TRADITIONAL POSTER - ismrm

Poster Sessions
3108. Fast Field Inhomogeneity and Concomitant Gradient Field Correction in Spiral Cardiac Imaging
Joseph Yitan Cheng 1 , Juan M. Santos 1,2 , John M. Pauly 1
1 Electrical Engineering, Stanford University, Stanford, CA, United States; 2 HeartVista, Inc., Los Altos, CA, United States
Off-resonance blurring from main field inhomogeneities and concomitant gradient fields degrade the quality of spiral imaging. For cardiac imaging, offisocenter
acquisitions are unavoidable resulting in significant artifacts from these effects. We present the importance of correcting both the field
inhomogeneity and the concomitant gradient field using two fast and accurate algorithms. The advantages of our algorithms are demonstrated in cardiac
imaging: their computation speed in a real-time study and their accuracy in a high-resolution study.
3109. One Step Real-Time Image Correction with GUSTO (Gradient Warp and UnderSampled Transform
Operator)
Matthew Ethan MacDonald 1,2 , Randall Brooke Stafford, 2,3 , Michel Louis Lauzon, 2,4 , Richard Frayne, 2,4
1 Electrical and Biomedical Engineering, University of Calgary, Calgary, Alberta, Canada; 2 Seaman Family MR Research Centre,
Calgary, Alberta, Canada; 3 Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada; 4 Radiology and Clinical
Neurosciences, University of Calgary, Calgary, Alberta, Canada
Real time imaging requires fast acquisition and low latency reconstruction algorithms. We propose the Gradient warp and UnderSampling Transform
Operator (GUSTO) algorithm as a fast method for correction of aliasing and gradient warped images using a single matrix transformation. Proof of concept
is shown with low resolution (64 x 64) phantom images.
3110. Real-Time Gradient Warp Correction with OpenGL NURBS Surfaces
Randall Brooke Stafford 1,2 , Matthew Ethan MacDonald, 2,3 , Richard Frayne, 2,4
1 Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada; 2 Seaman Family MR Research Centre,
Foothills Medical Centre, Calgary, AB, Canada; 3 Department of Electrical Engineering, University of Calgary, Calgary, AB, Canada;
4 Departments of Radiology and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
Gradient warp correction is computationally intensive, and therefore not always practical for real-time imaging. OpenGL (Open Graphics Language) is a
graphics display library with mathematical graphics functions called non-uniform rational B-splines (NURBS) that can project a 2D texture onto a 3D
surface within the fast display framework. In this study, we test collected raw data in real-time and projected the resulting uncorrected image onto the
NURBS surface for display. The NURBS-corrected images were then qualitatively compared to product-sequence gradient warp corrected images. Our
results support our hypothesis that NURBS surfaces have the capacity for real-time non-linear gradient warp correction.
Simulation in MR Teaching & Research
Hall B Monday 14:00-16:00
3111. Utility of Hand-On Scanning for Assimilating MRI Concepts (Www.learnmri.org)
Michelle Castro Cerilles 1 , Martin R. Prince 1 , Mitch Cooper 1 , Bo Xu 1 , Cynthia Wisnieff 1 , Robert Zubkoff 1 ,
Satre Stuelke 1
1 Radiology, Weill Cornell Medical College, New York, NY, United States
Effectiveness of learning basic MRI principles by following hands-on workbook exercises as demonstrated by 11 students/residents/fellows. The workbook
exercises teach MRI concepts such as MRI safety and patient screening, optimizing resolution, SNR and CNR on a phantom, optimizing T1 and T2
weighting in the volunteer brain, creating, identifying and eliminating various artifacts, adapting scanning parameters to match varying anatomy in the
volunteer knee and abdomen, and implementing various approaches to minimizing respiratory motion effects.
3112. Generalized Formalism of the Extended Phase Diagram and Computational Applications Including an
MRI Simulator.
Giuseppe Palma 1,2 , Marco Comerci 2 , Anna Prinster 2,3 , Mario Quarantelli 2 , Bruno Alfano 2
1 ESAOTE s.p.a., Naples, Italy; 2 Biostructure and Bioimaging Institute, National Research Council, Naples, Italy; 3 "S.D.N."
Foundation, Naples, Italy
We have built and generalized a rigorous formalism of the Extended Phase Diagram algorithm, in order to coherently include within a computational
framework also non-trivial dephasing effects arising from static magnetic field inhomogeneities. Computational applications are presented providing both
analytical and numerical outputs, including programs evolving the state populations according to virtually any pulse sequence provided by the user.
Presented examples include tools to derive in a fully automated way the analytic signal equations (developed in Mathematica®) and to simulate MR Image
formation process (developed in MATLAB®).
3113. Magnetic Resonance Parameter Mapping Using Computer Simulation
Yo Taniguchi 1 , Suguru Yokosawa 1 , Yoshitaka Bito 1
1 Central Research Laboratory, Hitachi, Ltd., Kokubunji, Tokyo, Japan
In MR parameter mapping, parameters are estimated from images obtained with various acquisition parameters. For the estimation, the intensity function,
which defines the relationship of image intensity to acquisition and MR parameters, needs to be formulated analytically in a simple form. A method to
formulate the intensity function numerically by computer simulation based on Bloch equations is proposed. Intensity functions of arbitrary pulse sequences
are formulated using this method so that rapid imaging is applied for the mapping. The intensity function for RF-spoiled gradient echo was formulated
numerically, and we confirmed that a T1 map was successfully estimated from images obtained in a phantom experiment.