Abstract:
An assembly, system, and method particularly adapted for a magnetic resonator apparatus in a magnetic resonance imaging (MRI) scanning system. Provided is a restraining assembly supportable by the supporting assembly and including at least a system that is selectively operable for positioning and restraining at least a portion of the body to be imaged, thereby optimizing image quality.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of medical imaging and, more particularly, to an assembly, system, and method particularly adapted for a magnetic resonator apparatus in a magnetic resonance imaging (MRI) scanning system. 
     MRI is a non-invasive procedure utilized to obtain images of anatomical features for diagnostic purposes. The images are formed when signals emitted by body tissue are analyzed and converted to medical images. MRI has necessitated the use of specifically designed system components, such as a portable birdcage imaging resonator, etc. Specifically, MRI depicts parameters associated with nuclear spins (typically hydrogen protons associated with water in tissue) that are considered of value in medical diagnostics in determining the state of health of tissue in a region examined. Successful MRI techniques have also been extended to in vivo spectroscopy of elements such as phosphorus and carbon, thereby providing researchers with tools to study chemical processes in a living organism. Obtaining proper nuclear spinning of body tissue of interest is critical for successful MRI. Accordingly, it is extremely important that when conducting it, the body tissue of interest be precisely and positively aligned. It is also important for the body portion being imaged be properly spaced relative to the apparatus in order to avoid generating interference with any resulting images. 
     To satisfy the foregoing concerns, present approaches require skilled technologists in labor-intensive procedures. Ordinarily, a patients body portion is in a prone position on a table within a scanning type magnetic resonance imaging device. Relatively recently, portable image resonating units have been used for purposes of exposing even smaller selected portions of a body, such as the arm or leg. These portable units have the advantage of localizing the application of the MRI procedure to selected regions of the body. However, technologists must still obtain and retain proper patient positioning. This is more problematic when using the portable units. Otherwise, inadvertent movement and/or contact with the portable unit might degrade image quality. Retention is typically accomplished by having technologists stuff particulate-filled bags between the body and the portable image resonating unit. It will be appreciated that known approaches are relatively time consuming and tedious. In addition, they may be highly uncomfortable for patients with injuries. 
     Hence, the prior art is absent, an assembly, system, and method that are particularly adapted for automatically positioning body portions within a magnetic resonance imaging unit, whereby precise imaging is enhanced in an expeditious, economical, and reliable manner that minimizes patient discomfort. Therefore, there is a need for an assembly, system, and method that are particularly adapted for automatically positioning body portions within a magnetic resonance imaging unit, whereby precise imaging is enhanced in an expeditious, economical, and reliable manner that minimizes patient discomfort. Without satisfying the above, the true potential of medical imaging will not be fully realized. 
     SUMMARY OF THE INVENTION 
     The present invention provides enhanced assembly, systems and methods for properly positioning and restraining a patient with respect to a magnetic resonance imaging unit without negative effect and that overcomes many of the disadvantages of the prior art. 
     A magnetic resonance imaging apparatus comprising: a housing assembly for at least partially encircling a body portion; and, an adjustable positioning and restraining system coupled to the housing assembly and operable for automatically positioning and restraining a patient&#39;s body portion in a predefined location with respect to a preferred location along a longitudinal axis of the housing assembly. 
     A portable assembly adapted for magnetic resonance imaging of a body portion, the assembly comprising: a magnetic resonance imaging apparatus comprising: a housing assembly for at least partially encircling a body portion; and, an adjustable positioning and restraining system coupled to the housing assembly that is selectively operable for positioning and restraining a patient&#39;s body portion in a predefined location in an X-Y plane with respect to a longitudinal axis of the housing assembly. 
     In a preferred illustrated embodiment, the assembly includes a targeting mechanism, which facilitates positioning the specific body portion of interest to be relative to the radiofrequency elements of the supporting assembly. 
     An aspect of the present invention is an assembly, system, and method that are particularly adapted for automatically positioning body portions within a magnetic resonance imaging unit, whereby image quality is enhanced. 
     Another aspect of the present invention is to achieve the foregoing in an expeditious, economical, and reliable manner. 
     Another aspect of this invention is to achieve the foregoing in a manner that minimizes patient discomfort. 
     These and other features and aspects of the present invention will be more fully understood from the following detailed description of the preferred embodiments, which should be read in light of the accompanying drawings. It should be understood that both the foregoing generalized description and the following detailed description are exemplary, and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a magnetic resonance imaging (MRI) scanner system including an RF image resonator apparatus. 
         FIG. 2  is an exploded perspective view of one preferred embodiment of an RF image resonator for use with a positioning and restraining assembly of the present invention. 
         FIG. 3  is a schematic perspective view of an RF image resonator apparatus with a positioning and restraining assembly of the present invention in an expanded condition. 
         FIG. 4  is a schematic perspective view of an RF image resonator apparatus with a positioning and restraining assembly and a patient targeting apparatus. 
         FIG. 5  is a schematic perspective view of the targeting apparatus adapted to be part of the positioning and restraining assembly of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates one embodiment of a Magnetic Resonance Imaging (MRI) scanner system, generally denoted by reference numeral  100 . The Magnetic Resonance Imaging (MRI) system  100  may be conventional type, such as is commercially available from General Electric. In the MRI system  100 , use is made of a magnetic resonance imaging apparatus  110 . In the present embodiment, the magnetic resonance imaging apparatus  110  may be a birdcage image resonator apparatus  110 . 
     The MRI scanner system  100  may include a toroidal shaped coil area  120  that accommodates magnets  130  and gradient coils  140 . The birdcage image resonator apparatus  110  may be a RF (Radio Frequency) type. The birdcage image resonator apparatus  110  may be of the kind that is commercially available from General Electric. Clearly, other kinds of MRI scanner systems are contemplated for use with the present invention. During the taking of MRI images, the birdcage image resonator apparatus  110  is placed within the toroidal shaped coil area  120 . Although not shown an appendage of a patient is placed within the resonator apparatus  110 . The construction and operation of the MRI scanner system  100  and the birdcage image resonator apparatus  110 , per se, do not form aspects of the present invention. Consequently, only those aspects considered necessary for understanding the present invention will be set forth. 
     Reference is now made to  FIG. 2  for illustrating the birdcage image resonator apparatus  110  that essentially includes a generally toroidal shaped housing assembly  150 , and a cylindrical birdcage RF coil assembly  160  that is supported in the housing assembly. The RF coil assembly  160  is coupled to MRI electronics  170  by a cable  180  and connector  185 . The MRI electronics  170  is further coupled to a computer system  190 , which analyzes the data for a particular MRI image and stores and/or presents it to medical personnel for interpretation. 
       FIG. 2  illustrates one preferred embodiment of the birdcage image resonator apparatus  110 . The birdcage image resonator apparatus  110  is particularly adapted for use in combination with the MRI system and an adjustable physical positioning and restraining system to be described hereinafter. The toroidal housing assembly  150  includes, preferably, upper and lower generally semi-circular, in cross-section, shell members  200 ,  202 ; respectively. The shell members  200 ,  202  are suitably joined to each other to form an inner housing core assembly  204  that defines an axially extending cavity  205 . The shell members  200 ,  202  are, preferably, made of a plastic material, such as polycarbonate or the like that serves as a dielectric material, whereby the propagation of RF signals that are generated by the RF coil assembly  160  are not diminished. The inner housing core assembly  204  may be translucent and/or transparent. This facilitates placement thereof over or relative to a patient. The inner housing core assembly  204  is sized and configured to encompass a portion, such as an arm, leg, etc. of a patient (not shown) to be imaged. The present invention is not limited to any size and/or configuration of the inner housing core assembly  204  or for that matter the remainder of the birdcage resonator. 
     The RF coil assembly  160  is mounted on the inner housing core assembly  204 . The RF coil assembly  160  may include a series of inductors and capacitors (not shown) that are generally longitudinally extending and circumferentially spaced with respect to each other along a toroidal flex sleeve  206  to define radiofrequency elements. The toroidal sleeve  206  is mounted on the inner core assembly  204  and extends along a longitudinal axis  208  of the latter. The series of inductors and capacitors (not shown) of the toroidal flex sleeve  206  are operable for generating a uniform field for use in the diagnostic imaging to be performed by the birdcage image resonator apparatus  110 . 
     The toroidal housing assembly  150  includes an outer housing core assembly  210  that surrounds the RF coil assembly  160 . The outer housing core assembly  210  includes, preferably, upper and lower generally semicircular shell members  212 ,  214  that are joined to each other. The outer housing core assembly  210  includes a plurality of circumferentially spaced transparent windows  216  that allow a technologist to visually locate the patient&#39;s body portion of concern relative to the toroidal housing assembly, whereby the body portion of concern may be properly located for imaging in a manner to be described. The windows  216  may be an integral part of the outer housing core assembly  210 . A pair of plastic end caps  218 ,  220  serves to hold housing assembly together in a known manner. The cable  180  extends thru one of the end caps  218  and is suitably coupled to the RF coil assembly  160  at one end and the connector  185  at the other end. The connector  185  is coupled to the MRI electronics  170  in a controller  172 . The controller is coupled to one or more computers in a computer system  190 . 
     Reference is now made to  FIGS. 4 &amp; 5  for illustrating a patient targeting apparatus  230  that is, preferably, releasably coupled to the housing assembly  150 . The targeting system  230  is operable for generating targeting beams that are directed at the axis  208  of the RF coil assembly  160 . A housing assembly  232  is, preferably, made of a material that does not affect any of the RF frequencies used by the RF coil assembly  160 . Such material may be plastic, such as polycarbonate or the like. Other suitable materials may be utilized. The patient targeting apparatus  230  has, preferably, its housing assembly  232  constructed to be releasably clipped to one end of the housing assembly  150 . A fixed connection is also contemplated. The housing assembly  232  may include a pair of generally parallel leg portions  236  extend inwardly into the cavity from a body portion  238 . The body portion  238  may include a power source  240 , such as a battery. The power source  240  is connected to a pair of light-emitting diodes (not shown) within the body portion  234 . Each of the leg portions  236  may include plastic lightpipes (not shown) that axially extend therewithin. Each of the lightpipes may terminate at an aperture  242  formed in the leg portions  236 . The leg portions  236  are dimensioned so that the apertures  238  are located over that area of the patient that the magnetic imaging beam generated by the MRI system  100  is directed. As a result, the beams of targeting lights facilitate properly locating the patient&#39;s body portion concern. A switch (not shown) can be provided to control illumination. 
       FIGS. 3 and 4  illustrate one preferred embodiment of an adjustable physical positioning and restraining system  300  made consistent with the teachings of the present invention. Essentially, the system  300  includes an expansible sleeve assembly  302  and a bladder system including, preferably, a plurality of fluidically expandable bladder units  304   a - n  (collectively  304 ) that are intended to engage and restrain a body portion within the cavity. Each of the bladder units  304  is a generally longitudinally extending and circumferentially spaced with respect to each other. To avoid or minimize interference with operation of the birdcage image resonator, the material of the bladder units  304  is selected to avoid interference with the RF and the visual sighting of a targeting system to be described. In this regard, the material of the bladder units  304  may, preferably, be of a suitable transparent and/or translucent polypropylene material for example. Other suitable materials exhibiting such properties may be utilized. 
     Preferably, each of the bladder units  304  is comprised of a generally flexible material for receiving pressurized fluid. In response, the bladder unit  304  expands in a generally radial direction inwardly toward the axis  208  along the longitudinal extent of the bladder. As a result, the body portion received within the cavity size of the opening may be snuggly restrained. The bladder units  304  may be also be releasably coupled to the housing assembly  150 . It will be noted that the legs  236  of the targeting system are, preferably, disposed in such a manner as to not obstruct the operation of the bladders  304 . 
     The control system  310  is adapted to be fluidically connected with a source of pressurized air (not shown). Each one of the bladder units  304  is preferably adapted to be individually under the control of the control system  310 . The control system  310  may include a user activated fluid switch mechanism  320 . The fluid switch mechanism  320  may be a pneumatic type whereby a handle  330  is manipulated to control pressurizing and venting depending on the position of the handle. Other similar kinds of switches may be utilized. The control system  310  regulates the admission and venting of air from each bladder unit  304  in a controlled manner through flexible tubes  340 . A supply of pressurized fluid (not shown) is provided to supply the pressurized air. By being independently actuated, the bladder units  304  facilitate precise positioning and restraint of a patient within an X-Y plane defined within the cavity relative to the longitudinal axis  208 . It will be appreciated that after a patient&#39;s limb is placed in the housing assembly it may be positioned thru selective regulation of the expandable bladder units  304 . Not only will the bladder units  304  be utilized for achieving the correct positioning, but also will serve to retain the patient&#39;s limb in the desired position. Because of the compressible nature of the expandable bladder units  304 , the patient need not experience much if any inconvenience or discomfort. It will be appreciated that the invention is not limited to particular types of birdcage image resonators or MRI systems, since its principles embrace other similar imaging systems. The present invention can be used in a variety of other imaging apparatus for effecting patient positioning and restraint while doing it in a manner that facilitates patient comfort. 
     Operation of the foregoing construction is self-evident. However, to supplement such description the following brief description is provided. A technologist will place the body portion of concern in the cavity in juxtaposed relationship with respect to the supporting assembly. The targeting mechanism is operated for accurately positioning the body portion of concern along the axis. The pneumatic control is operated to expand the bladder units in the X-Y plane after the body portion of concern has been precisely positioned. Thereafter, the radiofrequency elements are operated to effect an imaging in the usual manner associated with the art. 
     The embodiments and examples set forth herein were presented in order to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching without departing from the spirit and scope of the following claims.