Abstract: 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.
Competing Interests: 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.
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