99mTc-HMPAO is one of several brain-specific agents that can be used for brain death scintigraphy. The others are 99mTc-EDC and 99mTc-DTPA. Brain-specific agents cross the blood-brain barrier are preferred because their interpretation is not dependent on the quality of the bolus and proper acquisition of the flow phase, since delayed images can be obtained (as in this case) which are definitive for the assessment of cerebral blood flow.