Diagnosis of brain death: superiority of perfusion studies with 99Tcm-HMPAO over conventional radionuclide cerebral angiography.

The use of technetium-99m hexamethyl-propyleneamine oxime (99Tcm-HMPAO) in the diagnosis of brain death has been evaluated in 41 studies of 37 patients with severe brain injury, who were under the effect of drugs or when other diagnostic methods were equivocal. HMPAO studies were compared with conventional radionuclide angiography performed simultaneously by intravenous administration of HMPAO as a bolus. The ages of patients ranged from 4 months to 75 years. Dynamic flow images and 5-min static uptake images were acquired following bolus injection of 555 Mbq of 99Tcm-HMPAO. All patients showing no brain uptake were confirmed as brain-dead by standard clinical criteria, with no contradictory cases in the static study. In addition, all patients who were not brain-dead showed HMPAO uptake at least in the brainstem. Dynamic flow images were equivocal in five patients, four of whom had no uptake on static images and clinically confirmed brain death. In addition, two other cases showed "mismatched" dynamic and static images: in one case no perfusion was observed on flow images but uptake restricted to the posterior fossa was seen on static images; the other case showed perfusion on the dynamic study and static imaging revealed hemispheric uptake with no posterior fossa uptake. Static perfusion 99Tcm-HMPAO studies offer advantages over conventional brain scintigraphy, better results being due to adequate assessment of posterior fossa activity and avoiding equivocal studies.