Feasibility of Using Angioscopy to Visualize the Internal Vessel Wall of the Internal Carotid Artery.

Abstract

Background: Digital subtraction angiography lacks the ability to visualise intimal surface changes. Angioscopy, in contrast, enables direct imaging of the endoluminal surface, revealing luminal alterations, as established in cardiovascular imaging. Its application in the internal carotid artery (ICA) could allow assessment of pathological changes and the visualization of implant structures such as stents or flow diverters, including their apposition to the vessel wall. This study evaluates the feasibility of using a thin fibre-optic endoscope for angioscopy in the ICA anatomy.

Methods: Five 3D DSA image sets of the ICA with varying anatomies were selected. Tube-based vessel models were fabricated to replicate the corresponding vascular segments, incorporating a measurement scale and, optionally, a stent or a flow diverter. The advancement of a fibre-optic endoscope and the related influence on vessel deformation were assessed in each model. Spatial and colour resolution were evaluated by applying coloured markings to the inner tube surface to simulate vessel wall discolouration. The visibility of structural details, including flow diverter meshes and stent struts, was assessed based on image contrast and sharpness within the angioscope's defined field of view.

Results: The endoscope was successfully advanced to the distal end in all models. Increased vascular curvature required greater mechanical force for navigation and positioning, leading to observable straightening of the vessel model. In all cases, endoscopic imaging produced clear visualizations of vessel wall markings and implant structures. Stent struts and flow diverter meshes were distinguishable, as were discolorations simulating pathological changes.

Conclusion: Angioscopy of the ICA is technically feasible and enables endoluminal visualization, including implant structures. Feasibility was strongly dependent on vessel curvature and required substantial increases in delivery force in highly tortuous anatomies.