Background Mechanical thrombectomy (MT) is the standard of care for patients with a stroke and large vessel occlusion. Clot composition is not routinely assessed in clinical practice as no specific diagnostic value is attributed to it, and MT is performed in a standardized ‘non-personalized’ approach. Whether different clot compositions are associated with intrinsic likelihoods of recanalization success or treatment outcome is unknown.
Methods We performed a prospective, non-randomized, single-center study and analyzed the clot composition in 60 consecutive patients with ischemic stroke undergoing MT. Clots were assessed by ex vivo multiparametric MRI at 9.4 T (MR microscopy), cone beam CT, and histopathology. Clot imaging was correlated with preinterventional CT and clinical data.
Results MR microscopy showed red blood cell (RBC)-rich (21.7%), platelet-rich (white,38.3%) or mixed clots (40.0%) as distinct morphological entities, and MR microscopy had high accuracy of 95.4% to differentiate clots. Clot composition could be further stratified on preinterventional non-contrast head CT by quantification of the hyperdense artery sign. During MT, white clots required more passes to achieve final recanalization and were not amenable to contact aspiration compared with mixed and RBC-rich clots (maneuvers: 4.7 vs 3.1 and 1.2 passes, P<0.05 and P<0.001, respectively), whereas RBC-rich clots showed higher probability of first pass recanalization (76.9%) compared with white clots (17.4%). White clots were associated with poorer clinical outcome at discharge and 90 days after MT.
Conclusion Our study introduces MR microscopy to show that the hyperdense artery sign or MR relaxometry could guide interventional strategy. This could enable a personalized treatment approach to improve outcome of patients undergoing MT.
Data availability statement
Data are available upon reasonable request.
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Contributors KK-J: performed all aspects of the study, performed MRI readings, statistical analysis, and wrote the manuscript. MF, VS, TC and SHe: performed MRI and cone beam CT measurements. UN, FP, NS, and KS: supported image analysis. AK and LS and FSa performed histopathology. GB, PAR, and WW: provided clinical data. UN, DS, DFV, CU, FSe JJ, TH, and CH: collected study material. MB and MAM supported study design and interpretation of results. MOB designed the study, performed the analysis, and wrote the manuscript with input from all coauthors. MOB is the study guarantor.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests KK-J received research support from Novartis Pharma GmbH, unrelated to this work (Nürnberg, Germany). DFB reports consultancy for Medtronic and payed lectures for Cerenovus, and a research grant by MicroVention, unrelated to this work. KS received funding from the Olympia-Morata-Program of the Medical Faculty of Heidelberg University and from the Daimler-Benz-Foundation unrelated to this work. CU received travel funding and/or speaker honoraria from Cerenovus unrelated to this work. CH reports consultancy payments by Brainomix and lecture fees by Stryker. LS reports research support and consultancy fees from Novartis, Roche, Bristol-Myers Squibb, and Merck. MB served on the scientiﬁc advisory board of ECASS, TENSION, Springer, Boehringer, BBRaun, and Vascular Dynamics; received speaker honoraria from Guerbet, Bayer, Novartis, Codman, Roche, and Teva; is coeditor of Clinical Neuroradiology; and received research support from Novartis Pharma GmbH (Nürnberg, Germany), Guerbet, Siemens, Bayer Healthcare, Hopp Foundation, European Union, and DFG. MOB received funding from DFG (SFB1389 and Emmy Noether program, BR 6153/1-1) and Novartis Pharma GmbH, unrelated to this work. UN, DS, MF, GB, AK, VS, TH, FSe, FP, NS, JJ, TC, SHa, FSa, SHe, PAR, WW and MAM report no disclosures relevant for this work.
Provenance and peer review Not commissioned; internally peer reviewed.
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