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Original research
Non-porous thrombi are less pervious and easier to be retrieved: implication from scanning electron microscopy study
  1. Yaode He,
  2. Jinjin Xu,
  3. Wansi Zhong,
  4. Zhicai Chen,
  5. Ying Zhou,
  6. Jiaping Li,
  7. Zhongyu Luo,
  8. Min Lou
  1. Department of Neurology, the Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
  1. Correspondence to Professor Min Lou, Neurology, Zhejiang University School of Medicine Second Affiliated Hospital, Hangzhou, China; lm99{at}


Background Scanning electron microscopy (SEM) studies found that the porosity of thrombi might vary among individuals. However, its relationship with the clinical presentation and efficacy of mechanical thrombectomy (MT) remains unknown. We aimed to characterize the ultrastructure of thrombi and explore its association with the complexity of MT and clot perviousness.

Methods SEM was used to observe the morphological features of different components of thrombi obtained from patients with anterior circulation large vessel occlusion undergoing MT and to determine the porosity of thrombi by semi-quantitative analysis. Non-porous thrombi were defined as thrombi with porosity <2%. Clot perviousness was also evaluated using thrombus attenuation increase on CT perfusion (TAIctp). We assessed the complexity of MT by attempts of retrieval >3 and procedural duration >60 min, defined as the time interval between groin puncture and recanalization.

Results A total of 49 thrombi were analyzed and 31 (63.3%) were classified as non-porous thrombi. The presence of non-porous thrombi was negatively associated with procedure >60 min (OR 0.152, 95% CI 0.031 to 0.734, p=0.019) and attempts >3 (OR 0.194, 95% CI 0.046 to 0.822, p=0.026) after adjustment. Additionally, receiver operating characteristic curve analysis indicated that TAIctp <17.9 Hounsfield units could predict the presence of non-porous thrombi with an area under the curve of 0.915.

Conclusions Non-porous thrombi on SEM are easier to be retrieved during MT and could be identified as less pervious clots on CT images.

  • Stroke
  • Thrombectomy

Data availability statement

Data are available upon reasonable request. Not applicable.

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Data availability statement

Data are available upon reasonable request. Not applicable.

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  • YH and JX contributed equally.

  • Contributors ML contributed to the conception of the study and is responsible for the overall content as guarantor. YH, JX, YZ, JL and ZL collected thrombus samples. YH and JX processed and analyzed the images. YH and WZ performed the data analyses and drafted the manuscript. ZC, YZ and ML edited the manuscript with constructive discussions.

  • Funding This study was supported by the National Natural Science Foundation of China (81971101, 82171276), and the Science Technology Department of Zhejiang Province (2018C04011).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.