Abstract:
A patient support structure for use in a magnetic resonance image (MRI) scanner includes a base and a first and a second arm pivotally connected to the base. The patient support structure supports an anatomical region being imaged and positions an antenna array around the anatomical region. Access to the patient is improved by: providing a flexible coil that wraps around the anatomical region being imaged, providing a support structure open to the anterior region of the anatomical region being imaged, and providing a support structure that may be opened and closed about the anatomical region being imaged.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional application Ser. No. 61/475,884, filed Apr. 15, 2011, entitled Pediatric Imaging Assembly, the entire contents of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The subject matter disclosed herein relates to a system for use in obtaining a magnetic resonance image (MRI) of a pediatric patient. More specifically, the assembly includes support structures both for patient comfort and stability as well as structures to position antenna arrays with respect to the patient. 
         [0003]    As is known to those skilled in the art, obtaining MRIs of pediatric patients presents unique challenges. The quality of images obtained in MRI scanners is in part, a function of the location of the antenna array with respect to the anatomical region being images. Currently, most imaging systems are of a rigid or fixed construction, requiring different coils to be used for patients of different sizes. Because pediatric patients are generally smaller in size and present greater variation in the size of patients than adults, coils are not always properly sized for the patient. Further, due to the expense of coils and due to the majority of MRI patients being adults, it may be cost prohibitive for some imaging centers to maintain pediatric imaging assemblies. 
         [0004]    Current systems on the market are made of rigid non-formable construction. Such systems limit the use of non-uniform shapes that must fit inside the predefined contour of the coil. These systems may also include a rigid mechanical latching system to secure the coil in position, which requires a person skilled in the equipment to release the latch in order to gain access to the patient. 
         [0005]    Thus, it would be desirable to provide a MRI imaging assembly adaptable to varying sizes of patients and easily accessible to enhance imaging of pediatric patients. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    The subject matter disclosed herein describes an imaging assembly which includes a patient support structure and at least one imaging coil. More specifically, the imaging assembly is configured to facilitate pediatric imaging. 
         [0007]    The patient support structure includes a recessed portion configured to receive an imaging coil such that a desired anatomical region of the patient may be placed on the imaging coil. The patient support structure further includes an exoskeleton configured to open and close anterior to the anatomy to be imaged, providing, for example, easy access to the face of a patient. In addition, the imaging coils may be used independently of the patient support structure for other imaging applications. Thus, the customers overall cost for imaging solutions is reduced. 
         [0008]    The patient support structure according to one embodiment of the current invention adapts to non-uniform shapes and can be configured for patients of varying sizes to improve patient comfort. The anterior opening exoskeleton accommodates medical incubation and ventilation and allows quick and easy access by medical professionals to patients in the event of an emergency. 
         [0009]    The patient support structure according to one embodiment of the current invention allows patient set up for precise patient placement and improved comfort by allowing the technician to adjust and maneuver the patient along with any external elements a patient may require in stepped fashion. The pivotal connector is configured to be easily positioned to a desired position for imaging, and openings in the structure permit viewing to the opposite side of the coil. Thus, the technician is able to position and access the patient from the top, front, back and one side of the coil, allowing improved patient comfort and positioning for imaging. The patient support structure further provides an audible click when opening and an audible click when properly closed. This frictional interfering engagement is robust enough to hold the coil in position and light enough to allow the coil to be readily opened without the need for depressing or deactivating a mechanical latch. 
         [0010]    The patient support structure includes an exoskeleton with a c-clip insert system. The c-clip system is designed to fit into the exoskeleton as a separate component, but optionally may be integrally formed with the exoskeleton. The c-clip may be configured to provide an increased or reduced radial torque for placing the exoskeleton into a full closed or full open position. The c-clip further provides multiple latch and hold positions, easy field repair, and disassembly for cleaning and sanitizing. The exoskeleton may be designed with one or more arms. 
         [0011]    According to one embodiment of the invention, the c-clip arm includes multiple position locating teeth. Each tooth on the c-clip arm is designed to cooperate with a corresponding tooth on the c-clip cam. C-clip jaws are designed and positioned to provide a resilient force sufficient to hold an arm of the exoskeleton in an aligned position relative to a base of the exoskeleton when the locating tooth of the arm and the corresponding tooth of the cam are engaged. The c-clip arm is curved to cooperate with the exoskeleton arm in proper assembly. Locating holes on the c-clip engage bosses on the exoskeleton to provide for correct radial alignment between the c-clip and the exoskeleton. A spring activation slot on the c-clip allows variation in the force required to position the arm. Increasing the slot width or depth will reduce the load force required to position the clip. Thus, the c-clip may be manufactured to provide differing positioning forces as needed to meet customer demands. 
         [0012]    A cooperating cam includes a stop position engaging the locating tooth of the c-clip. The locating tooth butts against the stop position to limit radial positioning. A radial alignment portion of the cam is designed with a minimum clearance or slight interference condition to maintain concentricity between the c-clip and the cam during radial movement of the c-clip arm. The cam further includes an orientation and anti-rotation feature such that the cam may be used on any face of the exoskeleton base, eliminating the need for left or right orientated cams. The cam may be positioned on the base such that the orientation feature sets the left side radial position independently of the right side radial position. Optionally, the cam orientation and anti-rotation feature can be designed with a spline-type center, allowing the cam to be positioned such that the open and closed position are left or right of center as needed. 
         [0013]    According to a first embodiment of the invention, a patient support structure for supporting an anatomical region of a patient and for positioning a flexible antenna array with respect to the anatomical region while obtaining a Magnetic Resonance Image (MRI) is disclosed. The patient support structure includes a base, a first arm, and a second arm. The base includes a first end, a second end opposite the first end, a first side, and a second side opposite the first side. Each of the first and second sides extend between the first and second ends. The base also includes at least one mounting surface proximate to the first side of the base and at least one mounting surface proximate to the second side of the base. The first arm includes a first end proximate to the base, a second end distal from the base, at least one mounting surface pivotally connected to the at least one mounting surface proximate to the first side of the base, and at least one antenna guide configured to slidably engage the flexible antenna array. The first arm is movable between a first position and a second position. The second arm includes a first end proximate to the base, a second end distal from the base, at least one mounting surface pivotally connected to the at least one mounting surface proximate to the second side of the base, and at least one antenna guide configured to slidably engage the flexible antenna array. The second arm is movable between a first position and a second position. 
         [0014]    According to another aspect of the invention, a first friction mount may pivotally connect the mounting surface of the first arm to the mounting surface proximate to the first side of the base, and a second friction mount may pivotally connect the mounting surface of the second arm to the mounting surface proximate to the second side of the base. The base may include a channel extending between the first and second ends and configured to receive a member protruding from a surface of the antenna array. Optionally, the patient support structure further includes a riser block extending longitudinally between the first and second ends of the base and extending away from the base between the first and second arms. The riser block engages the antenna array to position the antenna array between the first and second arms. 
         [0015]    According to still another aspect of the invention, the first arm may include an arcuate central support member, and the second arm may include an arcuate central support member. The antenna guide of the first and second arms each include a first retention member extending outward in a first direction from a center axis of the arcuate central support member proximate to the second end of the respective arm and a second retention member extending outward in a second direction, opposite the first direction, from the center axis of the arcuate central support member proximate to the second end of the respective arm. The first and second retention members of the first and second arms may each define a channel extending along the end of the retention member distal from the center axis of the arcuate central support member and extending generally parallel to the arcuate central support member. 
         [0016]    According to yet another aspect of the invention, the antenna guide of the first arm may include a first channel extending along at least a portion of a first side of the first arm and a second channel extending along at least a portion of a second side of the first arm. The antenna guide of the second arm may include a first channel extending along at least a portion of a first side of the second arm and a second channel extending along at least a portion of a second side of the second arm. The base may include a planar lower surface. Optionally, the base may include an upper surface extending between the first end, the second end, the first side and the second side. The upper surface has a first side facing the first and second arms and a second side opposite the first side. A handle may protrude from the second side of the upper surface into a cavity defined by the first end, the second end, the first side, the second side and the upper surface. 
         [0017]    According to another embodiment of the invention, a patient support structure for use with a Magnetic Resonance Image (MRI) scanner includes a base having a first end, a second end opposite the first end, a first side, a second side opposite the first side, and an upper surface defined generally by an upper edge of each of the first end, second end, first side, and second side. The patient support structure also includes a first mounting block protruding from the upper surface and extending generally parallel to and proximate with the first side of the base and a second mounting block protruding from the upper surface and extending generally parallel to and proximate with the second side of the base. Each of the first and second mounting blocks has a first end and a second end opposite the first end. The patient support structure also includes a first and a second arm. The first arm has a first end, a second end opposite the first end, a front wall, a rear wall opposite the front wall, and a curved side wall extending between at least a portion of an, outer edge of each of the front wall and the rear wall. The first end of the front wall is configured to pivotally mount to the first end of the first mounting block and the first end of the rear wall is configured to pivotally mount to the second end of the first mounting block. The second arm has a first end, a second end opposite the first end, a front wall, a rear wall opposite the front wall, and a curved side wall extending between at least a portion of an outer edge of each of the front wall and the rear wall. The first end of the front wall is configured to pivotally mount to the first end of the second mounting block, and the first end of the rear wall is configured to pivotally mount to the second end of the second mounting block. Each of the first and second arms also include an antenna array guide for positioning a flexible antenna array within the patient support structure. 
         [0018]    According to another aspect of the invention, the antenna array guide for each of the first and second arms may include a first retaining surface extending from the front wall toward the center of the respective arm, along a portion of the length of the front wall. The first retaining surface is generally parallel to and offset from the curved side wall. The antenna array guide may also include a second retaining surface extending from the rear wall toward the center of the respective arm, along a portion of the length of the front wall. The first retaining surface is generally parallel to and offset from the curved side wall. 
         [0019]    According to yet another aspect of the invention, the antenna array guide for each of the first and second arms may include a first retention member proximate to the second end of the respective arm extending outwardly from the front wall of the respective arm, and a second retention member proximate to the second end of the respective arm extending outwardly from the rear wall of the respective arm. Each retention member including a first surface extending from the respective front or rear wall, a retaining surface, offset from and generally parallel to the first surface, and an outer surface connecting the distal edge of each of the first surface and the retaining surface. A channel is formed by the first surface, retaining surface, and outer surface, where the channel slidably engages the antenna array. 
         [0020]    According to still another aspect of the invention, the first arm is pivotally mounted to the first mounting block by a first friction mount and the second arm is pivotally mounted to the second mounting block by a second friction mount. The first friction mount may include at least one washer compressible between the front wall of the first arm and the first end of the first mounting block and at least one washer compressible between the rear wall of the first arm and the second end of the first mounting block, and the second friction mount includes at least one washer compressible between the front wall of the second arm and the first end of the second mounting block and at least one washer compressible between the rear wall of the second arm and the second end of the second mounting block. Optionally, each friction mount includes a clip and a cam. The clip is connected to the first end of the front or rear wall and includes a body mounted to the front or rear wall, a pair of arcuate members extending from the body and defining an opening therebetween, and a slot in communication with the opening and extending along at least a portion of a length of the body. The cam is connected to each end of the first and second mounting blocks and includes an outer periphery complementary to the opening defined between the arcuate members. The arcuate members are deflected apart by the outer periphery of the cam as each arm is rotated between a first and a second position. 
         [0021]    According to yet another aspect of the present invention, a patient support structure for supporting an anatomical region of a patient and for positioning a flexible antenna array with respect to the anatomical region while obtaining a Magnetic Resonance Image (MRI) is disclosed. The patient support structure includes a base, a first arm including a first retention means to hold the flexible antenna array along the inner periphery of the first arm, a second arm including a second retention means to hold the flexible antenna array along the inner periphery of the second arm, a first friction mounting means to pivotally connect the first arm to the base, and a second friction mounting means to pivotally connect the second arm to the base. 
         [0022]    These and other objects, advantages, and features of the invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
         [0023]    Various exemplary embodiments of the subject matter disclosed herein are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
           [0024]      FIG. 1  is a perspective view of the patient support assembly according to one embodiment of the invention; 
           [0025]      FIG. 2  is an exploded view of the patient support assembly of  FIG. 1 ; 
           [0026]      FIG. 3  is a perspective view of the patient support assembly according to another embodiment of the invention; 
           [0027]      FIG. 4  is an exploded view of the patient support assembly of  FIG. 3 ; 
           [0028]      FIG. 5  is a perspective view of a curved patient support structure used in the patient support structure of HO shown in a home position; 
           [0029]      FIG. 6  is front elevation view of the curved patient support structure of  FIG. 5 ; 
           [0030]      FIG. 7  is a top plan view of the curved patient support structure of  FIG. 5 ; 
           [0031]      FIG. 8  is a side elevation view of the curved patient support structure of  FIG. 5 ; 
           [0032]      FIG. 9  is a perspective view of the curved patient support structure used in the patient support structure of  FIG. 1  shown in a open position; 
           [0033]      FIG. 10  is a top plan view of the curved patient support structure of  FIG. 9 ; 
           [0034]      FIG. 11  is a side elevation view of the curved patient support structure of  FIG. 9 ; 
           [0035]      FIG. 12  is a front elevation view of a base of the curved patient support structure of  FIG. 5 ; 
           [0036]      FIG. 13  is a perspective view from the top, rear, and side of the curved patient support structure used in the patient support structure of  FIG. 3  shown in a home position; 
           [0037]      FIG. 14  is a perspective view from the top, front, and side of the curved patient support structure used in the patient support structure of  FIG. 3  shown in a home position; 
           [0038]      FIG. 15  is a top plan view of the, curved patient support structure of  FIG. 13 ; 
           [0039]      FIG. 16  is a side elevation view of the curved patient support structure of  FIG. 13 ; 
           [0040]      FIG. 17  is front elevation view of the curved patient support structure of  FIG. 13 ; 
           [0041]      FIG. 18  is a perspective view from the end, side, and bottom of the curved patient support structure according to another embodiment of the invention; 
           [0042]      FIG. 19  is a side view of the curved patient support structure of  FIG. 18 ; 
           [0043]      FIG. 20  is a bottom plan view of the curved patient support structure of  FIG. 18 ; 
           [0044]      FIG. 21  is a perspective view of the curved patient support structure according to another embodiment of the invention; 
           [0045]      FIG. 22  is a top plan view of the curved patient support structure of  FIG. 21 ; 
           [0046]      FIG. 23  is a side elevation view of the curved patient support structure of  FIG. 21 ; 
           [0047]      FIG. 24  is front elevation view of the curved patient support structure of  FIG. 21 ; 
           [0048]      FIG. 25  a perspective view of a curved patient support structure according to another embodiment of the invention; 
           [0049]      FIG. 26  is a top plan view of the curved patient support structure of  FIG. 25 ; 
           [0050]      FIG. 27  is a side elevation view of the curved patient support structure of  FIG. 25 ; 
           [0051]      FIG. 28  is front elevation view of the curved patient support structure of  FIG. 25 ; 
           [0052]      FIG. 29  is a front elevation view of one embodiment of a c-clip used in the curved patient support structure of  FIG. 5 ; 
           [0053]      FIG. 30  is a front elevation view of one embodiment of a cam used in cooperation with the c-clip of  FIG. 29 ; 
           [0054]      FIG. 31  is a front elevation view of another embodiment of a c-clip used in the curved patient support structure, of  FIG. 5 ; 
           [0055]      FIG. 32  is a front elevation view of one embodiment of a cam used in cooperation with the c-clip of  FIG. 31 ; 
           [0056]      FIG. 33  is a side elevation view of one embodiment of an arm used in the curved patient support structure of  FIG. 5 ; 
           [0057]      FIG. 34  is a cross-sectional view of the arm in  FIG. 33  taken at  34 - 34 ; 
           [0058]      FIG. 35  is a front elevation view the arm used in  FIG. 33 ; 
           [0059]      FIG. 36  is a partial cross-sectional view of the arm in  FIG. 35  taken at  36 - 36 ; 
           [0060]      FIG. 37  is a side elevation view of another embodiment of a curved patient support structure shown in a open position; 
           [0061]      FIG. 38  is a perspective view of another embodiment of a curved patient support structure shown in a open position; 
           [0062]      FIG. 39  is a bottom plan view of the curved patient support structure of  FIG. 38 ; 
           [0063]      FIG. 40  is a top plan view of a hinge used in the curved patient support structure of  FIG. 38 ; 
           [0064]      FIG. 41  is a side elevation view of the hinge of  FIG. 40 ; 
           [0065]      FIG. 42  is a cross-sectional view of the hinge of  FIG. 41  taken at  42 - 42 ; 
           [0066]      FIG. 43  is a front elevation view of the pin assembly for the hinge of  FIG. 40 ; 
           [0067]      FIG. 44  is a cross-sectional view of the pin assembly of  FIG. 43  taken at  44 - 44 ; 
           [0068]      FIG. 45  is a perspective view of another embodiment of an arm used in the curved patient support structure; and 
           [0069]      FIG. 46 . is a reversed perspective view of the arm of  FIG. 45 . 
       
    
    
       [0070]    In describing the preferred embodiments of the invention which are illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word “connected,” “attached,” or terms similar thereto are often used. They are not limited to direct connection but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0071]    The various features and advantageous details of the subject matter disclosed herein are explained more fully with reference to the non-limiting embodiments described in detail in the following description. 
         [0072]    Turning initially to  FIGS. 1 and 2 , one embodiment of a patient support assembly  10  includes at least one patient stabilization structure used to position a patient within a MRI scanner. According to the illustrated embodiment, a first patient support  30  includes a top surface  32 , a bottom surface  34 , and multiple side walls  36 , a front wall  38 , and a rear wall  40  joining the top surface  32  and the bottom surface  34 . The first patient support  30  may be a single molded assembly or, optionally, may include two or more components joined to form the first patient support  30 . 
         [0073]    The top surface  32  includes a first recess  31  configured to receive a first antenna array  12 . The antenna array  12  may be, for example, an antenna array as provided by applicant and described in U.S. Pat. Pub. No. 2010/0315085, herein incorporated by reference. The depth of the first recess  31  is equal to or greater than the thickness of the first antenna array  12  such that a top surface  11  of the first antenna array  12  is at or below the top surface  32  of the first patient support  30 . The walls of the recess  31  extending above the antenna array  12  may help position and/or retain a pediatric patient on the first patient support  30 . For example, the top surface  32  of each wall may be formed to support the arms of a patient. A first channel  33  is in communication with the recess  31  and is configured to receive a cable  13  extending from the first antenna array  12  to the MRI scanner. A first preamplifier module  22  may be connected in series between the first antenna array  12  and the MRI scanner. Optionally, preamplifier circuits may be incorporated into the antenna array  12  and the cable  13  may be connected directly to the MRI scanner. The first preamplifier module  22  is supported within a cavity  45  of a tray  44  mounted to a side  36  of the first patient support  30 . Optionally, the tray  44  may be integrally formed with the first patient support  30  and the cavity  45  may be another recessed portion of the first patient support  30 . According to still another embodiment, if the electronic circuits of the first preamplifier module  22  are incorporated into the first antenna array  12 , the tray  44  may be eliminated. 
         [0074]    The top surface  32  includes a second recess  35  configured to receive a second patient support  50 . The second patient support  50  may be used to support the head of a pediatric patient, and is also referred to herein as the head support  50 . Optionally, the second patient support  50  may be used to support, for example, arms or legs of adult patients. The head support  50  is configured to support a second antenna array  14 . A second channel  37  is in communication with the second recess  35  and is configured to receive a cable extending from the second antenna array  14  to the MRI scanner. A second preamplifier module  24  may be connected in series between the second antenna array  14  and the MRI scanner. Optionally, preamplifier circuits may be incorporated into the second antenna array  14  and the, cable may be connected directly to the MRI scanner. If the second preamplifier module  24  is included, a third recess  39  may be formed in the first patient support  30  and configured to receive the second preamplifier module  24 . If the cable from the second antenna array  14  is connected directly to the MRI scanner, the third recess  39  may be eliminated. 
         [0075]    The spatial relationship of the first recess  31  with respect to the second recess  35  is configured to provide improved image quality if both the first and second antenna arrays,  12  and  14  respectively, are used. Adjacent or overlapping antennas in the antenna arrays,  12  and  14 , can cause coupling between the coils, degrading image quality. However, if the arrays,  12  and  14 , are oriented properly with respect to each other, the coupling can be reduced or eliminated, providing improved image quality. Consequently, the first and second recesses,  31  and  35 , are configured such that the first and second antenna arrays,  12  and  14 , are oriented in a preferred alignment to minimize coupling between the arrays. 
         [0076]    Referring next to  FIGS. 3 and 4 , another embodiment of a patient support assembly  10  includes at least one patient stabilization structure used to position a patient within a MRI scanner. According to the illustrated embodiment, a first patient support  30  includes a top surface  32 , a bottom surface  34 , and multiple side walls  36 , a front wall  38 , and a rear wall  40  joining the top surface  32  and the bottom surface  34 . The first patient support  30  may be a single molded assembly or, optionally, may include two or more components joined to form the first patient support  30 . 
         [0077]    The top surface  32  includes a first recess  31  configured to receive a first antenna array  12 . The depth of the first recess  31  is equal to or greater than the thickness of the first antenna array  12  such that a top surface  11  of the first antenna array  12  is at or below the top surface  32  of the first patient support  30 . A first channel  33  is in communication with the recess  31  and is configured to receive a cable  13  extending from the first antenna array  12  to the MRI scanner. 
         [0078]    The walls of the recess  31  extending above the antenna array  12  may help position and/or retain a pediatric patient on the first patient support  30 . For example, the top surface  32  of each wall may be formed to support the arms of a patient. Optionally, it may be desirable to more firmly retain a patient to the support assembly  10  to prevent movement during imaging. A strip of material  41  made up of one side of a hook and loop fastener may be adhered along each side  36  of the patient support assembly  10 . One or more straps (not shown) made up of the other side of the hook and loop fastener may engage the strip of material  41  along one side  36  of the patient support assembly  10 , extend over the patient, and engage the strip of material  41  along the other side  36  of the patient support assembly  10 . 
         [0079]    The top surface  32  includes a second recess  35  configured to receive a second patient support  50 . The second patient support  50  may be used to support the head of a pediatric patient, and is also referred to herein as the head support  50 . Optionally, the second patient support  50  may be used to support, for example, arms or legs of adult patients. When the second patient support  50  is used to support the head of a patient, a contoured pad  47  may be inserted within the second patient support  50  to provide comfort and support for patient&#39;s head during the procedure. The head support  50  is configured to support a second antenna array  14 . A riser  49  may placed between the pivot mounts  160  to which a first end  72  of each arm  70  is mounted. The riser  49  helps position the contoured pad  47  at a desired height to support the patient&#39;s head and defines the second channel  37  which is in communication with the second recess  35  and is configured to receive a cable extending from the second antenna array  14  to the MRI scanner. The riser  49  includes an opening  48  along an upper surface  46  configured to receive the spine of the antenna array  14   
         [0080]    Referring next to  FIGS. 5-12 , the head support  50  includes a base  52  and two arms  70 . The base  52  is configured generally to connect each arm  70  to the first patient support  30 . According to one embodiment of the invention, the base  52  includes a front wall  54 , a rear wall  56 , and a central member  58  extending between the front wall  54  and the rear wall  56 . The central member  58  is joined to the front wall  54  and the rear wall  56  between a top edge  61  and a bottom edge  62  of each wall,  54  and  56 , and extends generally between each side  63  of the front wall  54  and the rear wall  56 . The central member  58  is generally planar with a channel  51  extending longitudinally along a center line  53  of the central member  58  between the front wall  54  and the rear wall  56 . 
         [0081]    The channel  51  is configured to receive a spine of the second antenna array  14 . The channel  51  has a width, W, and extends from the front wall  54  toward the rear wall  56  for a length, L, suitable to receive the spine of the second antenna array  14 . The cable connecting the second antenna array  14  to the second preamplifier module  24  extends out the front of the head support  50  and is routed to the second preamplifier module  24 . 
         [0082]    The front wall  54  includes a notch  55  extending from the top edge  61  of the front wall  54  to the depth of the channel  51  and for a width, W, of the channel  51 . The channel preferably slopes from the front to the rear of the head support  50  complementary to the shape of the spine of the antenna array  14 . The rear wall  56  may similarly include a notch  57  having a width, W, of the channel  51  and extending from a depth less than the depth of the notch in the front wall  54  and preferably above the height of the central member  58 . Optionally, the channel  51  may be reversed such that the deepest portion of the channel extends out the rear wall  56  and slopes upward toward the front wall  54 . As still another option, the channel  51  may have a substantially uniform depth and may accept the spine of the antenna array  14  in either orientation. 
         [0083]    The base  52  further includes a plurality of ribs  60  extending laterally across the width of the central member  58 . The ribs  60  protrude down from the central member  58  such that the bottom edges  62  of the front wall  54 , rear wall  56 , and each rib  60  extend a generally uniform distance below the central member  58  and are complementarily formed to a profile of the recess  35  in the first patient support  30 . 
         [0084]    Referring next to  FIGS. 13-17 , another embodiment of the base  52  and head support  50  is illustrated. The base  52  includes a front wall  54 , a rear wall  56 , and a central member  58  extending between the front wall  54  and the rear wall  56 . A raised portion  65  extends longitudinally along the middle of the central member  58  between the front wall  54  and the rear wall  56  and is configured to support the riser  49 . The raised portion  65 , in combination with the riser  49 , positions the second antenna array  14  and the contoured pad  47  generally in alignment with the first antenna array  12  to provide comfort and support for a patient extending between the first and second antenna arrays,  12  and  14 . The base  52  is configured to mount within the second recess  35  of the first patient support  30 . Any suitable alignment method may be used to position the base  52  within the second recess  35 , including, but not limited to, tabs, posts or a recess complementary to the outer periphery of the base  52 . A first and second pivot mount  160  extends along each side of the raised portion  65  and, in cooperation with a pivoting assembly  100 , connects each arm  70  to the base  52 . Optionally, the base  52  may be integrally formed with the first patient support  30 . 
         [0085]    Referring next to  FIGS. 18-20 , another embodiment of the base  52  is illustrated. The base  52  includes a first end  150  and a second end  150  opposite the first end  150 . A generally planar upper surface  152  extends between each of the first and second ends  150 . Side portions  154  extend from each of the first and second ends  150  along a portion of the upper surface  152  but not to the center line of the upper surface  152 , defining a space between the two side portions  154 . Each side portion  154  extends a sufficient distance along the upper surface  152  such that the pivoting assembly  100  may connect each arm  70  to the base  52  at each side portion  154 . Optionally, it is contemplated, that a solid side surface may extend between each  150  of the base  52 . A cavity  153 , generally open to a lower surface, is defined within the base  52  by the upper surface  152 , first and second ends  150  and each side portion  154 . A handle  156  is mounted to the interior side of the upper surface  152  and extends into the cavity  153 . As illustrated, the handle  156  forms a “T” shape; however, it is contemplated that the handle  156  may be of any suitable shape. The handle  156  is preferably contained within the cavity  153  such that the base  52  may be placed within the second recess  35  of the first patient support. Optionally, the handle  156  may extend beyond the cavity  153  and the second recess  35  may be configured to receive the portion of the handle  156  extending beyond the cavity  153 . 
         [0086]    Referring next to  FIGS. 21-24 , still another embodiment of the base  52  is illustrated. It is contemplated that the second support structure  50  may be used separately to support other anatomical regions, for example, arms or legs of adult patients during imaging. The base  52  is similar to the base  52  illustrated in  FIGS. 13-17  except it has a wider footprint. The lower surface of the base  52  includes at least a first and a second generally planar surface  67 . Optionally, the generally planar surface  67  may extend across the entire lower surface of the base  52 , as shown in  FIG. 24 . Each of the first and second surfaces  67  extend out beyond the pivot mounts  160  to provide stability to the second support structure  50  as each arm  70  is moved to an open position. The planar lower surface  67  may be set directly on a table of the MRI scanner and the entire support structure  50  may be positioned on the table as needed to accommodate the desired anatomical region to be imaged. 
         [0087]    A pivoting assembly  100  connects each arm  70  to the base  52 . According to one embodiment of the invention, a first pivoting assembly  100  connects the arm  70  to the front wall  54  and a second pivoting assembly  100  connects the arm  70  to the rear wall  56  of the base  52 . Both arms  70  connect to the base  52  proximate to the top edge  61  of the front and rear walls,  54  and  56  respectively. The first arm  70  is connected proximate to a first side  63  and the second arm  70  is connected proximate to the second side  63  of the base  52 . 
         [0088]    Referring also to  FIGS. 12 , and  29 - 32 , one embodiment of the pivoting assembly  100  includes a clip  110 , a cam  140 , and a mounting boss  170 . The clip  110  has an elongated body, having a first end  112 , a second end  114 , a thickness, and a width, Wc, greater than the thickness. A pair of arcuate members  120 , or jaws, extend from the first end  112 . Each arcuate member  120  first curves outward in a direction opposite from the other arcuate member  120  and then curves back inward toward the opposing arcuate member  120 . According to one embodiment, each of the arcuate members  120  are symmetrical about a center line  130  extending axially from the first end  112  of the clip. The arcuate members  120  define an opening  122  therebetween configured to receive the cam  140 . Each arcuate member  120  has, an outer periphery  125  and an inner periphery  124 . The inner periphery  124  includes one or more tabs  127  or recesses  128  configured to engage a complementary feature on the cam  140  and to define at least one desired spatial relationship between the cam  140  and the clip  110   
         [0089]    The clip  110  farther includes a slot  132  in communication with the opening  122  defined by the arcuate members  120 . The slot  132  extends from the opening  122  into the body of the clip  110 . The slot  132  may be straight or curved and preferably extends along the center line  130  of the clip. The slot  132  permits the arcuate members  120  to be deflected apart and return to an unbiased position as the clip  110  is rotated about the cam  140 . The force required to deflect the arcuate members  120  apart is a function of the length and width of the slot  132 . 
         [0090]    The clip  110  includes at least one locating hole  134  extending through the clip  110  proximate to the second end  114  of the clip  110 . According to one embodiment of the invention, two locating holes  134  spaced apart along the length of the clip  110  are configured to receive a complementary boss  76  protruding from one of the arms  70 . Two locating holes  134  prevent rotation of the arm  70  with respect to the clip  110 . Optionally, a single locating hole  134  having a non-circular periphery may be used to both align the clip  110  to the arm  70  and prevent rotation. As still another option, the clip  110  may include one or more bosses which engage holes in the arm  70 . 
         [0091]    The cam  140  is designed to have an outer periphery  142  complementary to the opening  122  defined by the arcuate members  120  of the clip  110 . The outer periphery  142  includes one or more tabs  144  or recesses  146  configured to engage the tabs  127  or recesses  128  of the inner periphery  124  of the opening  122  in the clip  110 . One of the tabs  144  and/or recesses  146  defines a home position. A complementary tab  127  or recess  128  on the clip  110  engaging the tab  144  or recess  146  that defines the home position causes the arm  70  to be aligned in a preferred relationship to the base  52  to reduce image artifacts resulting from overlapping loops in the antenna array  14 . 
         [0092]    The cam  140  is mounted in a fixed relationship to the base  52  of the head support  50 . An opening  148  in the cam  140  engages the boss  170  protruding from the base  52 . Optionally, the cam  140  may have a boss which engages an opening in the base  52 . The opening  148  is non-circular to prevent rotation of the cam  140  with respect to the base  52 . The opening  148  may also be non-symmetric such that the orientation of the boss  170  defines the angular orientation of the cam  140  to the base  52 . 
         [0093]    Referring next to  FIGS. 38-39 , a pivoting assembly connects each arm  70  along a side edge of the central member  58 . Referring also to  FIGS. 40-44 , the pivoting assembly is a hinge  200  having a first leaf  202  and a second leaf  204 . Each of the first leaf  202  and the second leaf include at least one mounting hole  205  configured to receive a securing member, such as a screw or a bolt, to mount the respective leaf to either the arm  70  or the base  52 . Each of the first leaf  202  and the second leaf  204  include at least one barrel section  206  connected along an edge of the leaf,  202  or  204 . Each barrel section  206  is generally cylindrical, has a hollow interior  208 , and is uniform in size to the other barrel sections  206 . The first leaf  202  and the second leaf  204  are positioned adjacent to each other such that the barrel sections  206  on the first leaf  202  align with the barrel sections  206  on the second leaf  204 , defining a chamber  210  having a first end  211  and a second end  212  into which a central assembly  220  may be inserted. 
         [0094]    The central assembly  220  is configured to provide a variable resistance to pivoting the hinge  200 . The assembly  220  includes a first insert  230  and a second insert  240  which define a first end  232  and a second end  242 , respectively, of the assembly  220 . Each insert,  230  and  240 , has a generally smooth outer periphery having a diameter configured to slidably engage the chamber  210  defined by the barrel sections  206 . The first end  232  of the assembly  220  extends generally to the first end  211  of the chamber  210  and the second end  242  of the assembly  220  extends generally to the second end  212  of the chamber  210 . 
         [0095]    The first insert  230  includes a generally cylindrical cavity  235  extending through at least a portion of the first insert  230 . A first end  234  of the first insert  230 , proximate to the first end  211  of the chamber  210 , may be a wall and define a stop for a pin  250  inserted into the central assembly  220 . Optionally, a flange or other protrusion may extend into the cavity  235  to define the stop. The first insert  230  extends for a distance from the first end  211  into the chamber  210 . The thickness of a wall of the first insert  230  is defined by the diameter of the outer periphery and the diameter of the cylindrical cavity  235 . 
         [0096]    The second insert  240  includes a generally cylindrical cavity  245  extending through the second insert  240 . A first end  244  of the second insert  240  is proximate to the second end  212  of the chamber  210 , and the second insert  240  extends for a distance from the second end  212  into the chamber  210 . A gap  216  is defined within the chamber  210  between the first insert  230  and the second insert  240 . At least a portion  241  of the cavity  245  is threaded. The thickness of a wall of the second insert  240  is defined by the diameter of the outer periphery and the diameter of the cylindrical cavity  245  and is preferably the same thickness as the wall of the first insert  230 . 
         [0097]    The pin  250  is configured to engage both the first insert  230  and the second insert  240 . A first end  252  of the pin  250  slidably engages the cavity  235  of the first insert  230 , and a threaded portion  256  of the pin  250 , proximate to a second end  254  of the pin  250 , engages the threaded portion  241  of the second insert  240 . The second end  254  of the pin  250  includes a recess  255  configured to accept a tool, for example a screw driver or box-head wrench, to rotate the pin  250 . As the pin  250  is rotated, the threaded portion  256  causes the pin  250  to move axially within the first and second inserts,  230  and  240  respectively. The pin  250  includes a flange  258  extending around the periphery of the pin  250 . The flange  258  has a thickness equal to or less than the thickness of the second insert  240  and is configured to engage the end of the second insert  240  within the chamber  210 . Multiple washers  260  and o-rings  270  are alternately disposed along the outer periphery of the pin  250  to substantially fill the gap  216  between the first insert  230  and the second insert  240 . 
         [0098]    Referring next to  FIGS. 33-36 , each arm  70  is preferably symmetric about a center line  75  such that the same arm  70  may be mounted to either side of the base  52  by rotating the arm  70  about the center line  75  to reverse its orientation. In a first embodiment of the invention, the arm  70  includes a first curved member  78  and a second curved member  80 , each curved member,  78  and  80 , extending from a first end  72  to a second end  74  of the arm  70 . A front face  82  of the arm  70  is joined to a first curved side face  84  of the arm  70  along a front edge  83  to generally define the first curved member  78 . A rear face  86  of the arm  70  is joined to a second curved side face  88  of the arm  70  along a rear edge  87  to generally define the second curved member  80 . 
         [0099]    Each of the front and rear faces,  82  and  86  respectively, extends beyond the respective side face,  84  and  88 , at the first end  72  of the arm  70  and is configured to receive the clip  110  of the pivoting assembly  100 . The portion of each of the front and rear faces,  82  and  86  respectively, proximate to the first end  72  is curved complementary to the arcuate members  120  of the clip  110 . A mounting hole  90  extends through each of the front and rear faces,  82  and  86  respectively, within the curved portion, to receive a fastener, for example, a screw or a bolt, which positively retains the arm  70  to the mounting boss  170  of the pivoting assembly  100 . At least one boss  76  protrudes from the interior surface of each of the front and rear faces,  82  and  86  respectively, toward the other of the front and rear faces to engage each of the locating holes  134  in the clip  110 . 
         [0100]    The interior surface of the front and rear faces,  82  and  86  respectively, further includes a curved retaining surface,  92  and  94  respectively. Each curved retaining surfaces,  92  and  94 , is spaced apart from the first or second curved side face,  84  or  88  respectively, defining a channel,  93  and  95 , configured to receive the second antenna array  14 . 
         [0101]    Each arm  70  further includes at least one support member  96  extending between the first curved member  78  and the second curved member  80 . In one embodiment of the invention, a first support member  96  extends between the curved members,  78  and  80 , proximate to the first end  72  of the arm  70  and a second support member  96  extends between the curved members,  78  and  80 , proximate to the second end  74  of the arm  70 . A space  97  defined by interior edges of each of the support members  96  and the curved members,  78  and  80 , provides a line of sight and permits access to a patient through the arm  70 . 
         [0102]    Another embodiment of the arm  70  is illustrated in  FIGS. 45-46 . Each arm  70  is preferably symmetric about a center line  75  such that the same arm  70  may be mounted to either side of the base  52  by rotating the arm  70  about the center line  75  to reverse its orientation. The arm  70  includes a central curved member  79  joined to a front face  82  along a front edge  83  and joined to a rear face  86  along a rear edge  87 . Each of the front face  82 , central curved member  79 , and rear face,  86  extend from the second end  74  of the arm  70 . Each of the front face  82  and rear face  86  extend to the first end  72  of the arm  70  with the central curved member  79  extending along only a portion of the distance between the second and first ends,  74 ,  72 . The width of each of the front and rear face  82 ,  86  is preferably equal to or greater than the width of a pickup assembly on the antenna array  14 , thereby defining a channel  77  between the front face  82 , central curved member  79 , and the rear face  86  configured to receive the pickup assemblies of the second antenna array  14 . Each of the front face  82  and rear face  86  also includes a mounting hole  90 , extending through each face,  82  and  86 , to receive a fastener, for example, a screw or a bolt, which positively retains the arm  70  to one of the pivot mounts  160 . Proximate the second end  74  of the arm, a recess  71  may be included to receive one side of a hook and loop fastener. A strap (not shown) made up of the other side of the hook and loop fastener may engage the fastener on one arm  70  and extend over the antenna array  14  to engage the fastener on the other arm  70 . 
         [0103]    A pair of retention members  400  extend from each of the front face  82  and the rear face  86  proximate to the second end  74  of the arm. Each retention member  400  includes a first surface  402  connected to either the front face  82  or the rear face  86  along at least a portion of the interior edge  401  of the face. The first surface  402  extends away from each respective face  82 ,  86  to an outer surface  404  of the retention member  400 . The outer surface  404  extends between the first surface  402  and a retaining surface  406  which is generally parallel to the first surface, forming a channel  405  defined by the first surface  402 , the outer surface  404 , and the retaining surface  406 . Each of the first surface  402 , outer surface  404 , retaining surface  406 , and the channel  405  defined therein are generally curved, corresponding to the curvature of the central member  79  of the arm  70 . Each retention member  400  is configured to receive a portion of the second antenna array  14  therein. 
         [0104]    A pair of washers  420 ,  430  may be inserted between the interior surface of each of the front  82  and rear face  86  where they engage the pivot mount  160 . A boss  415  on the interior surface is positioned such that the mounting hole  90  extends therethrough. The boss is preferably has a non-circular periphery and is complementary to an inner periphery  422 ,  432  of each washer  420 ,  432  respectively. The non-circular periphery prevents rotation of the washers  420 ,  432  as the arm  70  is moved between a first position and a second position. According to one embodiment of the invention, the first washer  420  may be made of viton and the second washer  430  may be made of nylon. Optionally, other materials may be used. As a fastener connects each arm  70  to the pivot mount  160 , the washers  420 ,  430  are compressed generating a friction force resisting rotation of the arm  70  about the pivot. Application of a force to the arm  70  of sufficient magnitude to overcome the resistance causes rotation of the arm  70  in the direction of the applied force. When the force is removed, the friction force is of sufficient magnitude to retain the arm at its current point at or between, the first and second positions. 
         [0105]    According to another embodiment of the invention, shown in  FIGS. 38-39 , each of the hinges  200  connects the arm  70  along a side edge of the central member  58 . A first hinge  200  connects the first side face  84  to the central member  58  proximate to one of the front wall  54  and the rear wall  56  and, a second hinge  200  connects the second side face  88  to the central member  58  proximate to the other of the front wall  54  and the rear wall  56 . The portion of each of the front and rear faces,  82  and  86  respectively, proximate to the first end  72  extends generally contiguous with the respective side face,  84  and  88 . 
         [0106]    Referring next to  FIGS. 37-38 , the second end of one of the arms  70  may be configured to receive a clip  110  or a hinge  200 . A second arm  70  may then be connected on each side of the head support  50 , providing a second pivot point for each arm. The combination of two arms  70  on each side permits a larger coil array  14  to be used with the head support  50 . 
         [0107]    Referring next to  FIGS. 25-28 , still another embodiment of the patient support structure  300 , which is configured to hold an antenna array  14  around a shoulder, is illustrated. The patient support structure  300  includes a first arm  302  and a second arm  304  connected by friction hinges  200  to a base  52 . The base  52  includes a channel  51  configured to receive the spine of an antenna array  14 , thereby positioning the antenna array  14  on the shoulder. The first arm  302  is configured to extend down the chest of the patient and the second arm  304  is configured to extend down the back of the patient. Each arm  302 , 304  holding the antenna array  14  against the patient. 
         [0108]    In operation, the modularity of the patient support assembly  10  permits the assembly to be configured for imaging the back of a patient, the head of a patient, or both simultaneously. The first antenna array  12  is placed within the first recess  31  if back and/or spine imaging is desired and the head support  50  and second antenna array  14  is placed in the second recess  35  if head imaging is desired. If included, the corresponding preamplifier modules,  22  or  24 , are also inserted into the patient support assembly  10 , and a patient may be placed on the assembly  10  for imaging. Each of the antenna arrays,  12  or  14 , is configured to detect nuclear magnetic resonance (NMR) signals resulting from the magnetic field generated by the MRI scanner. The NMR signals are transferred from each antenna array,  12  or  14 , via the connecting cable to the corresponding preamplifier module,  22  or  24 , and subsequently to the MRI scanner to generate a desired image. Optionally, if the electronic circuits of the preamplifier modules,  22  and  24 , are incorporated into the respective antenna arrays,  12  and  14 , the connecting cables may be configured to interface directly with the MRI scanner. 
         [0109]    If a patient&#39;s head is to be imaged, the arms  70  of the head support  50  may be rotated outward to an open position, see  FIG. 9 , in order to receive the patient. This permits easy placement and alignment of the patient within the head support  50 , particularly if the patient requires medical incubation and ventilation. Once the patient has been positioned, the arms  70  may be rotated back to the home position, see  FIG. 5 , to perform the, imaging. 
         [0110]    Rotation between the home position and the open position, or optionally, other angular positions, is facilitated by the pivoting assembly  100 . According to a first embodiment of the invention, one of the tabs  127  or recesses  128  on the clip  110 , along with a corresponding tab  144  or recess  146  on the cam  140 , defines the home position. For example, a tab  127  on the clip  110  engages a recess  146  on the cam  140  to positively retain the clip  110 , and consequently the arm  70  connected to the clip  110  in the home position. Rotating the arm  70  from the home position requires the arcuate members  120  on the clip  110  to be biased apart from each other such that the space between the ends of the arcuate members  120  is sufficient to permit the tab  127  to disengage from the recess  146 . Once the tab  127  has disengaged from the recess  146 , the arcuate members  120  return to an unbiased state to permit rotation of the arm  70 . Optionally, the cam  140  may be configured to such that the arcuate members  120  remain in a biased state requiring some force to rotate the arm  70 . 
         [0111]    The arm  70  is then rotated to the open position. The open position may be defined by a second recess  146  on the cam  140 . The tab  127  may consequently engage the second recess  146  and positively retain the arm  70  in the open position. Optionally, multiple tabs  127  positioned along the inner periphery of the arcuate members  120  may define multiple angular positions at which the arms  70  may be aligned. As still another option, a stop  145  may protrude from the outer periphery of the cam  140 . The arm  70  is then permitted to rotate until the tab  127  on the clip  110  engages the stop  145  on the cam  140 . 
         [0112]    According to another embodiment of the invention, the arm  70  may include a stop member  440  along the inner surface of each of the front face  82  and rear face  86  proximate to the first end  72  of the arm  70 . The stop member  440  includes a first end  442  which engages a complementary stop member mounted, for example and the face of the pivot mount  160 . Optionally, the first end  442  may engage the raised portion  65  of the base  52 , restricting further rotation toward the center of the patient support  50 , defining the home position. The stop member  440  also includes a second end  444  which engages a complementary stop member mounted, for example and the face of the pivot mount  160 . Optionally, the second end  444  engages the upper surface of the base  52 , restricting further rotation away from the center of the patient support  50 , defining the open position. 
         [0113]    After positioning the patient, the arm  70  may be returned to the home position by reversing the steps described above. When the arm  70  returns to the home position, the arcuate members  120  on the clip  110  must again be biased apart from each other such that the space between the ends of the arcuate members  120  is sufficient to permit the tab  127  to engage the recess  146 . The action of the arcuate members  120  provides both a tactile sensation to the operator as well as an audible click such that the operator is aware that the arm  70  is in the home position. Similarly, the tactile sensation and/or the audible click may indicate alignment of the arm  70  in any of the other desired positions corresponding to the recesses  146  on the cam  140 . The force required to pivot the arm  70  may be varied by adjusting the length and/or width of the slot  132  in the clip  110  according to the requirements of each application. 
         [0114]    According to another embodiment of the present invention, the hinge  200  permits torque adjustment for pivoting the arm  70  about the base  52 . The torque adjustment is achieved by inserting a tool into the recess  255  on the pin  250  and rotating the pin  250  into the first insert  230 . As the pin  250  is rotated, the threaded portion  256  of the pin  250  engages the threaded portion  241  of the second insert  240  to cause the pin  250  to move axially toward the first insert  230 . The flange  258  applies a force to the washers  260  and o-rings  270  located in the gap  216  between the first insert  230  and the second insert  240 . This force causes the o-ring  270  volume to displace toward the inner periphery of the chamber  210 . The increased interference between the o-rings  270  and the chamber  210  result in an increased torque to rotate the arm  70 . The radial torque can be adjusted by the end user or set to a preferred force during assembly. 
         [0115]    It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention