Integration of magnetoencephalography-generated functional brain maps into dose planning during arteriovenous malformation radiosurgery.

Background: Magnetoencephalography (MEG) can delineate critical regions of the cortex and facilitate conformal stereotactic radiosurgery (SRS) dose planning. Despite the substantial role of Gamma Knife® SRS in arteriovenous malformation (AVM) management, MEG-generated maps of critical regions have never been utilized to improve dose planning.

Purpose: To assess the value of integrating functional brain mapping using MEG with dose planning during treatment of brain AVMs with SRS.

Methods: This case series encompassed 5 patients with motor region AVMs. Noninvasive eloquent cortex mapping was achieved using a whole-head 306-channel Neuromag® Vectorview MEG System 5-10 days before SRS. On the day of SRS, the functional brain maps were integrated onto the intraoperative dose planning magnetic resonance imaging for Leksell GammaPlan® version 10. The median AVM volume treated was 12.7 cm(3), and 18 Gy was the median margin dose.

Results: Functional image integration of MEG improved the recognition of critical brain structures adjacent to the AVM. This facilitated anatomical planning designed to reduce the dose to adjacent critical structures while maintaining a therapeutic dose to the AVM target. The 5 patients had no adverse radiation effects during the follow-up.

Conclusion: Coregistration of MEG data improves the accuracy and dose sparing needed for optimal planning during Gamma Knife SRS.