[Comparison of cerebral blood flow in primary visual cortex by administration of 99mTc-ECD while having eyes open or...

Four healthy volunteers were administered 99mTc-ECD while having their eyes open or closed (by an eye mask) on different days and the accumulation of the tracer in their primary visual cortex was compared. The accumulation in the cerebellum and the primary visual cortex was about the same when the volunteers were administered the tracer while having their eyes closed. On the other hand, the accumulation was higher in the primary visual cortex than the cerebellum when the volunteers were administered the tracer while having their eyes open. In the primary visual cortex, the accumulation of the tracer was 15% higher on the average when the tracer was administered while having their eyes open than the value obtained while having their eyes closed. It was assumed that 99mTc-ECD depicted the increase of the regional cerebral blood flow at natural state of opened eyes without active stimuli such as photic stimulation.