Benefit of Multimodality Image Acquisition in the Treatment Planning of Stereotactic Radiosurgery (SRS) of Arteriovenous Malformation (AVM)

Background: Digital subtraction catheter angiography (DSA) is utilized at our institution in addition to MRI for treatment planning of arteriovenous malformations (AVMs) stereotactic radio surgery (SRS).We hypothesized MRI over-predicts the size of AVM nidus and compared MRI alone versus combined imaging as input for target delineation for AVM SRS.Methods: 90 AVMs from 78 patients treated with SRS at our institution from March 2013 to July 2017 were retrospectively analyzed.A Neuroradiologist contoured the AVM nidus from MRI alone in a blinded manner.In addition to volumetric parameters from the treatment planning software, DICOM images were exported to abstract the spatial information of the contoured volumes.Results: Of the evaluable 81 AVMs from 69 patients, all underwent MRI and DSA.40 patients (58%) were male and median age was 36 (range 3-72).Median target volume from SRS treatments, AVM nidus generated by MRI alone and DSA alone were 1.33 cm 3 , 1.13 cm 3 , and 1.30 cm 3 , respectively.The ratios of these volumes were also not significantly different, refuting our hypothesis.Interestingly, a strong agreement was found between the target and DSA-generated volume.Spatial analysis of these volumes with DICE and Jaccard Index (JI) revealed significantly greater similarity and overlap between the target and DSA-generated volume than with MRI-generated volume (p < 0.0001).Conclusions: SRS target AVM volume at our institution is significantly more similar to DSA-generated volume than that of MRI.This finding indicates our neurosurgeons and neurovascular surgeons rely more on the vascular data of DSA containing temporal and spatial information, albeit in a two-dimensional (2D) format when creating the target AVM nidus volume.Furthermore, a significant number of cases showed disagreement between the volumes delineated by MRI and DSA.Together, these findings support the need for multimodality image acquisition for effective treatment planning of AVM SRS.