Initial experience with exoscopic-based intraoperative indocyanine green fluorescence video angiography in cerebrovascular surgery: A preliminary case series demonstrating feasibility, safety and next generation handheld form-factor

BACKGROUND: Native vessel patency and residual lesion are primary sources of morbidity in Cerebrovascular Surgery (CVS) requiring real-time visualization to inform surgical judgement, as is available in endovascular procedures. Micro Doppler and Indocyanine Green Fluorescence-microscopy (ICG-M) are promising evolutions over Intraoperative Angiography (IA), while digital subtraction angiography (DSA) remains gold standard. Exoscopic visualization in CVS is emerging; however, feasibility of exoscopic-based ICG (ICG-E) for CVS has not yet been reported. OBJECTIVE: Provide initial experience with ICG-E video angiography in CVS. METHODS: Retrospective study where two ICG-E form-factors (exoscopic-couple or self-contained handheld imager) were used to determine native vessel patency and residual and compared to DSA. RESULTS: 11 patients (8 aneurysms, 3 arteriovenous malformations (AVMs)) were included. ICG-E was feasible in all, providing real-time information leading to operative decisions impacting surgical judgement. For aneurysms, discordance of IA with ICG-E and DSA was 12%. In one case, IA showed non-flow restrictive branch stenosis; however, both ICG and DSA showed patency. All AVM cases were fully obliterated, with 100% concordance between all modalities. ICG averaged 4.2 mg dose/run (1-4 doses/case); 1.25mg being the lowest dose allowing visualization with no advantage with escalating dosages. There were no intra/perioperative complications. CONCLUSION: In this preliminary study, ICG-E was safe and feasible, providing real-time visualization informing surgical decision-making. The last 4 cases (2 aneurysms and 2 AVMs) evolved towards a portable handheld device-a readily accessible real-time modality providing contextual anatomic and flow visualization. Larger studies will be needed to assess broader safety, dose escalation, and efficacy