A 55-year-old man presented with intracerebral hemorrhage and his angiographic evaluation revealed a S-M Grade 4 AVM in his right parietal area [] and was selected for microsurgery. As demonstrated in Figure –, ICG studies are helpful in different stages of the surgery. After opening the dura, the AVM is observed [], and ICG-VA shows the precise anatomy of the vessels []. To distinguish arteries from veins, this image was further reinforced by the color-coded FLOW 800 [] where one can observe the feeding artery in red and the draining vein in blue. This visual color map featured an overview of blood flow dynamics and facilitated identifying the feeding arteries at a single glance. As the operation goes on, changes of blood flow in AVM can be tracked by further color-coded images []. When the resection was completed, a final ICG-VA depicted total AVM removal with no residual nidus [].
Case 2: A 53-year-old woman presented with recurrent severe headache. She was found to have 2 aneurysms located in the right middle cerebral artery []. Following complete microsurgical dissection of the aneurysms, parent vessels and their branches, intraoperative ICG-VA was performed. The blood flow in the aneurysms and the MCA branches was clearly observed before clip application. After clipping of the proximal aneurysm, ICG-VA was repeated to confirm the exclusion of the aneurysm and to detect any residual blood flow in the clipped aneurysm. However, due to the repeated injections of ICG within a short interval, the originally injected volume was still detectable in the aneurysm []. Hence it was difficult to confirm the occlusion of aneurysm on the basis of simple ICG-VA. To clear this dilemma, the intensity diagram function integrated into the surgical microscope was used to check the variation in the blood flow of clipped aneurysm over time. The curve of the aneurysm had no obvious upslope, which implied complete obliteration on the color map [Figure and ]. Therefore, no readjustment was warranted and we left the clips in place based on this finding. Later, the complete obliteration of the aneurysm was re-confirmed by postoperative 3D-CTA examination obtained 2 days after surgery.