are both disposed on the substrate in a staggered spiral pattern relative to each other. Respective interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and to circulate the coolant to cool the conductive coil assembly.

Description

BACKGROUND OF THE INVENTION

[0001] The subject matter disclosed herein relates to medical imaging and, more particularly, to a homogeneous field generating coil for a magnetic resonance imaging system.

[0002] Non-invasive imaging techniques allow for the acquisition of images of the internal structure or characteristics of a patient / object without performing an invasive procedure on the patient / object. Specifically, such non-invasive imaging techniques rely on various physical principles (such as differential transmission of X-rays through a target volume, reflection of acoustic waves within a volume, paramagnetism of different tissues and materials within a volume, decay of a target radionuclide within the body, etc.) to acquire data and construct an image or otherwise represent the observed internal characteristics of the patient / object.

[0003] During MRI, when a substance such as human tissue is subjected to a homogeneous magnetic field (polarizing field B 0 ), the individual magnetic moments of the spins in the tissue attempt to align with the polarizing field, but precess about the polarizing field in a random order at their characteristic Larmor frequency. If the substance or tissue is subjected to a magnetic field (excitation field B 1 ) that is in the x-y plane and near the Larmor frequency, the net alignment torque or "longitudinal magnetization" M z can be rotated or "tilted" into the x-y plane to produce a net transverse magnetic moment M t . After the excitation signal B 1 terminates, signals are emitted by the excited spins, and these signals can be received and processed to form an image.

[0004] When using these signals to generate an image, magnetic field gradients (G x , G y and G z ) are employed. Typically, the region to be imaged is scanned in a series of measurement cycles in which these gradient fields vary according to the particular localization method being used. The resulting set of received nuclear magnetic resonance (NMR) signals is digitized and processed to reconstruct an image using one of the well-known reconstruction techniques.

[0005] Rapidly switching magnetic fields can cause peripheral nerve stimulation in the patient being imaged. Accordingly, an upper limit is placed on the magnetic field gradient strength utilized in MRI to avoid peripheral nerve stimulation. It has been shown that using an additional homogeneous accompanying field coil in combination with a gradient coil to avoid peripheral nerve stimulation while allowing for a greater rate of change of the gradient over time. However, the performance of the homogeneous accompanying field coil is limited due to cooling problems. Specifically, the path length of the homogeneous accompanying field coil may be too long to be cooled properly. SUMMARY OF THE INVENTION

[0006] An overview of certain embodiments disclosed herein is shown below. It should be understood that these aspects are provided merely to give the reader a brief overview of these particular embodiments and are not intended to limit the scope of the disclosure. Indeed, the disclosure may cover various aspects that may not be shown below.

[0007] In one embodiment, a conductive coil for a magnetic resonance imaging (MRI) system is provided. The conductive coil assembly includes a substrate. The conductive coil assembly also includes a first hollow conductor coil. The conductive coil assembly further includes a second hollow conductor coil. The first hollow conductor coil and the second hollow conductor coil are both disposed on the substrate in an interleaved spiral pattern relative to each other. Corresponding interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and are configured to circulate the coolant to cool the conductive coil assembly.

[0008] In another embodiment, a magnetic resonance imaging (MRI) uniform field generating coil assembly is provided. The MRI uniform field generating coil assembly includes a substrate. The MRI uniform field generating coil assembly also includes a first hollow conductor coil. The MRI uniform field generating coil assembly further includes a second hollow conductor coil. The first hollow conductor coil and the second hollow conductor coil are both disposed on the substrate in an interleaved spiral pattern relative to each other. The first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the interleaved spiral pattern.

[0009] In another embodiment, a method for forming a magnetic resonance imaging (MRI) uniform field generating coil is provided. The method includes disposing a first hollow conductor coil on a substrate. The method also includes disposing a second hollow conductor coil on the substrate such that the first hollow conductor coil and the second hollow conductor coil are both disposed on the substrate in an interleaved spiral pattern relative to each other. Corresponding interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and are configured to circulate the coolant to cool the MRI uniform field generating coil assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features, aspects, and advantages of the subject matter of the present invention will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like reference symbols represent like parts throughout the drawings, wherein:

[0011] Figure 1 A schematic diagram of a magnetic resonance imaging (MRI) system in accordance with aspects of the present disclosure is shown;

[0012] Figure 2 Shows in accordance with aspects of the present disclosureFigure 1 Schematic cross-sectional view of a magnet assembly of a magnetic resonance imaging system in

[0013] Figure 3 Cross-sectional view showing a portion of a uniform field generating coil assembly integrated within a gradient coil assembly in accordance with aspects of the present disclosure;

[0014] Figure 4 Schematic cross-sectional view of a uniform field generating coil of a uniform field generating coil assembly disposed on a substrate in accordance with aspects of the present disclosure;

[0015] Figure 5 Cross-section of a portion of a uniform field generating coil in accordance with aspects of the present disclosure;

[0016] Figure 6 Schematic view of a cooling system for a uniform field generating coil assembly in accordance with aspects of the present disclosure;

[0017] Figure 7 and Figure 8 Top view of a uniform field generating coil in two different mirror configurations in accordance with aspects of the present disclosure;

[0018] Figure 9 Perspective view showing a uniform field generating coil (e.g., B x uniform field generating coil) in accordance with aspects of the present disclosure;

[0019] Figure 10 Perspective view showing a uniform field generating coil (e.g., B y uniform field generating coil) in accordance with aspects of the present disclosure;

[0020] Figure 11 Perspective view showing a uniform field generating coil (e.g., primary B y uniform field generating coil) in accordance with aspects of the present disclosure;

[0021] Figure 12 Perspective view showing a uniform field generating coil (e.g., primary B y uniform field generating coil) (e.g., having an additional cooling circuit) in accordance with aspects of the present disclosure;

[0022] Figure 13 Perspective view showing in accordance with aspects of the present disclosure Figure 12 shielded B y uniform field generating coil and primary B y uniform field generating coil in accordance with aspects of the present disclosure;

[0023] Figure 14shows a method for forming a magnetic resonance imaging (MRI) uniform field generating coil according to aspects of the present disclosure; and

[0024] Figure 15 shows a method for reducing uniform patient stimulation using a uniform field generating component according to aspects of the present disclosure. Detailed Description

[0025] One or more specific embodiments will be described below. To provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints that may vary with the implementation. In addition, it should be understood that such development efforts may be complex and time-consuming, but would still be a routine task of design, fabrication, and manufacture for those of ordinary skill in the art who would benefit from the present disclosure.

[0026] When introducing elements of various embodiments of the present inventive subject matter, the articles "a," "an," "the," and "said" are intended to mean that there is one or more (s) of the element. The terms "comprising," "including," and "having" are intended to be inclusive and mean that additional elements may exist in addition to the listed elements. Moreover, any numerical examples in the following discussion are intended to be non-limiting, and thus additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments.

[0027] The present disclosure provides a uniform field generating coil assembly (e.g., an accompanying field assembly or a peripheral nerve stimulation reducing coil assembly) for a magnetic resonance imaging system. The uniform field generating coil assembly is integrated with a gradient coil assembly of the magnetic resonance imaging system. The uniform field generating coil assembly is configured to be sufficiently cooled to maintain the same performance as the gradient coil. Thus, when the uniform field generating coil assembly is utilized, it is configured to reduce peripheral nerve stimulation. When sufficiently cooled, the uniform field generating coil assembly enables scans to be performed at a higher slew rate and a higher peak gradient intensity without encountering patient stimulation. The higher slew rate results in faster scan times and reduced distortion. In addition, the higher gradient intensity with a shorter duration improves the signal-to-noise ratio in diffusion imaging. The disclosed structure for the uniform field generating coil assembly can also be implemented on the gradient field generating coil assembly.

[0028] A conductive coil (e.g., a magnetic resonance imaging uniformity generating coil assembly or a gradient field generating coil assembly) includes a substrate. The conductive coil assembly also includes a first hollow conductor coil. The conductive coil assembly further includes a second hollow conductor coil. The first hollow conductor coil and the second hollow conductor coil are both disposed on the substrate in a staggered helical pattern relative to each other. The respective interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and are configured to circulate the coolant to cool the conductive coil assembly.

[0029] In certain embodiments, the first hollow conductor coil includes a first coiled portion defining a first series of rings of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of rings of increasing radius, the first coiled portion defines a coiled portion boundary, and the second coiled portion is located within the coiled portion boundary. In certain embodiments, the first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the coiled portion boundary.

[0030] In certain embodiments, the second pair of lead ends is side-connected by a lead end of the first pair of lead ends in the single corner. In certain embodiments, the first hollow conductor coil includes a first lead coupled to a first central portion of the first coiled portion, and wherein the second hollow conductor coil includes a second lead coupled to a second central portion of the second coiled portion. In certain embodiments, the first hollow conductor coil includes a third lead coupled to a first outer portion of the first coiled portion, the second hollow conductor coil includes a fourth lead coupled to a second outer portion of the second coiled portion, and the third lead and the fourth lead are disposed on the same side of the conductive coil assembly as the single corner.

[0031] In certain embodiments, a first elbow joint is coupled to the first coiled portion of the first hollow conductor coil, and a second elbow joint is coupled to the second coiled portion of the second hollow conductor coil. Both the first elbow joint and the second elbow joint are coupled to respective cooling circuits or conduits to supply coolant to the conductive coil assembly.

[0032] The MRI uniform field generating coil assembly includes a substrate. The MRI uniform field generating coil assembly also includes a first hollow conductor coil. The MRI uniform field generating coil assembly further includes a second hollow conductor coil. The first hollow conductor coil and the second hollow conductor coil are both disposed on the substrate in an interleaved spiral pattern relative to each other. The first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the interleaved spiral pattern.

[0033] In certain embodiments, the second pair of lead ends is side-connected by a lead end of the first pair of lead ends in the single corner. In certain embodiments, the first hollow conductor coil includes a first coiled portion defining a first series of rings of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of rings of increasing radius, the first coiled portion defines a coiled portion boundary, and the second coiled portion is located within the coiled portion boundary. In certain embodiments, the first hollow conductor coil includes a first lead coupled to a first central portion of the first coiled portion, and wherein the second hollow conductor coil includes a second lead coupled to a second central portion of the second coiled portion. In certain embodiments, the first hollow conductor coil includes a third lead coupled to a first outer portion of the first coiled portion, the second hollow conductor coil includes a fourth lead coupled to a second outer portion of the second coiled portion, and the third lead and the fourth lead are disposed on the same side of the MRI uniform field generating coil assembly as the single corner.

[0034] In certain embodiments, a cooling system, wherein the cooling system includes a first cooling circuit disposed within a first interior of the first hollow conductor coil and a second cooling circuit disposed within a second interior of the second hollow conductor coil, and both the first cooling circuit and the second cooling circuit are configured to receive a coolant and are configured to circulate the coolant to cool the MRI uniform field generating coil assembly. In certain embodiments, the first hollow conductor coil includes a first coiled portion defining a first series of rings of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of rings of increasing radius, wherein the cooling system further includes a third cooling circuit and a fourth cooling circuit, the third cooling circuit is coupled to a first elbow joint, the first elbow joint is coupled to the first coiled portion of the first hollow conductor coil, the fourth cooling circuit is coupled to a second elbow joint, the second elbow joint is coupled to the second coiled portion of the second hollow conductor coil, and both the third cooling circuit and the fourth cooling circuit are configured to supply the coolant to the MRI uniform field generating coil assembly.

[0035] A method for forming a magnetic resonance imaging (MRI) uniform field generating coil includes disposing a first hollow conductor coil on a substrate. The method also includes disposing a second hollow conductor coil on the substrate such that both the first hollow conductor coil and the second hollow conductor coil are disposed on the substrate in a staggered helical pattern relative to each other. Corresponding interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and are configured to circulate the coolant to cool the MRI uniform field generating coil assembly. In some embodiments, the first hollow conductor coil includes a first coiled portion defining a first series of rings of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of rings of increasing radius, the first coiled portion defines a coiled portion boundary, and the second coiled portion is located within the coiled portion boundary. In some embodiments, the first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the coiled portion boundary. In some embodiments, the second pair of lead ends is side-connected by a lead end of the first pair of lead ends in the single corner. In some embodiments, the first hollow conductor coil includes a first lead coupled to a first central portion of the first coiled portion, and wherein the second hollow conductor coil includes a second lead coupled to a second central portion of the second coiled portion.

[0036] Now referring to Figure 1 , there are shown the major components of an MRI system 10 incorporating one embodiment of the present invention. Operation of the system 10 is controlled by an operator console 12, which includes a keyboard or other input device 14, a control panel 16, and a display screen 18. The console 12 communicates via a link 20 with a separate computer system 22, which enables an operator to control the generation and display of images on the display screen 18. The computer system 22 includes a plurality of modules that communicate with one another via a backplane 24. These modules include an image processor module 26, a CPU module 28, and a memory module 30 (which may include a frame buffer for storing an array of image data). The computer system 22 communicates via a high-speed serial link 34 with a separate system control or control unit 32. The input device 14 may include a mouse, a joystick, a keyboard, a trackball, a touch-activated screen, a light wand, voice controls, or any similar or equivalent input device, and may be used for interactive geometry prescription. The computer system 22 and the MRI system control 32 together form an "MRI controller" 36.

[0037] The MRI system control 32 includes a set of modules connected together via a backplane 38. These modules include a CPU module 40 and a pulse generator module 42, which is connected to the operator console 12 via a serial link 44. Via the link 44, the system control 32 receives commands from the operator indicating the scan sequence to be performed. The pulse generator module 42 operates the system components to perform the desired scan sequence and generates data indicating the timing, intensity, and shape of the generated RF pulses, as well as the timing and length of the data acquisition window. The pulse generator module 42 is connected to a set of gradient amplifiers 46 to indicate the timing and shape of the gradient pulses generated during the scan. The pulse generator module 42 may also receive patient data from a physiological acquisition controller 48, which receives signals from a plurality of different sensors connected to the patient, such as an ECG signal from an electrode attached to the patient. And finally, the pulse generator module 42 is connected to a scan room interface circuit 50, which receives signals associated with the condition of the patient and the magnet system from various sensors. The patient positioning system 52 also receives commands via the scan room interface circuit 50 to move the patient to the desired position for scanning.

[0038] The pulse generator module 42 operates the gradient amplifiers 46 to achieve the desired timing and shape of the gradient pulses generated during the scan. The gradient waveforms generated by the pulse generator module 42 are applied to a gradient amplifier system 46 having G x amplifiers, G y amplifiers, and G z amplifiers. Each gradient amplifier excites a corresponding physical gradient coil in a gradient coil assembly generally labeled 54 to generate a magnetic field gradient for spatially encoding the acquired signals. The gradient coil assembly 54 forms part of a magnet assembly 56, which also includes a polarization magnet 58 (in operation, the polarization magnet provides a homogenized longitudinal magnetic field B0 throughout the entire target space 60 surrounded by the magnet assembly 56) and an integral (transmit and receive) RF coil 62 (in operation, the coil provides a transverse magnetic field B 1 , which is generally perpendicular to B 0 throughout the entire target space 60). As discussed in more detail below, a uniform field generating coil assembly (e.g., an accompanying field coil assembly) is integrated within the gradient coil assembly 54, which is configured to reduce peripheral nerve stimulation when utilized.

[0039] The resulting signal emitted by the excited nuclei within the patient can be sensed by the same RF coil 62 and coupled to the preamplifier 66 via the transmit / receive switch 64. The amplified MR signal is demodulated, filtered, and digitized in the receiver section of the transceiver 68. The transmit / receive switch 64 is controlled by a signal from the pulse generator module 42 to electrically connect the RF amplifier 70 to the RF coil 62 during the transmit mode and to connect the preamplifier 66 to the RF coil 62 during the receive mode. The transmit / receive switch 64 can also enable a separate RF coil (e.g., a surface coil) to be used in the transmit or receive mode.

[0040] The MR signal picked up by the RF coil 62 is digitized by the transceiver module 68 and transmitted to the memory module 72 in the system control 32. When an array of raw k-space data has been acquired in the memory module 72, the scan is complete. For each image to be reconstructed, this raw k-space data is rearranged into separate k-space data arrays, and each of these separate k-space data arrays is input to the array processor 76, which operates to perform a Fourier transform on the data into an array of image data. This image data is transferred via the serial link 34 to the computer system 22, where it is stored in the memory 30. In response to commands received from the operator console 12, this image data can be archived in long-term storage or can be further processed by the image processor 26 and transmitted to the operator console 12 and presented on the display 18.

[0041] As Figure 2 shown, a schematic side elevation view of a magnet assembly 56 according to an embodiment of the present invention is illustrated. The magnet assembly 56 is of a cylindrical shape having a central axis 78. The magnet assembly 56 includes a cryostat 80 and one or more radially aligned longitudinally spaced superconducting coils 82 that form the polarization magnet 58. The superconducting coils 82 are capable of carrying large currents and are designed to generate a B 0 magnetic field within the patient / target space 60. As will be appreciated, the magnet assembly 56 may also include both an end shield and a vacuum vessel surrounding the cryostat 80 (not shown) in order to help isolate the cryostat 80 from the heat generated by the remainder of the MRI system 10 ( Figure 1 ). The magnet assembly 56 may further include other elements such as covers, supports, suspension members, end caps, brackets, etc. (not shown). Although Figure 1 and Figure 2 the embodiment of the magnet assembly 56 shown utilizes a cylindrical topology, it should be understood that topologies other than cylindrical may also be used. For example, the flat geometry in an open MRI system may also utilize the embodiments of the present invention described below. As Figure 2Further shown, a patient / imaging subject 84 is inserted into the magnet assembly 56.

[0042] Figure 3 is a cross-sectional view of a part of a homogeneous field generating coil assembly 86 integrated within the gradient coil assembly 54. As depicted, the gradient coil assembly 54 includes an outer portion 88 (e.g., an outer diameter portion) and an inner portion 90 (e.g., an inner diameter portion). The outer portion 88 is positioned further away from the central axis 78 of the magnet assembly (e.g., Figure 1 and Figure 2 the magnet assembly 56 in Figure 3 than the inner portion 90 in the radial direction 92. The gradient coil assembly 54 includes an X-axis gradient coil assembly, a Y-axis gradient coil assembly, and a Z-axis gradient coil assembly. Only a part of the gradient coil assembly 54 is shown in

[0043] As Figure 3 depicted, the outer portion 88 of the gradient coil assembly 54 includes a shielded Z-axis gradient coil 94 and leads 96 of the shielded Z-axis gradient coil 94. Additionally, as Figure 3 depicted, the inner portion 90 of the gradient coil assembly 54 includes a secondary X-axis gradient coil 98 and an eye lead 100 of the secondary X-axis gradient coil 98.

[0044] As Figure 3 depicted, the homogeneous field generating coil assembly 86 includes a shielded B y homogeneous field generating coil 102 and a shielded B x homogeneous field generating coil 104 in the outer portion 88 of the gradient coil assembly 54. The shielded B x homogeneous field generating coil 104 is positioned more radially inward (e.g., with respect to the central axis 78) than the shielded B y homogeneous field generating coil 102. Both the shielded B y homogeneous field generating coil 102 and the shielded B x homogeneous field generating coil 104 are positioned more radially inward (e.g., with respect to the central axis 78) than the shielded Z-axis gradient coil 94 of the gradient coil assembly 54. The shielded B y homogeneous field generating coil 102 is radially positioned between the shielded B x homogeneous field generating coil 104 and the shielded Z-axis gradient coil 94.

[0045] As Figure 3 depicted, the homogeneous field generating coil assembly 86 includes both a primary B y homogeneous field generating coil 106 and a primary B x homogeneous field generating coil 108 in the inner portion 90 of the gradient coil assembly 54. The primary B y homogeneous field generating coil 106 is more... than the shielded Bx The uniform field generating coil 108 is positioned more radially inward (e.g., relative to the central axis 78). The secondary X-axis gradient coil 98 of the gradient coil assembly 54 is more radially inward than the primary B y uniform field generating coil 106 and the primary B x Both the uniform field generating coil 108 are positioned more radially inward (e.g., relative to the central axis 78). The primary B y uniform field generating coil 106 is positioned radially between the primary B x and the secondary X-axis gradient coil 98. Due to lead routing, the primary B y uniform field generating coil 106 and the shield B y uniform field generating coil 102 has a higher gain than the primary B x uniform field generating coil 108 and the shield B x uniform field generating coil 104. The primary B y uniform field generating coil 106, the shield B y uniform field generating coil 102, the primary B x uniform field generating coil 108 and the shield B x uniform field generating coil 104 is configured to minimize B z stray components.

[0046] Figure 4 A schematic cross-sectional view of the uniform field generating coils of the uniform field generating coil assembly 86 disposed on the substrate 110 is shown. As depicted, the substrate 110 is cylindrical. The substrate 110 (e.g., a former) supports the uniform field generating coils of the uniform field generating coil assembly 86 and maintains the uniform field generating coils in a desired position and shape (e.g., a circular shape around an aperture in which an object to be imaged is disposed) relative to the imaging volume and / or other coils of the magnetic resonance imaging system. The substrate 110 can be made of a flexible material (e.g., a polyester laminate or any other extensible or flexible non-conductive material such as a thin fiberglass substrate). In some embodiments, all or a portion of the uniform field generating coils can be formed into a desired shape or pattern (e.g., a series of rings of increasing radius) and then attached to the substrate 110 (e.g., using epoxy). In some embodiments, the substrate 110 is a single one-piece substrate. In various embodiments, the substrate 110 can be formed of separate pieces. Additionally, the substrate 110 can include cuts or other openings to allow a portion of the uniform field generating coils (e.g., end run portions and / or return run portions) to pass under the substrate 110 (or on the opposite side of the substrate 110). Further, it should be noted that the substrate 110 can include alignment holes or other alignment features to assist in aligning two or more coils or portions thereof disposed on the substrate 110.

[0047] The primary By uniform field generating coil 106 and the shield By uniform field generating coil 102 form a first pair 112B disposed at a first position 113 on a substrate 110 (such as a cylindrical substrate or former). y Uniform field generating coil. Another primary B y Uniform field generating coil 114 and shield B y The uniform field generating coil 116 and the shield B form a second pair 118B disposed at a second position 119 on the substrate 110 and positioned 180 degrees from the first pair 112 in the circumferential direction 118. y Uniform field generating coil.

[0048] Primary B x Uniform field generating coil 108 and shield B x The uniform field generating coil 104 and the shield B form a first pair 120B disposed at a third position 122 on a substrate 110 (such as a cylindrical substrate or former). x Uniform field generating coil. Another primary B x Uniform field generating coil 124 and shield B x The uniform field generating coil 126 and the shield B form a second pair 128B disposed at a fourth position 130 on the substrate 110 and positioned 180 degrees from the first pair 120 in the circumferential direction 118. x Uniform field generating coil. As depicted, B y Portions of the uniform field generating coil with B x Portions of the uniform field generating coil overlap in the circumferential direction 118 and the axial direction 132.

[0049] Figure 5 A cross-section of a portion of the uniform field generating coil 134 is shown. The uniform field generating coil 134 can be Figure 4Any one of the uniform field generating coils in the uniform field generating coil assembly 86. The uniform field generating coil 134 is a hollow conductor coil. The uniform field generating coil 134 includes a wall 136 that defines a cavity or channel 138. The wall 136 of the uniform field generating coil 134 is made of a conductive material (e.g., copper) and is supplied with current to generate an accompanying field for use in MRI. Specifically, the uniform field generating coil 134 is utilized during a magnetic resonance imaging scan and, when sufficiently cooled, is configured to reduce peripheral nerve stimulation in the subject being imaged. The uniform field generating coil 134 can be formed from a tube (e.g., a cylindrical tube, a rectangular tube, or a square tube (or a tube having a cylindrical, rectangular, or square cross-section)). For example, a given uniform field generating coil 134 can be formed by bending or otherwise shaping at least a portion of the length of the tube. The cavity or channel 138 forms a cooling circuit and is configured to receive a coolant (e.g., deionized water) that circulates within the uniform field generating coil 134 to cool the uniform field generating coil 134. As described in more detail below, each uniform field generating coil 134 has two hollow conductors or conductor coils (e.g., two cooling circuits) in a staggered helical form. In certain embodiments, Figure 5 the structures described therein are applied to the gradient field generating coils.

[0050] Figure 6 A schematic diagram of a cooling system 140 for the uniform field generating coil assembly 86 is shown. The uniform field generating coil assembly 86 includes a plurality of uniform generating coils 142 (e.g., Figure 4 primary B in y uniform field generating coils 106 and 114, shield B y uniform field generating coils 102 and 116, primary B x uniform field generating coils 108 and 124, and shield B x uniform field generating coils 104 and 126). Each uniform field generating coil 142 is made of two hollow conductors or conductor coils 144 that are arranged in a staggered helix relative to each other, which forms two corresponding cooling circuits. The hollow conductors 144 are configured to receive a coolant (e.g., deionized water) and are configured to circulate the coolant. The staggered helix forms a shortened cooling circuit length for each uniform field generating coil 142. In certain embodiments, the respective coiled portions of the two hollow conductors 144 can be coupled (e.g., via respective elbow joints) to respective coolant tubes or conduits 146, thereby forming additional cooling circuits. The coolant tubes 146 are configured to receive a coolant (e.g., deionized water) and are configured to circulate the coolant. The hollow conductors and / or the coolant tubes 146 are coupled to a coolant source 148 that supplies them with coolant for circulation to cool the uniform field generating coil assembly 86. In certain embodiments, Figure 6The cooling system 140 described in can be utilized with a gradient field generating coil.

[0051] In certain embodiments, the structures described below in Figures 7 to 13 with respect to the uniform field generating coil can also be utilized with other types of conductive coils, such as gradient field generating coils. Figure 7 and Figure 8 show a top view of the uniform field generating coils 150, 151 in a mirror configuration. The uniform field generating coils 150, 151 are shown as being unfolded or flattened. In certain embodiments, as Figure 13 depicted, the uniform field generating coil 150 can be used as a primary uniform field generating coil, and the uniform field generating coil can be rotated 180 degrees to be located above the uniform generating coil 150 and used as a shim uniform field generating coil. As depicted, each of the uniform field generating coils 150, 151 has a first hollow conductor coil 152 and a second hollow conductor coil 154 disposed relative to each other in a staggered helical pattern. The uniform field generating coils 150, 151 are disposed on a substrate (e.g., Figure 4 the substrate 110 in Figure 7 and Figure 8 not shown). The interiors (e.g., cavities) of both the first hollow conductor coil 152 and the second hollow conductor coil 154 are configured to receive a coolant (e.g., deionized water) and are configured to circulate the coolant to the uniform field coil generating coil assembly. The first hollow conductor coil 152 and the second hollow conductor coil 154 form respective cooling circuits 153, 155. The staggered helical pattern of the first hollow conductor coil 152 and the second hollow conductor coil 154 shortens the cooling circuit length such that the respective uniform field generating coils 150, 151 can be adequately cooled. This cooling of the respective uniform field generating coils 150, 151 enables the coils 150, 151 to maintain the same performance as the gradient coils and reduces peripheral nerve stimulation in the subject being imaged. Specifically, the uniform field generating coils 150, 151 enable the scan to operate at a higher slew rate and a higher peak gradient intensity without encountering patient stimulation.

[0052] The first hollow conductor coil 152 includes a first coiled portion 156 that defines a first series of increasing radius loops relative to the aperture 158 (e.g., center) of the respective uniform field generating coils 150, 151. The second hollow conductor coil 154 includes a second coiled portion 160 that defines a second series of increasing radius loops relative to the aperture 158 of the respective uniform field generating coils 150, 151. The aperture 158 is formed by the second hollow conductor coil 154. The first coiled portion 156 of the first hollow conductor coil 152 has a first center or inner portion 162 and a first outer portion 164 that is radially outward of the first center portion 162. The second coiled portion 160 of the second hollow conductor coil 154 has a second center or inner portion 166 and a second outer portion 168 that is radially outward of the second center portion 166. The first outer portion 164 of the first hollow conductor coil 152 defines a coiled portion boundary 170. The second coiled portion 160 of the second hollow conductor coil 154 is located within the coiled portion boundary 170. In some embodiments, a first elbow joint is coupled to the first coiled portion 156 of the first hollow conductor coil 152, a second elbow joint is coupled to the second coiled portion 160 of the second hollow conductor coil 154, and both the first elbow joint and the second elbow joint are coupled to respective additional cooling circuits or conduits that supply coolant to the MRI uniform field generating coils 150, 151.

[0053] The first hollow conductor coil 152 of each uniform field generating coil 150, 151 includes a pair of leads 172, 174. The lead 172 is coupled to the first center portion 162 of the first coiled portion 156. The lead 174 is coupled to the first outer portion 164. The second hollow conductor coil 154 of each uniform field generating coil 150, 151 includes a pair of leads 176, 178. The lead 176 is coupled to the second center portion 166 of the second coiled portion 160. Specifically, the lead 176 is coupled to the aperture 158. The lead 178 is coupled to the second outer portion 168. The pair of leads 172, 174 includes respective lead ends 180, 182. The pair of leads 176, 178 includes respective lead ends 184, 186.

[0054] The leads 174, 178 are located on the same side 188 of each uniform field generating coil 150, 151 and extend along that same side. The leads 172, 176 initially extend from the respective center portions 162, 166 to a center portion 190 of a side 192 that is adjacent to the side 188. When extending to the side 192, the leads 172, 176 extend over the coiled portions 156, 160. In some embodiments, when extending to the side 192, the leads 172, 176 extend under the coiled portions 156, 160 (see Figure 13)。The leads 172, 176 then rotate 90 degrees in the direction 194 towards the side 188 and extend along the side 192 in the direction 194. The lead ends 180, 182, 184, 186 are located in a single corner 196 (where the sides 188, 192 meet) outside the coil portion boundary 170. The lead ends 180, 182 flank the lead ends 184, 186.

[0055] Figure 9 A perspective view of the uniform field generating coil 198 is shown. The uniform field generating coil 198 is a B x uniform field generating coil. The uniform field generating coil 198 is shown in a rolled-up or bent state. The uniform field generating coil 198 is as Figure 7 and Figure 8 described. As depicted, the uniform field generating coil 198 has a longitudinal length 200. The longitudinal length 200 extends the entire axial length 202 of the gradient coil. As depicted, the uniform field generating coil 198 has a first hollow conductor coil 152 and a second hollow conductor coil 154 arranged relative to each other in a staggered spiral pattern. The uniform field generating coil 198 is disposed on a substrate (e.g., Figure 4 the substrate 110 in Figure 9 which is not shown).

[0056] The first hollow conductor coil 152 includes a first coil portion 156 that defines a first series of rings of increasing radius relative to the aperture 158 (e.g., the center) of the uniform field generating coil 198. The second hollow conductor coil 154 includes a second coil portion 160 that defines a second series of rings of increasing radius relative to the aperture 158 of the uniform field generating coil 198. The aperture 158 is formed by the second hollow conductor coil 154. The first coil portion 156 of the first hollow conductor coil 152 has a first center or inner portion 162 and a first outer portion 164 located radially outward of the first center portion 162. The second coil portion 160 of the second hollow conductor coil 154 has a second center or inner portion 166 and a second outer portion 168 located radially outward of the second center portion 166. The first outer portion 164 of the first hollow conductor coil 152 defines a coil portion boundary (see Figure 7 and Figure 8 ). The second coil portion 160 of the second hollow conductor coil 154 is located within the coil portion boundary.

[0057] The first hollow conductor coil 152 of the uniform field generating coil 198 includes a pair of leads 172, 174. The lead 172 is coupled to the first central portion 162 of the first coiled portion 156. The lead 174 is coupled to the first outer portion 164. The second hollow conductor coil 154 of the uniform field generating coil 198 includes a pair of leads 176, 178. The lead 176 is coupled to the second central portion 166 of the second coiled portion 160. Specifically, the lead 176 is coupled to the aperture 158. The lead 178 is coupled to the second outer portion 168. The pair of leads 172, 174 includes respective lead ends 180, 182. The pair of leads 176, 178 includes respective lead ends 184, 186.

[0058] The leads 174, 178 are located on the same side 188 of the uniform field generating coil 198 and extend along that same side. The leads 172, 176 initially extend from the respective central portions 162, 166 to the central portion 190 of the side 192 adjacent to the side 188. When extending to the side 192, the leads 172, 176 extend over the coiled portions 156, 160. In some embodiments, when extending to the side 192, the leads 172, 176 extend under the coiled portions 156, 160 (see Figure 13 ). The leads 172, 176 then turn 90 degrees in the direction 194 toward the side 188 and extend along the side 192 in the direction 194. The lead ends 180, 182, 184, 186 are located in a single corner 196 (where the sides 188, 192 meet) outside the coiled portion boundary 170. The lead ends 180, 182 are adjacent to the lead ends 184, 186.

[0059] Figure 10 A top view of the coiled portion of the uniform field generating coil 204 is shown. The axial (z) and radial (r) dimensions of the uniform field generating coil 204 are shown. The uniform field generating coil 204 is a B y uniform field generating coil (e.g., a primary B y uniform field generating coil). The uniform field generating coil 204 is shown in an unrolled or flat state. The uniform field generating coil 204 is as Figure 7 and Figure 8 described. As depicted, the uniform field generating coil 204 has a first hollow conductor coil 152 and a second hollow conductor coil 154 disposed relative to each other in a staggered helical pattern. The uniform field generating coil 204 is disposed on a substrate (e.g., Figure 4 the substrate 110 in Figure 10 ), which is not shown in

[0060] The first hollow conductor coil 152 includes a first coiled portion 156 that defines a first series of rings of increasing radius relative to the aperture 158 (e.g., center) of the uniform field generating coil 204. The second hollow conductor coil 154 includes a second coiled portion 160 that defines a second series of rings of increasing radius relative to the aperture 158 of the uniform field generating coil 204. The aperture 158 is formed by the second hollow conductor coil 154. The first coiled portion 156 of the first hollow conductor coil 152 has a first center or inner portion 162 and a first outer portion 164 that is radially outward of the first center portion 162. The second coiled portion 160 of the second hollow conductor coil 154 has a second center or inner portion 166 and a second outer portion 168 that is radially outward of the second center portion 166. The first outer portion 164 of the first hollow conductor coil 152 defines a coiled portion boundary 170. The second coiled portion 160 of the second hollow conductor coil 154 is located within the coiled portion boundary 170.

[0061] Figure 11 A perspective view of a uniform field generating coil 206 (e.g., primary B y uniform field generating coil) is shown. The uniform field generating coil 206 is shown in a rolled or bent state. The uniform field generating coil 206 is as Figure 7 and Figure 8 described. As depicted, the uniform field generating coil 206 has a first hollow conductor coil 152 and a second hollow conductor coil 154 that are disposed relative to each other in a staggered helical pattern. The uniform field generating coil 206 is disposed on a substrate (e.g., Figure 4 substrate 110 in Figure 9 ), which is not shown in

[0062] The first hollow conductor coil 152 includes a first coiled portion 156 that defines a first series of rings of increasing radius relative to the aperture 158 (e.g., center) of the uniform field generating coil 206. The second hollow conductor coil 154 includes a second coiled portion 160 that defines a second series of rings of increasing radius relative to the aperture 158 of the uniform field generating coil 206. The aperture 158 is formed by the second hollow conductor coil 154. The first coiled portion 156 of the first hollow conductor coil 152 has a first center or inner portion 162 and a first outer portion 164 that is radially outward of the first center portion 162. The second coiled portion 160 of the second hollow conductor coil 154 has a second center or inner portion 166 and a second outer portion 168 that is radially outward of the second center portion 166. The first outer portion 164 of the first hollow conductor coil 152 defines a coiled portion boundary (see Figure 7 and Figure 8)。The second coiled portion 160 of the second hollow conductor coil 154 is located within the coil portion boundary.

[0063] The first hollow conductor coil 152 of the uniform field generating coil 206 includes a pair of leads 172, 174. The lead 172 is coupled to the first central portion 162 of the first coiled portion 156. The lead 174 is coupled to the first outer portion 164. The second hollow conductor coil 154 of the uniform field generating coil 206 includes a pair of leads 176, 178. The lead 176 is coupled to the second central portion 166 of the second coiled portion 160. Specifically, the lead 176 is coupled to the eyelet 158. The lead 178 is coupled to the second outer portion 168. The pair of leads 172, 174 includes respective lead ends 180, 182. The pair of leads 176, 178 includes respective lead ends 184, 186.

[0064] The leads 174, 178 are located on the same side 188 of the uniform field generating coil 206 and extend along the same side. The leads 172, 176 initially extend from the respective central portions 162, 166 to the central portion 190 of the side 192 adjacent to the side 188. When extending along the side 192, the leads 172, 176 extend above the coiled portions 156, 160. The leads 172, 176 then turn 90 degrees in the direction 194 towards the side 188 and extend along the side 192 in the direction 194. The lead ends 180, 182, 184, 186 are located in a single corner 196 (where the sides 188, 192 meet) outside the coil portion boundary 170. The lead ends 180, 182 are adjacent to the lead ends 184, 186.

[0065] Figure 12 A perspective view of a uniform field generating coil 208 (e.g., a primary B y uniform field generating coil) (e.g., having an additional cooling circuit) is shown. The uniform field generating coil 208 is as Figure 11 described. In addition, a first elbow joint 210 is coupled to the first coiled portion 156 of the first hollow conductor coil 152, and a second elbow joint 212 is coupled to the second coiled portion 160 of the second hollow conductor coil 154. Both the first elbow joint 210 and the second elbow joint 212 are coupled to respective additional cooling circuits or conduits 214, 216 that supply coolant to the MRI uniform field generating coils 150, 151. The first hollow conductor coil 152 and the second hollow conductor coil 154 provide a first cooling circuit and a second cooling circuit for receiving and circulating coolant (e.g., deionized water) to cool the uniform field generating coil 208. The cooling conduits 214 and 216 form a third cooling circuit and a fourth cooling circuit for receiving and circulating coolant (e.g., deionized water) to cool the uniform field generating coil 208.

[0066] Figure 13 shows Figure 12 shield B in y the homogeneous field generating coil 218 and primary B y Perspective view of the homogeneous field generating coil 208. Shield B y The homogeneous field generating coil 218 is generally structurally the same as primary B y the homogeneous field generating coil 208, with several exceptions. As depicted, no additional cooling circuits are coupled to shield B via elbows y to the homogeneous field generating coil 218. In addition, when extending to side 292, shield B y the corresponding leads 272, 276 of the homogeneous field generating coil 218 are below the coiled portions 256, 260.

[0067] Figure 14 shows a method 300 for forming a homogeneous field generating coil for magnetic resonance imaging (MRI). One or more steps of method 300 may be performed simultaneously or in a different order than depicted. A method similar to method 300 may be utilized to form a gradient field generating coil. Method 300 includes providing a first hollow conductor coil and a second hollow conductor coil (block 302). Method 300 includes winding both the first hollow conductor coil and the second hollow conductor coil (block 304). The winding of both the first hollow conductor coil and the second hollow conductor coil may be performed to provide corresponding generally flat or planar winding portions that will be attached to a generally flat or planar substrate (which may subsequently be bent into a desired shape). Figure 14 Method 300 includes disposing the first hollow conductor coil on the substrate (block 306). Method 300 also includes disposing the second hollow conductor coil on the substrate such that both the first hollow conductor coil and the second hollow conductor coil are disposed on the substrate in a staggered spiral pattern relative to each other (block 308). Generally, the substrate is configured to provide support to the hollow conductor coils, which are configured to provide an accompanying field for use with an MRI system to reduce peripheral nerve stimulation. For example, epoxy resin may be used to attach the first hollow conductor coil and the second hollow conductor coil to the substrate. In some embodiments, the winding portions of the first hollow conductor coil and the second hollow conductor coil may be covered with paint or enamel for improved adhesion to the substrate via the epoxy resin. For example, the first hollow conductor coil and the second hollow conductor coil may be disposed at desired locations on the substrate to which epoxy resin has been applied, and the resulting assembly may be cured. The respective interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and are configured to circulate the coolant to cool the MRI homogeneous field generating coil assembly.

[0068] ​

[0069] Method 300 also includes forming respective leads from the first conductor coil and the second conductor coil, the leads extending from the interior or central portion of the respective coiled portion (block 310). The leads are routed together with the leads on the other ends of the first conductor coil and the second conductor coil to a single corner. Method 300 also includes bending (e.g., roll pressing) the substrate and the uniform field generating coil into a desired shape (e.g., cylindrical) (block 312).

[0070] Figure 15 Method 314 for reducing uniform patient stimulation using a uniform field generating assembly is shown. One or more steps of method 314 may be performed simultaneously or in an order different from that Figure 15 depicted. Method 300 includes placing a subject (e.g., a patient) in the bore of the magnet of a magnetic resonance imaging system (block 316). While in the bore (or before the subject is placed in the bore), method 314 includes determining the orientation of the subject (and a portion of the subject's body to be imaged) (block 318). For example, a camera system in the scan room may be utilized to determine the orientation of the subject and a portion of the subject's body to be imaged. For example, it may be determined whether the subject is head first or feet first in the bore (or entering the bore). Method 314 also includes setting the sign (e.g., positive or negative) for a peripheral nerve stimulation (PNS) reduction coil (e.g., a uniform field generating coil) based on the orientation of the subject (block 320). Method 314 even further includes checking or determining that the PNS reduction coil is enabled in a pulse sequence diagram (PSD) (block 322).

[0071] Method 314 also includes determining B x and B y the optimal amplitude of the PNS reduction coil to reduce the magnetic field amplitude and the measured base intensity (rb) and temporal value (c) time from a previous PNS study. IEC60601 (for a cylinder length of 80 cm and a magnet radius of 20 cm) is used to determine the optimal amplitude. In certain embodiments, the optimal amplitude may be 1 A PNS coil per 1 A gradient. Method 314 also includes calculating the PNS threshold on the nerve (using a nerve atlas body) to determine B x and B y the amplitude for PNS. It is desirable to maintain the current proportional to the gradient current throughout the pulse sequence diagram such that the gray scale deviation (gradwarp) (e.g., a system-specific correction for image geometric distortion due to gradient non-linearity) works with the enabled PNS coil.

[0072] Method 314 even further includes simultaneously in X and B x and Y and B yPlay the waveform above (e.g., scaled by the values determined above) (block 328). Reducing the use of the PNS coil enables a faster slew rate to be achieved at a higher amplitude without inducing PNS in the subject. In addition, reducing the use of the PNS coil enables a faster echo-planar imaging readout gradient to be achieved at a higher amplitude or a faster slew rate to maximize the diffusion pulse, thereby increasing the signal-to-noise ratio. In some embodiments, a higher bandwidth may be required in the receiver to achieve a higher-intensity readout gradient.

[0073] The technical effects of the disclosed subject matter include providing a uniform field generating coil assembly that is configured to be sufficiently cooled to maintain the same performance as the gradient coil. Thus, when the uniform field generating coil assembly is utilized, it is configured to reduce peripheral nerve stimulation. When sufficiently cooled, the uniform field generating coil assembly enables scanning to operate at a higher slew rate and a higher peak gradient intensity without encountering patient stimulation. The higher slew rate results in faster scan times and reduced distortion. In addition, the higher gradient intensity with a shorter duration improves the signal-to-noise ratio in diffusion imaging.

[0074] Referring to the technology presented herein and claimed and applying it to physical objects and specific examples having practical properties that clearly improve the current art and are thus not abstract, intangible, or purely theoretical. Further, if any claim appended to the end of this specification contains one or more elements designated as "means for [performing]... function" or "steps for [performing]... function", such elements are intended to be interpreted in accordance with 35 U.S.C. 112(f). However, for any claim containing elements designated in any other manner, such elements are not intended to be interpreted in accordance with 35 U.S.C. 112(f).

[0075] This written description uses examples to disclose the subject matter, including the best mode, and also enables those skilled in the art to practice the subject matter, including making and using any device or system and performing any included method. The patent scope of the subject matter is defined by the claims and may include other examples that occur to those skilled in the art. If such other examples have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that have only minor differences from the literal language of the claims, such other examples are intended to fall within the scope of the claims.

Claims

1. A conductive coil assembly for a magnetic resonance imaging (MRI) system, the conductive coil assembly comprising: substrate; a first hollow conductor coil; and a second hollow conductor coil, wherein the first hollow conductor coil and the second hollow conductor coil are arranged on the substrate in a staggered spiral pattern relative to each other, and wherein the respective interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and are configured to circulate the coolant to cool the conductive coil assembly.

2. A conductive coil assembly according to claim 1, wherein the first hollow conductor coil includes a first coiled portion defining a first series of loops of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of loops of increasing radius, the first coiled portion defines a coiled portion boundary, and the second coiled portion is located within the coiled portion boundary.

3. A conductive coil assembly according to claim 2, wherein the first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the boundary of the winding portion. 4 . The conductive coil assembly of claim 3 , wherein the second pair of lead ends are flanked in the single corner by lead ends of the first pair of lead ends.

5. The conductive coil assembly of claim 3, wherein the first hollow conductor coil comprises a first lead coupled to a first center portion of the first coiled portion, and wherein the second hollow conductor coil comprises a second lead coupled to a second center portion of the second coiled portion.

6. A conductive coil assembly according to claim 5, wherein the first hollow conductor coil includes a third lead coupled to a first outer portion of the first winding portion, the second hollow conductor coil includes a fourth lead coupled to a second outer portion of the second winding portion, and the third lead and the fourth lead are arranged on the same side of the conductive coil assembly as the single corner.

7. The conductive coil assembly according to claim 2 further comprises a first elbow joint coupled to the first winding portion of the first hollow conductor coil, a second elbow joint coupled to the second winding portion of the second hollow conductor coil, and both the first elbow joint and the second elbow joint are coupled to corresponding cooling circuits to provide the coolant to the conductive coil assembly.

8. The conductive coil assembly of claim 1 , wherein the conductive coil assembly comprises an MRI uniform field generating coil assembly, and wherein the MRI uniform field generating coil assembly is configured to, when utilized during an MRI scan performed by an MRI scanner, reduce peripheral nerve stimulation of a subject being imaged during the MRI scan.

9. The conductive coil assembly of claim 1, wherein the conductive coil assembly comprises an MRI gradient field generating coil assembly.

10. A magnetic resonance imaging (MRI) uniform field generating coil assembly, the MRI uniform field generating coil assembly comprising: substrate; a first hollow conductor coil; and A second hollow conductor coil, wherein the first hollow conductor coil and the second hollow conductor coil are arranged on the substrate in a staggered spiral pattern relative to each other, and wherein the first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the staggered spiral pattern. 11 . The MRI uniform field generating coil assembly of claim 10 , wherein the second pair of lead ends are flanked in the single corner by lead ends of the first pair of lead ends.

12. An MRI uniform field generating coil assembly according to claim 10, wherein the first hollow conductor coil includes a first coiled portion defining a first series of loops of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of loops of increasing radius, the first coiled portion defines a coiled portion boundary, and the second coiled portion is located within the coiled portion boundary.

13. The MRI uniform field generating coil assembly of claim 12, wherein the first hollow conductor coil comprises a first lead coupled to a first center portion of the first coiled portion, and wherein the second hollow conductor coil comprises a second lead coupled to a second center portion of the second coiled portion.

14. The MRI uniform field generating coil assembly of claim 13, wherein the first hollow conductor coil includes a third lead coupled to a first outer portion of the first coiled portion, the second hollow conductor coil includes a fourth lead coupled to a second outer portion of the second coiled portion, and the third lead and the fourth lead are disposed on the same side of the MRI uniform field generating coil assembly as the single corner portion.

15. The MRI uniform field generating coil assembly according to claim 10, comprising a cooling system, wherein the cooling system comprises a first cooling circuit disposed within a first interior of the first hollow conductor coil and a second cooling circuit disposed within a second interior of the second hollow conductor coil, and both the first cooling circuit and the second cooling circuit are configured to receive a coolant and are configured to circulate the coolant to cool the MRI uniform field generating coil assembly.

16. The MRI uniform field generating coil assembly of claim 15, wherein the first hollow conductor coil includes a first coiled portion defining a first series of loops of increasing radius, the second hollow conductor coil includes a second coiled portion defining a second series of loops of increasing radius, wherein the cooling system further includes a third cooling circuit and a fourth cooling circuit, the third cooling circuit being coupled to a first elbow joint, the first elbow joint being coupled to the first coiled portion of the first hollow conductor coil, the fourth cooling circuit being coupled to a second elbow joint, the second elbow joint being coupled to the second coiled portion of the second hollow conductor coil, and both the third cooling circuit and the fourth cooling circuit being configured to provide the coolant to the MRI uniform field generating coil assembly.

17. A method for forming a uniform field generating coil for magnetic resonance imaging (MRI), the method comprising: placing a first hollow conductor coil on a substrate; as well as A second hollow conductor coil is disposed on a substrate such that the first hollow conductor coil and the second hollow conductor coil are disposed on the substrate in a staggered spiral pattern relative to each other, and wherein respective interiors of both the first hollow conductor coil and the second hollow conductor coil are configured to receive a coolant and to circulate the coolant to cool the MRI uniform field generating coil assembly.

18. The method of claim 17, wherein the first hollow conductor coil comprises a first coiled portion defining a first series of loops of increasing radius, the second hollow conductor coil comprises a second coiled portion defining a second series of loops of increasing radius, the first coiled portion defining a coiled portion boundary, and the second coiled portion being located within the coiled portion boundary.

19. The method of claim 18, wherein the first hollow conductor coil includes a first pair of lead ends, the second hollow conductor coil includes a second pair of lead ends, and both the first pair of lead ends and the second pair of lead ends are located in a single corner outside the boundary of the coiled portion, wherein the second pair of lead ends are flanked by lead ends of the first pair of lead ends in the single corner.

20. The method of claim 19, wherein the first hollow conductor coil comprises a first lead coupled to a first center portion of the first coiled portion, and wherein the second hollow conductor coil comprises a second lead coupled to a second center portion of the second coiled portion.

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