Utility of 4D digital subtraction angiography in operative localization of micro-arteriovenous malformations

Abstract

Background: Micro-arteriovenous malformations (mAVM), defined with a nidus smaller than one centimeter, can lead to intracranial hemorrhage. Surgery can be curative, but precise intra-operative localization of the nidus is often challenging. Finding the mAVM is particularly important when in an eloquent area. Due to their small size, mAVMs that are diagnosed on high quality angiography (occult on non-invasive imaging) may not be seen with intra-operative image guidance systems. Time-resolved 3D angiography (4D DSA) fuses the 3D volumes from different angiographic acquisition phases, and may help with mAVM localization. To illustrate the utility of 4D DSA in the localization of mAVMs for pre-operative surgical planning and during intra-operative resection.Methods: We present 4 surgically managed cases of ruptured paracentral mAVM where 4D DSA proved useful. First, 3D FLAIR MRI was used for cortical surface segmentation.4D DSA was then used to select two 3D volumes; one at time of maximal shunting (to show the mAVM nidus) and one with maximal venous filling (to show normal venous anatomy). These were merged using a neuronavigation system as 3D objects, fused to the 3D FLAIR volume, and used pre- and intra-operatively to precisely locate the mAVM.Results: Intra-operatively, segmentation of sulco-gyral and normal venous anatomy were used to confirm the accuracy of surgical planning. In all cases, the mAVM at ‘maximal shunt’ time guided the dissection to precisely locate the nidus. There were no instances of neurological deterioration with surgery, and complete resection was confirmed by indocyanine green fluorescent angiography, followed by delayed (3 months) catheter angiography.Conclusions: 4D DSA may be useful for surgical planning and precise intra-operative localization of mAVMs.