Haemodynamic imaging of thoracic stent-grafts by computational fluid dynamics (CFD): presentation of a patient-specific method combining magnetic resonance imaging and numerical simulations.
OBJECTIVE
In the last decade, there was been increasing interest in finding imaging techniques able to provide a functional vascular imaging of the thoracic aorta. The purpose of this paper is to present an imaging method combining magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) to obtain a patient-specific haemodynamic analysis of patients treated by thoracic endovascular aortic repair (TEVAR).


METHODS
MRI was used to obtain boundary conditions. MR angiography (MRA) was followed by cardiac-gated cine sequences which covered the whole thoracic aorta. Phase contrast imaging provided the inlet and outlet profiles. A CFD mesh generator was used to model the arterial morphology, and wall movements were imposed according to the cine imaging. CFD runs were processed using the finite volume (FV) method assuming blood as a homogeneous Newtonian fluid.


RESULTS
Twenty patients (14 men; mean age 62.2 years) with different aortic lesions were evaluated. Four-dimensional mapping of velocity and wall shear stress were obtained, depicting different patterns of flow (laminar, turbulent, stenosis-like) and local alterations of parietal stress in-stent and along the native aorta.


CONCLUSIONS
A computational method using a combined approach with MRI appears feasible and seems promising to provide detailed functional analysis of thoracic aorta after stent-graft implantation.


CONCLUSIONS
• Functional vascular imaging of the thoracic aorta offers new diagnostic opportunities                                                  • CFD can model vascular haemodynamics for clinical aortic problems                                                  • Combining CFD with MRI offers patient specific method of aortic analysis                                                  • Haemodynamic analysis of stent-grafts could improve clinical management and follow-up.
Cardiovascular Radiology, University Hospital of Lille, Lille, France. marco.midulla@chru-lille.fr
Marco
M
Midulla
Ramiro
R
Moreno
Adil
A
Baali
Ming
M
Chau
Anne
A
Negre-Salvayre
Franck
F
Nicoud
Jean-Pierre
JP
Pruvo
Stephan
S
Haulon
Hervé
H
Rousseau
D001013:Aorta, Thoracic / Q000000981:diagnostic imaging* / Q000601:surgery*; D003198:Computer Simulation; D005260:Female; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015607:Stents; D058017:Vascular Grafting