MR imaging of the brain in neurofibromatosis

Fifteen children and young adults with neurofibromatosis underwent CT and MR imaging (0.5-T superconducting magnet). Seven had optic gliomas and five had other intracranial neoplasms. Before thin-section MR imaging became available, CT was superior for demonstrating the optic nerves, although MR imaging better delineated tumor spread to the optic chiasm and tract. MR imaging was superior for demonstrating other gliomatous lesions associated with neurofibromatosis. Most lesions had long T1 and T2 values and were best seen on T2-weighted images. MR imaging revealed small areas of increased signal intensity on T2-weighted images in nearly half the patients. These lesions were not apparent on CT and were usually located in the globus pallidus, but were seen in many areas of the brain, commonly in the white matter, and in the brain steam and the cerebellar peduncles. Their exact etiology is unknown. Their imaging characteristics are somewhat different from those of gray matter. They may represent hamartomas or areas of glial scarring. Differentiation from a small glioma is presently not possible on a single examination