The value of metrizamide CT cisternography in the diagnosis of suprasellar and posterior fossa tumors

We have studied the diagnostic value of metrizamide CT cisternography (MCTC) in 22 patients. Six patients received metrizamide for the delineation of suprasellar tumors, 8 for posterior fossa tumors, and 8 for miscellaneous lesions, such as congenital cystic lesions and subdural fluid collections. Metrizamide with a concentration of 170 mgI/ml was used; 10 ml of it was introduced through the lumbar intrathecal route in every case. The patients were kept in a 15-degree Trendelenburg position, and Computed Tomography with an ACTA scanner (ACTA 200FS) was performed in principle one hour after the intrathecal injection and, if necessary, serially thereafter. The morphology of the subarachnoid space was well visualized in detail by CSF enhancement with metrizamide in all cases. The contours of the tumors in and around the basal cisterns were clearly shown; their relationship to the adjacent structures became more evident upon direct coronal section or upon coronal and sagittal reconstruction. It is suggested that the differential diagnosis in the suprasellar tumors and the C-P angle tumors can be made by means of the exact representation of the contours and extension of these tumors. MCTC can delineate the brain-stem glioma more accurately than the conventional CT scan: thus, it offers a definite advantage for the diagnosis and evaluation of those tumors which show isodensity on precontrast and no enhancement on postcontrast conventional CT scan. An arachnoid cyst or a porencephalic cyst can be diagnosed by the evaluation of the CSF-flow pattern. (author)