Figure – shows a 62-year-old man diagnosed with a cerebellar AVM with feeders from left superior and posterior inferior cerebellar arteries. After exposing the lesion, ICG-VA demonstrates AVM vessels []. illustrates the same view after being rendered by the FLOW 800. Early appearing blood flow is showed in red and late appearing flow in blue. After selecting ROIs for the software, semi-quantitative characteristics of the blood flow in desired vessels were analyzed and demonstrated in curves by the FLOW 800 []. After microsurgical resection of the AVM was complete, ICG-VA showed no remnant of the AVM []. Visual color map showed hemodynamic changes after AVM resection [] in contrast with preresection status []. Furthermore, analytical graphs show changes in flow parameters immediately after AVM resection [Figure and ]. To make it easy to understand, we removed all curves of except for one to demonstrate image analysis performed with ImageJ software []. Time to peak, rise time, and MFI are all showed on the curve. Although CBFI is also calculated, we should notice that this curve is derived from a venous blood flow not brain parenchyma and this index is demonstrated as an example to explain its calculation.
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.