Extra-Axial Tumors

Extra-axial tumors most commonly arise from the meninges, calvarium, or skull base. Localization of a lesion as extra-axial or extra-cerebral in origin has significant clinical importance in terms of treatment planning and predicting prognosis. High-resolution fat-suppressed imaging is crucial for specific evaluation of the skull base, and correlation with computed tomography (CT) is often helpful in these cases. This unit presents basic MRI protocols for imaging extra-axial tumors in specific locations; sequence modifications are discussed where necessary. The sequences described in this unit are based on a 1.5 T scanner (GE Medical Systems), but can be expected to be equally applicable to other field strengths and scanners from other manufacturers.