Regional blood flow in RT-9 brain tumors.

Regional blood flow (BF) was measured in RT-9 experimental brain tumors using carbon-14 labeled iodoantipyrine, the Kety tissue-exchange equations, and quantitative autoradiographic techniques. Blood flow was variable within tumor tissue, and the range of BF increased with increasing tumor size; the overall range was 6 to 138 ml/100 gm/min and the maximum range within an individual tumor was 55 ml/100 gm/min. In all but one case, mean tumor BF was less than that in the same anatomic region of the contralateral hemisphere (CBA). The magnitude of BF within individual tumor foci generally could be related to tumor size, location (intraparenchymal versus extraparenchymal), and the presence of necrosis or cysts; it was lower in the geometric centers than in the periphery of medium-sized and large tumors. Brain adjacent to tumor had higher BF's than the tumor periphery; generally, the BF in the brain adjacent to the tumor was less than that in the CBA. A global depression of BF was observed within tumor-free cortex and corpus callosum of the hemisphere ipsilateral to tumor implantation and primary growth, suggesting a hemispheric reduction in metabolic and functional activity.