Four patients were shown to have ischemic injury to the posterior limb of the internal capsule on brain SPECT with 99mTc-HMPAO. These findings were later corroborated by transmission CT scans in three patients. In the interpretation of high-resolution SPECT imaging of regional cerebral blood flow, it is important to inspect the deep white and gray matter activity for asymmetry and perfusion deficits. The blood flow to the diencephalon, which is critical for brain function, can be imaged with high-resolution brain SPECT. The early ascertainment of ischemic changes in the diencephalon may lead to important patient management decisions.