Intracranial radio frequency coil for intraoperative magnetic resonance imaging.

Abstract

The present disclosure provides systems and methods for magnetic resonance imaging using a radio frequency coil, such as an intracranial radio frequency coil. In at least one aspect, the system can include a surgical instrument and a magnetic resonance imaging system. The surgical instrument can include a distal end portion and a radio frequency receiving coil attached to the distal end portion. The magnetic resonance imaging system can be configured to project a magnetic field into a field of view and image the radio frequency receiving coil within the field of view during surgery.

Description

[Background technology]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of and priority under 35 U.S.C. Section 120 to U.S. patent application Ser. No. 18 / 147,452, filed December 28, 2022, and entitled "INTRACRANIAL RADIO FREQUENCY COIL FOR INTRAOPERATIVE MAGNETIC RESONANCE IMAGING," the disclosure of which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to magnetic resonance imaging (MRI), medical imaging, medical intervention, and surgical intervention. MRI systems often involve large, complex machines that generate significantly high magnetic fields, resulting in significant constraints on the feasibility of certain surgical interventions. Limitations may include limited physical access to the patient by the surgeon and / or surgical robot and / or limitations on the use of certain electrical and mechanical components in the vicinity of the MRI scanning device. Such limitations are inherent in the underlying designs of many existing systems and are difficult to overcome. Summary of the Invention [Means for solving the problem]

[0003] In one aspect, the present disclosure describes a surgical system. The surgical system can include a surgical instrument and a magnetic resonance imaging system. The surgical instrument can include a distal end portion and a radio frequency receive coil attached to the distal end portion. The magnetic resonance imaging system can be configured to project a magnetic field into a field of view and image the radio frequency receive coil within the field of view during surgery.

[0004] In another aspect, the present disclosure describes a low-field magnetic resonance imaging system. The low-field magnetic resonance imaging system can include a dome-shaped housing, a surgical instrument, and a control unit. The dome-shaped housing can define a region of interest. The dome-shaped housing can include an array of permanent magnets, a gradient coil assembly, and a radio frequency transmission coil. The array of permanent magnets can be configured to project a magnetic field into the region of interest. The radio frequency transmission coil can be configured to transmit radio frequency signals to excite magnetization within the region of interest. The surgical instrument can include a radio frequency receive coil configured to receive radio frequency signals corresponding to the excited magnetization within the field of view. The control unit can include a processor and a memory communicatively coupled to the processor. The memory can store instructions executable by the processor to transmit radio frequency pulses to the radio frequency transmission coil and receive radio frequency signals from the radio frequency receive coil.

[0005] In yet another aspect, the present disclosure describes a method. The method can include positioning a housing around a patient's head. The housing can include a dome-shaped array of magnets configured to project a static magnetic field into a region of interest within the patient's head and a radio frequency transmission coil configured to excite magnetization in the region of interest. The method can further include inserting a surgical instrument into the region of interest through an opening in the housing. The surgical instrument can include a radio frequency receiving coil. The method can further include transmitting radio frequency pulses to the radio frequency transmission coil, receiving radio frequency signals from the radio frequency receiving coil, and reconstructing an image of at least a portion of the patient's head from the radio frequency signals. [Brief explanation of the drawings]

[0006] The various aspects described herein, both as to organization and method of operation, together with objects and advantages thereof, can be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

[0007] [Figure 1] FIG. 1 depicts components of an MRI scanning system according to at least one aspect of the present disclosure, including a dome-shaped housing for a magnetic array, the dome-shaped housing enclosing a region of interest therein, and further depicts the dome-shaped housing positioned to receive at least a portion of a patient's head reclined on a table within the region of interest.

[0008] [Figure 1A] FIG. 1A depicts a patient's head positioned within the region of interest of the MRI scanning system of FIG.

[0009] [Figure 2] 2 is a perspective view of an alternative dome-shaped housing for a magnetic array for use with the MRI scanning system of FIG. 1 having an access opening defined in the dome-shaped housing, in accordance with at least one aspect of the present disclosure.

[0010] [Figure 3] 3 is a perspective view of an alternative dome-shaped housing for a magnetic array for use with the MRI scanning system of FIG. 1 having an access opening and an adjustable gap defined within the dome-shaped housing, in accordance with at least one aspect of the present disclosure.

[0011] [Figure 4] FIG. 4 depicts a dome-shaped housing for use with an MRI scanning system having an access opening in the form of a centrally defined hole, in accordance with at least one aspect of the present disclosure.

[0012] [Figure 5] FIG. 5 is a cross-sectional view of the dome-shaped housing of FIG. 4 according to at least one aspect of the present disclosure.

[0013] [Figure 6]FIG. 6 depicts a control schematic for an MRI system in accordance with at least one aspect of the present disclosure.

[0014] [Figure 7] FIG. 7 is a flowchart illustrating a method for acquiring imaging data from an MRI system in accordance with at least one aspect of the present disclosure.

[0015] [Figure 8] FIG. 8 depicts an MRI scanning system and a robotic system according to at least one aspect of the present disclosure.

[0016] [Figure 9] FIG. 9 illustrates an RF receiving coil and a Canadian penny in accordance with various aspects of the present disclosure.

[0017] [Figure 10] FIG. 10 is a schematic diagram of an intracranial RF receive coil according to various aspects of the present disclosure.

[0018] [Figure 11] FIG. 11 is a schematic diagram of another intracranial RF receive coil according to various aspects of the present disclosure.

[0019] [Figure 12] FIG. 12 is a schematic image illustrating sensitive regions of an exemplary intracranial RF receive coil, according to various aspects of the present disclosure.

[0020] [Figure 13] FIG. 13 is a flowchart depicting a method for intraoperatively acquiring MR images of a patient's brain according to various aspects of the present disclosure.

[0021] Corresponding reference characters indicate corresponding parts throughout the several views. The examples presented herein are illustrative of various disclosed embodiments and are in one form only, and such examples are not to be construed as in any way limiting the scope thereof. DETAILED DESCRIPTION OF THE INVENTION

[0022] (Detailed explanation) The applicant of the present application owns the following patent applications, each of which is incorporated herein by reference in its individual entirety: -International Patent Application No. PCT / US2022 / 72143, filed May 5, 2022, entitled "NEURAL INTERVENTIONAL MAGNETIC RESONANCE IMAGING APPARATUS"; -U.S. Patent Application No. 18 / 057,207, filed November 19, 2022, entitled "SYSTEM AND METHOD FOR REMOVING ELECTROMAGNETIC INTERFERENCE FROM LOW-FIELD MAGNETIC RESONANCE IMAGES"; -U.S. Patent Application No. 18 / 147,418, filed December 28, 2022, and entitled "MODULARIZED MULTI-PURPOSE MAGNETIC RESONANCE PHANTOM"; -U.S. Patent Application No. 18 / 147,556, filed December 28, 2022, and entitled "DEEP LEARNING SUPER-RESOLUTION TRAINING FOR ULTRA LOW-FIELD MAGNETIC RESONANCE IMAGING."

[0023] Before describing various aspects of the interventional magnetic resonance imaging device in detail, it should be noted that the illustrative examples are not limited in application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative examples may be implemented or incorporated in other aspects, variations, and modifications, and may be practiced or carried out in various ways. Furthermore, unless otherwise indicated, the terms and phrases employed herein are chosen for the purpose of describing the illustrative examples for the convenience of the reader, and not for purposes of limitation thereof. It should also be understood that one or more of the aspects, aspect expressions, and / or examples described below may be combined with any one or more of the other subsequently described aspects, aspect expressions, and / or examples.

[0024] Various aspects are directed to neurointerventional magnetic resonance imaging (MRI) devices that enable the integration of MRI with surgical intervention and guidance. This includes providing physical access to the patient's surrounding area as well as access to the patient's head using one or more access openings. In addition, neurointerventional MRI devices may enable the use of robotic guided instruments and / or conventional surgical tools. In various instances, neurointerventional MRI can be used intraoperatively to obtain scans of the patient's head and / or brain during surgical interventions, such as surgical procedures like brain biopsies or neurosurgery.

[0025] 1 depicts an MRI scanning system 100 including a dome-shaped housing 102 configured to receive a patient's head. The dome-shaped housing 102 may further include at least one access opening configured to allow access to the patient's head and allow for neurointervention. The space within the dome-shaped housing 102 forms a region of interest for the MRI scanning system 100. Target tissue within the region of interest is subjected to magnetization fields / pulses to obtain imaging data representative of the target tissue, as further described herein.

[0026] 1A , a patient can be positioned so that their head is positioned within a region of interest within the dome-shaped housing 102. The brain can be positioned entirely within the dome-shaped housing 102. In such cases, to facilitate intracranial intervention (e.g., neurosurgery) in coordination with magnetic resonance (MR) imaging, the dome-shaped housing 102 can include one or more openings that provide access to the brain. The openings can be spaced around the periphery of the dome-shaped housing.

[0027] The MRI scanning system 100 may include an auxiliary cart (see, for example, auxiliary cart 540 in FIG. 6 ) that stores certain conventional MRI electrical and electronic components (e.g., a computer, a programmable logic controller, a power distribution unit, amplifiers, etc.). The MRI scanning system 100 may also include a magnet cart that holds the dome-shaped housing 102, gradient coils, and / or transmission coils, as further described herein. In addition, the magnet cart may, in various instances, be attached to a receive coil. Referring primarily to FIG. 1 , the dome-shaped housing 102 may further include a radio frequency (RF) transmission coil, a gradient coil 104 (depicted on its exterior), and a shim magnet 106 (depicted on its interior). Alternative configurations for the gradient coil 104 and / or the shim magnet 106 are also envisioned. In various instances, the shim magnet 106 may be adjustably positioned within a shim tray within the dome-shaped housing 102, which may allow a technician to configure the magnetic flux density of the dome-shaped housing 102 in fine detail.

[0028] Various structural housings for receiving a patient's head and enabling neurointervention can be utilized with MRI scanning systems such as MRI scanning system 100. In one aspect, MRI scanning system 100 may be equipped with an alternative housing, such as dome-shaped housing 202 (FIG. 2) or a two-piece housing 302 (FIG. 3) configured to form a dome shape. Dome-shaped housing 202 defines multiple access openings 203. Two-piece housing 302 also defines multiple access openings 303 and further includes an adjustable gap 305 between the two parts of the housing.

[0029] In various instances, housing 202 and housing 302 may include a bonding agent 308, such as, for example, an epoxy resin, that holds the plurality of magnetic elements 310 in a fixed position. The plurality of magnetic elements 310 may be bonded to a structural housing 312, such as, for example, a plastic substrate. In various aspects, bonding agent 308 and structural housing 312 may be non-conductive or diamagnetic materials. Referring primarily to FIG. 3 , two-piece housing 302 includes two structural housings 312. In various aspects, the structural housing for receiving the patient's head may be formed from more than two sub-components. Access opening 303 in structural housing 312 provides direct access to the patient's head and is not blocked by structural housing 312, bonding agent 308, or magnetic elements 310. Access opening 303 may be positioned, for example, within an open space of housing 302.

[0030] There are many possible configurations of neurointerventional MRI devices that can achieve improved access for surgical intervention. Many configurations are based on two main designs, commonly known as Halbach cylinders and Halbach domes, described in the following article: "Design of sparse Halbach magnet arrays for portable MRI using a genetic algorithm," IEEE transactions on magnetics, 54(1), 5100112, by Cooley et al. (e.g., Cooley, CZ, Haskell, MW, Cauley, SF, Sappo, C., Lapierre, CD, Ha, CG, Stockmann, JP, and Wald, LL (2018)). The article by Cooley et al., "Design of sparse Halbach magnet arrays for portable MRI using a genetic algorithm," published in IEEE transactions on magnetics, 54(1), 5100112 (2018), is incorporated herein by reference in its entirety.

[0031] In various cases, a dome-shaped enclosure for an MRI scanning system such as system 100 can include, for example, a Halbach dome, which defines the dome shape and is configured based on several factors, including main magnetic field B strength, field size, field homogeneity, device size, device weight, and patient access for neurointervention. In various aspects, the Halbach dome includes an outer radius and an inner radius at the base of the dome. The Halbach dome may include an elongated cylindrical portion extending from the base of the dome. In one aspect, the elongated cylindrical portion includes outer and inner radii that are the same as the base of the dome and continues a predetermined length from the base of the dome at a constant radius. In another aspect, the elongated cylindrical portion includes outer and inner radii that are different from the base of the dome (see, e.g., FIGS. 2 and 3). In such cases, the different outer and inner radii of the elongated cylindrical portion can blend with the base radius within a transition region.

[0032] 4 illustrates an example Halbach dome 400 for an MRI scanning system (e.g., system 100, etc.) in accordance with at least one aspect of the present disclosure. For example, the example Halbach dome 400 defines an access opening in the form of a hole or access opening 403, where the dome 400 is configured to receive the head and brain B of a patient P within a region of interest therein, and the access opening 403 is configured to allow access to the patient P for neurointervention using medical instruments and / or robotically controlled surgical tools. The Halbach dome 400 can be established with a single access opening 403 on an upper side 418 of the dome 400, which allows access to the top of the skull while minimizing impact on the magnetic field. Additionally or alternatively, the dome 300 can be configured with multiple access openings around the periphery of the structure 416 of the dome 400, as shown in FIGS. 2 and 3 .

[0033] Diameter D of access opening 403 hole may be small (e.g., about 2.54 cm) or very large (substantially the outer diameter r of the dome 400). ext) As the access opening 403 becomes larger, the dome 400 begins to resemble, for example, a Halbach cylinder. The access opening 403 is not limited to being at the apex of the dome 400. The access opening 403 can be located anywhere on the surface or structure 416 of the dome 400. In various instances, the entire dome 400 can be rotated so that the access opening 403 can be positioned with a desired physical location on the patient P.

[0034] FIG. 5 shows the diameter D of the access opening 403. hole , the length L of the dome 400, and the outer radius r of the dome 400. ext and the inner radius r in 1 depicts the relative dimensions of the Halbach dome 400, including the outer radius r. The Halbach dome 400 comprises a plurality of magnetic elements arranged in a Halbach array to form a magnetic assembly. The magnetic elements have an outer radius r. ext and the inner radius r in In one aspect, exemplary dimensions are r in =19.3cm, r ext = 23.6 cm, L = 38.7 cm, and 2.54 cm ≤ D < 19.3 cm.

[0035] Based on the above example dimensions, the Halbach dome 400 with access opening 403 may be configured with a magnetic flux density B of approximately 72 mT and an overall mass of approximately 35 kg. It should be understood that the dimensions may be selected to achieve a desired magnetic flux density B, total weight of the Halbach dome 400 and / or magnet cart, and geometry of the neuro-interventional access opening 403 based on a particular application.

[0036] In various aspects, the Halbach dome 400 may be configured to define a plurality of access openings 403 located around the periphery of the structure 416 of the dome 400. These plurality of access openings 403 may be configured to allow access to the patient's head and brain B using instruments (e.g., surgical instruments) and / or a surgical robot.

[0037] In various aspects, the access opening 403 may be adjustable. The adjustable configuration may include, for example, adjusting the diameter D of the access opening 403. hole The access opening 403 may be provided with the ability to be adjusted using either a motor, mechanical assistance, or a manual system with a mechanical iris diaphragm arrangement to adjust the aperture 403. This would allow for a configuration of the dome without the access opening 403, to perform an imaging scan, and then adjust the dome 400 and its mechanical iris diaphragm arrangement to include the access opening 403, thus allowing surgical intervention through the access opening 403.

[0038] Halbach domes and their magnetic arrays for facilitating neurointervention are further described in International Patent Application No. PCT / US2022 / 72143, filed May 5, 2022, and entitled "NEURAL INTERVENTIONAL MAGNETIC RESONANCE IMAGING APPARATUS," which is incorporated herein by reference in its entirety.

[0039] Referring now to FIG. 6, a schematic diagram for an MRI system 500 is shown. For example, the MRI scanning system 100 (FIG. 1) and various dome-shaped housings and magnetic arrays therefor, as described further herein, can be incorporated into the MRI system 500, for example. The MRI system 500 includes a housing 502, which may be similar in many aspects to the dome-shaped housing 102 (FIG. 1), the dome-shaped housing 202 (FIG. 2), and / or the dome-shaped housing 302 (FIG. 3). The housing 502 is dome-shaped and configured to form a region of interest or field of view 552 therein. For example, the housing 502 can be configured to receive a patient's head, in various aspects of the present disclosure.

[0040] Housing 502 includes a magnet assembly 548 having a plurality of magnets (e.g., a Halbach array of magnets) arranged therein. In various aspects, a main magnetic field B generated by magnetic assembly 548 extends into a field of view 552 containing an object (e.g., a patient's head) being imaged by MRI system 500.

[0041] The MRI system 500 also includes an RF transmit / receive coil 550. The RF transmit / receive coil 550 is combined into an integrated transmit-receive (Tx / Rx) coil. In other cases, the RF transmit coil can be separate from the RF receive coil. For example, the RF transmit coil can be incorporated into the housing 502, and the RF receive coil can be positioned within the housing 502 to acquire imaging data.

[0042] The housing 502 also includes one or more gradient coils 504 configured to generate gradient fields to facilitate imaging of objects within a field of view 552 generated by a magnet assembly 548 (e.g., enclosed by a dome-shaped housing and a dome-shaped array of magnetic elements therein). A shim tray adapted to receive shim magnets 506 can also be incorporated within the housing 502.

[0043] During the imaging process, a main magnetic field B0 extends into the field of view 552. The direction of the effective magnetic field (B1) changes in response to RF pulses and associated electromagnetic fields transmitted by the RF transmit / receive coil 550. For example, the RF transmit / receive coil 550 may be configured to selectively transmit RF signals or pulses to objects (e.g., tissue in a patient's brain) within the field of view 552. These RF pulses may modify the effective magnetic field experienced by spins in the sample tissue.

[0044] The housing 502 is in signal communication with an auxiliary cart 530, which is configured to provide power to the housing 502 and send / receive control signals to / from the housing 502. The auxiliary cart 530 includes a power distribution unit 532, a computer 542, a spectrometer 544, a transmit / receive switch 545, an RF amplifier 546, and a gradient amplifier 558. In various instances, the housing 502 can be in signal communication with multiple auxiliary carts, each of which can support one or more of the power distribution unit 532, the computer 542, the spectrometer 544, the transmit / receive switch 545, the RF amplifier 546, and / or the gradient amplifier 558.

[0045] The computer 542 is in signal communication with the spectrometer 544 and is configured to transmit and receive signals between the computer 542 and the spectrometer 544. When an object within the field of view 552 is excited with RF pulses from the RF transmit / receive coil 550, the precession of the object results in an induced current, i.e., an MR current, which is detected by the RF transmit / receive coil 550 and transmitted to the RF preamplifier 556. The RF preamplifier 556 is configured to boost or amplify the excitation data signals and transmit them to the spectrometer 544. The spectrometer 544 is configured to transmit the excitation data to the computer 542 for storage, analysis, and image construction. The computer 542 is configured to combine multiple stored excitation data signals, for example, to generate an image. In various instances, the computer 542 is in signal communication with at least one database 562 that stores a reconstruction algorithm 564 and / or a pulse sequence 566. The computer 542 is configured to utilize the reconstruction algorithm to generate an MR image 568.

[0046] From the spectrometer 544, the signal can also be relayed to an RF transmit / receive coil 550 within the housing 502 via an RF power amplifier 546 and a transmit / receive switch 545 positioned between the spectrometer 544 and the RF power amplifier 546. From the spectrometer 544, the signal can also be relayed to a gradient coil 560 within the housing 502 via a gradient power amplifier 558. For example, the RF power amplifier 546 is configured to amplify the signal and transmit it to the RF transmit coil 560, and the gradient power amplifier 558 is configured to amplify the gradient coil signal and transmit it to the gradient coil 560.

[0047] In various cases, the MRI system 500 can include a noise cancellation coil 554. For example, the auxiliary cart 530 and / or the computer 542 can be in signal communication with the noise cancellation coil 554. In other cases, the noise cancellation coil 554 can be optional. For example, some MRI systems disclosed herein may not include a supplemental / auxiliary RF coil for detecting and canceling electromagnetic interference (i.e., noise).

[0048] A flowchart depicting a process 570 for acquiring an MRI image is shown in FIG. 7. The flowchart can be implemented, for example, by the MRI system 500. In various instances, in block 572, a target object (e.g., a portion of a patient's anatomy) is positioned within a main magnetic field B within a region of interest (e.g., region of interest 552) such as in a dome-shaped housing (e.g., magnet assembly 548) of various MRI scanning devices described further herein. The main magnetic field B is configured to magnetically polarize hydrogen protons (H protons) in the target object (e.g., all organs and tissues), known as net longitudinal magnetization M. This is proportional to the tissue's proton density (PD) and evolves exponentially in time, with a time constant known as the tissue's longitudinal relaxation time T. The T value of individual tissues depends on several factors, including, for example, their microscopic structure, the water and / or lipid content therein, and the strength of the polarizing magnetic field. For these reasons, the T1 value of a given tissue sample depends on the age and state of health.

[0049] In block 574, a time-varying oscillating magnetic field B1, i.e., an excitation pulse, is applied to the magnetically polarized target object using an RF coil (e.g., RF transmit / receive coil 550). The carrier frequency of the pulsed B1 field is set to the resonance frequency of 1H protons, which diverts the longitudinal magnetization from its equilibrium longitudinal direction, resulting in a rotated magnetization vector, which can generally have a transverse magnetization component as well as a longitudinal magnetization component, depending on the diversion angle used. Typical B1 pulses include inversion pulses (i.e., 180-degree pulses) and 90-degree pulses. The 180-degree pulse reverses the direction of the magnetization of 1H protons in the longitudinal axis. The 90-degree pulse rotates the magnetization of 1H protons by 90 degrees so that the magnetization is in the transverse plane. The MR signal is a time-varying current proportional to the transverse component of the magnetization and is detected using a suitable RF coil. These MR signals decay exponentially in time, with a time constant known as the transverse relaxation time, T2, which also depends on, for example, the microscopic tissue structure, water / lipid content, and the strength of the magnetic field used.

[0050] In block 576, the MR signals are spatially encoded by exposing the target object to an additional magnetic field (known as a gradient field) generated by a gradient coil (e.g., gradient coil 560). The gradient field, which varies linearly in space, is applied for short-duration periods in pulsed form, with spatial variation in each direction. The end result is the generation of multiple spatially encoded MR signals, which can be detected in block 577 and reconstructed to form an MR image depicting a slice of the object. An RF receive coil (e.g., RF transmit / receive coil 550) can be configured to detect the spatially encoded RF signals. The slice may be oriented in the transverse, sagittal, coronal, or any oblique plane.

[0051] In block 578, the spatially encoded signals for each slice of the scanned region are mathematically digitized and spatially decoded using a computer reconstruction program (e.g., by computer 542) to generate an image depicting the internal anatomical structures of the subject. In various instances, the reconstruction program may utilize an (inverse) Fourier transform to convert the spatially encoded data (k-space data) back to geometrically decoded data.

[0052] FIG. 8 depicts a graphical illustration of a robotic system 680 that can be used for neurointervention using an MRI scanning system 600. The robotic system 680 includes a computer system 696 and a surgical robot 682. The MRI scanning system 600 can be similar to the MRI system 500 and can include a dome-shaped housing with an access opening and a magnetic array, as further described herein. For example, the MRI system 500 can include one or more access openings defined in a Halbach array of magnets in a permanent magnet assembly to provide access to one or more anatomical portions of a patient being imaged during a medical procedure. In various cases, the robotic arm and / or instruments of the surgical robot 682 are configured to extend through the access openings in the permanent magnet assembly to reach the patient or target site. Each access opening can provide access to the patient and / or surgical site. For example, in the case of multiple access openings, the multiple access openings can allow access from different directions and / or proximal locations.

[0053] According to various embodiments, the robotic system 680 is configured to be installed outside the MRI system 600. As shown in FIG. 8 , the robotic system 680 can include a robotic arm 684 configured for movement with one or more degrees of freedom. According to various embodiments, the robotic arm 684 includes one or more mechanical arm sections including a hollow shaft 686 and an end effector 688. The hollow shaft 686 and the end effector 688 are configured to be moved, rotated, and / or pivoted through various ranges of motion via one or more motion controllers 690. The double-headed curved arrows in FIG. 8 represent example rotational movements produced by the motion controllers 690 at various joints in the robotic arm 684.

[0054] According to various embodiments, the robotic arm 684 of the robotic system 682 is configured to access various anatomical portions of interest through or around the MRI scanning system 600. According to various embodiments, the access opening is designed to take into account the size of the robotic arm 684. For example, the access opening defines a perimeter configured to accommodate the robotic arm 684, hollow shaft 686, and end effector 688 therethrough. In various instances, the robotic arm 684 is configured to access various anatomical portions of a patient from around the side of the magnetic imaging device 600. The hollow shaft 686 and / or the end effector 688 can be adapted to receive a robotic instrument 692 (e.g., a biopsy needle having a cutting edge 694 for collecting a biopsy sample from a patient, etc.).

[0055] The reader will understand that robotic system 682 can be used in combination with various dome-shaped and / or cylindrical magnetic housings described further herein. Also, robotic system 682 and robotic instrument 692 in FIG. 8 are exemplary. Alternative robotic systems can be utilized in conjunction with the various MRI systems disclosed herein. Hand-held surgical instruments and / or additional imaging devices (e.g., endoscopes) and / or systems can also be utilized in conjunction with the various MRI systems disclosed herein.

[0056] In various aspects of the present disclosure, the MRI systems described herein may comprise low-field MRI (LF-MRI) systems. In such cases, the main magnetic field B generated by the permanent magnet assembly may be, for example, 0.1 T to 1.0 T. In other cases, the MRI systems described herein may comprise ultra-low-field MRI (ULF-MRI) systems. In such cases, the main magnetic field B generated by the permanent magnet assembly may be, for example, 0.03 T to 0.1 T.

[0057] Higher magnetic fields, such as those above 1.0 T, can preclude the use of certain electrical and mechanical components near MRI scanning equipment. For example, the presence of surgical instruments and / or surgical robotic components made of metal, particularly ferrous metals, can be dangerous near higher magnetic fields because such instruments can be attracted toward the magnetization source. Also, higher magnetic fields often require specially designed rooms with additional precautions and shielding to limit magnetic interference. Despite the limitations for high-field MRI systems, low-field and very-low-field MRI systems present various challenges to obtaining high-quality images with sufficient resolution to achieve desired imaging objectives.

[0058] LF and ULF-MRI systems generally define relatively poor overall magnetic field homogeneity compared to higher field MRI systems. For example, as further described herein, a dome-shaped enclosure for an array of magnets can comprise a Halbach array of permanent magnets that generates a magnetic field B0 with a homogeneity of 1,000 ppm to 10,000 ppm within a region of interest in various aspects of the present disclosure.

[0059] In some cases, an MRI system, such as the MRI scanning system 100 shown in FIG. 1, can be utilized in coordination with a neurosurgical intervention. For example, as shown in FIG. 1A, a patient can be positioned on a table, with the patient's head positioned within a region of interest defined by a dome-shaped housing 102. A clinician can access the patient's brain with a surgical device through an opening in the dome-shaped housing 102. Also, the MRI scanning system 100 can be an LF-MRI or ULF-MRI. In various cases, surgical devices (e.g., handheld instruments and / or robotic instruments) can be utilized in the presence of a low or very low magnetic field, such that the MRI scanning system 100 can be utilized intraoperatively to image the patient's brain (or a portion thereof). Images can be acquired intraoperatively, for example, during a neurological procedure such as a brain biopsy.

[0060] In various instances, obtaining high-resolution MR images of a patient's brain (or portions thereof) can be challenging, particularly when using LF-MRI or ULF-MRI. Lower magnetic field strength generally corresponds to a lower signal-to-noise ratio (SNR) and correspondingly lower resolution. Additionally or alternatively, in various instances, intraoperatively identifying and / or tracking the location of certain surgical devices, such as during neurological procedures where the patient's head is enclosed within the MRI system and / or at least partially surrounded by magnets and / or coils, can be challenging.

[0061] In various cases, the RF coil can be attached to a surgical device (such as a biopsy needle, scalpel, or other surgical device positioned within the patient's brain) positioned within the patient's brain. In some cases, the RF coil can be integrated into and / or supported by the surgical device (e.g., wrapped around and / or extending through the surgical device). In other cases, the RF coil can be integrated into and / or supported by a separate base mounted on or otherwise attached to the surgical device (e.g., wrapped around and / or extending through the separate base). The RF coil can be an RF receive coil used in connection with an MRI system. In various cases, placement of the RF receive coil within a region of interest (e.g., positioned within the patient's head and / or brain) can be configured to generate higher resolution MR images than those acquired using an external RF receive coil (e.g., positioned outside the patient's head and / or brain, such as within the housing of an MRI scanning system). Additionally or alternatively, the RF receive coil can be used to identify and / or track the position of the RF receive coil (and therefore the surgical device to which the RF receive coil is attached) during a surgical intervention.

[0062] In various instances, an RF receive coil for an MRI system can be positioned within the field of view to increase image resolution and / or facilitate tracking of a surgical device within the field of view. The RF receive coil can be much smaller than an external MR receive coil. The compact size of such RF receive coils allows for insertion of the coil within a patient's anatomy (e.g., within the patient's brain). In various instances, such RF receive coils can be referred to as "microcoils" due to their relatively small size compared to conventional external RF receive coils.

[0063] In some cases, the RF receive coil can define a loop of wire having a diameter less than 2.0 mm. In some cases, the RF receive coil can define a loop of wire having a diameter less than 2.0 mm and greater than 1.0 mm. For example, in various cases, the RF receive coil can define a loop of wire having a diameter of 1.2 mm. Alternative coil diameters are also contemplated. The reader will understand that the coil diameter can be minimized to correspond to the diameter of a surgical device to be inserted into the patient's anatomy. Additionally, or alternatively, the coil diameter can be selected to avoid interference with anatomical structures (that would otherwise not be affected by the surgical procedure or intervention).

[0064] 9 , exemplary RF receive coils 1000, 1002, 1004, 1006 are shown relative to a Canadian penny 1010 for reference. For example, the Canadian penny 1010 has a diameter of 19.05 mm. Any of the RF receive coils 1000, 1002, 1004, 1006 can be integrated into and / or supported by (e.g., wrapped around and / or extending through) the base 1012. In some cases, the base 1012 can be part of a surgical device. In other cases, the base 1012 can be mounted to or otherwise supported by the surgical device. 9 can be structured for use within a neurosurgical procedure. For example, RF receive coils 1000, 1002, 1004, 1006, and / or base 1012 can be dimensioned for insertion into intracranial vasculature. In some cases, any of RF receive coils 1000, 1002, 1004, 1006 can define a loop of wire having a diameter less than 2.0 mm (such as a loop of wire having a diameter less than 2.0 mm and greater than 1.0 mm).

[0065] 10 and 11, RF receive coil 1100 (FIG. 10) and RF receive coil 1200 (FIG. 11) are shown. RF receive coils 1100, 1200 can be used in association with MRI scanning system 100 (FIG. 1) and / or MRI system 500 (FIG. 6). For example, referring primarily to FIG. 6, RF receive coil 1100 or RF receive coil 1200 can be used in various aspects of the present disclosure with RF transmit / receive coil 550 in MRI system 500. For example, RF transmit / receive coil 550 can include a first (i.e., primary) receive coil, and RF receive coil 1100 or RF receive coil 1200 can be a second (i.e., secondary) receive coil for MRI system 500. For example, the primary receive coil of the MRI system (e.g., RF transmit / receive coil 550) can be used to determine the intracranial position of a surgical device, which has a secondary receive coil (e.g., RF receive coil 1100 or 1200) attached thereto. Furthermore, the secondary receive coil can be positioned proximate to the intracranial region of interest so that the secondary receive coil can be used to obtain high-resolution images of the intracranial region of interest. In other aspects, the MRI system 500 can include separate transmit and receive coils. For example, a transmit-only coil can be incorporated into the housing 502, and the RF receive coil 1100 or RF receive coil 1200 can function as a receive-only coil configured to detect magnetization induced by RF pulses transmitted by the transmit-only coil.

[0066] 10 , the RF receive coil 1100 forms a double opposed solenoid having a first solenoid 1112 at a proximal portion 1114 of the RF receive coil 1100 and a second solenoid 1116 at a distal portion 118 of the RF receive coil 1100. The first solenoid 1112 is formed from a piece of wire 1120 that forms a helical coil having a proximal end 1124 and a distal end 1128. At the distal end 1128 of the first solenoid 1112, the wire 1120 is routed back toward the proximal end 1124 of the first solenoid 1112 through a central opening 1126 formed by the helical coil. The wire pieces 1120 proximal to the proximal end 1124 of the first solenoid 1112 may be generally parallel and / or fused toward a parallel arrangement.

[0067] Similarly, the second solenoid 1116 is formed from a piece of wire 1130 that forms a helical coil having a proximal end 1134 and a distal end 1138. At the distal end 1138 of the second solenoid 1116, the wire 1130 is routed back through a central opening 1136 formed by the helical coil toward the proximal end 1134 of the second solenoid 1116. The wire 1130 is further routed back through the central opening 1136 formed by the helical coil of the first solenoid 1112 toward its proximal end 1124. The wire pieces 1130 proximal to the proximal end 1134 of the second solenoid 1116 can be generally parallel and / or fused toward a parallel arrangement.

[0068] The second solenoid 1116 is a longitudinally offset (with respect to the longitudinal axis A of the RF receive coil 1100) mirror image reflector of the first solenoid 1112. In various instances, a dual opposing solenoid, such as the RF receive coil 1100, can be used for intracranial vascular vessel wall imaging. For example, the RF receive coil 1100 can be integrated into and / or supported by a surgical instrument (such as a biopsy needle or catheter) that is inserted into the intracranial vessel. Intracranial vascular vessel wall imaging is further described herein.

[0069] 11 , RF receive coil 1200 forms a double quadrature solenoid having a first solenoid 1212 and a second solenoid 1216 that are rotationally offset and longitudinally overlapping. First solenoid 1212 has a proximal end 1224 and a distal end 1228 and is formed from a piece of wire 1220 that forms a helical coil defining a central opening 1226 that extends along axis A1. At distal end 1228 of first solenoid 1212, wire 1220 is routed back through central opening 1226 toward proximal end 1224 of first solenoid 1212. Proximal to the proximal end 1224 of the first solenoid 1212, the wire segments 1220 merge toward a generally parallel arrangement.

[0070] Similarly, the second solenoid 1216 is formed from a piece of wire 1230 that forms a helical coil having a proximal end 1234 and a distal end 1238. At the distal end 1238 of the second solenoid 1216, the wire 1230 is routed back toward the proximal end 1234 of the second solenoid 1216 through a central opening 1236 formed by the helical coil. Proximal to the proximal end 1234 of the second solenoid 1216, the wire pieces 1230 merge into a generally parallel arrangement.

[0071] The second solenoid 1216 is rotationally offset 90 degrees from the first solenoid 1212. For example, axis A1 can be rotationally offset 45 degrees in a first rotational direction from the longitudinal axis L, and axis A2 can be rotationally offset 45 degrees in an opposite rotational direction from the longitudinal axis L. In various cases, the rotational offset between the first solenoid 1212 and the second solenoid 1216 can be less than 135 degrees and greater than 45 degrees. The rotational offset can be selected to optimize imaging in a particular direction. For example, by rotating each solenoid symmetrically (e.g., 45 degrees) in opposite directions about the longitudinal axis L, the RF receive coil 1200 can be designed to assist in intracranial vascular surgical procedures. In some instances, the dual orthogonal solenoid design of the RF receive coil 1200 can be configured to generate a sensitive region that enables imaging distal to the RF receive coil 1200 when the RF receive coil 1200 is advanced inside the cranial vasculature by a needle or catheter. Imaging distal to the RF receive coil 1200 allows a surgeon performing an intracranial vascular intervention using the receive coil 1200 to identify and / or avoid penetrating critical cranial vascular structures. Figure 12 is a schematic image illustrating an exemplary sensitive region 1250 that may be associated with the RF receive coil 1200 of Figure 11. As shown in Figure 12, the sensitive region 1252 can include a distal region 1252 extending distally from the RF receive coil. Methods of intracranial vascular intervention are further described herein.

[0072] Referring now to FIG. 13 , an imaging method 1300 is described. The imaging method 1300 can be used to image a patient's brain or a portion of a patient's brain. In block 1302, an MRI housing is positioned around the patient's head. For example, dome-shaped housing 102 ( FIG. 1 ), dome-shaped housing 202 ( FIG. 2 ), or dome-shaped housing 302 ( FIG. 3 ) can be positioned around the patient's head so that a region of interest is defined within the housing. The patient can, for example, lean back on a table or sit upright.

[0073] In block 1304, a static magnetic field B is generated and projected into the region of interest. The static magnetic field B can be a low or very low magnetic field. For example, the static magnetic field B can be less than 1.0 T, and in various cases, can be, for example, 0.5 T. In other cases, the static magnetic field B can have a field strength higher than that of a low or very low magnetic field.

[0074] A surgical instrument having an RF receive coil is inserted into the region of interest at block 1306. The surgical instrument may have, for example, a distal end with an RF receive coil. The surgical instrument, in various cases, may be inserted into the region of interest through an opening in the housing. The surgical instrument may be, for example, a biopsy needle or a scalpel. Alternative surgical instruments, such as probes, retractors, and dissectors, are also contemplated.

[0075] In block 1308, excitation pulses are transmitted to a region of interest, and gradient fields are applied in block 1310. In block 1312, RF signals are detected by an RF receive coil mounted on a surgical instrument within the region of interest. Blocks 1308, 1310, and 1312 can be implemented, for example, according to a pulse sequence stored in memory accessible to the computer / control circuitry of the MRI system. In various cases, the excitation pulses, gradient fields, and signal receive cycles can be performed in different orders and / or different repeating patterns according to the pulse sequence. In block 1314, an image of the patient's brain (or at least a portion of the patient's brain) can be generated from the spatially encoded RF signals received from the RF receive coil according to the pulse sequence. In various cases, a local intracranial RF receive coil can enable very high-resolution images, for example, for various applications (e.g., tumor characterization, etc.).

[0076] In some cases, the RF coil can be tracked in real time, as shown in block 1316. As a result, a clinician can track the position of a surgical instrument (on which an RF receive coil is mounted) in real time and during surgery.

[0077] Additionally or alternatively, in various cases, an image reconstructed from the spatially encoded RF signals received by the RF receive coil can be combined with imaging data from another RF receive coil (such as a primary RF receive coil positioned outside the patient's brain), as shown in block 1318. In various cases, the primary RF receive coil can be positioned, for example, within a housing. Image combination from both a local perspective (via an intracranial RF receive coil) and a global perspective (via an external RF receive coil) can, in some cases, provide improved visualization for a neurosurgeon.

[0078] example Various additional aspects of the subject matter described herein are presented in the following numbered examples.

[0079] Example 1: A surgical system comprising: a surgical instrument having a distal end portion and a radio frequency receive coil attached to the distal end portion; and a magnetic resonance imaging system configured to project a magnetic field into a field of view, the magnetic resonance imaging system configured to image the radio frequency receive coil within the field of view during surgery.

[0080] Example 2: The surgical system of Example 1, wherein the surgical instrument comprises a biopsy needle.

[0081] Example 3: The surgical system of Example 1, wherein the surgical instrument comprises a scalpel.

[0082] Example 4: The surgical system of any one of Examples 1-3, wherein the radio frequency receiving coil defines a coil loop.

[0083] Example 5: The surgical system of any one of Examples 1-3, wherein the radio frequency receiving coil has an outer diameter of less than 2 mm.

[0084] Example 6: The surgical system of Example 5, wherein the outer diameter is greater than 1 mm.

[0085] Example 7: The surgical system of Example 6, wherein the outer diameter is 1.2 mm.

[0086] Example 8: The surgical system of any one of Examples 1-7, wherein the magnetic resonance imaging system is configured to track the radio frequency receive coil in real time.

[0087] Example 9: The surgical system of any one of Examples 1-8, wherein the magnetic resonance imaging system further comprises a primary radio frequency transmission coil, the primary radio frequency transmission coil configured to transmit a radio frequency signal configured to excite magnetization within the field of view.

[0088] Example 10: The surgical system of Example 9, wherein the magnetic resonance imaging system further comprises a primary radio frequency receive coil, the primary radio frequency receive coil configured to receive a radio frequency signal corresponding to the excited magnetization within the field of view.

[0089] Example 11: A low-field magnetic resonance imaging system comprising: a dome-shaped housing defining a region of interest, the dome-shaped housing comprising an array of permanent magnets configured to project a magnetic field into the region of interest, a gradient coil assembly, and a radio frequency transmission coil configured to transmit radio frequency signals to excite magnetization in the region of interest; a surgical instrument comprising a radio frequency receive coil configured to receive radio frequency signals corresponding to the excited magnetization in the field of view; and a control unit comprising a processor and a memory communicatively coupled to the processor, the memory storing instructions executable by the processor to transmit radio frequency pulses to the radio frequency transmission coil and receive radio frequency signals from the radio frequency receive coil.

[0090] Example 12: The low-field magnetic resonance imaging system of example 11, wherein the memory further stores instructions executable by the processor to reconstruct an image of the region of interest.

[0091] Example 13: The low-field magnetic resonance imaging system of any one of Examples 11 and 12, wherein the memory further stores instructions executable by the processor to track the radio frequency receive coil within the region of interest in real time.

[0092] Example 14: The low-field magnetic resonance imaging system of any one of Examples 11 and 12, wherein the magnetic field has a field strength below 1 T.

[0093] Example 15: The low-field magnetic resonance imaging system of example 14, wherein the field strength comprises a field strength below 0.3 T.

[0094] Example 16: The low-field magnetic resonance imaging system of any one of Examples 11 and 12, wherein the surgical instrument is selected from the group consisting of a biopsy needle and a scalpel.

[0095] Example 17: The low-field magnetic resonance imaging system of any one of Examples 11-16, wherein the radio frequency receive coil defines a coil loop defining an outer diameter of less than 2 mm and greater than 1 mm.

[0096] Example 18: A method comprising: positioning a housing around a patient's head, the housing comprising a dome-shaped array of magnets configured to project a static magnetic field into a region of interest within the patient's head and a radio frequency transmission coil configured to excite magnetization in the region of interest; inserting a surgical instrument into the region of interest through an opening in the housing, the surgical instrument comprising a radio frequency receiving coil; transmitting radio frequency pulses to the radio frequency transmission coil; receiving radio frequency signals from the radio frequency receiving coil; and reconstructing an image of at least a portion of the patient's head from the radio frequency signals.

[0097] Example 19: The method of example 18, wherein the static magnetic field has a field strength below 1 T.

[0098] Example 20: The method of any one of Examples 18 and 19, further comprising tracking the radio frequency receiving coil in real time.

[0099] Although various aspects disclosed herein are directed to brain imaging and / or neurological intervention, the reader will understand that the various systems and methods disclosed herein may, in various instances, be used to image other portions of a patient's anatomy and / or different structures.

[0100] While several embodiments have been illustrated and described, it is not the applicant's intention to restrict or limit the scope of the appended claims to such details. Numerous modifications, variations, changes, substitutions, combinations, and equivalents to those embodiments may be implemented and will occur to those skilled in the art without departing from the scope of the present disclosure. Furthermore, the structure of each element associated with the described embodiments can alternatively be described as a means for providing the function performed by that element. Furthermore, where a material is disclosed for a component, other materials may also be used. It is therefore to be understood that the foregoing description and the appended claims are intended to cover all such modifications, combinations, and variations that fall within the scope of the disclosed embodiments. The appended claims are intended to cover all such modifications, variations, changes, substitutions, modifications, and equivalents.

[0101] The foregoing detailed description sets forth various aspects of the present devices and / or processes through the use of block diagrams, flowcharts, and / or examples. To the extent that such block diagrams, flowcharts, and / or examples contain one or more functions and / or operations, it will be understood by those skilled in the art that each function and / or operation within such block diagrams, flowcharts, and / or examples can be individually and / or collectively implemented by a wide range of hardware, software, firmware, or virtually any combination thereof. Those skilled in the art will recognize that some aspects of the embodiments disclosed herein may equivalently be implemented, in whole or in part, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or in integrated circuits, as virtually any combination thereof, and that designing circuitry and / or writing code for the software and / or firmware would be clearly within the skill of one of ordinary skill in the art in light of this disclosure. Additionally, those skilled in the art will understand that the subject mechanisms described herein can be distributed as one or more program products in a variety of forms, and that the illustrative embodiments of the subject matter described herein apply regardless of the particular type of signal-bearing medium used to actually effect the distribution.

[0102] The instructions used to program the logic to implement various disclosed aspects can be stored in memory within the system, such as dynamic random access memory (DRAM), cache, flash memory, or other storage device. Additionally, the instructions can be distributed over a network or using other computer-readable media. Thus, a machine-readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer), including, but not limited to, floppy diskettes, optical disks, compact disks, read-only memories (CD-ROMs), and magneto-optical disks, read-only memories (ROMs), random access memories (RAMs), erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), magnetic or optical cards, flash memories, or tangible machine-readable storage devices used in transmitting information via the Internet via electrical, optical, acoustical, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.). Thus, non-transitory computer-readable media includes any type of tangible machine-readable medium suitable for storing or transmitting electronic instructions or information in a form readable by a machine (e.g., a computer).

[0103] As used in any aspect of this specification, the term "control circuit" may refer to, for example, hardwired circuitry, programmable circuitry (e.g., a computer processor including one or more individual instruction processing cores, processing units, processors, microcontrollers, microcontroller units, controllers, digital signal processors (DSPs), programmable logic devices (PLDs), programmable logic arrays (PLAs), or field programmable gate arrays (FPGAs)), state machine circuitry, firmware that stores instructions executed by the programmable circuitry, and any combination thereof. Control circuits may collectively or individually be embodied as circuitry that forms part of a larger system (e.g., an integrated circuit (IC), an application-specific integrated circuit (ASIC), a system-on-chip (SoC), a desktop computer, a laptop computer, a tablet computer, a server, a smartphone, etc.). Thus, as used herein, a "control circuit" includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application-specific integrated circuit, electrical circuitry forming a general-purpose computing device configured by a computer program (e.g., a general-purpose computer configured, at least in part, by a computer program to perform the processes and / or devices described herein, or a microprocessor configured, at least in part, by a computer program to perform the processes and / or devices described herein), electrical circuitry forming a memory device (e.g., a form of random access memory), and / or electrical circuitry forming a communications device (e.g., a modem, a communications switch, or an optoelectronic appliance). Those skilled in the art will recognize that the subject matter described herein can be implemented in analog or digital form or some combination thereof.

[0104] As used in any aspect of this specification, the term "logic" may refer to apps, software, firmware, and / or circuitry configured to perform any of the foregoing operations. Software may be embodied as a software package, code, instructions, instruction sets, and / or data recorded on a non-transitory computer-readable storage medium. Firmware may be embodied as hard-coded (e.g., non-volatile) code, instructions or instruction sets, and / or data in a memory device.

[0105] When used in any aspect of this specification, the terms "component," "system," "module," and the like may refer to a controlled circuit computer-related entity that is either hardware, a combination of hardware and software, software, or software in execution.

[0106] As used in any aspect of this specification, an "algorithm" refers to a self-consistent sequence of steps leading to a desired result, and a "step" refers to manipulations on physical quantities and / or logical states which may, but need not, take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is common usage to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. These and similar terms can be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities and / or states.

[0107] The network may include a packet-switched network. The communication devices may be capable of communicating with each other using a selected packet-switched network communication protocol. One exemplary communication protocol may include an Ethernet communication protocol, which may enable communication using Transmission Control Protocol / Internet Protocol (TCP / IP). The Ethernet protocol may conform to or be compatible with the Ethernet standard published by the Institute of Electrical and Electronics Engineers (IEEE), published in December 2008 and entitled "IEEE 802.3 Standard," and / or later versions of this standard. Alternatively, or in addition, the communication devices may be capable of communicating with each other using an X.25 communication protocol. The X.25 communication protocol may conform to or be compatible with standards promulgated by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). Alternatively, or in addition, the communication devices may be capable of communicating with each other using a frame relay communication protocol. The frame relay communication protocol may conform to or be compatible with standards promulgated by the Consultative Committee for International Telegraph and Telephone (CCITT) and / or the American National Standards Institute (ANSI). Alternatively, or in addition, the transceivers may be capable of communicating with each other using an Asynchronous Transfer Mode (ATM) communication protocol. The ATM communication protocol may conform to or be compatible with the ATM standard published by the ATM Forum, published in August 2001 and entitled "ATM-MPLS Network Interworking 2.0," and / or later versions of this standard. Of course, different and / or later-developed connection-oriented network communication protocols are equally contemplated herein.

[0108] Unless otherwise specifically stated as is apparent from the foregoing disclosure, throughout the foregoing disclosure, discussions using terms such as "processing," "computing," "calculating," "determining," "displaying," or the like, should be understood to refer to the actions and processes of a computer system or similar electronic computing device that manipulates and converts data represented as physical (electronic) quantities in the computer system's registers and memory into other data that is similarly represented as physical quantities in the computer system's memory or registers or other such information storage, transmission, or display device.

[0109] One or more components may be referred to herein as being "configured to," "configurable to," "operable / operative to," "adapted / adaptable," "able to," "conformable / conformed to," etc. Those skilled in the art will recognize that, unless the context requires otherwise, "configured to" can generally encompass active and / or inactive and / or standby state components.

[0110] The terms "proximal" and "distal" are used herein with reference to a clinician manipulating a handle portion of a surgical instrument. The term "proximal" refers to the portion closest to the clinician, and the term "distal" refers to the portion located away from the clinician. It should be further understood that for convenience and clarity, spatial terms such as "vertical," "horizontal," "up," and "down" may be used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and / or absolute.

[0111] Those skilled in the art will generally recognize that terms used herein, particularly in the appended claims (e.g., the body of the appended claims), are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those skilled in the art that where a specific number of introduced claim recitations are intended, such intention will be expressly recited in the claim, and that in the absence of such recitation, no such intention exists. For example, as an aid to understanding, the following appended claims may contain the use of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed as implying that introducing a claim recitation with the indefinite article "a" or "an" limits any particular claim containing such an introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should typically be interpreted to mean "at least one" or "one or more"); the same applies to the use of a definite article used to introduce a claim recitation.

[0112] Additionally, even when a claim recitation incorporating a specific number is explicitly recited, those of skill in the art will recognize that such recitation should typically be interpreted to mean at least the number recited (e.g., a literal recitation of "two recitations" without other modifiers typically means at least two recitations or two or more than two recitations). Furthermore, in those instances where notation similar to "at least one of A, B, and C, etc." is used, such a construct is generally intended in the sense that one of skill in the art would understand the notation (e.g., "a system having at least one of A, B, and C" would include, without limitation, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where notation similar to "at least one of A, B, or C, etc." is used, generally, such constructs are intended in the sense that one of ordinary skill in the art would understand the notation (e.g., "a system having at least one of A, B, and C" would include, but not be limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B and C together, etc.). It will be further understood by those of ordinary skill in the art that disjunctive words and / or phrases presenting two or more alternative terms, whether in the description, claims, or drawings, should typically be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms, unless the context indicates otherwise.For example, the phrase "A or B" will typically be understood to include the possibilities of "A," or "B," or "A and B."

[0113] With respect to the appended claims, those skilled in the art will understand that the actions recited therein may generally be performed in any order. Also, while various operational flow diagrams are presented in a certain sequence, it should be understood that various actions may be performed in other orders than those depicted, or may be performed in parallel. Examples of such alternative orderings may include overlapping, interleaved, interrupted, reordered, incremental, prelude, supplemental, simultaneous, reverse, or other variant orderings, unless the context indicates otherwise. Furthermore, terms such as "responsive to," "related to," or other past tense adjectives generally are not intended to exclude such variants, unless the context indicates otherwise.

[0114] It should be noted that any reference to "one aspect," "an aspect," "an exemplification," "one exemplification," and the like means that a particular feature, structure, or characteristic described in connection with an aspect is included in at least one aspect. Thus, appearances of the phrases "in one aspect," "in an aspect," "in an exemplification," and "in one exemplification" in various places throughout this specification do not necessarily all refer to the same aspect. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.

[0115] Any patent application, patent, non-patent publication, or other disclosure material referred to herein and / or listed in any Application Data Sheet is incorporated herein by reference to the extent the incorporated material does not contradict this specification. Accordingly, to the extent necessary, the disclosure as expressly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is considered to be incorporated herein by reference but that conflicts with existing definitions, descriptions, or other disclosure material set forth herein will be incorporated only to the extent that no conflict arises between the incorporated material and the existing disclosure material.

[0116] In summary, numerous benefits resulting from employing the concepts described herein have been described. The foregoing description of one or more embodiments has been presented for purposes of illustration and explanation. It is not intended to be exhaustive or to be limited to the precise embodiments disclosed. Modifications or variations are possible in light of the above teachings. One or more embodiments have been selected and described, along with various modifications as suited to particular uses, to illustrate the principles and practical applications, thereby enabling those skilled in the art to utilize various embodiments. It is intended that the claims submitted herewith define the overall scope.

Claims

1. 1. A surgical system, comprising: a surgical instrument having a distal end portion and a radio frequency receiving coil attached to the distal end portion; a magnetic resonance imaging system configured to project a magnetic field into a field of view, the magnetic resonance imaging system configured to image the radio frequency receive coil within the field of view during surgery; A surgical system comprising:

2. The surgical system of claim 1 , wherein the surgical instrument comprises a biopsy needle.

3. The surgical system of claim 1 , wherein the surgical instrument comprises a scalpel.

4. The surgical system of claim 1 , wherein the radio frequency receive coil defines a coil loop.

5. The surgical system of claim 1 , wherein the radio frequency receive coil comprises an outer diameter of less than 2 mm.

6. The surgical system of claim 5 , wherein the outer diameter is greater than 1 mm.

7. The surgical system of claim 6 , wherein the outer diameter is 1.2 mm.

8. The surgical system of claim 1 , wherein the magnetic resonance imaging system is configured to track the radio frequency receive coil in real time.

9. 10. The surgical system of claim 1, wherein the magnetic resonance imaging system further comprises a primary radio frequency transmission coil configured to transmit a radio frequency signal configured to excite magnetization within the field of view.

10. 10. The surgical system of claim 9, wherein the magnetic resonance imaging system further comprises a primary radio frequency receive coil configured to receive a radio frequency signal corresponding to the excited magnetization within the field of view.

11. 1. A low-field magnetic resonance imaging system, comprising: A dome-shaped enclosure defining a region of interest, the dome-shaped enclosure comprising: an array of permanent magnets configured to project a magnetic field into the region of interest; a gradient coil assembly; a radio frequency transmission coil configured to transmit a radio frequency signal to excite magnetization in the region of interest; a dome-shaped housing comprising: a surgical instrument comprising a radio frequency receive coil configured to receive a radio frequency signal corresponding to the excited magnetization within the field of view; A control unit comprising a processor and a memory communicatively coupled to the processor, the memory comprising: transmitting radio frequency pulses to the radio frequency transmission coil; receiving a radio frequency signal from the radio frequency receiving coil; a control unit storing instructions executable by said processor to perform 1. A low-field magnetic resonance imaging system comprising:

12. The low-field magnetic resonance imaging system of claim 11 , wherein the memory further stores instructions executable by the processor to reconstruct an image of the region of interest.

13. The low-field magnetic resonance imaging system of claim 11 , wherein the memory further stores instructions executable by the processor to track the radio frequency receive coil within the region of interest in real time.

14. The low-field magnetic resonance imaging system of claim 11 , wherein the magnetic field comprises a field strength below 1 T.

15. The low-field magnetic resonance imaging system of claim 14 , wherein the field strength comprises a field strength below 0.3 T.

16. The low-field magnetic resonance imaging system of claim 11 , wherein the surgical instrument is selected from the group consisting of a biopsy needle and a scalpel.

17. 12. The low-field magnetic resonance imaging system of claim 11, wherein the radio frequency receive coil defines a coil loop defining an outer diameter of less than 2 mm and greater than 1 mm.

18. 1. A method, comprising: positioning a housing around a patient's head, said housing comprising: a dome-shaped array of magnets configured to project a static magnetic field into a region of interest within the patient's head; a radio frequency transmission coil configured to excite magnetization within the region of interest; and inserting a surgical instrument through an opening in the housing and into the region of interest, the surgical instrument comprising a radio frequency receiving coil; transmitting radio frequency pulses to the radio frequency transmission coil; receiving a radio frequency signal from the radio frequency receiving coil; reconstructing an image of at least a portion of the patient's head from the radio frequency signals; A method comprising:

19. 20. The method of claim 18, wherein the static magnetic field has a field strength below 1 T.

20. 20. The method of claim 18, further comprising tracking the radio frequency receive coil in real time.

Images