[Demonstration total brain infarct with radioisotope angiography]

In the field of organ transplantation and in brain death patients where intensive-care measures may seem superfluous, the demonstration of cessation of cerebral blood flow by X-ray angiography is generally agreed to be the diagnostic procedure of choice to prove irreversible loss of cerebral function. There are, however, certain drawbacks involved in X-ray angiography. Arterial puncture is necessary. Furthermore, the procedure can be time-consuming, thus making the continuation of adequate intensive-care measures more difficult. At the same time the circulatory condition may worsen causing hypoxic damage to the organ to be transplanted. In the present paper, the authors report on 13 patients with clinical signs of brain death where cessation of cerebral blood flow was demonstrated atraumatically by intravenous radioisotope angiography (RIA) using a multicrystal gammacamera (Baird Atomic) and the bolus-injection technique with 99m Tc-pertechnetate. Nine patients had severe brain injuries, 2 patients had brain tumours, 1 patient had encephalitis and 1 patient had suffered prepartal thrombosis of the sinus sagittalis. In all patients EEG recordings were isoelectric. At the time when the RIA was performed systolic blood pressure had decreased to 62-85 mmHg (x = 71 mmHg), while body temperature had declined to 31-36,5 degrees C (x = 34 degrees). According to the present results, which were all confirmed by subsequent bilateral carotid X-ray angiography, total brain infarction is unequivocal when the following criteria are satisfied using RIA: 1. when the radioisotope bolus flows along the common carotid arteries but does not proceed any further than to the base of the skull or around the scalp structures, 2. when, at the moment when the radioactivity outlines the scalp structures, neither the intracranial arteries nor the capillary bed or the venous sinuses are visible, 3. when the time-activity curves across the hemispheres show simply a plateau of low count rate without the activity peak typical for cerebral tracer circulation and 4. when the activity peak, typical for venous outflow, is missing from the time-activity curves for the cervical areas. In 12 patients with extremely reduced cerebral blood flow it was demonstrated that the RIA findings were clearly different from those obtained at brain death. Moreover, not one of 438 other patients undergoing RIA exhibited the same features which were associated with brain death. The authors conclude that RIA involves the same degree of safety as X-ray angiography in the diagnosis of total brain infarction but is superior to the latter when the diagnostic procedure has to be performed quickly, thus reducing the risk of any further damage to a prospective donor organ.