Impact of Clot Shape on Successful M1 Endovascular Reperfusion

Abstract

Objectives: The susceptibility-vessel-sign (SVS) allows thrombus visualization, length estimation and composition, and it may impact reperfusion during mechanical thrombectomy (MT). SVS can also describe thrombus shape in the occluded artery: in the straight M1-segment (S-shaped), or in an angulated/traversing a bifurcation segment (A-shaped). We determined whether SVS clot shape influenced reperfusion and outcomes after MT for proximal middle-cerebral-artery (M1) occlusions.Methods: Between May 2015 and March 2018, consecutive patients who underwent MT at one comprehensive stroke center and who had a baseline MRI with a T2* sequence were included. Clinical, procedural and radiographic data, including clot shape on SVS [angulated/bifurcation (A-SVS) vs. straight (S-SVS)] and length were assessed. Primary outcome was successful reperfusion (TICI 2b-3). Secondary outcome were MT complication rates, MT reperfusion time, and clinical outcome at 90-days. Predictors of outcome were assessed with univariate and multivariate analyses.Results: A total of 62 patients were included. 56% (35/62) had an A-SVS. Clots were significantly longer in the A-SVS group (19 mm vs. 8 mm p = 0.0002). Groups were otherwise well-matched with regard to baseline characteristics. There was a significantly lower rate of successful reperfusion in the A-SVS cohort (83%) compared to the S-SVS cohort (96%) in multivariable analysis [OR 0.04 (95% CI, 0.002–0.58), p = 0.02]. There was no significant difference in long term clinical outcome between groups.Conclusion: Clot shape as determined on T2* imaging, in patients presenting with M1 occlusion appears to be a predictor of successful reperfusion after MT. Angulated and bifurcating clots are associated with poorer rates of successful reperfusion.

3D Turbo Spin-echo MRI-based Mechanical Thrombectomy at Middle Cerebral Artery Bifurcations

“…Specifically, thrombi at MCA bifurcations can be localized in the distal M1 involving a single M2 branch. 6) Guenego et al demonstrated that thrombi in the M2 extension had a low rate of successful reperfusion compared with a straight distal M1 thrombus. 6) In cases of an M1 with a single M2 thrombus, partial thrombus complement by stent retrieval from the non-buried M2 branch has a risk of fragmentation, leading to incomplete revascularization and distal embolization during the procedure.…”

“… 6) Guenego et al demonstrated that thrombi in the M2 extension had a low rate of successful reperfusion compared with a straight distal M1 thrombus. 6) In cases of an M1 with a single M2 thrombus, partial thrombus complement by stent retrieval from the non-buried M2 branch has a risk of fragmentation, leading to incomplete revascularization and distal embolization during the procedure. 11) Multiple thrombectomy procedures can also increase the risk of procedural complications due to endothelial injury and naturally prolong the ischemic interval.…”

“… 13) A thrombus on T2* gradient-echo sequence MRI (the susceptibility vessel sign) was used to detect thrombus location and evaluate thrombus length. 6) The development of 3D-TSE imaging with variable refocusing flip angles, which captures a wide range of high-resolution images with reduced partial volume artifacts via decreased image blurring, has contributed to diagnosis of vessel wall lesions or brain tumor invasion. 14 , 15) In particular, 3D-TSE T1WI and T2WI have a high sensitivity for intramural hematomas and a dilated outer arterial diameter in cerebral artery dissection, respectively, using multiplanar or curved planar reconstruction.…”

“…Thrombus length was evaluated from measurements between the proximal and distal extent obtained by curved planar reconstruction of 3D-TSE T1WI. 6) …”

“…Various techniques for thrombus imaging, including histological composition, etiology, and recanalization, have been performed after mechanical thrombectomy. 6,13) Non-cardioembolic strokes, which have higher proportions of erythrocytes, were associated with the hyperdense artery sign on CT, decreased distance from the ICA-terminus, and longer thrombi compared with cardioembolic strokes. 13) A thrombus on T2* gradient-echo sequence MRI (the susceptibility vessel sign) was used to detect thrombus location and evaluate thrombus length.…”