Magnetic resonance imaging in the investigation of sensorineural hearing loss: is contrast enhancement still necessary?

High resolution T2-weighted magnetic resonance (MR) imaging has been propos ed as a rapid, inexpensive means of investigating patients with sensorineur al deafness, particularly to exclude vestibular schwannomas. Whether the ac cepted 'gold standard' of contrast-enhanced T1-weighted images can be omitt ed, however, remains controversial. Over a 22-month period the use of axial turbo-spin echo T2-weighted images (T2W) were prospectively compared with contrast-enhanced T1-weighted spin echo scans in the evaluation of 513 pati ents presenting with audiovestibular symptoms. A 2-D T2W turbo spin echo (T SE) sequence with 3 mm slices was used in 340 patients while a 3-D sequence with overlapping 1 mm slices was used in 173 patients. The T2-weighted ima ge findings were documented and subsequently compared with contrast-enhance d images. With the 2-D sequence 24 patients (25 lesions) had internal audit ory meatus (IAM)/cerebello-pontine angle (CPA) masses identified by contras t-enhanced T1-weighted images, all of which were seen on the T2-weighted TS E sequence; there was one false positive 'mass' on the T2-weighted scans an d one false negative case of IAM dural enhancement on T1-weighted imaging; six were considered normal initially on the T2-weighted images although thr ee were subtly abnormal in retrospect. With the 3-D sequence three acoustic neuromas were all identified correctly with no false positive and only one false negative result (labyrinthitis). The 2-D and 3-D images were judged technically inadequate for clinical assessment in 15 and nine per cent resp ectively. We conclude that mass lesions of the IAM/CPA can be reliably iden tified on T2W TSE imaging but labyrinthine lesions may be missed without co ntrast enhancement. This is of particular importance in planning the manage ment of neurofibromatosis type 2. Non-neoplastic disorders of the inner ear are also likely to be missed.