Leptomeningeal metastasis: a comparison of gadolinium-enhanced MR and contrast-enhanced CT of the brain.

We evaluated 14 consecutive patients with leptomeningeal metastasis prospectively, using both T1-weighted (T1W) gadolinium-DTPA-enhanced MR (Gd-MR) and contrast-enhanced CT (CE-CT). Thirteen had positive CSF cytology; the remaining patient had an atypical CSF lymphocytosis and primary CNS lymphoma. The patients (8M/6F) ranged in age from 8 to 70 years (median, 42 years). Tumor histology included 3 systemic and 2 primary CNS lymphomas, 3 breast carcinomas, 2 leukemias, 1 malignant schwannoma, 1 small cell lung cancer, 1 prostate cancer, and 1 melanoma. Both imaging methods demonstrated parenchymal volume loss equally well in all patients. Gd-MR revealed abnormal enhancement of meninges or parenchyma in 10 patients, including all 5 patients with positive CE-CT. Neither technique revealed any foci of abnormal enhancement in 4 patients. Gd-MR was superior to CE-CT in demonstrating and quantifying enhancing subarachnoid and parenchymal nodules in 6 patients and in demonstrating sulcal, dural, cisternal, tentorial, and ependymal enhancement. Our findings indicate that T1W Gd-MR is the preferred imaging modality in leptomeningeal metastasis and suggest that CE-CT is unnecessary.