PhD Defense: Ali Mokhtari Lays Foundation for More Personalized Stroke Risk Assessment

In this thesis, Ali presented a comprehensive investigation of carotid artery hemodynamics that integrates 4D flow MRI with patient specific computational fluid dynamics (CFD) simulations. Carotid artery atherosclerosis is a major cause of ischemic stroke. His aim was to (i) clarify the hemodynamic mechanisms underlying carotid atherosclerosis, (ii) quantify the capabilities and limitations of 4D flow MRI for hemodynamic assessment, (iii) identify geometric and flow-related risk factors beyond stenosis severity, and (iv) develop advanced methods for improving plaque vulnerability assessment and imaging data quality.

Through a controlled phantom study, a patient-specific comparison, a comprehensive geometric analysis, an integrative biomechanical study, and the development of a deep learning model with attention mechanisms, Ali demonstrated that carotid atherosclerosis and plaque vulnerability are governed by a patient-specific interplay between vascular geometry, hemodynamics, and biomechanics rather than stenosis severity alone.

His thesis shows that while 4D flow MRI enables noninvasive flow visualization, accurate quantification of clinically relevant metrics such as wall shear stress requires validated CFD, with geometric features emerging as powerful predictors of disturbed, pro-atherogenic flow.

Congratulations to Dr. Ali Mokhtari on this incredible achievement and laying the groundwork for more personalized and mechanistically informed stroke risk assessment!

Publications:

Mokhtari, Ali; Meulendijks, Merel; Bergmann, Ariel; Andrae, Jonathan; Harloff, Andreas; Obrist, Dominik (n.d.). On the uncertainties of hemodynamic measurements with 4D flow magnetic resonance imaging and super-resolution in a phantom carotid artery model. Under review.

Mokhtari, Ali; Bergmann, Ariel; Ghaderi, Hosna; Andrae, Jonathan; Harloff, Andreas; Obrist, Dominik (n.d.). Integrating Patient-Specific Hemodynamic Forces and Plaque Morphology for Improved Assessment of Carotid Plaque Vulnerability. Under review.

Mokhtari, Ali; Bergmann, Ariel; Andrae, Jonathan; Harloff, Andreas; Obrist, Dominik (n.d.). Hemodynamic and Geometrical Parameters Associated with Carotid Artery Stenosis: A Cross-Sectional Study Using 4D Flow MRI and CFD. Under review.

Zheng, Shaokai; Mokhtari, Ali; Jung, Bernd; Harloff, Andreas; Obrist, Dominik (2026). Uncertainty Quantification in Hemodynamic Metrics from 4D Flow MRI with Super-resolution in a Carotid Bifurcation Model. Journal of Imaging Informatics in Medicine. Springer Nature 10.1007/s10278-025-01796-w

Mokhtari, Ali; Corso, Pascal; Jung, Bernd; Ferrari, Lorenzo; Zheng Shaokai; Obrist, Dominik (2025). Comparison of 4D flow MRI and computational fluid dynamics in carotid models with different stenosis levels. Computers in Biology and Medicine 194:110405. Elsevier 10.1016/j.compbiomed.2025.110405