Consistency between Targets Delineated by Angiography, Computed Tomography, and Magnetic Resonance Imaging in Stereotactic Radiosurgery for Arteriovenous Malformation.

BACKGROUND: Target identification is important for radiosurgery for arteriovenous malformations (AVMs). Targets defined by different imaging modalities may be inconsistent in practice.
OBJECTIVES: The goal of this study is to review and analyze the consistency between targets defined by different imaging modalities in radiosurgery for AVMs.
METHODS: From March 2007 to June 2011, AVM patients for radiosurgery whose targets were delineated by angiography/computed tomography (CT)/magnetic resonance imaging (MRI) were reviewed. Spetzler-Martin grades, hemorrhage history, and treatment volumes were checked. Dice similarity coefficients (DSCs) between targets were calculated and analyzed.
RESULTS: Twenty-three patients were enrolled. The mean DSCs were between 0.37 and 0.51 for targets by different modalities. There was no significant difference in DSCs regarding Spetzler-Martin grades and hemorrhage history. For CT-delineated target volumes <3 cm3, MRI-delineated target volumes <5 cm3, and angiography-delineated target volumes <2 cm3, the DSCs between the different image modalities were significantly decreased.
CONCLUSIONS: Consistency between targets delineated using different image modalities was likely to be unsatisfactory and worsen significantly in niduses with volumes <5 cm3. An iterative multimodality approach to confirm the delineated targets of AVMs is suggested to be indispensable for robust treatment in radiosurgery.