The use of macroaggregates of radioiodinated human serum albumin in brain scanning.

Intra-arterially injected macroaggregates of radioiodinated human serum albumin were used in the detection of brain tumours in mice and in human subjects. The mean size of particle used was 29 mu. Brain-to-tumour ratios in ependymoblastoma-bearing mice ranged from 43.5:1 to 2.8:1. Autoradiographs of brain and tumour from sacrificed mice indicated that most of the macroaggregates were trapped within cerebral and cerebellar grey matter. Tumour retained little activity. Particles within small vessels did not cause complete obstruction, although temporary vessel spasm, cessation and reversal of flow were observed. Twelve patients with clinically evident brain tumours received carotid or vertebral injections of macroaggregates. Ten had histologically proved tumours, and six of these were correctly localized by external scanning. The quality of the scans was not superior to that obtained with other tracers currently in use. Because four patients developed transient neurological complications that could be attributed to the procedure, the clinical pilot study was terminated.