TY  - JOUR
A1  - Gaidzik, Franziska
A1  - Pathiraja, Sahani Darschika
A1  - Saalfeld, Sylvia
A1  - Stucht, Daniel
A1  - Speck, Oliver
A1  - Thevenin, Dominique
A1  - Janiga, Gabor
T1  - Hemodynamic data assimilation in a subject-specific circle of Willis geometry
JF  - Clinical Neuroradiology
N2  - Purpose The anatomy of the circle of Willis (CoW), the brain's main arterial blood supply system, strongly differs between individuals, resulting in highly variable flow fields and intracranial vascularization patterns. To predict subject-specific hemodynamics with high certainty, we propose a data assimilation (DA) approach that merges fully 4D phase-contrast magnetic resonance imaging (PC-MRI) data with a numerical model in the form of computational fluid dynamics (CFD) simulations. Methods To the best of our knowledge, this study is the first to provide a transient state estimate for the three-dimensional velocity field in a subject-specific CoW geometry using DA. High-resolution velocity state estimates are obtained using the local ensemble transform Kalman filter (LETKF). Results Quantitative evaluation shows a considerable reduction (up to 90%) in the uncertainty of the velocity field state estimate after the data assimilation step. Velocity values in vessel areas that are below the resolution of the PC-MRI data (e.g., in posterior communicating arteries) are provided. Furthermore, the uncertainty of the analysis-based wall shear stress distribution is reduced by a factor of 2 for the data assimilation approach when compared to the CFD model alone. Conclusion This study demonstrates the potential of data assimilation to provide detailed information on vascular flow, and to reduce the uncertainty in such estimates by combining various sources of data in a statistically appropriate fashion.
KW  - hemodynamics
KW  - CFD
KW  - uncertainty quantification
KW  - PC-MRI
KW  - LETKF
Y1  - 2020
U6  - https://doi.org/10.1007/s00062-020-00959-2
SN  - 1869-1439
SN  - 1869-1447
VL  - 31
IS  - 3
SP  - 643
EP  - 651
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Rödel, Claudia Jasmin
A1  - Otten, Cecile
A1  - Donat, Stefan
A1  - Lourenço, Marta Sofia Rocha
A1  - Fischer, Dorothea
A1  - Kuropka, Benno
A1  - Paolini, Alessio
A1  - Freund, Christian
A1  - Abdelilah-Seyfried, Salim
T1  - Blood Flow Suppresses Vascular Anomalies in a Zebrafish Model of Cerebral Cavernous Malformations
JF  - Circulation Research
N2  - RATIONALE: Pathological biomechanical signaling induces vascular anomalies including cerebral cavernous malformations (CCM), which are caused by a clonal loss of CCM1/KRIT1 (Krev interaction trapped protein 1), CCM2/MGC4607, or CCM3/PDCD10. Why patients typically experience lesions only in lowly perfused venous capillaries of the cerebrovasculature is completely unknown. OBJECTIVE: In contrast, animal models with a complete loss of CCM proteins lack a functional heart and blood flow and exhibit vascular anomalies within major blood vessels as well. This finding raises the possibility that hemodynamics may play a role in the context of this vascular pathology. METHODS AND RESULTS: Here, we used a genetic approach to restore cardiac function and blood flow in a zebrafish model of CCM1. We find that blood flow prevents cardiovascular anomalies including a hyperplastic expansion within a large Ccm1-deficient vascular bed, the lateral dorsal aorta. CONCLUSIONS: This study identifies blood flow as an important physiological factor that is protective in the cause of this devastating vascular pathology.
KW  - animal models
KW  - cerebral cavernous malformations
KW  - endothelial cell
KW  - hemodynamics
KW  - zebrafish
Y1  - 2019
U6  - https://doi.org/10.1161/CIRCRESAHA.119.315076
SN  - 0009-7330
SN  - 1524-4571
VL  - 125
IS  - 10
SP  - E43
EP  - E54
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  -