Functional magnetic resonance imaging at 1 T: motor cortex, supplementary motor area and visual cortex activation.

Functional activation of the brain has been visualized using magnetic resonance imaging (MRI). Early studies used echo planar imaging and magnetic fields of 2 T and above. However, recent studies have successfully shown the activation of visual and motor areas of the brain using conventional clinical 1.5 T MRI systems. The purpose of the present study was to replicate these studies at a lower field strength. Eight motor and two visual activation studies were performed using a 1 T clinical scanner. Activation was seen in the contralateral motor cortex during motor stimulation in six of the eight volunteers. Activation was also documented within the contralateral supplementary motor area in four of the six volunteers with motor cortex activation. The supplementary motor area was located in the posteromedial aspect of the superior frontal gyrus. Both volunteers subjected to photic stimulation showed activation within the visual cortex. Results show that functional imaging can be successfully carried out with a 1 T clinical scanner. The size of the image intensity on activation change suggests that contrast may not be due solely to susceptibility changes.