MRI in acoustic neuroma: a review of 35 patients

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Abstract
This retrospective study is aimed to assess the diagnostic efficacy of MRI in relation to contrast enhanced CT and air-CT-cisternography. MRI examinations were performed in 35 patients with suspected neurosensorial damage and suggestive of acoustic neuroma: 27 presented on MRI with unilateral tumors, 3 patients had a bilateral tumor and 5 patients were negative on all imaging modalities. The total number of acoustic neuromas detected was therefore 33. To date microscopic analysis has been performed on 12 tumors and histological data based on type Antoni A and Antoni B classification is available. Contrast enhanced CT detected 19 tumors, yielding an overall sensitivity rate of 58%. Air-CT cisternography identified an additional 5 tumors with a sensitivity rate of 100%. MRI identified 33 acoustic neuromas in 30 patients and was negative in 5 patients (sensitivity and accuracy 100%). Considering sensitivity in relation to location, MRI was much better than contrast enhanced CT for internal auditory canal (IAC) tumors (100% versus 36%) and better for cerebello-pontine angle tumors (CPA) tumors (100% versus 68%). The evolution of MRI technique, the various pulse sequences used and their actual selection is discussed. Seven patients received a paramagnetic contrast agent (Gadolinium-DTPA) with the additional benefit of a better demonstration of the tumor. The results suggest that MRI is the best non invasive technique for demonstrating acoustic neuromas.