Depiction of the Vasa Vasorum during Carotid Endarterectomy by Intraoperative Videoangiography

Abstract

The aim of the study was to investigate the depiction of the carotid artery by fluorescein sodium (FS) videoangiography compared with indocyanine green (ICG) videoangiography, focusing on how the vasa vasorum of the carotid artery is depicted. Thirty-five patients (19 FS patients, 16 ICG patients, mean age 69.4 ± 5.1 years, mean degree of stenosis 78.7% ± 11.7%) who underwent a carotid endarterectomy (CEA) were enrolled. FS (5-6 mg/kg) or ICG (.2-.3 mg/kg) was injected intravenously as a bolus before the arterectomy during the CEA. The intravascular fluorescence signal was recorded with a digital video camera integrated on a microscope. Magnetic resonance imaging black-blood (BB) T1-weighted imaging (WI) was preoperatively performed using a 1.5-T whole-body imager, and the signal intensity ratio relative to the ipsilateral sternocleidomastoid muscle on BB-T1WI (BB-SIR) was calculated. We also performed an immunohistochemistry study using CD31 and CD68 antibodies for plaque specimens. In the FS videoangiography series, the vasa vasorum of carotid adventitia was depicted first, followed by augmentation of FS of the wall and partially the inner lumen (pattern A) in 6 cases. Augmentation of FS of the wall and inner lumen prior or simultaneous to the depiction of the vasa vasorum of the carotid adventitia (pattern B) were observed in 13 cases. The average BB-SIR value of the pattern B cases was significantly higher than that in the pattern A group (P < .05). Most of the plaques with BB-SIR values higher than 1.25 also belonged to the pattern B group (90.9%). Microvessels stained by CD31 and macrophages stained by CD68 were more frequently observed in the high-BB-SIR plaques. In contrast, the ICG videoangiography uniformly showed pattern B in all 16 cases, because of the fluorolucency of the carotid wall revealed by the ICG. The early depiction of adventitial vasa vasorum in FS videoangiography was inversely associated with the BB-SIR values of the plaques, along with many microvessels and macrophages that have been reported to have a tendency of intraplaque hemorrhage or symptoms. The present results may support the idea of an intimal origin of the neovascularization in vulnerable carotid plaques, and they demonstrated the potential of intraoperative plaque imaging by FS videoangiography.