CN111610477A - Mobile MRI system with improved RF coil - Google Patents

Abstract

Apparatus for in-surgical imaging comprising an operating room for surgery and an MRI for periodically acquiring images during surgery by moving a magnet up to an operating table. The magnet wires are formed of a superconducting material, such as magnesium diboride or titanium niobium, which is cooled to superconductivity by a vacuum cryogenic cooling system without the use of liquid helium. The magnets weigh less than 1 to 2 tons and have a footprint of 15 to 35 square feet and can therefore be placed on the floor by a support system having an air cushion covering the bottom area of the magnet with side skirts, thereby distributing the weight over the entire bottom area. During surgery, the magnet remains in the room and, in a second position away from the table, the magnet is de-energized to turn off the magnetic field.

Description

Mobile MRI system with improved RF coil

Technical Field

The present invention relates to a mobile MRI system for surgery.

Background

Magnetic Resonance Imaging (MRI) is a non-invasive imaging modality that can distinguish between various types of objects based on the components inherent in the objects, and is also an imaging technique that can provide one-, two-, or three-dimensional imaging of objects. Conventional MRI systems typically include a main magnet providing a main static magnetic field, B0, magnetic field gradient coils, and Radio Frequency (RF) coils for spatially encoding, exciting, and detecting nuclei for imaging. Typically, the main magnet is designed to provide a uniform magnetic field in an interior region within the main magnet, for example, in the air space of the large central bore of the solenoid or in the air gap between the pole plates of the C-shaped magnet. The patient or object to be imaged is placed in a uniform field region located in such air space. The gradient fields for converting distance to frequency and the RF coils for transmitting and receiving signals from the patient are typically located outside the patient or object to be imaged and inside the geometry of the main magnet surrounding the air space.

Typically, a uniform magnetic field B0 is generated by the main magnet on a high magnetic field MRI system (>1.0 tesla), which then remains on for the life of the magnet, although the magnetic field will occasionally enhance the magnetic field during the operational life of the magnet. In conventional MRI devices, the patient is brought to the magnet, laid on a patient table, and then slid into the magnet, wherein the region to be imaged is as close as possible to the isocenter of the magnet. This requires that the patient either be ambulatory or that the patient be taken to the magnet on the wheel table and slid into the magnet. Many times, the physician prefers to bring the MRI magnet to the patient because the patient cannot move. Examples include patients undergoing surgery or interventional procedures where a physician needs to take an image of, for example, a stroke patient or a patient with an accident, all of which should not move under the circumstances at the time.

Modern neurosurgery includes surgical treatment of many complex conditions such as primary intracranial or spinal tumors, skull and skull base injuries, cerebrovascular diseases (including arteriovenous malformations, cavernous hemangiomas, and intracranial aneurysms), and inflammation. When these changes occur, imaging is performed by computed tomography, magnetic resonance, positron emission tomography and magnetic wave processing, which greatly improves understanding of brain structures and functional events. Imaging data has been incorporated into stereotactic space by many means to allow precise point access and volume understanding for planning and cross-brain navigation in which the size of the operative working channel is significantly reduced. However, there is a need to bring this imaging technique to the operating room so that changes caused by brain displacement and tissue removal and surgical treatment can be accommodated. Many intraoperative MRI devices have been developed, the most popular of which is the MRI device sold by IMRIS. The challenge with such IMRIS devices is that installing such IMRIS devices requires extensive retrofitting of hospital operating rooms, which is costly and for a significant period of time, the operating rooms are unusable.

Disclosure of Invention

The invention may be used independently of other features described herein, and according to one aspect of the invention there is provided an apparatus for use in surgery comprising:

an operating room having a floor and a plurality of walls and including an operating table for positioning a patient for a surgical procedure; and

a magnetic resonance imaging system for acquiring images of a portion of a patient at multiple times throughout a surgical procedure for analysis by a surgical team so that the surgical team can monitor the progress of the procedure, the magnetic resonance imaging system comprising:

a magnet system comprising a cylindrical magnet of a magnet wire, the cylindrical magnet defining a cylindrical bore within which a portion of a patient is located for placement within a high magnetic field generated by the magnet;

a control system for controlling and varying the magnetic field;

a radio frequency emission and detection system for exciting and detecting nuclear magnetic resonance signals in a portion of a patient in response to a magnetic field, the radio frequency emission and detection system including an RF probe disposed proximate to a portion of the patient;

and a computer and display monitor for decoding and displaying the detected signals;

a table support system mounting a magnet for movement relative to the table in a direction away from a first end of the table from a first position of the table to a second position away from the table;

the first position of the magnet is arranged such that a portion of the patient is positioned in the magnetic field of the magnet while the patient remains in position on the table;

the second position of the magnet is arranged such that the magnet is spaced from the first end of the table by a distance sufficient to allow the surgical team to move around the first end of the table and each side of the table to contact the patient while the distance is sufficient to allow the surgical team to perform the surgical procedure;

wherein the magnet wires are made of a superconducting material that can be cooled to superconductivity by a cooling system without the use of liquid helium.

Preferably, the magnet wires are formed from magnesium diboride, which requires temperatures up to about 40 degrees absolute, which can be achieved without the use of liquid helium, typically using a vacuum cryogenic cooling system with a vacuum pump. Other materials that may be used are niobium titanium, and possibly (although less suitably) niobium tin.

For example, using these techniques, the magnet may have a weight of less than 2 tons and a floor area in the range of 15 to 40 square feet, and typically around 35 square feet, which most standard floor systems can withstand.

This allows the magnets to be preferably brought to a support system supported by the floor. In particular, the support system may comprise an air cushion covering the bottom area of the magnets with side skirts, in order to distribute the weight over the entire bottom area. In order to use the air cushion in an operating room, the air cushion system is preferably arranged such that it does not eject particles from the side skirt.

While the magnets preferably float on the air cushion to distribute the load, preferably the support system is guided on the rails from a first position to a second position.

In another preferred arrangement, the magnets are carried on a pair of side rails in the manner of a skid steer loader so that the side rails along the sides of the magnet base carry weight and can be controlled with sufficient precision to drive the magnets forward relative to the table position. It will be appreciated that the magnet bore exactly matches the table and therefore the drive accuracy must be very high to ensure the correct position required for the magnet without the use of guide rails.

As explained in more detail below, the track also allows the magnet to rotate about a vertical axis at or near the center of the magnet, thereby moving the front end of the magnet into the room in a desired orientation.

This type of arrangement may preferably allow the magnet to be de-energized to turn off the magnetic field when the magnet is in the second position. In this way, the magnet can remain dormant in the same room during surgery, but preferably the cooling system remains in the start state during periods when the magnetic field is de-energized. In this arrangement, the magnet is preferably dedicated to surgery within the operating room and remains within the operating room. Although the cost of the magnet can be amortized by using it multiple times, in this arrangement the magnet itself is small in construction so that it can be supported on the ground while being simple to connect to cooling water and a power supply, all of which make the subsequent cost of the magnet very small. At the same time, the selected magnet may provide a magnetic induction in excess of 1 tesla, which is sufficient to provide effective imaging.

To reduce weight, the magnet preferably has a minimum aperture of about 60 to 70cms, typically about 65cms, and a length in the range of 5 feet.

In addition to keeping the overall size as small as possible, in some cases the RF probe includes a local transceiver RF coil to avoid the use of a cylindrical coil at the bore, which would otherwise increase the diameter of the magnet. However, in other cases, a body coil may be used within the bore, particularly as a transmit coil, while a receive coil is provided as a separate component, particularly a coil surrounding the head.

To avoid shielding the entire room from stray RF signals as is normally required, it is preferred to provide a shielding structure for excluding RF fields from the RF probe, the shielding structure comprising an arcuate support frame for extending over the patient while supporting a shielding fabric or shielding material, the shielding fabric extending from the feet to the body part of the access opening; a metal plate as part of the table under the patient and extending across the table to both sides of the shielding fabric; a cylindrical shielding layer located in the hole; and a hinged door located at an end of the hole opposite the work table and including a shield layer. The shielding material may be a shielding material encapsulated in a plastic material to form a rigid structure that maintains its shape as an arch when deployed over a patient on a table.

According to another aspect of the present invention, there is provided an apparatus for use in surgery, comprising:

an operating room having a floor and a plurality of walls and including an operating table for positioning a patient for a surgical procedure; and

a magnetic resonance imaging system for acquiring images of a portion of a patient at multiple times throughout a surgical procedure for analysis by a surgical team so that the surgical team can monitor the progress of the procedure, the magnetic resonance imaging system comprising:

a magnet system comprising a cylindrical magnet of a magnet wire, the cylindrical magnet defining a cylindrical bore within which a portion of a patient is located for placement within a high magnetic field generated by the magnet;

a control system for controlling and varying the magnetic field;

a radio frequency emission and detection system for exciting and detecting nuclear magnetic resonance signals in a portion of a patient in response to a magnetic field, the radio frequency emission and detection system including an RF probe disposed proximate to a portion of the patient;

and a computer and display monitor for decoding and displaying the detected signals;

a table support system mounting a magnet for movement relative to the table in a direction away from a first end of the table from a first position of the table to a second position away from the table;

the first position of the magnet is arranged such that a portion of the patient is positioned in the magnetic field of the magnet while the patient remains in position on the table;

the second position of the magnet is arranged such that the magnet is spaced from the first end of the table by a distance sufficient to allow the surgical team to move around the first end of the table and each side of the table to contact the patient while the distance is sufficient to allow the surgical team to perform the surgical procedure;

wherein the magnet wire is composed of magnesium diboride or niobium titanium.

According to another aspect of the present invention, there is provided an apparatus for use in surgery, comprising:

an operating room having a floor and a plurality of walls and including an operating table for positioning a patient for a surgical procedure; and

a magnetic resonance imaging system housed in an operating room for acquiring a portion of an image of a patient at multiple times throughout a surgical procedure for analysis by a surgical team so that the surgical team can monitor the progress of the procedure, the magnetic resonance imaging system comprising:

a magnet system comprising a cylindrical magnet of a magnet wire, the cylindrical magnet defining a cylindrical bore within which a portion of a patient is located for placement within a high magnetic field generated by the magnet;

a control system for controlling and varying the magnetic field;

a radio frequency emission and detection system for exciting and detecting nuclear magnetic resonance signals in a portion of a patient in response to a magnetic field, the radio frequency emission and detection system including an RF probe disposed proximate to a portion of the patient;

and a computer and display monitor for decoding and displaying the detected signals;

a table support system mounting a magnet for movement relative to the table in a direction away from a first end of the table from a first position of the table to a second position away from the table;

the first position of the magnet is arranged such that a portion of the patient is positioned in the magnetic field of the magnet while the patient remains in position on the table;

the second position of the magnet is arranged such that the magnet is spaced from the first end of the table by a distance sufficient to allow the surgical team to move around the first end of the table and each side of the table to contact the patient while the distance is sufficient to allow the surgical team to perform the surgical procedure;

wherein the magnet weighs less than 2 tons and has a footprint in the range of 15 to 40 square feet, and typically 35 square feet, and is carried on a support system supported by the floor.

According to another aspect of the present invention, there is provided a method for surgery, comprising:

providing an operating room having a floor and a plurality of walls and including a surgical table for positioning a patient for performing a surgical procedure; and

installing a magnetic resonance imaging system in an operating room for acquiring images of a portion of a patient at multiple times throughout a surgical procedure for analysis by a surgical team so that the surgical team can monitor the progress of the procedure, the magnetic resonance imaging system comprising:

a magnet system comprising a cylindrical magnet of a magnet wire, the cylindrical magnet defining a cylindrical bore within which a portion of a patient is located for placement within a high magnetic field generated by the magnet;

a control system for controlling and varying the magnetic field;

a radio frequency emission and detection system for exciting and detecting nuclear magnetic resonance signals in a portion of a patient in response to a magnetic field, the radio frequency emission and detection system including an RF probe disposed proximate to a portion of the patient;

and a computer and display monitor for decoding and displaying the detected signals;

mounting the magnet for movement relative to the table in a direction away from the first end of the table from a first position of the table to a second position away from the table;

the first position of the magnet is arranged such that a portion of the patient is positioned in the magnetic field of the magnet while the patient remains in position on the table;

the second position of the magnet is arranged such that the magnet is spaced from the first end of the table by a distance sufficient to allow the surgical team to move around the first end of the table and each side of the table to contact the patient while the distance is sufficient to allow the surgical team to perform the surgical procedure;

wherein the magnet is dedicated to surgery within the operating room;

wherein the magnet remains in the operating room at all times;

wherein when the magnet is in the second position, the magnet is de-energized to turn off the magnetic field;

and wherein the magnet is cooled by a cooling system which remains on when the magnetic field is de-energized.

The magnets attract ferromagnetic materials and products made from these ferromagnetic materials become projectiles when in proximity to the MRI magnet, so that the movable magnet can only generate a magnetic field when required for imaging and spend its remaining time at a magnetic field of 0 tesla. The arrangement of the present invention allows the magnetic field to be switched off when the system is not being used for imaging.

Furthermore, if the magnet is to be moved, the present arrangement allows the magnet to contain no liquid helium because the use of liquid helium requires the quench tube to be attached to the magnet because a large amount of helium gas can escape from the magnet very quickly during quenching. Such a large amount of helium gas is dangerous to escape to the imaging chamber and should not be allowed to occur. The arrangement of the present invention thus avoids the use of an insulating tube attached to the magnet to deliver all of the helium gas to the exterior of the building when this occurs. Thus, the present arrangement allows the use of a system using liquid nitrogen as a coolant.

The quality of the images produced by MRI techniques depends in part on the strength of the Magnetic Resonance (MR) signals received from the precessing nuclei. For this reason, a separate RF coil is placed near the region of interest of the imaging subject, more specifically on the table top of the imaging subject, as a local coil or table top coil, in order to improve the strength of the received signals. These coils receive signals from the tissue.

The present device allows the use of a worktop coil of the type described in U.S. patent No.4,522,587. U.S. patent No.4,825,162 shows a countertop coil for MRI/NMRI imaging and methods related to MRI/NMRI imaging. In a preferred embodiment of the present invention, each of the table top coils is connected to the input terminal of an associated one of the same plurality of low input impedance preamplifiers, which minimizes interaction between any table top coil and any other table top coil that is not immediately adjacent to the table top coil. These countertop coils can have a square, circular, etc. geometry. This results in an array of a plurality of closely spaced table top coils, each positioned so as to not substantially interact with all adjacent table top coils. At each different table top coil, a different response signal is received from a relevant portion of a sample enclosed within an imaging volume defined by the array. Each different MR response signal is used to construct a different one of a plurality of different images from each of the table top coils. The images are then combined point-by-point to produce a single composite MR image of the total sample portion, which consists of MR response signals from the entire array of the table-top coils.

The arrangement of the present invention allows the use of a countertop coil as both the transmit and receive coils, thereby avoiding the use of a conventional body coil (referred to as a transmit coil) for excitation in most high-field MRI systems, which is located just within the bore as a cylindrical structure. The position of these coils inside the cylindrical gradient coil takes up space in the magnet, thus requiring a diameter of the magnet bore of about 10cm when the body coil is not present. Such larger diameter magnets require more wire to make a uniform magnet, which results in much heavier magnets and thus more severe floor loading problems.

It should be appreciated that it is contemplated that the MRI method of the present invention will be used in connection with the performance of clinical, diagnostic, interventional, and/or surgical procedures. It is therefore envisaged, and within the skill of the person skilled in the art, to adapt the MRI method of the present invention to the performance of such clinical, diagnostic, interventional and/or surgical procedures, if desired.

However, the arrangement herein is designed to be continuously maintained in its assigned room, which is typically an operating room for neurosurgery or other procedures, or may be a diagnostic room.

The MRI magnet of the present invention is made of magnesium diboride (MgB)₂) 1 or more Tesla magnets made of niobium-tin or niobium-titanium wire, the magnesium diboride (MgB)₂) The wire being a high-temperature superconducting wire (T)_c400K or<400K) In that respect Such a high superconducting temperature (T)_c40K) means that MgB can be based on by modern cryocooling devices₂The system of (a) is cooled without the need for liquid nitrogen, which is expensive, problematic and dangerous. Thus, the magnet does not need to be attached to the quench tube and is therefore more mobile than any conventional MRI magnet. The magnet may be acquired in 10 to 15 minutes to provide stability sufficient for high quality MRI imagingA uniform magnetic field. The field is stabilized using a control current that is applied to the magnet wires in response to detection of the field to cause rapid stabilization.

Thus, the magnet can be constantly diffusing near zero field when not imaging, while also being activated by applying a current to provide a magnetic field when needed for imaging. Such magnets have an internal diameter of 70 to 80 cm and weigh less than 2 tons, so that the magnets can be moved around on the hospital floor, which is a standard or conventional floor, using an air cushion or rail support system, without the need for additional reinforcement to receive the necessary loads. When using an air cushion, the magnet transport system is configured so that no particles spill out of the skirt, which is designed to prevent all particles from entering the hospital environment.

The RF coil will be a transceiver design that is structurally malleable to create the actual design required to match the body region that needs to be imaged. Thus, the RF transceiver may be formed from a flexible structure, such as a fabric containing coils or loops, without the need for any reinforcing components to hold the structure in the desired position, thereby allowing the structure to cover the imaging area. The structure is arranged to be located at or around a conventional headclamp used in neurosurgery.

This device is not the device normally required to perform whole-body imaging, but a device designed to image a specific body region with high resolution and high sensitivity. The coil, which is a receive coil, has a number of channels, the number of which depends on the body region to be imaged, and the signals from each element are summed to provide the required image. These receive channels are switched so that they are all connected for the RF transmit process to excite all the hydrogen nuclei in the tissue of interest.

The invention also discloses a method for imaging in surgery, which comprises the following steps: in an operating room, providing a surgical table for receiving a patient for performing a surgical procedure; engaging the patient's head with a head clamp to hold the head in a fixed position while the patient lies on the table; installing in a room a magnetic resonance imaging system for acquiring images of a portion of a patient over a surgical procedure over a series of times for analysis by a surgical team to allow the surgical team to monitor procedure progress, the magnetic resonance imaging system comprising: a magnet system, comprising: a cylindrical magnet of the magnet wire defining a cylindrical bore within which a portion of the patient is positioned for placement within a high magnetic field generated by the magnet; a control system for controlling and varying the magnetic field; a radio frequency transmission and detection system for initiating and detecting a nuclear magnetic resonance signal from the portion of the patient in response to the magnetic field, the radio frequency transmission and detection system including an RF probe disposed adjacent to the portion of the patient; and a computer control system and display monitor for decoding and displaying the detected signals; the patient on the table is supported for surgery; the RF probe includes a lower RF coil assembly arranged to be mounted relative to a head clamp beneath the head of the patient; the RF probe includes an upper RF coil assembly arranged to engage the head of the patient; rendering at least the coil assembly sterile for use during the surgical procedure; a sterile RF upper coil assembly is suspended over the patient's head and is made resilient so as to conform at least partially to the shape of the portions of the head to which the assembly is engaged.

Wherein the upper coil assembly is suspended in direct contact with the patient's head so as to conform to the patient's head.

Wherein, in order to provide effective sterilization for surgical procedures, at least the upper coil assembly is made disposable and includes a disposable medical connector for connection with a signal cable and a computer control system.

Wherein, in order to provide effective sterilization for use in surgical procedures, at least the upper coil assembly is inserted into a sterilization bag during use to reuse a previously used upper coil assembly.

Wherein at least the upper coil assembly comprises a coil structure formed of resilient conductor means encapsulated in a resilient plastics material which directly engages and conforms to the patient's head.

Wherein the resilient plastic material is formed of an MR compatible material as it is magnetic field tolerant and does not produce artifacts in the image.

Wherein the thickness of the resilient plastics material is less than 5.0 mm.

Wherein the resilient plastics material is resilient such that when it is applied over the patient's head, the edge of the upper coil hangs under its own weight under the head without the application of additional force.

Wherein the upper coil assembly includes a preamplifier mounted in a container on a signal cable connected to the computer control system, such that the coil structure itself is very thin and light.

Wherein the lower coil assembly includes a preamplifier mounted in a container on a signal cable connected to the computer control system, whereby the coil structure itself is very thin and light.

Wherein the upper coil assembly includes: a coil element, a preamplifier assembly connected between said coil elements, and a cable connected to said computer control system, and wherein a phase shift circuit is provided between said preamplifier and said coil element, the coil element connected to the coil element at the other end producing a phase shift equal to half a wavelength at the operating frequency of the MR system.

Wherein an electrical connector is provided between at least the upper coil assembly and a cable connected to the computer control system, thereby making the upper coil assembly lighter to improve workflow.

Wherein the elasticity and drapability of the upper coil assembly results in the coil being closer to the patient and improving SNR by up to 50%.

Wherein the flexibility and drapability of the upper coil assembly allows it to be adapted to fit the head of a wide variety of people from 6 months old infants to adult males.

Wherein the upper coil assembly uses a plurality of coil loops arranged in a row, each coil loop partially overlapping a next coil loop; wherein adjacent pairs of coil loops are decoupled by partially overlapping and configuring one shared capacitor coupling two coil loops of the pair of coil loops; and the next lower coil loop is also decoupled by using a shared capacitor connected to the next two adjacent coil loops.

Wherein the upper coil assembly comprises at least first, second and third coil loops arranged in a row; each coil loop includes a plurality of capacitors at spaced locations therearound; each coil loop partially overlapping the next coil such that the first coil loop partially overlaps the second coil loop, and the second coil loop partially overlaps the third coil loop; wherein the first and second coil loops are decoupled by their partial overlap and a first additional decoupling capacitor shared over a common portion of the first and second coil loops is configured; wherein the second and third coil loops are decoupled by their partial overlap and a second additional decoupling capacitor shared over a common portion of the second and third coil loops is configured; and the first coil loop and the third coil loop are decoupled by using a third additional capacitor in the connection conductor between the first coil loop and the third coil loop.

Wherein a second connection conductor is provided between the first coil ring and the third coil ring.

The invention further discloses an imaging method, which comprises the following steps: supporting a portion of a patient in a fixed position; installing a magnetic resonance imaging system in the room to acquire a partial image of the patient, the magnetic resonance imaging system comprising: a magnet system, comprising: a cylindrical magnet of the magnet wire defining a cylindrical bore within which a portion of the patient is positioned for placement within a high magnetic field generated by the magnet; a control system for controlling and varying the magnetic field; a radio frequency transmission and detection system for initiating and detecting a nuclear magnetic resonance signal from the portion of the patient in response to the magnetic field, the radio frequency transmission and detection system including an RF probe disposed adjacent to the portion of the patient; and a computer control system and display monitor for decoding and displaying the detected signals; the radio frequency probe comprises a radio frequency coil assembly arranged to engage the portion of the patient; wherein the coil assembly comprises at least first, second and third coil loops arranged in a row; each coil loop includes a plurality of capacitors at spaced locations therearound; each coil loop overlaps the next coil portion such that the first coil loop partially overlaps the second coil loop, which partially overlaps the third coil loop; wherein the first and second coil loops are decoupled by their partial overlap and a shared first additional decoupling capacitor arranged on a common portion of the first and second coil loops; wherein the second and third coil loops are decoupled by their partial overlap and a shared second additional decoupling capacitor arranged on a common portion of the second and third coil loops; and wherein the first coil loop and the third coil loop are decoupled by using a third additional capacitor in the connecting conductor between the first coil loop and the third coil loop.

Wherein a fourth coil loop is provided, arranged in a row, wherein the third coil loop and the fourth coil loop are decoupled by their partial overlap and a shared third additional decoupling capacitor arranged on a common part of said third and fourth coil loops, wherein the second coil loop and the fourth coil loop are decoupled by using a fifth additional capacitor in the connection conductor between the second coil loop and the fourth coil loop.

Wherein the coil assembly includes a preamplifier mounted in a container on a signal cable connected to the computer control system, whereby the coil assembly itself is very thin and light.

Wherein the coil assembly includes: a coil element, a preamplifier assembly connected between said coil elements, and a cable connected to said computer control system, and wherein a phase shift circuit is provided between said preamplifier and said coil element, which is connected to the coil element on the other end, such that the phase shift produced is equal to half a wavelength at the operating frequency of the MR system.

Wherein an electrical connector is provided between at least the upper coil assembly and a cable connected to the computer control system, making the upper coil assembly lighter to improve workflow.

To perform imaging during normal neurosurgical procedures, the magnet is placed on the patient as previously described.

For deep brain stimulation and other manipulations of the brain by neurosurgeons, the power of the magnet is reduced to zero field and the system is then moved so that the magnet is positioned over the patient's chest and stomach. This exposes the patient's head to the end of the magnet remote from the table. The surgeon begins the surgical procedure, which requires the use of ferromagnetic materials that would be attracted to the magnet if subjected to a non-zero magnetic field. Typically, this is used to form a burr hole in the skull using a burr tool. Thus, the surgeon can perform conventional surgery using conventional tools without the risk of attracting the magnet.

After completing a portion of the procedure, the magnet will be turned on and the surgeon can continue to perform the procedure, but only using the MRI safety device. To accomplish these tasks, appropriate support is required to introduce one or two insertion cannulas or electrodes through a burr hole made in the skull of the patient in the first part of the procedure. These trajectories are based on stereotactic imaging. When the magnet is in the magnetic field, relative motion of the patient and the magnet is provided such that the patient's head is received into the uniform field of view of the magnet. This can be achieved by the magnet moving on its moving system in the longitudinal direction of the table. In an alternative embodiment, the telescoping assembly of the patient bed is moved to place the head of the patient in the imaging field of view. Images are acquired and fused with preoperative images, which may contain anatomical, functional, and ophthalmic imaging information. These images are used to verify that the trajectory of the electrode or other probe is correct. These images can also be used to verify that the target has not moved due to the brain movement after the skull has been opened. If the inserted cannula or electrode is not aligned with the target, a new trajectory must be calculated to bring the implanted electrode to the true target. Upon completion of this procedure, the surgeon would implant the electrode into the patient's brain and verify that the implanted electrode is located at the target. The inserted cannula and electrodes can be advanced into the brain using a robot with or without image guidance. The description has been directed to the introduction of stereotactic electroencephalogram electrodes, but another embodiment of the present invention would be laser ablation to control tumors or other lesions.

The magnets mounted on the mover are preferably capable of rotating 180 ° about a vertical axis while inside the storage module so that the patient end of the magnets is always pointing at the OR table in the room being served. Preferably, the axis is stationary during movement and is located at or near the centre of the magnet. It will be appreciated that the magnet is only required to rotate so that the axis may not be fixed and may move as rotation occurs. The axis may be located at one end of the magnet or elsewhere.

Three key elements of the magnet's ability to rotate 180 ° are:

-a-ultra-precise mover control: the left and right tracks are driven by servomotors which engage in opposite directions during rotation, preferably inside the storage module, but in some cases at different operating positions elsewhere between the two modules, to provide precise rotation of the magnets. A laser guidance sensor is provided that can detect if there is a deviation in the precise rotation required and provide motor compensation to maintain accuracy. This allows the magnet to be rotated exactly 180 deg. about a fixed vertical axis.

B-biaxial CC design and flexible tube guidance, allowing cable racks to enter the first surgery room to the left or the second surgery room to the right, and also to park in the center. The central parking position is guided by a flexible tube hinged between two positions by a guided tack assembly having actuated pins that lock the guide in different positions. By moving the mover into the desired selected room, the flexible tube will naturally move in this direction until it stops at the end of the curved track, where it is locked by the controlled actuator pin. The curved profile is determined by a fixed arc profile. When the magnet returns to the storage module in the opposite direction, the flexible tube must be locked to maintain its bent position. Just before the magnet has fully entered the interior of the storage module, the actuator locking pin is released, thereby straightening the flexible tube and matching the second position.

-c-rotational support actuator control: the rotary bearing mounted to the magnet has two parts, the lower part of which is firmly mounted to the magnet and the upper part of which is firmly mounted to the cable tray. The two parts of the rotary bearing are either locked together at 0 ° or 180 ° or are free to rotate by the rotary bearing actuator. To allow rotation, the upper portion remains locked or engaged to the storage module by the actuator while the rotary support actuator is disengaged to allow rotation of the magnet. To allow the magnet to travel, the module actuator is disengaged while the rotary support actuator is engaged.

The MRI system memory module accesses two adjacent rooms. It moves between rooms on a servo motor controlled tracked mover. Doors on either side of the storage module allow access to one or the other room. An interlock is provided so that only one door can be opened at any one time.

As mentioned above, instead of shielding the entire room, a partial shielding is used. This may be in the form of a table-mounted shield, where the local RF shield is a separate component from the table and stored in the memory module until needed. In the storage module, the protective cover is positioned on the wheel-type cart, is stored in the storage module and is positioned behind the roller shutter door on the front side of the storage module. This wheeled cart can also be used as an alignment/skull clamp positioning tool in preparation for a patient to perform a surgery. The positioning tool mates with the magnet bore and allows the staff to position the patient preoperatively to ensure that he/she fits within the MR before reaching it. This will identify any patient as free from interference and save time when the magnet arrives. This is part of the patient preparation.

The bottom of the cart has a flip that folds downward to engage the front of the table base and ensure that the cart is aligned with the magnet travel. The table must be bolted to the floor by two set screws behind the table. This arrangement is therefore used to move the positioning magnet into position relative to the table, guided by the movement of the magnet, thereby ensuring that the magnet does not move erroneously towards the table, resulting in a potential collision or an incorrect final position. The cart carries an alignment ring or a positioning rod which is movable on the cart relative to the table.

The operating room staff picks up the tether and then scans the volume representing the magnet hole location (when the hole is in place on the table). Any patient/cranial clamp contact must reposition the cranial clamp to clear the strip. If the patient clears the rod while rotating, simulating the internal bore of the magnet, it will clear the MR bore.

According to another feature of the invention herein, an RF coil design for an intraoperative MRI apparatus is provided.

The transmitting coil may be provided as a conventional body coil inside a magnet at ISO centre, with a flare on the patient side of the magnet. It will produce a quadrature uniform transmit RF B1 field. This design can greatly reduce the weight of the receiving coil and improve the work flow. However, the coils described below may have both transmit and receive functions.

For head imaging, the receive coil includes an upper and lower coil design: the lower coil is of a thin flexible design that can be inserted between the patient's head and a Head Fixation Device (HFD). The upper coil is an ultra-thin flexible coil, which can improve the SNR by about 50%. The use of flexible conductors captured in a thin flexible encapsulation material allows the structure to be fully flexible to cover the patient's face while contacting substantially all parts of the patient's skin, including the forehead, cheeks and chin.

The upper and lower coils can be integrated with B0 shimming coils, thereby further improving the coil performance

To provide effective sterilization of the coil for use in a surgical environment, both the upper and lower coils can be made disposable with a disposable medical connector. Alternatively, the coil may be of the reusable type, but inserted into a sterile bag during use.

The coil design uses a plurality of (e.g., four) coil elements arranged in rows, each coil element partially overlapping the next coil element. The adjacent coil elements 1 and 2, 2 and 3, 3 and 4 are decoupled by using a known overlap method obtained by partially overlapping and providing a shared capacitor coupling the two coil elements. In addition, the adjacent coil elements 1 and 3, 2 and 4 are also decoupled by using a shared capacitor connecting the two adjacent coil elements. The last coil provides decoupling between adjacent coil elements only by using a shared capacitor between them. There is no decoupling between the next adjacent coil elements.

The required pre-amplifier can be placed in a small box in the system cable that couples the coil structure to the system. This allows the coil structure itself to be very thin and lighter.

The differences in current coil construction relative to previous designs of flexible coils are as follows:

a-the coil design provides effective decoupling between coil elements by overlap, direct proximity decoupling, and next proximity decoupling;

b-providing cable connections, making the coil structure lighter, thereby improving the workflow;

the-c-preamplifiers may be internal or external to the coil structure, making the coil very thin and thus overhung

-d-coils can be sterilized by disposal using a sterile bag;

the high flexibility and drapability of the e-coil structure brings the coil closer to the patient and improves the SNR by up to 50%.

The coil construction should have the following features:

the placement and positioning of the cranial skull on the head fixation device should not be inhibited or limited;

it should not limit the use of the navigation system;

it will produce a uniform RF field with high sensitivity in the desired imaging volume;

must not interfere with or occupy the same space as the designated operating area;

it should generate orthogonal and uniform transmitted radio frequency fields, avoiding interference with the electronics of the surgical robot;

it should control the pattern of Specific Absorption Rate (SAR) deposition on the human head.

It should be possible to adjust it to various human heads from 6 months old babies to 95% of adult males according to drapability

Again, due to its high drape, should be easy to integrate with the head fixation device;

-easily sterilized by disposal or in a soft bag or in a size required so as not to disturb the sterile field;

to obtain a higher SNR, the RF coil must again use high drapability, as close as possible to the patient

The upper and lower coil sizes are 31cm × 22 cm. The total number of coil elements is 8. This dimension is optimized for the penetration depth received from the patient's head.

Traditionally, the upper coil is located on a surgical drape that wraps around the head of the patient. While these methods are effective, they also have some drawbacks, namely that the upper RF coil is far from the patient, which can result in an image SNR loss of about 40% to 50%. Coil cables are too long, heavy, and difficult to carry and handle.

According to other aspects of the invention, which may be used independently of other features described or defined herein, there are provided:

the arrangements described herein may provide one or more of the following advantages:

high resolution and recent image quality.

Cryogen free 1.0T superconducting MRI.

Helium gas is not needed, and a quenching line is not needed.

All the content contained in one module can be placed in most ORs:

without a dedicated control room

There is no dedicated equipment room.

Fast installation time-typically less than 3 weeks.

Local RF shielding-no RF shielded room is required.

When the door is closed, the module has a clean and tidy professional appearance and a 30dB signature sound attenuation.

Including portable MR compatible with OR tables suitable for local RF Shield.

All system components, including the local RF shield, may be stored inside the memory module to reduce OR clutter.

The magnets may be placed on a track that distributes the load over a 0.5 square meter area of ground, thereby minimizing ground loading.

Drawings

An embodiment of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is an isometric view of an operating room including a surgical table and an MRI imaging system showing a magnet in a retracted position at one wall in the room in accordance with the present invention.

Fig. 2 is a similar isometric view of the same operating room with the magnet in the imaging position.

Fig. 3 is a longitudinal cross-sectional view of the surgical table and magnet in the position of fig. 2.

Fig. 4 is a transverse cross-sectional view of the surgical table and magnet in the position of fig. 2.

Fig. 5 is a cross-sectional view similar to fig. 3, on an enlarged scale, showing the head clamp and the RF transceiver.

Fig. 6 is an isometric view of an operating room including a second embodiment of a magnet for an MRI imaging system magnet according to the present invention, showing the magnet being moved into the room from a storage module.

Fig. 7, 8, 9 and 10 are cross-sectional views showing the magnet of fig. 6 in different positions relative to a surgical table, such that an imaging system using the magnet and table can be used in a functional imaging method in which a surgeon can perform surgery using ferromagnetic and non-ferromagnetic tools.

Fig. 11 is an isometric view showing the transport and alignment work cart used with the table of fig. 7 before the magnet is moved up the table.

Fig. 12 is an isometric view of the cart of fig. 11 in a transport position.

Fig. 13 is a front view of the magnet of fig. 6 movable between two operating rooms with a storage and manipulation module therebetween.

Fig. 14 is a plan view of the RF coil of fig. 5 showing a series of coil loops connected to a communication cable for connection to a computer control system.

Fig. 15 is a cross-sectional view of the RF coil of fig. 5, showing the RF coil in cross-section.

Fig. 16, 17 and 18 show a cable carrying system for use with the magnet of fig. 6 in the room of fig. 13.

In the drawings, like reference numerals designate corresponding parts throughout the different views.

Detailed Description

The apparatus for surgery in the embodiment of the figures comprises an operating room 10, the operating room 10 having a floor 11 and walls 12 and containing a surgical table 13 for receiving a patient for surgery. The table includes a table top 14 on which the patient lies and an upright support 15 which is generally adjustable to move the patient to a desired position. Suitable table configurations are well known in the art.

The surgical table cooperates with a magnetic resonance imaging system 16 for acquiring a portion of a patient's image in multiple passes throughout the surgical procedure. After completing part of the surgery, these images are taken for the surgical team to assess the progress through the analysis so that the surgical team can monitor the progress of the surgery.

The magnetic resonance imaging system 16 includes a magnet system 17, the magnet system 17 including a cylindrical magnet 18 of magnetic wire defining a cylindrical bore 19, a portion of the patient being located within the cylindrical bore 19 for placement within the high magnetic field generated by the magnet. The control system 21A is arranged in a suitable container 21 at one side of the room. The control system operates the MRI system and includes a computer and display monitor for decoding and displaying the detected signals using computer-operated programs, for decoding the various signals to produce images, and for operating the RF system, the field of the magnet, and other conventional components in such systems.

In fig. 5, there is shown a radio frequency emission and detection system 22 for exciting and detecting nuclear magnetic resonance signals in a portion of a patient in response to a magnetic field, the radio frequency emission and detection system including an RF probe disposed adjacent to a portion of the patient;

the magnet is mounted on a support system 23, which support system 23 mounts the magnet for movement relative to the table in a direction away from a first end 24 of the table, from a first position shown in fig. 2 on the table or on a portion of the table to a second position shown in fig. 1 away from the table. The second portion is located at a wall 12 so that the second portion is remote from the table so that the surgeon is not obstructed by the magnet during the procedure.

Thus, the first position of the magnet is arranged such that the patient's head is placed in the magnetic field of the magnet while the patient remains in place on the table. Thus, the second position of the magnet is arranged such that the magnet is spaced from the first end of the table by a distance sufficient to allow the surgical team to move around the first end of the table and each side of the table to contact the patient, while the distance is sufficient to allow the surgical team to perform the surgical procedure.

As described above, the magnet 17 is designed and arranged in a simple structure having a relatively light weight and a relatively small size so that the magnet can be introduced into an existing operating room and moved between two parts in the room. Thus, the magnet is dedicated to surgery in the operating room and remains in the room.

Thus, the magnet has a small diameter hole of about 60 to 70 centimeters, so that the magnet has a minimum overall diameter, thereby reducing the length of wound wire required. Thus, the magnet weighs about 1 to 2 tons, has a width of about 4 to 5 feet, and has a length of about 5 to 7 feet, which defines a footprint in the range of 15 to 35 square feet, typically about 20 square feet.

This small size is facilitated by selecting superconducting materials of suitable materials, such as magnesium diboride, niobium tin, niobium titanium, which are superconducting at absolute temperatures of about 40 degrees (kelvin) or less, so that the magnesium diboride can be cooled to superconductivity without the use of liquid nitrogen through a cooling system.

I.e. the magnet 17 of the material is cooled by a vacuum cryogenic cooling system 25, which vacuum cryogenic cooling system 25 has a vacuum pump 26 driven electrically, wherein the pump itself is cooled by a flow of cooling water. Arrangements of this type are previously known to the person skilled in the art and therefore do not require further explanation.

This weight and size of the magnets allows the magnets to be carried on an air cushion support system 23, or a rail system as described below, which air cushion support system 23 is supported by the floor of a conventional operating room, applying the appropriate load to the structure of the building without the need for additional structural reinforcement or support components. Thus, the use of the air cushions n allows 2000 to 4000 pounds of load to be spread over a 20 to 35 square foot footprint to distribute the load without overloading existing floor structures.

The support system thus comprises an air cushion formed in a chamber 27, the chamber 27 covering the bottom area of the magnet, and the air cushion being generated by a fan 28 located within the magnet housing. The chamber has side skirts 29 to contain the air cushion within the chamber and distribute the weight over the entire bottom area.

The fan is associated with a suitable high efficiency filtration system 29 so that the fan expels particles and no particles enter the chamber 27 so that no contaminants are expelled from the side skirt.

Further, the support system is guided on the rail from a first position to a second position, wherein the wheels are guided along the track to ensure that the magnets move properly between the two positions.

A control processor 31 is provided on the magnet 17, the control processor 31 operating in response to input control from the control system 21A such that the magnet is arranged to de-energise to switch off the magnetic field when the magnet is in the second position. In this way, the magnetic field is turned off during the surgical procedure to avoid interfering with the surgeon's activities, and is turned on only during imaging. In addition, the lift system fan 28 is also turned off if not needed. At the same time, the magnets are arranged so that the cooling control pump 26 is kept energized by the power supply 32 and the cooling water 33 from the wall connection 34 when the magnetic field is de-energized. The water and power source are arranged such that the supply cable is slack enough to allow movement between the first and second positions.

As shown in FIG. 5, the RF probe 22 includes a local transceiver RF coil 36 to avoid the use of a cylindrical coil at the bore. These are of the type and construction described above to avoid the use of body coils in the bore. They are arranged to surround the head clamp 37.

To avoid having to shield the entire room, a shielding structure 38 is provided for excluding the RF field from the RF probe, which includes an arched support frame 39 for extending over the patient while supporting a shielding fabric or screen 40, the shielding fabric 40 extending from the exterior of the patient's feet at one end of the table top 14 to the body part 41 of the access opening. Thus, the fabric forms an arched upper portion 42 over the patient, while also forming a semi-circular end 43, the semi-circular end 43 closing the end of the gantry.

The shielding structure 22 also includes a metal plate 45, the metal plate 45 being part of the table top 14, located beneath the patient and extending across the table to the side of the shielding fabric or screen 40.

The shield structure 22 includes a cylindrical shield layer 46 positioned within the aperture; and a hinged door 47 at the end of the hole opposite the table and containing a shield 48.

All of the components of the shielding structure 22 are connected together to form an integral shield to completely surround the patient and the RF probe.

Thus, the magnets are free of cryogen and superconductivity (less than 40K, nominally 39K) is achieved only by a vacuum pump located above the magnets that can produce a 'Cjooka-Cjooka' sound pattern and requires water cooling. It is a design that is filled with a cryogen (liquid helium). The technical needA cryocooler and a helium compressor requiring water cooling. Advances in vacuum pump technology (aka cryocooler) achieved a partial vacuum at 39K that allowed (using MgB)₂Wire) superconducting occurs. Liquid helium is not involved because there is no quench tube to handle the liquid: the gas phase changes.

The system and PDU cabinets are combined into a single cabinet. The listed cabinets all have a nominal depth of 970mm/37 ". This is not really a problem when considering new buildings using dedicated machine rooms, but when considering retrofitting existing hospitals, space is a problem and we have to put these cabinets in unconventional locations (e.g. corridors, observation rooms, closets, etc.). The cabinet is only 660mm/26 "deep, with all wiring from the top and nothing coming out of the back. This is so that all cables come out from the top. Since hospital space is usually at a premium, all equipment to run the MRI system is located in a separate memory module, which is approximately 2m x 4m x 3.2m in size. The magnetic mover cables, equipment and accessories are all located within the module as described later.

Within the heat exchanger cabinet is a closed loop system with a water-to-water heat exchanger and an independent circulation pump. There is a closed loop water cooling system with an internal heat exchanger.

The cabinet is provided with a city water bypass inside (for draining), but the city water bypass can be arranged outside the cabinet if space is at a premium. To minimize the cost of external cooler installation, the system uses direct hospital chilled water. City water bypass is not lost as a risk mitigation option if the chiller is shut down or in service. City water can run a helium compressor (vacuum pump). City water, however, cannot be an alternative to cooling the gradient coils and gradient amplifiers, because both gradient coils and gradient amplifiers have stringent requirements for cooling water (e.g., deionized water). Another option is to use an internal charge cooler directly with hospital chilled water.

Vacuum pumps are also known as cryocoolers, and industry standards use the term cryocooler, which is simply a fancy vacuum pump. (pure vacuum is 0K; outer space is almost vacuum-3K).

The water-water heat exchanger has 2 isolated chambers with solid transfer plates between them for heat transfer. The MR side of the closed loop system will always have deionized water. There will be cold water or city water on the cold water device side. There is never contamination between the two.

The cabinet needs water cooling, and is quieter through the water cooling mode. Noise is always a problem. The cabinet is located in a machine room separate from the operating room. We generally do not complain of cabinet noise. With a cryogen-free magnet, we would not need a helium compressor. The system may compress the heat exchanger and place the heat exchanger in a small cabinet below the gradient amplifier cabinet. The cryogen-free magnet still requires a helium compressor.

There is no conventional penetration plate. Most cables run directly from the cabinet to the magnet and are contained primarily in the cabinet or module. There is a conventional local RF shield around the patient and inside the MR bore. The OR (operating room) patient table has a waveguide and small penetration plate that associates the RF filter with the Tx/Rx coil. It is inserted directly into this small perforated plate. It requires the use of compact (DB9 size) RF filters and connectors or fiber optic cables through the waveguide. The system has an all-digital receiver design and fiber optic cable and is therefore not bulky even when used in a 16ch system. The Tx cable is copper.

Conventional superconducting MR systems use a fixed cable tray between the (fixed) MR and the equipment cabinet. The system uses a moving cable tray/carriage or Boom solution to follow the magnets. This system requires a nominal separation of 12 "/300 mm between the gradient cable and the RF cable. This is reduced by adding additional shielding around the gradient or RF cable. Still other fiber optic cables are not affected by the magnetic field generated by the high power copper gradient/radio frequency cable. This system requires a large space between the gradient cable and the RF cable. The system uses fiber optic cables, and we have extra shielding around the gradient cables. The user can turn on and off the refrigerant-free superconducting electromagnet, requiring a field settling time of about 15 minutes. In addition to the gradient cable, there should be a magnet charging cable to charge/discharge the magnet. The magnet charging cable is fixed to the magnet so as to be frequently opened and closed. In an effort to minimize cabling, the gradient and charging cables are the same cable, which contains a programmable double pole single throw switch depending on the operating current of the magnet and the peak current required for the gradient.

Conventional superconducting MR systems have a cable set (e.g. siemens: less than 4 m/greater than 16m) selected according to the location of the penetration plate. Superconducting MR systems also consist of selected cables due to cost and performance. The system herein uses movable magnets and requires the most flexible available cable.

In this embodiment, the system uses a non-ferrous metal air tray that slides around the OR. The load bearing is not a problem. The thrust force was 10 pounds of force at 5,000 pounds. We expect the nominal value of the MR floor support to be 2,000 pounds. A nominal 32SCFM @30PSI is required. There are many manufacturers, such as Hoverair. For safety reasons, two people are required to move/manipulate the MR. Depending on the cable management system chosen, these moments must be overcome since the cable stiffness problem must be overcome, and additional moments are generated.

Dust is reduced by adjusting the tray to include a skirt around the perimeter that traps and directs the exhaust through the HEPA filter. This will reduce OR contamination of dust blown from the floor. The air supply is provided by a small rotary screw compressor located above the control cabinet, which will supply air. A large volume of air is required but minimizing noise must be a priority. The system uses an accumulator (large storage tank) to provide the reserve. Wheel back-up is provided in the event of an air supply failure. The magnets are bolted to this tray.

A magnet/surgical table interface key is provided that includes a physical "key" that mates/aligns the magnets/surgical tables to each other because the magnets slide on the floor with little resistance so that the magnets do not hit the surgical table.

Alternatively, the magnet may have a motorized wheel mechanism associated with the bottom frame. The MR is typically resting on the back wall. When desired, the user activates a pendant and moves the MR forward to engage the surgical table. The stroke will be controlled by a limit switch on the cable tray. The alignment may be according to the guidance of the strap on the floor or the strap embedded in the floor. The system includes a table-magnet engagement key to ensure proper table alignment. This eliminates the need for air supply (expensive screw compressor, storage tank, noise factor). The nurse does not have to guide it into position. It can be driven by itself without reducing dust.

The system has a modular concept, where the magnet and the cable tray must be located in the OR. The equipment rack module is placed at the OR at a remote location. It is desirable to place this individual module in an OR that requires a footprint of 4m x 2m OR in some cases 3.6m x 1.5.5 m and a height of 3m, as shown below. The module will be as quiet as possible after the roller shutter door is closed. The overall control of the system is achieved through an HMI (human machine interface) located on the front face of the module. The standard output is connected to the DICOM/PACS system of the hospital via the Internet OR directly to the OR room monitor. The standard inputs for the module are:

-electric power

Hospital chilled water (supply and return)

City water (water supply and drainage)

Hospital air (secondary)

There are currently two options as to how to manage the cables between the cabinet and the magnets:

a boom and a rolling cable tray. Note that cable management can add torque to the magnet transmission solution that must be overcome/managed. Furthermore, if desired, we must provide any additional shielding to adequately compensate for the required cable separation distance.

Cable tray: it is mounted near the magnet and inside the module and follows the magnet as it travels. All are hidden within the module when parked. A limit switch on the cable holder determines the position of the magnet. The width of the cable tray was 400mm/16 ".

The arcuate local RF antenna system and RF table base flange (RF transparent panel) are in contact with the RF gasket. There is an alignment key to ensure that the magnet is aligned with the surgical table. The RF gasket may also serve as an anti-collision sensor that will prevent the magnet from traveling if a collision occurs with the patient table/skull clamp.

An MR compatible OR table is provided that is capable of accepting MR compatible Mayfield type cranial clamps having standard OR table features and suitable for local RF shielding (see section above). The OR table is a non-ferrous metal that is located under a moveable arched house, which is secured to an RF table bottom flange that is electrically isolated from the rest of the table. The rear of the table includes two large waveguides to contact the patient through the shield. All things to the left (i.e., the rear portion) of the local RF antenna system (which mates with the magnet) are non-ferrous plastic. The OR workbench must also serve non-neurological cases. The patient can lie on the table tail or table head first. An extension is provided which allows the magnet to enter all parts of the human body.

A spinal plate is provided which is a fiberglass rigid plate that is placed on a countertop allowing for non-neurological procedures. This allows the load to be distributed across the entire table. The smaller spinal extension may be inserted into a hole in the cranial clamp. The additional support may comprise a side slide or a kick down support floor lever. All weight falls on the rear axle.

The table may have a sliding MR table top, more typically in line with that of a typical diagnostic table. Because the system includes a custom RF aperture liner, it may include a slide rail on which the table slides. During OR surgery, the table top does not move because the patient's tow hook has to move, which is too dangerous. The surgical table is moved and the hook is pulled into place before the surgery begins. There are lift, roll and trendelenberg functions in the base portion of the surgical table that are electrically isolated from the fiberglass sliding top portion.

Part of the neural solution is to have an MR compatible skull clamp. Radioactive Mayfield type skull clips are available off-the-shelf. The radio-localized Mayfield skull clamp is considered to be MR-incompatible because the carbon fiber structure generates eddy currents in high-field MR systems (> 1.5T). However, since the present system uses a magnet of about 1 Tesla, a carbon-radiolucent cranial clamp outside the shield may be used. This skull clamp is part of the RF Tx/Rx head coil and must be mounted around the RF Tx/Rx head coil.

Fig. 6-10 illustrate a modified embodiment using a track mover. This includes a support system 50 supported from a floor 51, the support system 50 mounting magnets for movement relative to the table.

The support system comprises first and second endless drive tracks 52, 53, each endless drive track 52, 53 being along or adjacent a respective side of the magnet and carried on a chassis 54 of the magnet. Each of which is wound around an end guide member 55, 56 and each of which has a lower rail 57 which engages the floor.

Each drive track is driven by a servo motor 59, the servo motor 59 being driven by a gear box 58a sprocket 60 engaged with the track. The servo motor avoids the use of hydraulic systems and ensures very precise control of the movement of the track. The servo motors are controlled by a drive system (not shown) to provide precise forward and backward movement when the drive rails are driven simultaneously. This will provide a turning motion to change the direction of motion or rotate about a vertical axis when the tracks are driven differently. The drive system uses sensors 61 and 62 located on the landing gear to detect light beams or lines or markings, such as laser beams generated by light sources 63 and 64 on the table of the floor 51, to guide the track to carry the magnets to the desired location. When moving towards the table, it is important that the magnets move exactly in a straight line along the table to avoid collisions with the table or the patient. Thus, the sensors on both sides of the magnet and back and forth ensure directional movement in the desired direction and immediately detect any deviation or distortion from the desired path. To provide accurate guidance, there are at least two laterally spaced guide lines on the floor or at the level of the table, which are detected by sensors in front of and behind the magnets.

In the storage module, rotation of the magnets about the fixed central vertical axis is achieved by driving the drive rails in precisely opposite directions, as described below.

In one embodiment shown in fig. 6, there is a single magnet mounted in a single room 66, which is retracted to the storage module 67 when not needed. The storage module has a front open face that can be closed by a tambour door 68 when the magnets are stored.

Turning now to the arrangement in fig. 13 and 16 to 18, two adjacent operating rooms 70 and 71 are provided, each having a floor and walls, containing an operating table (not shown) for receiving a patient for surgery. Between the rooms is a storage module 72, the storage module 72 having a rollup door 68 at each end for storing magnets. The modules 72 are located between rooms and the magnets can be moved on their drive rails or other transport systems into the storage modules 72 and from the storage modules to a work station that is moved to each room.

To serve both rooms, the magnet may be rotated on a drive track in the storage module as shown at 73 about a vertical axis 74 so that a front end 75 of the magnet may be moved into the room at the front end for use with the table.

As shown in fig. 16 to 18, a cable guide system 76 is provided, and the cable guide system 76 carries the power cable, the cooling water cable, and the signal cable together from the storage module 72 to the magnet. The cable guide system includes a rolling support 77 that can be moved to an extended position shown in fig. 16 and 18 into a selected room and can be rolled or folded into a socket 79 that can be received into a socket 78 defined by two parallel walls 79 and 80. Thus, when the magnets are moved to carry the cables in this horizontal position, the cable supports are generally maintained in a horizontal position extending from the top of the module 72 to the top of the magnets. When the magnet is retracted into the module, the folding or rolling action allows the cable support to retract into the socket. Below the outer end of the cable support at the magnet is a swivel ring arrangement, by means of which the rotation of the magnet in the storage module is accommodated. This combination of an expandable cable support and a rotating ring allows for feeding cables from the storage module to the magnets in each room and allows the magnets to rotate in this manner between the two rooms. The rotation of the magnets is driven by a track moving in the opposite direction, the rotation ring facilitating the movement exactly around a fixed vertical axis below the container in the module.

The left and right tracks are therefore driven by servomotors which engage in opposite directions during rotation, so that the magnets are caused to rotate precisely, preferably while inside the storage module, but in some cases at other positions between different operating positions. A laser guidance sensor is provided that can detect if there is a deviation in the precise rotation required and provide motor compensation to maintain accuracy. This allows the magnet to be rotated exactly 180 deg. about a fixed vertical axis.

The cable transport system is defined by a biaxial CC design and a flexible tube guide that allows the cable carrier to enter the first surgical room to the left or the second surgical room to the right and may also be parked in the center. The central parking position is guided by a flexible tube hinged between two positions by a guided tack assembly having actuated pins that lock the guide in different positions. By bringing the mover into the desired selected room, the flexible tube will naturally move in this direction until it stops at the end of the curved track, where it is locked by the controlled actuator pin. The curved profile of the cable guide as it rolls in the container is determined by the fixed arcuate profile 82. The rollable cable guide must lock onto the profile 82 so that it maintains its bent position when the magnet is moved back to the storage module in the opposite direction, as the magnet movement pushes the cable carrier and forces it back into the receptacle. Before the magnet is fully inside the storage module, the actuator locking pin is released, thereby straightening the cable guide and matching the second position.

The rotating ring, which is mounted between the magnet and the cable guiding magnet, has two parts, the bottom of which is firmly mounted on the magnet and the top of which is firmly mounted on the cable tray. The two portions of the rotating ring are locked together at 0 ° or 180 ° or are free to rotate by the rotating ring actuator. To allow rotation, the top portion remains locked or engaged to the storage module by the actuator while the rotary ring actuator is disengaged to allow rotation of the magnet. To allow the magnet to travel, the module actuator disengages when the rotary ring actuator is engaged.

The MRI system memory module thus accesses two adjacent rooms. It moves between two rooms on a servo motor controlled tracked vehicle. Doors 67 on either side of the storage module allow access to one or the other room. An interlock is provided so that only one door can be opened at any one time.

Figures 11 and 12 show alignment means for properly positioning the patient on the table relative to the position of the cylindrical bore when the magnet is moved to its desired position on the table. Thus, a positioning device is provided for simulating the position of the bore of the magnet when moving onto the table. This position is shown in the storage position (fig. 12) and the working position (fig. 11) prior to use.

The positioning means comprises a movable trolley 90 mounted on rear ground engaging wheels 91 and steerable front ground engaging wheels 92 so as to be movable into position on the magnets. The positioning system 93 comprises cooperating parts 93A on the trolley and cooperating parts 93B on the table, which position the trolley in a predetermined position fixed on the table. The cart includes a foldable extension 94, as shown in fig. 12, the foldable extension 94 being retractable to a storage condition. Thus, the bottom 15 of the table 13 is fixed to the floor by the fixing member 15A, and the cart is fixed to the table by the coupling 93, the cart remaining fixed in position relative to the floor so as to determine the position at which the magnet 16 is lifted onto the table.

The movable cart 90 provides a support base for housing the aforementioned shield assembly 38. Thus, the shielding structure may be moved for storage on the cart when not in use and not attached to the table. The shield structure carries an end guide ring which, in use, is arranged to abut against the front face of the magnet when the magnet is lifted to the imaging position. Thus, the ring 381 defines a first guide ring for simulating the position of the front end of the bore of the magnet when the shielding structure is attached to the table as shown in fig. 11, when the magnet is in the first imaging position.

The cart has a second guide ring 95, the second guide ring 95 being carried on a rail 96 standing on the bottom of the cart. The trolley is therefore fixed relative to the table and therefore relative to the ring 381 fixed to the table. The ring 95 is fixed relative to the cart and thus relative to the table. The ring 95 is positioned relative to the cart, and thus relative to the table, so as to simulate the position of the rear end of the magnet bore when the magnet is in the first imaging position. Thus, the two rings are coaxially supported at opposite positions. When the magnet is placed in its imaging position, it is possible to simulate the front and back of the magnet bore.

An elongated post member 97 having a post aperture 98 and an inner edge 99 is provided, the length of which spans the first and second guide rings. Each end has a shoulder 100, 101 that seats on the outer edge of the respective guide disc. The inner edge 99 of the rod is arranged such that rotation of the elongated rod member 97 about the first and second rings forms an imaginary cylindrical surface that exactly matches the actual cylindrical surface of the bore when the magnet is in the first imaging position. Thus, the inner edge of each ring matches the hole at its ends, and the inner edge 99 follows the inner edge of the ring, such that the inner edge lies in an imaginary cylinder, matching the hole at each location around the ring. With the patient and associated components (e.g., headpiece and imaging coil) in place on the table prior to placing the magnet in place, it should be understood that any impact of the rod member on the patient or any part of the patient support would be predictive of an unacceptable impact to the magnet when it is eventually brought into the imaging position. The rod thus acts as an a priori detection system to ensure that the patient has been correctly positioned, and repositioned if necessary, before the actual movement of the magnet.

As mentioned above, instead of shielding the entire room, a partial shielding is used. This may be in the form of a table-mounted shield, where the local RF shield is a separate component from the table and stored in the memory module until needed. In the storage module, the shield is located on the wheel cart and stored inside the storage module behind the roller door in front of the storage module. This wheeled cart may also be used as an alignment/skull clamp positioning tool in preparation for a patient to perform a surgery. The positioning tool mates with the magnet bore and allows the staff to position the patient before surgery to ensure that he/she can mate with the MR before reaching it. This will ensure that no patient is disturbed and save time when the magnet arrives. This is part of the patient preparation.

The cart 90 has a fold down tab 94 at its base, which tab 94 engages the front of the table base and ensures that the cart is aligned with the magnet travel. The table must be secured to the floor by two set screws 15A at the rear of the table. This arrangement is therefore used to position the magnet to move into its position relative to the table under the guidance of the magnet movement, thereby ensuring that the magnet does not move erroneously towards the table, resulting in a potential collision or incorrect final position. The cart carries an alignment ring or locator rod that is movable on the cart relative to the table.

The operating room staff picks up the bolted rod and then scans the volume representing the magnet bore location (when the bore is in place on the table). Any patient/cranial clamp contact must reposition the cranial clamp to clear the guide plate. If the patient clears the rod when rotated, simulating the internal bore of the magnet, it will clear the MR bore.

The system can be used to image many parts of a patient's body, but is primarily designed for imaging the head, and when arranged to image, the system includes a conventional head clamp 37 having side pins 371, the side pins 371 being used to clamp the patient's head between the pins. The pins are supported on brackets 372, and the brackets 372 are attached to supports 373 mounted on the extension 141 of the table 14.

The coil structure 36 is best shown in fig. 14 and 15 and includes a lower RF coil assembly 361, the lower RF coil assembly 361 being mounted on or within the headclamp 37 under the patient's head. The lower coil 361 may be rigid or elastic, and is preferably elastic, to occupy a desired position below the head but on top of the support 371. If it is elastic, it can be moved to lie closely adjacent the lower part of the head. The coil construction may be of the same type and arrangement as the coil construction of the top coil assembly 362 described below.

Thus, the RF probe includes an upper RF coil assembly 362, the upper RF coil assembly 362 being arranged to engage the head of the patient, as shown in fig. 15. Also in view of the fact that the coil remains in place during the surgical procedure, at least the RF upper coil assembly is in a sterile state so that it can be used for surgery;

a sterile RF upper coil assembly 362 is covered over the patient's head with the elasticity of the upper coil assembly so that it at least partially conforms to the shape of the portion of the head to which the assembly is engaged. That is, the upper coil assembly is snapped into direct contact with the patient's head and is sufficiently resilient to conform without applying a force that holds it in place. The upper coil structure includes a resilient conductor arrangement 363 encapsulated in a resilient plastic material 364 which is directly engaged with and conforms to the patient's head. Thus, the upper and lower surfaces of the coil are each formed from a plastics material in which the conductors are contained. The material may be cast in place around the formed conductor assembly or may be formed as two cover layers containing the conductor therebetween. The resilient plastic material is formed of a material that is MR compatible in that it can withstand magnetic fields and does not create artifacts in the image. The resilient plastics material 364 has a thickness of less than 5.0 mm. The resilient plastic material is flexible such that when applied on the head of a patient, the edges 365 of the upper coil hang under their own weight under the head without the application of additional force.

To provide effective sterilization for the surgical procedure, at least the upper coil assembly is made disposable and includes a disposable medical connector 366 for connecting the signal cable 367 to a computer control system. The connector 366 includes a portion at the end of the cable so that the cable is reusable, while the relatively small components defined by the conductor 363, the covering plastic and the connector 366 are arranged for single use.

Instead, to provide effective sterilization for the surgical procedure, at least the upper coil assembly 363 is inserted into the sterilization bag 368 during use to reuse the previously used upper coil assembly. Thus, each surgical procedure uses a separate sterile bag into which the coil assembly 363 is inserted during use.

The upper coil assembly 363 includes a preamplifier 369 mounted in a container 370 on a signal cable 367 connected to the computer control system, so that the coil structure 363 itself is very thin and light because the cable, including the connector 366 and the preamplifier 369, as shown in fig. 15, is not part of the suspended conductor.

For each conductor connected to a respective coil element 1, 2, 3 or 4 of the coil structure 363, the preamplifier 367 includes a respective phase shift circuit 371 between the respective conductor 373 and the respective preamplifier 372. Each conductor 373 is connected to the corresponding coil element 1, 2, 3, 4 according to the value of the selected component through inductors L1 to L4 connected to the coil elements on the other end, respectively, so that the phase shift of each coil element is equal to a half wavelength of the operating frequency of the MR system.

It has been found that the resiliency and drapability of the upper coil assembly brings the coil closer to the patient and improves the SNR by up to 50% and enables it to fit a wide variety of human heads from 6-month old infants to adult males.

The head transmitting coil may be provided as a conventional body coil, located inside the magnet at ISO centre, and having a bell mouth on the patient side of the magnet. It will produce a quadrature uniform transmit RF B1 field. This design can greatly reduce the weight of the receiver coil and improve the workflow. Alternatively, the upper and lower coil structures 361, 362 may be used to perform the transmit function.

For head imaging, the receive coil includes an upper and lower coil design: the lower coil is of a thin flexible design that can be inserted between the patient's head and a Head Fixation Device (HFD). The upper coil is an ultra-thin elastic coil, which can improve the SNR by about 50%. The use of elastic conductors in a thin elastic encapsulation material allows the structure to be fully elastic so that it drapes over the face of the patient while contacting substantially all portions of the patient's skin including the forehead, cheeks and chin.

Both the upper and lower coils may be integrated with B0 shim coils to further improve coil performance.

To provide effective sterilization of the coil for use in a surgical environment, both the upper and lower coils can be made disposable with a disposable medical connector. Alternatively, the coil may be of the reusable type, but inserted into a sterile bag during use.

As shown in fig. 14, at least the upper coil assembly uses a plurality of coil loops or elements 1, 2, 3 and 4 arranged in rows, each coil loop or element 1, 2, 3 and 4 partially overlapping the next. Such arrangements are well known and are used to provide decoupling between the individual coils.

That is, an adjacent pair of coil loops 1, 2 and 2, 3, etc. are decoupled by partial overlap 1A, 2A, etc. together with shared capacitors C2, C3 coupling the two coil loops of the pair. Likewise, the next adjacent coil loops 1, 3 and 2, 4 are also decoupled by using shared capacitors C20, C21 connecting the two next adjacent coil loops.

In this way, the upper coil assembly comprises at least first, second and third coil loops 1, 2, 3 arranged in a row, wherein each coil loop 1, 2, 3 comprises a plurality of capacitors at spaced locations around it. Thus, the coil 1 has capacitors C1, C2, C15, and C10. Coil 2 has capacitors C14, C7, C16 and C11, a portion of each coil loop overlapping the next coil portion, so that the first coil loop overlaps the second coil loop, which overlaps the third coil loop;

thus, the first coil loop and the second coil loop are decoupled by their partial overlap and the provision of a first additional decoupling capacitor C2, C3 shared on the common part of the first loop and the second loop. Likewise, the second and third coil loops 2, 3 are decoupled by the provision of a partial overlap 2A thereof with a second additional decoupling capacitor C3 shared on a common part of the second and third loops. Finally, the first and third coil loops 1, 3 are also decoupled by using a third additional capacitor C20 in the connecting conductor 1B between the first and third coil loops. A second connection conductor 1C is also provided between the first and third rings.

As shown, a fourth coil loop 4 arranged in the row is also provided, wherein the third coil loop 3 and the fourth coil loop 4 are decoupled by the provision of a third additional decoupling capacitor C4 which is partially overlapping and shared on a common part of the third and fourth coils. The second and fourth coil loops 2, 4 are decoupled by using a fifth additional capacitor C21 in the connecting conductor 2A between the second coil loop and the fourth coil loop.

The coil design uses a plurality of (e.g., four) coil elements arranged in rows, each coil element partially overlapping the next coil element. The adjacent coil elements 1 and 2, 2 and 3, 3 and 4 are decoupled by using a known overlap method obtained by partially overlapping and providing a shared capacitor coupling the two coil elements. In addition, the next adjacent coil elements 1 and 3, 2 and 4 are also decoupled by using a shared capacitor connecting the two next adjacent coil elements. The last coil decoupling only provides decoupling between adjacent coil elements which is done by using shared capacitors between them. There is no decoupling between the next adjacent coil elements.

The arrangement shown here best in fig. 7 to 10 can be used in a functional MRI procedure, where in a first position shown in fig. 7 the table 13 and magnet 16 position the head of the patient to be imaged on the head clamp 37 within the imaging region 161 of the magnet, and in a second position shown in fig. 9 the patient's head is exposed beyond the rear or distal end 751 of the magnet 16 to facilitate surgery.

To move between these positions, the magnet and the table are mounted for relative movement in the longitudinal direction of the table from a first imaging position to a second non-imaging position.

As shown in fig. 9, the magnet is movable along the table such that the patient end moves to a position proximate the bottom of the table and the table is suspended in the magnet and the table extends through the slide portion 133 on the rail 132 and longitudinally into the magnet in the second position.

In the second position shown in fig. 9, when the magnet is in the second position, the magnet is turned off by the controller 134 to turn off the magnetic field to enable surgery to be performed in the second position using a ferromagnetic tool 135 (e.g., a drill bit).

After exposing a portion of the patient in the second position of fig. 9, the portion is moved by relative motion to the first position of fig. 7 for imaging and power is applied to the magnet through control 134, while a non-ferromagnetic tool 137 is provided for performing additional surgery in the first position. The tool 137 may include a robotic guidance system 136 within the magnet for performing additional surgical procedures. The tool 137 may include a probe at a first location for insertion into the head of a patient under guidance of imaging, such as DBS.

For deep nerve stimulation and other procedures performed by the neurosurgeon on the brain, the power to the magnet is reduced to zero in fig. 9, and the system is then moved so that the magnet is positioned in the patient's chest and stomach. This exposes the patient's head to the end of the magnet remote from the table. The surgeon begins the surgical procedure, which requires the use of ferromagnetic materials that would be attracted to the magnet if subjected to a non-zero magnetic field. Typically, this is used to form a burr hole in the skull using a burr tool. Thus, the surgeon can perform conventional surgery using conventional tools without the risk of attraction by the magnet.

After completing a portion of the procedure, the magnet will be turned on and the surgeon can continue to perform the procedure, but only using the MRI safety device. To accomplish these tasks, appropriate support is required to introduce one or two insertion cannulas or electrodes through a burr hole made in the skull of the patient in the first part of the procedure. These trajectories are based on stereotactic imaging. When the magnet is in the magnetic field, relative motion of the patient and the magnet is provided such that the patient's head is received into the uniform field of view of the magnet. This can be achieved by the magnet moving on its moving system in the longitudinal direction of the table. In an alternative embodiment, the telescoping assembly of the patient bed is moved to place the head of the patient in the imaging field of view. Images are acquired and fused with preoperative images, which may contain anatomical, functional, and ophthalmic imaging information. These images are used to verify that the trajectory of the electrode or other probe is correct. These images can also be used to verify that the target has not moved due to the brain movement after the skull has been opened. If the inserted cannula or electrode is not aligned with the target, a new trajectory must be calculated to bring the implanted electrode to the true target. Upon completion of this procedure, the surgeon would implant the electrode into the patient's brain and verify that the implanted electrode is located at the target. The inserted cannula and electrodes can be advanced into the brain using a robot with or without image guidance. The description has been directed to the introduction of stereotactic electroencephalogram electrodes, but another embodiment of the present invention would be laser ablation or other lesion modalities of controlling tumors.

Claims (22)

1. A method of imaging in a surgical procedure, comprising:

in an operating room, providing an operating table for receiving a patient for performing a surgical procedure;

engaging the patient's head with a head clamp to hold the head in a fixed position while the patient lies on the table;

installing in a room a magnetic resonance imaging system for acquiring images of a portion of a patient over a surgical procedure over a series of times for analysis by a surgical team to allow the surgical team to monitor the procedure progress, the magnetic resonance imaging system comprising:

a magnet system, comprising: a cylindrical magnet of the magnet wire defining a cylindrical bore within which a portion of the patient is positioned for placement within a high magnetic field generated by the magnet;

a control system for controlling and varying the magnetic field;

a radio frequency transmission and detection system for initiating and detecting a nuclear magnetic resonance signal from the portion of the patient in response to the magnetic field, the radio frequency transmission and detection system including an RF probe disposed adjacent to the portion of the patient; and

a computer control system and display monitor for decoding and displaying the detected signals;

the patient on the table is supported for surgery;

the RF probe includes a lower RF coil assembly arranged to be mounted relative to a head clamp beneath the head of the patient;

the RF probe includes an upper RF coil assembly arranged to engage the head of the patient;

rendering at least the coil assembly on the RF sterile for use during the surgical procedure;

a sterile RF upper coil assembly is suspended over the head of the patient and is made resilient so as to conform at least partially to the shape of the portions of the head to which the assembly is engaged.

2. The method of claim 1, wherein the upper coil assembly is suspended in direct contact with the patient's head so as to conform to the patient's head.

3. The method of any of the preceding claims, wherein to provide effective sterilization for a surgical procedure, at least the upper coil assembly is made disposable and includes a disposable medical connector for connection with a signal cable and a computer control system.

4. A method according to any of the preceding claims, wherein in order to provide an efficient sterilization for use in a surgical procedure, at least the upper coil assembly is inserted into a sterilization bag during use to re-use a previously used upper coil assembly.

5. A method according to any preceding claim, wherein at least the upper coil assembly comprises a coil structure formed from resilient conductor means encapsulated in a resilient plastics material which directly engages and conforms to the patient's head.

6. The method of claim 5, wherein the resilient plastic material is formed of an MR compatible material in that it can tolerate magnetic fields and does not create artifacts in the image.

7. A method according to claim 5, wherein the thickness of the resilient plastics material is less than 5.0 mm.

8. The method of claim 5, wherein the resilient plastic material is resilient such that when it is applied over the patient's head, the edge of the upper coil hangs under its own weight under the head without applying additional force.

9. The method of claim 5, wherein the upper coil assembly includes a preamplifier mounted in a container on a signal cable connected to the computer control system, such that the coil structure itself is very thin and light.

10. The method of any preceding claim, wherein the lower coil assembly comprises a preamplifier mounted in a container on a signal cable connected to the computer control system, whereby the coil structure itself is very thin and light.

11. The method of any of the preceding claims, wherein the upper coil assembly comprises: a coil element, a preamplifier assembly connected between said coil elements, and a cable connected to said computer control system, and wherein a phase shift circuit is provided between said preamplifier and said coil element, the coil element connected to the coil element at the other end producing a phase shift equal to half a wavelength at the operating frequency of the MR system.

12. A method according to any one of the preceding claims, wherein an electrical connector is provided between at least the upper coil assembly and a cable connected to the computer control system, thereby making the upper coil assembly lighter to improve workflow.

13. The method of any of the preceding claims, wherein the elasticity and drapability of the upper coil assembly causes the coil to be closer to the patient and to improve the SNR by up to 50%.

14. The method of any preceding claim, wherein the flexibility and drapability of the upper coil assembly allows it to be adjusted to fit the head of a wide variety of people from 6-month old infants to adult males.

15. The method of any of the preceding claims, wherein the upper coil assembly uses a plurality of coil loops arranged in rows, each coil loop partially overlapping a next coil loop; wherein adjacent pairs of coil loops are decoupled by partial overlap and configuration of a shared capacitor coupling two coil loops of the pair of coil loops; and

the next lower adjacent coil loops are also decoupled by using a shared capacitor connected to the next two adjacent coil loops.

16. The method of claim 1, wherein the upper coil assembly comprises at least first, second, and third coil loops arranged in a row;

each coil loop includes a plurality of capacitors at spaced locations therearound;

each coil loop partially overlapping the next coil such that the first coil loop partially overlaps the second coil loop, and the second coil loop partially overlaps the third coil loop;

wherein the first and second coil loops are decoupled by their partial overlap and a first additional decoupling capacitor configured to be shared on a common portion of the first and second coil loops;

wherein the second and third coil loops are decoupled by their partial overlap and a second additional decoupling capacitor shared over a common portion of the second and third coil loops is configured;

and the first coil loop and the third coil loop are decoupled by using a third additional capacitor in the connection conductor between the first coil loop and the third coil loop.

17. A method according to claim 16, characterized in that a second connection conductor is provided between the first coil ring and the third coil ring.

18. An imaging method, comprising:

supporting a portion of a patient in a fixed position;

installing a magnetic resonance imaging system in the room to acquire a partial image of the patient, the magnetic resonance imaging system comprising: a magnet system, comprising: a cylindrical magnet of the magnet wire defining a cylindrical bore within which a portion of the patient is positioned for placement within a high magnetic field generated by the magnet;

a control system for controlling and varying the magnetic field;

a radio frequency transmission and detection system for initiating and detecting a nuclear magnetic resonance signal from the portion of the patient in response to the magnetic field, the radio frequency transmission and detection system including an RF probe disposed adjacent to the portion of the patient; and

a computer control system and display monitor for decoding and displaying the detected signals;

the radio frequency probe comprises a radio frequency coil assembly arranged to engage the portion of the patient; wherein the coil assembly comprises at least first, second and third coil loops arranged in a row;

each coil loop includes a plurality of capacitors at spaced locations therearound;

each coil loop partially overlaps the next coil such that the first coil loop partially overlaps the second coil loop, and the second coil loop partially overlaps the third coil loop.

Wherein the first and second coil loops are decoupled by their partial overlap and a shared first additional decoupling capacitor arranged on a common portion of the first and second coil loops;

wherein the second and third coil loops are decoupled by their partial overlap and a shared second additional decoupling capacitor arranged on a common portion of the second and third coil loops;

and wherein the first coil loop and the third coil loop are decoupled by using a third additional capacitor in the connecting conductor between the first coil loop and the third coil loop.

19. A method according to claim 18, characterized in that fourth coil loops are provided, arranged in a row, wherein the third coil loops and the fourth coil loops are decoupled by their partial overlap and a shared third additional decoupling capacitor arranged on a common part of said third and fourth coil loops, wherein the second coil loops and the fourth coil loops are decoupled by using a fifth additional capacitor in the connection conductors between the second coil loops and the fourth coil loops.

20. The method of claim 18 or 19, wherein the coil assembly comprises a preamplifier mounted in a container on a signal cable connected to the computer control system, whereby the coil assembly itself is very thin and light.

21. The method of claim 18, 19 or 20, wherein the coil assembly comprises: a coil element, a preamplifier assembly connected between said coil elements, and a cable connected to said computer control system, and wherein a phase shift circuit is provided between said preamplifier and said coil element, which is connected to the coil element on the other end, such that the phase shift produced is equal to half a wavelength at the operating frequency of the MR system.

22. The method of claim 18, 19, 20 or 21, wherein an electrical connector is provided between at least the upper coil assembly and a cable connected to the computer control system, making the upper coil assembly lighter to improve workflow.

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