Intraoperative Imaging Research for Paraclinoid Aneurysms Using the Indocyanine Green Angiography Technique

Background: Paraclinoid aneurysms are a challenging type of intracranial aneurysms due to their surrounding anatomy. Residual aneurysm after microsurgical clipping carries a risk of aneurysm growth and rupture. Microscope-integrated near-infrared indocyanine green angiography (ICGA) is a new technique that allows for real-time evaluation of blood flow in the aneurysm and vessels. It is increasingly utilized to confirm optimal clip positioning across the neck and to evaluate the adjacent vasculature. Objective: To explore the intraoperative research of neuroimaging assessment of neck residuals and patency of branches for paraclinoid aneurysms using the indocyanine green angiography (ICGA) technique in the surgery. Methods: From January 2009 to December 2014, a retrospective study to evaluate the intraoperative value of ICGA in patients who underwent microsurgical clipping of paraclinoid aneurysms was performed. Intraoperative ICGA was performed using a fluorescence microscope before and after clipping. After the operation, three-dimensional CT angiography (CTA), digital substraction angiography (DSA) were used to evaluate the use of intraoperative ICGA. The presence and patency of the parent artery and perforating artery around the aneurysm, and the information of aneurysm were analyzed in the surgical field through intraoperative imaging. These findings of ICGA were compared with those of postoperative DSA or CTA. Results: The study included 69 cases of adults and three out of them were noted as having significantly changed information provided by intraoperative ICGA. After initial clip placement, neck remnants of the aneurysm were found in 1 patient, inadvertent clipping of branching vessels in 2 patients, and inadvertent clipping of perforating vessels in two patients. After adjusting the aneurysm clipping, no such unexpected findings as parent or branching artery occlusion, or aneurysm sac omission were found on postoperative angiograms. The postoperative DSA and CTA results were consistent with the intraoperative ICGA findings. Conclusions: Microscope-integrated ICGA is useful in the clipping of paraclinoid aneurysms to monitor residual aneurysm, parent artery stenosis or perforating artery occlusion during paraclinoid aneurysm clipping. A combination of ICGA and microsurgical techniques may ultimately prove to be the most effective strategy for maximizing the safety and efficacy of aneurysm surgery.