Comparison of Intraoperative Microscopic and Endoscopic ICG Angiography in Aneurysm Surgery

BACKGROUND: Indocyanine green (ICG) angiography is used to detect vessel compromise by the clip, residual aneurysms after clipping, or persistent aneurysm filling due to incomplete clipping. For ICG angiography, the microscope must be in a direct line-of-sight with the region of interest, limiting the identification of hidden arteries and dog-ear remnants. OBJECTIVE: To use a prototype endoscope for visualization of ICG fluorescence in hidden regions of the microsurgical field and evaluate its potential usefulness compared with microscopic ICG angiography (m-ICG-A) in a consecutive series of 30 aneurysms in 26 patients. METHODS: In selected cases, before and routinely after microsurgical clip application, m-ICG-A and endoscopic ICG angiography (e-ICG-A) were performed. The information gained by m-ICG-A was compared with that gained by e-ICG-A. RESULTS: E-ICG-A was technically feasible in all operations. Intra-arterial fluorescence could be visualized up to 10 times longer with the endoscope than with the microscope. The endoscope allowed a closer view on the fluorescent artery-aneurysm-complex. e-ICG-A provided more information than m-ICG-A in 11 operations (confirmation of unhindered blood flow in microscopically hidden vessels [n = 6], neck remnant identification [n = 2], neck remnant exclusion [n = 2], blood flow control in 2 distant clipped aneurysms [n = 1]). In 14 operations, identical information was obtained, and in 1 operation e-ICG-A was inferior because of trapped intra-aneurysmal fluorescence. CONCLUSION: In selected cases, e-ICG-A provides the neurosurgeon with information that cannot be obtained by m-ICG-A. e-ICG-A is capable of emerging as a useful adjunct in aneurysm surgery and has the potential to further improve operative results.