Electronic Posters: Cardiovascular

Wednesday 13:30-15:30 Computer 37

13:30 3704. Combined PCMRI and CFD Hemodynamics in a Flow-Model and in the Thoracic Aorta

Aurelien F. Stalder^1,2, Zhenyu Liu³, Ramona Lorenz², Juergen Hennig^2,4, Jan Gerrit Korvink, ^4,5, Michael Markl<sup>2

1</sup>Dept. of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China; ²Dept. of Diagnostic Radiology - Medical Physics, University Hospital, Freiburg, Germany; ³Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Science, Changchun, China; ⁴Freiburg Institute for Advanced Studies (FRIAS), Freiburg, Germany; ⁵Dept. of Microsystems Engineering, University of Freiburg, Germany

Both flow-sensitive 4D MRI and computational fluid dynamics (CFD) have successfully been applied to analyze complex 3D flow. However, both modalities suffer from limitations related to measurements (MRI) or model assumptions (CFD). In this study, we compared both modalities in a model in vitro and in the complex 3D blood flow of the thoracic aorta in vivo. Although discrepancies were observed, overall coherent patterns were observed. The further potential of the method is illustrated by calculating detailed Wall Shear Stress maps using very fine boundary layer mesh. The combination of 4D flow-sensitive MRI and CFD may be used to enhance the assessment of blood flow in vivo.

14:00 3705. Visualization and Quantification of Increased Tangential Velocities in Ascending Aortic Aneurysms Using 4D Phase Contrast

Benjamin R. Landgraf¹, Kevin M. Johnson², Erik T. Bieging¹, Oliver Wieben², Christopher J. François<sup>1

1</sup>Radiology, University of Wisconsin - Madison, Madison, WI, United States; ²Medical Physics, University of Wisconsin - Madison, Madison, WI, United States

Complex blood flow patterns in the ascending aorta have been associated with the pathophysiology of various cardiovascular diseases, including ascending aortic aneurysms. Helical and vortical flow in patients with aneurysms present an increased tangential force that could lead to further aortic dilation, dissection, or rupture. Characterization and quantification of these flow patterns could help predict disease progression. This study investigates several hemodynamic parameters of the ascending aorta in 11 normal volunteers and 13 patients, including peak and mean velocities, calculation of a tangential percentage of velocity, and characterization of flow patterns.

14:30 3706. Long Term Follow-Up of Patients Status Post Valve-Sparing Aortic Surgery with 4D-Flow

Thomas A. Hope¹, Michael D. Hope¹, D Craig Miller², Michael Markl³, John-Peder E. Kvitting², Charles B. Higgins¹, Robert J. Herfkens<sup>4

1</sup>Department of Radiology, University of California San Francisco, San Francisco, CA, United States; ²Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, United States; ³Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; ⁴Department of Radiology, Stanford University, Stanford, CA, United States

12 patients status post valve sparing correction of ascending aortic aneurysms were imaged with 4D flow and were followed up for an average of 5 years. One patient had abnormal flow patterns in the ascending and descending aorta. Subsequently during the follow-up period, this patient developed a Stanford Type B aortic dissection. This is the first long-term follow-up study to correlate adverse outcomes to in vivo visualized abnormal flow patterns using MRI. Although this study is limited due to the small number of patients, it does suggest that abnormal flow patterns in the thoracic aorta may provide prognostic information.

15:00 3707. Elevated Aortic Wall Shear Stress in a Subgroup of Patients with Bicuspid Valves

Michael D. Hope¹, Thomas A. Hope¹, Thomas H. Urbania¹, Karen G. Ordovas¹, Alison K. Meadows¹, Marcus T. Alley², Charles B. Higgins<sup>1

1</sup>Radiology, UCSF, San Francisco, CA, United States; ²Stanford Radiology

4D Flow demonstrates significantly higher aortic wall shear stress in a subgroup of BAV patients with eccentric systolic flow jets. Studies have shown that only a subset of BAV patients have aortic dilation, and that those with dilation develop asymmetric aneurysms of the AsAo at the location where we have demonstrated elevated vWSS. As altered WSS can give rise to pathologic endothelial gene expression and extracellular matrix remodeling, we may have identified the mechanism that places a subgroup of BAV patients at risk for asymmetric AsAo aneurysm.