Background Compositional and structural features of retrieved clots by thrombectomy can provide insight into improving the endovascular treatment of ischemic stroke. Currently, histological analysis is limited to quantification of compositions and qualitative description of the clot structure. We hypothesized that heterogeneous clots would be prone to poorer recanalization rates and performed a quantitative analysis to test this hypothesis.
Methods We collected and did histology on clots retrieved by mechanical thrombectomy from 157 stroke cases (107 achieved first-pass effect (FPE) and 50 did not). Using an in-house algorithm, the scanned images were divided into grids (with sizes of 0.2, 0.3, 0.4, 0.5, and 0.6 mm) and the extent of non-uniformity of RBC distribution was computed using the proposed spatial heterogeneity index (SHI). Finally, we validated the clinical significance of clot heterogeneity using the Mann–Whitney test and an artificial neural network (ANN) model.
Results For cases with FPE, SHI values were smaller (0.033 vs 0.039 for grid size of 0.4 mm, P=0.028) compared with those without. In comparison, the clot composition was not statistically different between those two groups. From the ANN model, clot heterogeneity was the most important factor, followed by fibrin content, thrombectomy techniques, red blood cell content, clot area, platelet content, etiology, and admission of intravenous tissue plasminogen activator (IV-tPA). No statistical difference of clot heterogeneity was found for different etiologies, thrombectomy techniques, and IV-tPA administration.
Conclusions Clot heterogeneity can affect the clot response to thrombectomy devices and is associated with lower FPE. SHI can be a useful metric to quantify clot heterogeneity.
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information. Not applicable.
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Contributors YL, WB, and LS conceived the concept and YL designed the study. YL and MA performed data analysis and interpretation. MA, DD, JLAL, OMM, and SF performed histology. All the other authors provided leading effort in collecting patient clots and procedure data within their institutions in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP). YL drafted the article. The article was critically revised by YL, WB, DFK, and LS. WB, RK, DFK, and LS provided administrative, technical, supervisory, or other support. All authors reviewed the submitted version, and YL approved it on behalf of all the authors. YL and LS are guarantors of the integrity of the entire study.
Funding This work was supported by the National Institutes of Health (grant number NS105853).
Competing interests MJG is on the editorial board of the Journal of NeuroInterventional Surgery.
Provenance and peer review Not commissioned; externally peer reviewed.
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