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              Magnetic Resonance in Medicine                                                              979
























                                                                FIGURE 17  Cervical spine image. This high-resolution image of
                                                                a normal neck is shown for comparison with Fig. 16.

              FIGURE 15  Brain tumor. A sagittal image shows a large tumor
              present in the upper midsection of the patient’s brain. (Courtesy  extending almost the length of seven vertebrae. For con-
              of Dr. David Norman.)                             trast, Fig. 17 shows a high-resolution image of a normal
                                                                neck. In this case the spinal cord appears as a solid struc-
                                                                ture with no evidence of an internal cavity.
                                                                  Figure18isasurface-coilimageofthelowerspineillus-
                                                                trating disk herniation. Two normal invertebral disks are
                                                                seen in the upper portion of the image as relatively bright
                                                                structures. Near the center of the image the abnormal disk,
                                                                between the fifth lumbar and the first sacral vertebrae, is
                                                                seen to have herniated, or bulged, backward into the spinal
                                                                cord. Such herniations are a common cause of nerve injury
                                                                and irritation often leading to severe low back pain.


                                                                B. Current Trends
                                                                Magnets in which the patient is placed within a horizon-
                                                                tal gap between two magnetic pole faces are now being






















              FIGURE  16  Syringomyelia.  In  this  disease  a  fluid-filled  cavity
              forms  in  the  center  of  the  spinal  cord.  (Courtesy  of  Dr.  David  FIGURE 18 Herniated disk. This is a surface coil image of the
              Norman.)                                          lower spine. (Courtesy of GE Medical Systems.)
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