TRADITIONAL POSTER - ismrm

Poster Sessions
1348. Contribution of the Blood Flow Evaluation by MRI in the Ascending Thoracic Aorta in Patients at
Risk
Alain Lalande 1,2 , Clotilde Billard-Philip 2 , Marie Xavier 1 , Olivier Bouchot 1,2 , Eric Steinmetz 2 , Alexandre
Cochet 1 , Paul Michael Walker 1,2 , Jean-Eric Wolf 1,2 , François Brunotte 1,2
1 LE2I, University of Burgundy, Dijon, France; 2 University Hospital of Dijon, Dijon, France
Currently the evaluation of risk of rupture or dissection of the thoracic aorta is based on the aortic diameter, which is not a relevant parameter. To evaluate
functional properties of the aorta, maximum blood flow velocity was evaluated in patients with well-classified diseases. 3D velocity imaging, acquired with
velocity-encoded cine-MRI, and analysed with automatic post-processing allows the study of aortic blood flow. Compared with healthy subjects, the
maximum blood flow velocity was higher for patients with bicuspid valve and lower for patients with the MYH11 mutation. There was no significant
difference in patients with Marfan syndrome or annulo-aortic ectasia.
1349. Flow Sensitive 4D MRI at 1.5T and 3T
Christoph Strecker 1 , Andreas Harloff 2 , Michael Markl 3
1 Department of Neurology, University Hospital, Albert-Ludwigs-University , Freiburg, Germany; 2 Department of Neurology,
University Hospital, Albert-Ludwigs-University , Freiburg , Germany; 3 Department of Radiology, Medical Physics, University
Hospital, Albert-Ludwigs-University , Freiburg, Germany
Synopsis: It was the purpose of this study to evaluate the performance of flow-sensitive 4D MRI of the thoracic aorta at 1.5T and 3T. 10 healthy volunteers
were examined with 4D-MRI at both field strengths with regard to velocity noise, 3D flow visualization and quantitative flow analysis. 3T was superior
regarding reduced velocity noise, improved quality of blood flow visualization, and quantification of peak velocities. It could be shown that flow-sensitive
4D-MRI was feasible at both field strengths and can provide comprehensive information of aortic 3D hemodynamics and geometry.
1350. Reproducibility of Semi-Automated Measurement for Carotid Arterial Distensibility Using CINE MRI
at 3T
Gador Canton 1 , Jinnan Wang 2 , Li Dong 1 , William Sean Kerwin 1 , Chun Yuan 1
1 Radiology, University of Washington, Seattle, WA, United States; 2 Clinical Sites Research Program, Philips Research North
America, Briarcliff Manor, NY, United States
The aim of this study was to determine the inter-scan reproducibility of distensibility measurements at the common and internal carotid arteries using CINE
MRI at 3 T. Our results show a good agreement in the area and the distensibility measurements between the two scans. Furthermore, we compared the
difference in distensibility for both segments of the artery. We found a significant difference between the common and internal carotid arteries, suggesting
that mechanical modeling of the forces acting on the arterial wall could be further improved by incorporating the different mechanical properties of different
arterial segments.
1351. Comparing Wall Shear Stress Measurements in the Descending Aorta Using Different Velocity
Encoding Values
Larry Hernandez 1 , Andrew L. Wentland 1,2 , Erik T. Bieging 2 , Chris J. Francois 2 , Oliver Wieben 1
1 Medical Physics, University of Wisconsin, School of Medicine & Public Health, Madison, WI, United States; 2 Radiology, University
of Wisconsin, School of Medicine & Public Health, Madison, WI, United States
While studies have shown that high wall shear stress (WSS) creates aneurysms and low WSS contributes to aneurysmal growth, the downstream effects of
an aneurysm on WSS remain unknown. In this study we compared measurements of peak WSS in the descending aorta of volunteers and in patients with an
ascending aortic aneurysm. Measurements of peak WSS were lower in patients than in normal volunteers; the percent increase in WSS from diastolic
baseline to peak systole was greater in volunteers than in patients. The long-term effects of lower WSS in the patients require further investigation.
1352. Pressure Gradient Estimation from PC-MRI: Acceleration Versus Velocity Encoding
Jelena Bock 1 , Felix Staehle 1 , Ramona Lorenz 1 , Kevin Michael Johnson 2 , Juergen Hennig 1 , Michael Markl 1
1 Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; 2 University of Wisconsin, Madison,
United States
MRI can be used to estimate blood pressure gradients non-invasively by solving the Navier-Stokes equation. Most applications use velocity encoded MRI
data to calculate pressure gradients by deriving local acceleration based on spatial and temporal derivates of the measured velocities. To minimize noise
propagation errors, acceleration encoded MRI can be used to directly measure flow acceleration. In this study in-vitro and in-vivo data were used to
systematically evaluate the performance of acceleration and velocity encoding PC-MRI for pressure gradient estimation. Results indicate that data derived
from acceleration encoded MRI are less noisy and may provide more reliable pressure difference estimation.
1353. Waveform Optimized (Easy to Build) Pulsatile Flow Phantom of the Common Carotid Artery
Clemens Diwoky 1 , Christian Binter 1 , Johannes Konrad Strasser 1 , Rudolf Stollberger 1
1 Institute of Medical Engineering, Graz University of Technology, Graz, Austria
A phantom simulating the exact flow-velocity pulse shape within the common carotid artery is proposed. Beside the exact representation of the flow profile
attention is paid on keeping the system flexible, simple and inexpensive. Parameters of the used components are figured out in order to optimize and
manipulate the final pulsatile flow.