Scintigraphic evaluation of brain death with 99mTc-d,l-hexamethyl-propyleneamine oxime (HMPAO)

Lately, the criteria of brain death is being discussed. Cerebral scintigram, especially scintigraphic evaluation of brain death by dynamic study, has been previously reported. Cerebral imaging using radiolabeled amines such as 123I-IMP N-isopropyl-p-iodoamphetamin (IMP) or 99mTc d,l-hexamethyl-propyleneamine oxime (HMPAO) offers a significant information of brain death by the finding of "non visualized brain". However, the dynamic scintigram acquired during the bolus injection of 99mTc-HMPAO provides an additional information of brain death by classical "hot nose sign". 99mTc-HMPAO is able to be administered relatively in a large amount of dose. This cerebral perfusion tracer is lipophilic and remains in the central nervous system, which characterize its role as an reliable indicator of cerebral blood flow. As a result, this compound became suitable for the non-invasive study of brain circulation when the diagnosis of brain death is uncertain. We report a case of brain death in which diagnosis was made by the classical "hot nose sign" in dynamic scintigraphy performed when 99Tc-HMPAO was injected as well as the SPECT which showed a lack of cerebral visualization at the equilibrium state. As far as we are informed, this additional procedure used in the diagnosis of brain death has not reported before. The importance of performing a dynamic scintigram at the administration of 99mTc-HMPAO is also discussed in this report.