ARTERIOVENOUS MALFORMATION ANIMAL-MODEL FOR RADIOSURGERY - THE RETE-MIRABILE

PURPOSE: To study the effects of single-dose radiation on the porcine rete mirabile, a tangle of microvessels that mimics human arteriovenou s malformations of the brain. METHODS: Eight retia mirabilia received a single dose of radiation under stereotactic location with digital an giography and CT. The following doses were applied: 20, 30, 40, 50, 60 , 70, 80, and 90 Gy. The animals were followed up for a period of 7 mo nths. Findings at neurologic examination, serial angiography, and hist opathologic examination were analyzed. RESULTS: Progressive occlusion as observed by angiography corresponded to the histopathologic finding of intimal hyperplasia; that is, marked thickening of the vessel wall , progressing to occlusion of the vascular lumen, and associated throm bosis. A direct dose response was noted for these changes. Neurologic findings were related to the dose distribution and to histologic findi ngs in structures adjacent to the rete mirabile. CONCLUSION: The rete mirabile is an excellent model by which to study the radiologic and hi stologic effects of single-dose radiation to the microvasculature of t he central nervous system.