Uses and limitations of indocyanine green videoangiography for flow analysis in arteriovenous malformation surgery.

Intra-operative indocyanine green (ICG) videoangiography is a useful addition to cerebrovascular neurosurgery. ICG videoangiography is useful in different phases of arteriovenous malformation (AVM) surgery. Additionally, it can be used to perform semi-quantitative flow analysis. We reviewed our initial assessment of 24 patients who underwent ICG videoangiography during AVM surgery to assess the utility and limitations of the technique as well as to demonstrate semi-quantitative flow analysis, a new capability of ICG videoangiography. Over the course of 3 years, we performed 49 ICG videoangiographies in 24 patients with AVM. In 85% of the pre-resection videos, ICG was useful in localising the arterial feeders, the draining veins and the nidus. Intra-resection ICG videos were recorded for eight of the 23 patients (the ICG from one patient was missing). Post-resection ICG videos were recorded for 14 out of the 23 patients, which were useful in confirming no evidence of nidus in the exposed resection cavity and an absence of flow in the main draining vein. Semi-quantitative flow analysis was performed in eight patients with superficial AVM. The average T(½) peak intensities (time to 50% of peak intensity) were 32 s, 33.5 s, and 35.6 s for the arterial feeder, the draining vein and normal cortex, respectively. The arteriovenous T(½) peak time was 1.5 s, and the arteriocortex T(½) peak time was 3.6 s. The T(½) peak fluorescence rates were 84 average intensity of fluorescence (AI)/s, 62.9 AI/s and 28.7 AI/s, for the arterial feeder, the draining vein and normal cortex, respectively. Only one patient of 23 (4.3%) showed residual AVM on post-operative digital subtraction angiography or CT angiography despite negative intra-operative ICG. ICG videoangiography is a useful addition to AVM surgery, but it has some limitations. Flow analysis is a new capability that allows for semi-quantitative AVM perfusion analysis.