Evaluation of auditory cortex activation by using silent FMRI

Purpose: To evaluate auditory cortex activation evoked by pure-tone stimulus using silent functional magnetic resonance imaging (FMRI). Material and Methods: Nine volunteers with normal hearing as determined with pure-tone audiometry were studied. Auditory cortex activation was evoked by pure-tone stimuli presented monaurally at 1,000, 2,000, and 4,000 Hz. Images of auditory cortex activation were obtained using silent and conventional FMRI techniques. Heschl's gyrus activation was evaluated by the number of voxels exceeding a predetermined significance level (P < .0001). Results: In both techniques, all subjects showed activation in the Heschl's gyrus. Silent FMRI detected more activation in all studied frequencies compared with the conventional FMRI. The observed difference in the Heschl's gyrus activation between the techniques reached statistical significance for 1,000 Hz frequency (P < .05). Conclusions: The amount of Heschl's gyrus activation detected with silent FMRI is greater than that of conventional FMRI. Silent FMRI technique can be used to acquire functional images of the auditory cortex without the confounding effects of scanner noise.