Variant flow patterns in radionuclide cerebral imaging performed for brain death.

Radionuclide cerebral imaging (RCI) is a commonly used technique for detection of intracranial blood flow in patients with clinically suspected brain death. In 115 studies performed on 95 patients in a six-year period at the Geisinger Medical Center, a number of variant flow patterns have been observed. Although all have been described previously, there has been no review of these patterns on studies performed for brain death. The significance of normal blood flow, absent blood flow, isolated superior sagittal sinus activity, luxury perfusion, hypoperfusion, hemiperfusion, and jugular venous reflux is discussed. Any demonstrable intracranial blood pool activity is presently considered to counter a diagnosis of brain death, except that jugular reflux renders an examination uninterpretable. Technique must be top quality but, even so, RCI cannot evaluate basilar brain flow. Nonetheless, RCI is a valuable adjunct in helping to establish the clinical diagnosis of brain death.