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Original research
MR microscopy to assess clot composition following mechanical thrombectomy predicts recanalization and clinical outcome
  1. Kianush Karimian-Jazi1,
  2. Dominik F Vollherbst1,
  3. Daniel Schwarz1,
  4. Manuel Fischer1,
  5. Katharina Schregel1,
  6. Gregor Bauer2,
  7. Anna Kocharyan3,
  8. Volker Sturm1,
  9. Ulf Neuberger1,
  10. Jessica Jesser1,
  11. Christian Herweh1,
  12. Christian Ulfert1,
  13. Tim Hilgenfeld1,
  14. Fatih Seker1,
  15. Fabian Preisner1,
  16. Niclas Schmitt1,
  17. Tobias Charlet1,
  18. Stefan Hamelmann4,5,
  19. Felix Sahm4,5,
  20. Sabine Heiland1,
  21. Wolfgang Wick6,7,
  22. Peter A Ringleb2,
  23. Lucas Schirmer3,
  24. Martin Bendszus1,
  25. Markus A Möhlenbruch1,
  26. Michael O Breckwoldt1
  1. 1Department of Neuroradiology, University Hospital Heidelberg, Heidelberg, Germany
  2. 2Neurology Clinic, University Hospital Heidelberg, Heidelberg, Germany
  3. 3Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
  4. 4Department of Neuropathology, University of Heidelberg, Heidelberg, Germany
  5. 5Clinical Cooperation Unit Neuropathology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
  6. 6Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany
  7. 7Clinical Cooperation Unit Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
  1. Correspondence to Dr Michael O Breckwoldt, Department of Neuroradiology, University Hospital Heidelberg, Heidelberg, Germany; Michael.Breckwoldt{at}


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.

  • Stroke
  • Thrombectomy

Data availability statement

Data are available upon reasonable request.

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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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