This study is performed to confirm a clinical diagnosis of brain death. Brain-specific or lipophilic tracers which cross the blood-brain barrier (eg, Tc-99m HMPAO or Tc-99m ECD) are preferred over non-specific or lipophobic tracers (eg,Tc-99m DTPA), which are considered angiographic radionuclides.

source: newcastlenuclearmedicine.com.au