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Original research
Insights into the pathogenesis of cerebral fusiform aneurysms: high-resolution MRI and computational analysis
  1. Ryan Phillip Sabotin1,
  2. Alberto Varon2,
  3. Jorge A Roa1,
  4. Ashrita Raghuram1,
  5. Daizo Ishii3,
  6. Marco Nino4,
  7. Adam E Galloy4,
  8. Devanshee Patel1,
  9. Madhavan L Raghavan4,
  10. David Hasan3,
  11. Edgar A Samaniego1,3,5
  1. 1Department of Neurology, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
  2. 2Department of Neurology, The University of Iowa, Iowa City, Iowa, USA
  3. 3Department of Neurosurgery, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
  4. 4Roy J Carver Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa, USA
  5. 5Department of Radiology, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
  1. Correspondence to Dr Edgar A Samaniego, Department of Neurology, Neurosurgery, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA; edgarsama{at}gmail.com

Abstract

Background Intracranial fusiform aneurysms are complex and poorly characterized vascular lesions. High-resolution magnetic resonance imaging (HR-MRI) and computational morphological analysis may be used to characterize cerebral fusiform aneurysms.

Objective To use advanced imaging and computational analysis to understand the unique pathophysiology, and determine possible underlying mechanisms of instability of cerebral fusiform aneurysms.

Methods Patients with unruptured intracranial aneurysms prospectively underwent imaging with 3T HR-MRI at diagnosis. Aneurysmal wall enhancement was objectively quantified using signal intensity after normalization of the contrast ratio (CR) with the pituitary stalk. Enhancement between saccular and fusiform aneurysms was compared, as well as enhancement characteristics of fusiform aneurysms. The presence of microhemorrhages in fusiform aneurysms was determined with quantitative susceptibility mapping (QSM). Three distinct types of fusiform aneurysms were analyzed with computational fluid dynamics (CFD) and finite element analysis (FEA).

Results A total of 130 patients with 160 aneurysms underwent HR-MRI. 136 aneurysms were saccular and 24 were fusiform. Fusiform aneurysms had a significantly higher CR and diameter than saccular aneurysms. Enhancing fusiform aneurysms exhibited more enhancement of reference vessels than non-enhancing fusiform aneurysms. Ten fusiform aneurysms underwent QSM analysis, and five aneurysms showed microhemorrhages. Microhemorrhage-positive aneurysms had a larger volume, diameter, and greater enhancement than aneurysms without microhemorrhage. Three types of fusiform aneurysms exhibited different CFD and FEA patterns.

Conclusion Fusiform aneurysms exhibited more contrast enhancement than saccular aneurysms. Enhancing fusiform aneurysms had larger volume and diameter, more enhancement of reference vessels, and more often exhibited microhemorrhage than non-enhancing aneurysms. CFD and FEA suggest that various pathophysiological processes determine the formation and growth of fusiform aneurysms.

  • aneurysm
  • blood flow
  • MRI
  • technology
  • vessel wall

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Footnotes

  • Contributors Conception and study design: EAS. Acquisition of data: RPS, AV, AR, MN, AEG, and DP. Analysis and interpretation of results: RPS, AV, MN, AEG, MLR, and EAS. Drafting of the manuscript: RPS, AV, AR, DP, and EAS. Critical revision of the study: MLR, DH, and EAS. Funding Acquisition: EAS. All authors contributed to the continuous refinement of the study protocol and approved the final manuscript.

  • Funding This work was supported by the The Bee Foundation and by the 2019 Brain Aneurysm Research grant and the 'Society of Vascular and Interventional Neurology'' (SVIN) pilot research grant to EAS. This work was conducted on an MRI instrument funded by 1S10RR028821-01.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval University of Iowa - IRB01 / IRB ID #201803866201803866.

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

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. Raw data were generated at the University of Iowa. Derived data supporting the findings of this study are available from the corresponding author EAS, on request.

  • 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.

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