Next is Michael Bruno from Brussels, Belgium, who's going to talk to us about ICG in aneurysm clipping. Thank you for coming. Dr. Jacques, the chairman, the colleagues, thank you for giving me the opportunity to discuss with you the interests and limitations of near-infrared ICG video angiography when applied during aneurysm surgery. We have nothing to disclose. So it is clear for everybody that the goals of aneurysm surgery is on one end to achieve a complete execution of the aneurysm sac in order to avoid re-bleeding in case of incompletely clipping. On the other end, you have to obtain preservation patency of the parent branching and perforating vessel to avoid stroke due to unintentional vessel compromise. In fact, after a clip application, if you only look your vessel through the microscope by visual observation, if you perform a post-operative DSA, you note that aneurysm remnant can be observed in 3 to 44% of the cases. And inadvertent occlusions can be present in 4 to 22%, meaning that we have to try to improve our results. For this purpose, ICG video angiography has been introduced in the armamentarium of neurosurgeons early in 2000. We have recently published a meta-analysis of all the series published on this topic in neurosurgery in 2017. We have defined two primary endpoints. The first primary endpoint was to evaluate the ICG video angiography accuracy in comparison to microscopic visual observation. And as primary endpoint 2, we have evaluated the ICG video angiography accuracy in comparison with either intra- or post-operative digital subtraction angiography. As secondary endpoints, we have determined what are the dosages that are reported in the different studies, and finally, the side effects. This is the study selection process. We have looked into PubMed, all the publications with the terms endocyanin, green, and angiography between January 2003 and April 2016. It means around 3,000 publications. We have excluded publications related to non-clinical topics, those that are not related to armory surgery, those with few patients. And at the end, we have selected 35 studies for the analysis of the primary endpoints. Some of them is still to be excluded, meaning that for the primary endpoints, we will have 20 and 11 studies. This is the summary of the studies that allows to analyze a primary endpoint 1, meaning the comparison of ICG video angiography to visual inspection. 20 studies are reported. Out of them, 16 were retrospective, and four were prospective. It includes 1,359 surgical procedures with almost 1,500 aneurysms. Some of them is to be excluded because ICG video angiography was not performed in 30 cases, so it means that the study evaluated 1,465 aneurysms. The quality of the ICG video angiography was considered satisfactory in almost all cases, meaning between 95% and 100% of the aneurysms evaluated. What are the important things? In fact, ICG-supported surgery allows to determine misclipping in 6.1% of the cases. In fact, in 6.1% of operated aneurysms, it was eluded at visual inspection and identified at ICG video angiography. If you subdivide the studies between prospective 1 and retrospective 1, in fact, the results were quite similar, not statistically significant, with 7.3% of misclippings determined in prospective studies compared to 5.8% in retrospective studies. If you analyze how the misclippings were divided, you note that, in fact, in 55% of the cases, it is an aneurysm remnant that was identified and induced a clip repositioning. In 45% of the cases, it was a vessel that was stenosed. In two-thirds of those cases, it was a branching vessel. And in one-third, it was a perforating vessel. If you look more specifically on studies that report emergency or elective procedure with free publications, and the overall rate was 8% of misclipping detected by ICG video angiography, with the rate of 5.1% in ruptured aneurysm, and surprisingly, the rate was higher in unruptured aneurysm, with 11%, which doesn't know the reason, maybe a selection bias with unruptured aneurysm more complicated when the technique was applied. Now we come after to the analysis of the primary endpoint 2, comparison of ICG with video angiography to digital subtraction angiography. The number of studies is lower, 11 studies, 9 retrospective, and 2 prospective ones, meaning 800 surgical procedures, around 900 aneurysms that were clipped, out of them, 892 in which ICG was applied, and 849 patients controlled by either intra or post-operative digital subtraction angiography. The overall rate of misclipping detected after the intra or post-operative DSA was 4.5%. In this case, no difference at all between prospective studies and retrospective studies with rate of 4.3 and 4.5%. When you analyze more specifically the results, in this case, the rate of remnant was lower than in the primary endpoint 1, it was 46%, and regarding the stenosid vessel detected in 54% of the cases, two-thirds were branching vessel, then followed by parent vessel stenosis, and 7% of perforating vessel stenosis. If you look again and compare the procedure that are performed in emergency and elective procedure, in this case, there is absolutely no difference between the rate of misclipping that is detected with ICG and then DSA. Now, we've analyzed the secondary endpoints regarding the dosage, 13 studies were included. In 10 studies, a fixed dosage was injected, meaning 25 milligram in 2 to 5 milliliters, and in one cases, half of this dosage was injected. In this case, the study did not report a lowering in the image quality for detecting remnant, and in three studies, the others use a dosage that was adapted to the patient's weight, meaning between 0.2 to 0.5 milligram per kilo. If you look at the side effects, very few of them are reported in the 13 studies. In around almost 1,000 procedure, only two adverse reaction, a mild skin rash and a transit reduction in blood oxygenation without any consequence. If we look to the different techniques that are available for us in order to improve the clipping, of course, we have the angiography. The angiography is perfect for detecting the vessel permeability, the aneurysm occlusion to analyze the backside. For the perforating vessel permeability, the quality is moderate, but this modality is very good for hemispheric perfusion, deep aneurysm in case of bleeding, and in case of calcification or other rheumatosis. But on the other end, this technique is not quick, not simple, cannot be repeated, is invasive with the mobility, and is expensive. We have also techniques that can be more easily applied, endoscopy and Doppler, and I have shown you the result with ICG video angiography, which is very interesting because it is quick, simple, can be repeated, not invasive, without side effects. It is one of the best techniques to analyze the perforating vessels, but has some limitations. It is a local technique, some limitations to analyze the hemispheric perfusion. It is less good for analyzing deep aneurysm in case of blood or calcification. No doubt about this. As conclusion, our meta-analysis has demonstrated the interest of ICG video angiography. You have to know that in 6.1% of the operated aneurysm, misclipping was not detected at visual inspection and identified during ICG video angiography. This technique is safe, it is low cost, and easy for use, so its routine application is clearly justifiable. On the other hand, the technique has some limitations, and in 4.5% of the case in which we have visual inspection ICG control, still there is significant number of patients that have misclipping that is detected by intraoperative or postoperative DSA. So ICG video angiography should be considered complementary rather than competitive for replacing the digital subtraction angiogram. Thank you. I would just take the opportunity to invite you also to the next EANS Congress, organized in Brussels in October 2021-25, and if you need more information, you can access the Congress website, it is EANS2018.com. Thank you. It will be a pleasure to meet you in Brussels. Thank you, Michael. Any questions from the audience? I have one about your last slide where you were comparing ICG to angiography. You said angiography was not simple, that can be debated, but it's certainly repeatable. Could you explain what you meant by it cannot be repeated? I was speaking about intraoperative angiography, and it is difficult to repeat intraoperatively. With the interest of ICG application is that you perform an exam, you modify the clip, and you can directly re-inject and re-analyze your result in a few seconds. If you need to repeat the intraoperative angiogram, I think you add morbidity and the procedure becomes more and more difficult and lengthy. Microphone, please, because they're recording. I can, but I'm not sure that everybody can. We have a small experience in Toledo, we operate in a high region, and it's very easy, after the application, to verify, right there, and the solitude is 100%. So angiography, intraoperatively, is very feasible, especially if you use a hybrid. I agree. I completely agree. I'm not telling that angiography must not be performed anymore. I think the study has also demonstrated the interest of intra- and, of course, postoperative DSA. So I'm not against the fact that intraoperatively an angiogram is performed, but it is clear that this technique is also associated with adversary events that are not present with ICG video angiography. So on a routine basis, I think ICG video angiography can be applied. I'm not sure that intraoperative angiography should be applied for 100% of the anomalies that are clipped, but maybe ICG should be. Greg? Yeah. Quick question. That was a really nice summary. In the summarized data, you looked at, of the 5% where there was a discordance between the ICG and the intraoperative, postoperative angiography, are there risk factors where that was higher or lower? Giant aneurysms, deep location, you know, sort of type. Did you look at that? It was not able to look so deeply in the studies. Yeah. It can be a bias, of course, of animate analysis. Some of the studies that you included in that analysis have done that, and, you know, ACOM aneurysm location tends to be a location where the discordance rate between the ICG and the intraoperative catheter angiogram might be higher. And in any aneurysm, like a superior postoperative artery aneurysm, where you have to use a fenestrated clip, and so the aneurysm remnant would be on the other side of the parent vessel, those are some of the locations where the ICG may fail more than 5% compared to angiography. I have not discussed about that because the length was also limited, but there are also other ways to look at the backside of the aneurysm, and we have reported a few years ago the use of ICG endoscope. And so you can go deeply with your endoscope and have a microscopic visualization, but also an ICG visualization of the backside of the aneurysm. Again, this is complementary to any other technique. Yeah, that's cool. Yeah. Okay. Thank you so much.

near-infrared indocyanine green video angiography

aneurysm surgery

clipping

ICG video angiography

misclipping