[Diagnostic value of CT in spinal cord neurinomas]

The computed tomography (CT) in examination of the spine and spinal cord has rapidly advanced and its diagnostic value has been well documented. It is widely accepted that CT is very useful for the diagnosis of the spinal neurinomas, especially of dumb-bell tumors. In the last two years we have experienced with 11 cases of spinal neurinomas. These include 1 accessory neurinoma, 7 cervical neurinomas of dumb-bell type, 2 thoracic dumb-bell neurinomas, 1 intradural neurinoma in the conus medullaris and multiple neurofibromas in the cauda equina in one patient. The age distributed from 24 to 52 years, with an average of 41.5. In all of these patients except one, metrizamide CT was performed following a total myelography. In most of the cases, CT with and without an intravenous contrast medium injection was also carried out. The conventional radiologic examinations including plain radiography, tomography and angiography were done in most of the patients. Comparing with the results of those examinations, we reached the following conclusions: (1) metrizamide CT can disclose the superior border of the tumor which is often not visualized by conventional ascending myelography. The reconstruction CT clearly outlines the whole extent of the tumor. (2) The bony changes associated with a dumb-bell neurinoma, for example, the widening of the intervertebral foramen, can be found by plain CT in much earlier stage than by the plain roentgenogram. The findings can be more clearly using a "ReView" software program. (3) The extraspinal part of the dumb-bell tumor is shown in CT by an intravenous enhancement as a slightly high-dense, homogeneous mass with CT-number of approximately 70 HU. The capsule of the tumor is a little more enhanced in the most cases. (4) It is recommended to do a metrizamide CT with "ReView" technique when a tumor in the cauda equina is suspected on conventional myelography. (5) A tumor near the foramen magnum or in the upper cervical region is often overlOoked on metrizamide myelography. When a tumor in these regions is highly suspected on neurological examinations, it is also recommended to perform a metrizamide CT about 3 hours after conventional myelography.