Session Item

Radiosurgery (SRS) obtain a successful obliteration of arteriovenous malformations (AVMs). Radiation injury to the vascular endothelium induced the proliferation of smooth-muscle cells and the elaboration of extracellular collagen, which leads to progressive stenosis and obliteration of the AVM nidus thereby eliminating the risk of hemorrhage. The advantages of SRS, compared to microsurgical and endovascular treatments, are that it is noninvasive, has minimal risk of acute complications, and is performed as an outpatient procedure. The primary disadvantage of SRS is that cure is not immediate; thrombosis of the lesion is achieved in most cases, but it does not occur until 2-3 years after treatment. SRS has been shown to be less effective for lesions over 10 cc in volume. Aim of the study is to describe a monoistitutional series of AVMs pts treated with CyberKnife® system (CK) in collaboration with dedicated neuroradiologist

All pts performed angiography, CT-angio and MR-angio and were evaluated by an expert neuroradiologist before CK treatment. All imaging data were accurately co-registered in the CK-TPS and used for target contouring delineation. The delineation of AVM targets was as follows: AVM with prior embolization targets included nidus, embolization areas and some small draining veins; for pts without embolization, the target was nidus. All pts received a single fraction of radiation. The PTV was equal to GTV. Follow-up was performed with MR-angio after 2-3 months and angiography 1 year after the treatment

From Dec 2017 to May 2021, 9 pts (4m, 5f), mean age 42 (18-56) with AVMs were treated with CK. AVMs were located within cerebellum (3), temporal lobe (3), parietal lobe (2) and frontal lobe (1). 6 pts had previously undergone endovascular embolization. Median GTV was 3,65 cc (0,09-11,99) and median marginal dose was 19 Gy (18-21) with median isodose prescription of 80% (74-85). PTV median coverage was 99,76% (97,54-100) with median PTV CI of 1,6 (1,16-2,14). 6 pts completed the RT course, 1 pt had asymptomatic brain radionecrosis 19 months after the RT, 5 pts had > 1-year angiographic follow-up: 4 had stable disease and 1 AVM obliteration

A specialized team approach is necessary for CK treatment of AVMs, including an SRS expert radiation oncologist and medical physicist, and an interventional neuroradiologist. CK is safe and effective for AVMs treatment, but long-term data are needed