A COMPARISON OF COMPUTED TOMOGRAPHY-MYELOGRAPHY, MAGNETIC-RESONANCE-IMAGING, AND MYELOGRAPHY IN THE DIAGNOSIS OF HERNIATED NUCLEUS PULPOSUSAND SPINAL STENOSIS

The sensitivity, specificity, and accuracy of computed tomography (CT) -myelography, magnetic resonance imaging (MRI), and myelography in mak ing the diagnosis of herniated nucleus pulposus (HNP) and spinal steno sis were compared in a retrospective study involving 59 surgical proce dures in 57 patients who had all three tests performed preoperatively. One hundred nineteen levels were surgically explored for evidence of HNP and spinal stenosis. The results of each test were correlated with what was found at each surgical level explored. Overall, myelo-CT was the most accurate test for diagnosing HNP (76.4%) as well as the most sensitive (77.8%), whereas myelography was the most specific (89.2%). In making the diagnosis of spinal stenosis, myelo-CT and MRI were equ ally accurate (85.3%) and sensitive (87.2%), whereas myelography was t he most specific (88.9%). In a special subset of patients who had revi sion surgery, the accuracy rate in diagnosing spinal stenosis or HNP w as highest with MRI (84.9%), as was the sensitivity (69.2%) and specif icity (95%). According to the results obtained from this series of pat ients, myelo-CT seems to be the most sensitive and accurate test in di agnosing HNP and spinal stenosis, whereas myelography is the most spec ific, although no statistical significance was noted in this study. Ho wever, because MRI did compare favorably with myelo-CT in most instanc es, particularly in revision surgery, it may be the procedure of choic e due to its noninvasiveness and relative lack of side effects.