MR imaging of subarachnoid spread of neoplasms

One hundred nineteen MR examinations of 40 patients with cytologically proved subarachnoid dissemination of neoplasms were retrospectively reviewed. In the brain, 12 of 54 unenhanced (22.2%) and seven of 20 gadolinium-enhanced studies (35%) were positive for leptomeningeal metastases. Four of 29 (13.8%) unenhanced (13.8%) and six of 16 enhanced spine studies (37.5%) were positive. Patients with non-central nervous system primary tumors were most likely to show MR findings of leptomeningeal dissemination (31.4%). Hematologic malignancies were least likely (5.6%). The overall sensitivity of unenhanced (19.3%) and enhanced (36.1%) MR examinations in patients with cerebrospinal fluid positive for neoplastic seeding is low