FUNCTIONAL BRAIN IMAGING AT 1.5-T USING CONVENTIONAL GRADIENT-ECHO MR-IMAGING TECHNIQUES

There is considerable interest in the use of MR imaging to study brain function. Recently, it has been demonstrated that small changes in si gnal intensity occur in the visual cortex in T2-weighted imaging in r esponse to appropriate visual stimuli. Similar responses to activation have also been recorded in motor cortex as well as frontal lobes. To date most of these studies have been carried out at very high field st rength or they have used echo planar imaging. We report our preliminar y results showing that the effects of activation of visual and motor a reas of the brains of normal volunteers can be recorded using conventi onal MR imaging methods on a standard 1.5 T clinical scanner. Using gr adient-echo imaging sequences, we have been able to map activated visu al and motor cortex with high spatial resolution in multiple planes, a nd are using this technique to examine the relationship between physio logical response and stimulus parameters. Signal changes of the order of 2-12% in images with TE = 45 msec, TR = 120 msec, and alpha = 40-de grees, permit excellent depiction of the regions affected.