Electronic Posters: Cardiovascular

Tuesday 13:30-15:30 Computer 37

13:30 3700. Carotid Artery Wall Shear Stress: Distribution, Correlation with Geometry and Effect of Atherosclerosis

Michael Markl¹, Timo Zech², Simon Bauer¹, Felix Wegent², Aurelien F. Stalder¹, Christoph Strecker², Andreas Harloff<sup>2

1</sup>Diagnostic Radiology, Medical Physics, University Hospital, Freiburg, Germany; ²Neurology, University Hospital, Freiburg, Germany

The purpose of this study was to assess the physiological distribution of absolute wall shear stress and oscillatory shear index in the entire carotid bifurcation in healthy volunteers (n=64 carotid bifurcations) and to evaluate their dependence on individual bifurcation geometry. Further, the distribution of critical wall parameters was compared with findings in patients with moderate internal carotid artery (ICA) stenosis before (n=6) and after surgical recanalization (n=11). Bifurcation geometry predicted exposure to critical wall parameters and may thus be an indicator for the risk of developing flow-mediated atherosclerosis. Carotid artery stenosis and treatment altered the distribution of critical wall parameters.

14:00 3701. 3-Component Phase-Contrast MRI WSS Vectors in the Carotid Bifurcation Are Concurrent with Local Atherosclerotic Plaque Risk Hypotheses

Alex J. Barker¹, Fuxing Zhang², P E. Gates³, L A. Mazzaro⁴, A Stalder¹, J Fulford³, C J. Lanning^4,5, M Markl¹, Robin Shandas<sup>4,5

1</sup>Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; ²Mechanical Engineering, University of Colorado, Boulder, CO, United States; ³Peninsula Medical School, University of Exeter, United Kingdom; ⁴Center for Bioengineering, University of Colorado at Denver Health Sciences, CO, United States; ⁵Division of Cardiology, The Children's Hospital, CO, United States need to fill this out

14:30 3702. Onset Time of Retrograde Flow in the Pulmonary Artery in Pulmonary Arterial Hypertension Patients: An Estimator for Pulmonary Arterial Pressure?

Frank Helderman¹, Gert Jan Mauritz¹, J. Tim Marcus¹, Kirsten Andringa¹, Nico Westerhof¹, Anton Vonk Noordegraaf<sup>1

1</sup>VU University Medical Center, Amsterdam, Netherlands

The objective was to assess if mean pulmonary artery pressure (mPAP) could be estimated using a standard 2D MR phase-contrast velocity quantification in the main pulmonary artery. Included were 37 Pulmonary Arterial Hypertension (PAH) patients vs 8 controls. Onset time of the retrograde flow (Retrograde Onset Time = ROT) as fraction of cardiac cycle time, and cross sectional area (CSA) of the main pulmonary artery were measured. Regression analysis revealed an association between mPAP and ROT (r=0.74; p<0.001), and between mPAP and CSA (r=0.68; p<0.001). The early retrograde flow in PAH is explained with a recirculation zone.

15:00 3703. Time-Resolved 3D MR Velocity Mapping of the Great Hepatic Vessels at 3T: Simultaneous Visualization of Arterial and Venous Hemodynamics and Comparison with Ultrasound

Zoltan Csatari¹, Zoran Stankovic¹, Peter Deibert², Wulf Euringer¹, Wolfgang Kreisel², Mathias Langer¹, Michael Markl<sup>1

1</sup>Department of Diagnostic Radiology and Medical Physics, University Hospital Freiburg, Freiburg, Baden Württemberg, Germany; ²Gastroenterology, University Hospital Freiburg, Freiburg, Baden Württemberg, Germany

Flow-sensitive 4D-MRI allows the detailed depiction and quantification of the great hepatic vessels including the portal venous system as well as the coeliac trunc at the same time. As expected our results demonstrate differences in blood flow characteristics between the portal venous system and the arteries. In accordance with the literature lower values for velocities and higher values for areas were measured by MRI, but linear regression analysis showed an excellent agreement between MRI and the reference standard Doppler Ultrasound (r = 0,72; p < 0.001). In consideration of these results our findings underline that 4D-MRI could be an alternative, user indipendent method to Doppler US in investigating normal and pathological hemodynamics of the great hepatic vessels.