Endoscopic indocyanine green video angiography in aneurysm surgery: an innovative method for intraoperative assessment of blood flow in vasculature hidden from microscopic view

Abstract

Recently, intraoperative fluorescence video angiography using indocyanine green (ICG) has been widely used in aneurysm surgery. This is a simple and useful method to confirm complete occlusion of the aneurysm lumen and preservation of blood flow in the arteries around the aneurysm. However, the observation field of ICG video angiography is limited under a microscope, making it difficult to confirm the flow in the arteries behind the parent arteries or aneurysm. The authors developed a new technique of intraoperative endoscopic ICG video angiography to assess the blood flow in perforating arteries hidden by the parent arteries or aneurysm. The endoscope emits excitation light with a wavelength of approximately 800 nm, and video images were obtained through a cut filter. The authors used this ICG fluorescence endoscope in treating 3 patients with unruptured cerebral aneurysms. During clip placement, the endoscope was inserted to confirm aneurysm occlusion. Then, ICG was intravenously administered, and the fluorescence in the vessels was observed via the endoscope as well as under the microscope. The blood flow in the perforating arteries was clearly identified, and no procedural complication occurred. The authors conclude that the technique is very useful and facilitates intraoperative real-time assessment of the patency of perforating arteries behind parent arteries or aneurysms.

Indocyanine green video-angiography in neurosurgery: A glance beyond vascular applications

“…One interesting paper reports about a patient suffering from a giant aneurysm of the right MCA; indocyanine green was injected inside the aneurysm in order to identify a target middle cerebral artery branch (MCA) for bypass and allowing confident preservation of blood supply to distal areas to the sacrificed vessel [11]. The study published by Roessler [21] real-time assessment of the patency of perforating arteries behind parent arteries or aneurysms) [9].…”

“…Recently, ICG-VA has been also used for endoscopic procedures, like in the study published by Nishyama et al [9]for endoscopic-assisted aneurysm surgery, where the association of endoscopic view to standard microscopic one allows a better observation of perforating arteries, that often, because their deepness, are not visible to the sole microscopic view. ICG-VA has been also proposed for other endoscopic applications such as ETV for intraoperative visualization of the basilar artery and its perforators to reduce the risk of vascular injury, especially in the presence of aberrant vasculature, a nontranslucent floor of the third ventricle, or in case of re-operations [64].…”

Minimally Invasive Microsurgery for Cerebral Aneurysms

“…Endoscopic ICG-A has now been developed by Bruneau et al and Nishiyama et al, which combines the benefits of endoscopy and ICG-A. 41,42 Preliminary experience comparing microscopic with endoscopic ICG-A was published by Mielke et al on a case series of 26 patients with 30 ruptured and unruptured aneurysms. 43 No adverse event relating to the application of ICG or endoscopy was found, but several observations were made: (1) endoscopic detection of intra-arterial fluorescence was 10× longer than microscopic detection, thus giving the opportunity to move the endoscope and view the artery-aneurysm complex from multiple angles; (2) less contrast is required for endoscopic ICG-A.…”

“…As this technology evolves, endoscopy will become a more useful adjunct to improving the safety of aneurysm surgery. [41][42][43] A listing of the advantages and disadvantages of endoscope-assisted aneurysm surgery is provided in Table 3.…”

“…After injection into a peripheral vein, ICG fluorescence is induced as the dye circulates through the cerebral vessels under near-infrared illumination and images are collected through an optical filter. 41 Until recently, ICG angiography (ICG-A) was available only with a microscope integrated with near-infrared camera to capture ICG fluorescence. Therefore, ICG-A was affected by the same line-of-sight problems inherent to the operating microscope.…”