CEREBRAL VENOGRAPHY - COMPARISON OF CT AND MR PROJECTION VENOGRAPHY

OBJECTIVE. The purpose of the study was to show equivalence or superio rity of CT venography compared with the existing test of choice-MR ven ography-in the evaluation of dural sinus thrombosis and in the identif ication of cerebral veins and dural sinuses. MATERIALS AND METHODS. Tw enty-four patients underwent both CT and MR venography of the intracra nial venous circulation. Seventeen patients were examined for suspecte d dural sinus thrombosis. Four patients underwent projection venograph y to assess tumor invasion of a major dural sinus. The remaining three patients were examined for cavernous sinus thrombosis, arteriovenous malformation, and an elevated jugular bulb. Without knowledge of the p atients' case histories, two radiologists evaluated each CT venogram a nd MR venogram. The radiologists then arrived at a consensus regarding the absence or presence of dural sinus thrombosis. Later, the radiolo gists conducted a second interpretation with knowledge of the patients ' clinical histories during which time MR and CT venograms were compar ed with regard to the advantages and disadvantages of each imaging tec hnique. In addition, the venograms were assessed for the presence of 1 2 different venous structures. Projection venograms were displayed usi ng a maximum-intensity-projection (MIP) algorithm, and the individual source images were also evaluated. The CT venograms were also displaye d using shell-MIP and integral display algorithms. RESULTS. Using MR v enography, the two radiologists diagnosed dural sinus thrombosis in ei ght of the 17 patients with suspected dural sinus thrombosis, In these eight patients, the diagnosis was also made with CT venography. The d iagnosis was confirmed by follow-up CT in four patients and by follow- up MR imaging in two patients. The MIP algorithm did not allow direct visualization of thrombus by either the CT or the MR imaging technique ; however, the CT integral display algorithm enabled direct visualizat ion of thrombus on the three-dimensional projection venograms. The sys tematic comparison of imaging techniques showed that CT venography rel iably reveals all cerebral veins and sinuses when they are seen with M R venography, In addition, CT venography more frequently visualizes si nuses or smaller cerebral veins with low flow as compared with MR veno graphy. CONCLUSION. Cerebral CT venography is superior to MR venograph y in the identification of cerebral veins and dural sinuses and is at least equivalent in the diagnosis of dural sinus thrombosis. CT venogr aphy is a viable alternative to MR venography in the examination of pa tients with suspected dural sinus thrombosis.