DETECTION OF CEREBROSPINAL-FLUID METASTASIS - CT MYELOGRAPHY OR MR

PURPOSE: To determine the sensitivity of contrast MR versus myelograph y followed by CT in the detection of cerebrospinal fluid metastases in children with primary central nervous system tumors. METHODS: Thirty- three patients who had primary central nervous system malignancies had spinal MR with gadolinium within 2 weeks of a myelogram followed by C T. MR technique included T1-weighted image sequences of the entire spi ne with and without gadolinium. CT scans were routinely performed at T -12 to L-2, L-4 to S-1, and foramen magnum to C-2. All studies were re viewed blindly; the number, character, and location of all metastases was recorded and the results of the two studies compared. Cerebrospina l fluid cytologic findings were recorded for each patient, and compare d with the results of the imaging studies. RESULTS: Seven of the 33 pa tients had metastases detected; metastases were seen on both MR and my elography followed by CT. However, MR showed 24 lesions and myelograph y followed by CT showed only 15. When a lesion was seen on both MR and myelography followed by CT, the MR was usually more convincing. Super ficial lesions seen on MR sometimes would be missed on myelography fol lowed by CT. Both MR and myelography followed by CT were quite sensiti ve in the detection of small lesions (2 to 3 mm) when present on spina l nerve roots. Whereas MR showed multiple lesions not seen on myelogra phy followed by CT, CT failed to show any metastases not seen on MR. I maging studies showed metastases in 3 patients who had normal cytologi c findings. CONCLUSIONS: MR shows significantly more cerebrospinal flu id metastases than myelography followed by CT.