Abstract
BACKGROUND: Management of brain arteriovenous malformations (bAVMs) close to motor areas with stereotactic radiosurgery (SRS) is challenging due to the risk of radiation-related morbidity. This risk stems from the increased radiosensitivity of the surrounding white matter (WM), which is crucial for preserving motor function. PURPOSE: This study aimed to investigate the application of diffusion tensor imaging (DTI)-based magnetic resonance (MR) tractography SRS planning for bAVMs, with a focus on sparing WM tracts during CyberKnife treatment. The goal was to minimize radiation exposure to motor-relevant WM tracts, thereby reducing the risk of posttreatment motor deficits and improving patient outcomes. MATERIALS AND METHODS: The DTI-based reconstructions of WM tracts from 22 patients with motor-eloquent bAVMs were integrated into the CyberKnife planning system and co-registered with treatment planning images. The WM tracts, located within normal tissue and not overlapping with the target volume of the bAVMs, were delineated as dose constrain volumes. Initial treatment plans, excluding WM tracts, were compared with WM tracts constraint plans that incorporated these tracts to assess and compare radiation doses delivered to WM structures in both plans. RESULTS: With WM tracts constraint, maximum dose of WM tracts can be reduced by 17.68% on average (range 13.61%-33.29%), thus from 20.81 Gy to 17.13 Gy (P < 0.01). The dose-volume histogram analyses have shown that a significant reduction was achieved for WM tracts (V50% P < 0.01, V40% P < 0.01, V30% P < 0.001, and V20% P < 0.05). There was no significant impact on planning target volume coverage (96.26 ± 0.68 vs. 96.13 ± 0.47, P = 0.587) and all dose constraints for organs at risks and other planning parameters were fully satisfied. CONCLUSION: Integrating DTI-based MR tractography into CyberKnife SRS for motor-eloquent bAVMs was feasible and preserves critical motor tracts without compromising radiation therapy goals.