Outcome of cerebral arteriovenous malformations after linear accelerator reirradiation.

BACKGROUND: The aim of this study was to evaluate the clinical outcome of patients undergoing single-dose reirradiation using the Linear Accelerator (LINAC) for brain arteriovenous malformations (AVM). METHODS: A retrospective study of 37 patients with brain AVM undergoing LINAC reirradiation between April 2003 and November 2011 was carried out. Patient characteristics, for example, gender, age, use of medications, and comorbidities; disease characteristics, for example, Spetzler-Martin grading system, location, volume, modified Pollock-Flickinger score; and treatment characteristics, for example, embolization, prescription dose, radiation dose-volume curves, and conformity index were analyzed. During the follow-up period, imaging studies were performed to evaluate changes after treatment and AVM cure. Complications, such as edema, rupture of the blood-brain barrier, and radionecrosis were classified as symptomatic and asymptomatic. RESULTS: Twenty-seven patients underwent angiogram after reirradiation and the percentage of angiographic occlusion was 55.5%. In three patients without obliteration, AVM shrinkage made it possible to perform surgical resection with a 2/3 cure rate. A reduction in AVM nidus volume greater than 50% after the first procedure was shown to be the most important predictor of obliteration. Another factor associated with AVM cure was a prescription dose higher than 15.5 Gy in the first radiosurgery. Two patients had permanent neurologic deficits. Factors correlated with complications were the prescription dose and maximum dose in the first procedure. CONCLUSION: This study suggests that single-dose reirradiation is safe and feasible in partially occluded AVM. Reirradiation may not benefit candidates whose prescribed dose was lower than 15.5 Gy in the first procedure and initial AVM nidus volume did not decrease by more than 50% before reirradiation.

Resident peritoneal inflammatory cells are pivotal in the development of experimental atherosclerosis.

AIM: Based on evidence that ionizing radiation can ameliorate chronic and autoimmune diseases in patients and experimental animals, we investigated the effects of radiation on the induction and development of experimental atherogenesis. METHODS: Male New Zealand rabbits were divided into 5 groups and given an atherogenic diet for 90 days. Peritoneal and thoracic areas (9 Gy) were irradiated on the 1st and 45th days for groups 1 and 2, the 45th day for groups 3 and 4, and not at all for group 5. Prior to irradiation, the peritoneal cavity of animals from groups 1 and 3 was washed with buffered saline. Cells collected by peritoneal washing were reinfused into the peritoneal cavity of the same animal after irradiation. Animals from groups 2 and 4 were intraperitoneally injected with saline as a control. RESULTS: Despite similar lipid profiles among the experimental groups, the percentage of aortas covered by plaques was remarkably reduced (p<0.001) among animals submitted to irradiation (groups 2 and 4). These differences were completely abolished in irradiated animals reconstituted with their own peritoneal cells. CONCLUSIONS: These findings point to an important role of resident inflammatory peritoneal cells in experimental atherogenesis.