A second look at unenhanced spinal magnetic resonance imaging of malignant leptomeningeal disease

The purpose of this study is to evaluate the use of unenhanced magnetic resonance (MR) imaging in identifying malignant leptomeningeal disease (MLD). Included in this study were fifty patients with evidence of leptomeningeal enhancement on post-gadolinium MR images and with cytological confirmation of MLD. Unenhanced, T1-weighted spin-echo (SE) MR images of the spine were analyzed for loss of cerebrospinal fluid (CSF) clarity, poor definition of the conus medullaris, thickened and clumped nerve roots, and nodules. Patterns of leptomeningeal enhancement on post-gadolinium, T1-weighted SE images were noted. Findings of MLD on unenhanced MR images were observed in 41 (85%) of 48 studies of the lumbar spine, 10 (50%) of 20 studies of the thoracic spine, and two (33%) of six studies of the cervical spine. In the lumbar spine, thickened and clumped nerve roots, poor definition of the conus medullaris, loss of CSF clarity, and nodules were observed with decreasing frequency. The signs of MLD on unenhanced images of the cervicothoracic spine included nodules and clouding of CSF. Patterns of leptomeningeal enhancement included linear, linear/nodular, nodular, enhancement of nerve roots, and stacking, with tumor filling the lumbosacral canal. Findings of MLD were present on 73% of the unenhanced MR images of the spine. Recognition of MLD on unenhanced MR images can guide the appropriate work-up and therapeutic approach.