Background: Clot characteristics and porosity at the proximal portion of an arterial occlusion may influence potential recanalization. Thrombus permeability may be a factor in intravenous thrombolysis, whereas such features of clots prior to endovascular thrombectomy remains largely unexplored. We developed a technique to image clot porosity and yield quantitative measures that may predict mechanical recanalization.
Methods: Consecutive cases of large artery occlusion (ICA or proximal M1 MCA) with single-phase CT angiography (CTA) acquired immediately prior to endovascular thrombectomy were analyzed. 3D-reconstruction, vessel segmentation, centerline extraction, signal intensity gradient calculations and surface mapping of CTA yielded porosity images and quantitative measures. Porosity measures were correlated with angiography parameters and procedural details.
Results: 53 consecutive cases of acute stroke with contemporaneous sCTA and DSA were used to generate porosity images. Technical limitations precluded image processing in 9 cases, due to diminished contrast conspicuity in close proximity to bone interfaces. Porosity features on resulting images and the quantitative measures of clot penetration varied markedly, even within the subset of M1 or ICA occlusions, respectively.
The occlusions often exhibited long segments (mean 18 ± 11 mm) of luminal narrowing before complete occlusion. Current analyses examine whether higher porosity or greater proximal contrast penetration of the clot is associated with faster recanalization and fewer device passes during endovascular thrombectomy.
Conclusions: Clot porosity images and quantitative measures of proximal contrast penetration may be generated from routine CTA. Imaging of clot porosity may be a useful adjunct in planning of endovascular procedures and future strategies may focus on distinguishing atherosclerotic versus thromboembolic large artery occlusions.