Gadolinium enhanced MRI is the gold standard investigation for the detection of
acoustic neuroma. Non-contrast MRI sequences have been suggested as an alternative for screening examinations. In order to determine the utility of fast spin echo imaging, both
gadolinium enhanced T1 weighted images and fast spin echo T2 weighted images were acquired in 1233 consecutive patients referred for exclusion of
acoustic neuroma. Two radiologists independently recorded their findings. Fast spin echo T2 weighted images were evaluated with respect to the visibility of nerves within the internal auditory canals and allocated a confidence score for the presence or absence of
acoustic neuroma. 33
acoustic neuromas were identified. Only 56% were confidently identified on fast spin echo T2 weighted images alone;
gadolinium enhanced T1 weighted images were required to confirm the diagnosis in 44% of the cases, including 9 of the 10 intracanalicular tumours. However, when identification of two normal intracanalicular nerves is employed as the criterion of normality, the single fast spin echo T2 weighted sequence excluded
acoustic neuroma in 59% of this screened population. It is concluded that an imaging strategy intended to identify small intracanalicular
acoustic neuromas cannot rely on fast spin echo T2 weighted imaging alone.
Gadolinium enhanced T1 weighted imaging could be restricted to patients where fast spin echo images do not exclude
acoustic neuroma but this strategy requires continuous supervision by an experienced radiologist. In most practices the screening examination should continue to include a
gadolinium enhanced sequence in order to optimize the detection of small
acoustic neuromas.