High field magnetic resonance evaluation of acoustic neurinomas

Eight acoustic neurinomas were studied with magnetic resonance imaging (MRI) at 1.5 tesla utilizing spin-echo T1 and T2 weighted images (WI). T1 WI identified the tumors best and provided more exacting anatomic relationships particularly for small lesions than did T2 WI. Intracanalicular tumors are well defined. All tumors were hypointense on T1 WI but were usually heterogeneous and had variable intensity on T2 WI. Several lesions became obscured on T2 WI because of isointensity with the adjacent cerebellum or CSF. High signal to noise ratio at 1.5 tesla permits thin section imaging (3 mm) at relatively short imaging times. T1 MRI was considerably superior to CT for the detection and anatomic definition of acoustic neurinomas.