TRADITIONAL POSTER - ismrm

Poster Sessions
flexibility for choosing the gradient echo spacing to enable higher resolution acquisitions in reasonable scan times. We test this hypothesis in phantom
studies and show a new data acquisition approach to acquire high-resolution 3D T 2 -weighted fat-water separated images of the breasts and knee with higher
SNR in reduced scan times.
2907. Single-Image Water/fat Separation
Johan Berglund 1 , Håkan Ahlström 1 , Lars Johansson 1 , Joel Kullberg 1
1 Department of radiology, Uppsala university, Uppsala, Sweden
A post processing method is presented, that separates water and fat from a single complex image. Initially, each voxel is assumed to be either water- or fat
dominant, giving two alternative field heterogeneity phasors. Spatial smoothness of the field map is imposed by formulating an optimization problem, which
is solved approximately using a multiscale belief propagation algorithm. Smoothing of the field map relaxes the initial assumption of water- or fat
dominance. Water and fat signals are found analytically in each voxel. Initial results from abdomen and whole-body datasets at 1.5 T and 3.0 T were found
promising.
2908. Noise Analysis for Chemical Shift Based Water-Fat Separation with Independent T2* Correction for
Water and Fat
Venkata Veerendranadh Chebrolu 1 , Huanzhou Yu 2 , Angel R. Pineda 3 , Charles A. McKenzie 4 , Jean H.
Brittain 5 , Scott B. Reeder, 1,6
1 Biomedical Engineering, University of Wisconsin Madison, Madison, WI, United States; 2 Applied Science Laboratory, GE
Healthcare,, Menlo Park,, CA, United States; 3 Department of Mathematics, California State University, Fullerton, CA, United States;
4 Department of Medical Biophysics, University of Western Ontario,, London, Ontario; 5 Applied Science Laboratory, GE Healthcare,,
Madison, WI, United States; 6 Radiology, University of Wisconsin Madison, Madison, WI, United States
The noise analysis for chemical shift based decomposition of water and fat was theoretically computed for methods that account for single and dual
exponential T2* correction along with spectral modeling of fat. The Cramer–Rao bound (CRB) formulation was used to study the variance of the estimates
of the water and fat images by computing the maximum effective number of signals averaged (NSA) for a range of echo combinations and fat-water ratios.
These theoretical results predict that noise performance degrades with independent estimation of T2* of water and fat.
2909. Lipid Suppresion Using Spectral Editing of Fast Spin Echo Trains
Andrew J. Wheaton 1 , James B. Murdoch 1 , Robert Anderson 1
1 Toshiba Medical Research Inst. USA, Mayfield, OH, United States
The REFUSAL [REFocusing Used to Selectively Attenuate Lipids] technique incorporates a spectrally-selective editing pulse in the position of the first
refocus pulse of an rf echo train. By fully refocusing water and while minimally refocusing lipid resonances, fat signal is “refused” from evolving in the rf
echo train. The phase-modulated REFUSAL pulse is designed for B1-robustness with a sharp transition between fat and water for good δB0-insensitivity.
REFUSAL produces images with uniform, T1-insensitive fat suppression over a wide range of B1.
2910. PASTA++: B1- And T1-Robust Fat Suppression at 3T
Andrew J. Wheaton 1 , Robert Anderson 1
1 Toshiba Medical Research Inst. USA, Mayfield, OH, United States
PASTA uses a combination of low rf excitation bandwidth and alternate excitation and refocus slice selection gradient polarities to remove fat signal via
chemical shift. PASTA++ is an improved version of PASTA designed for 3T. Using 3T-tailored rf pulse choices and irregular echo spacing, PASTA++ can
be included in an fast spin-echo readout with short echo spacing. PASTA++ delivers high SNR images with uniform fat suppression even in the presence of
B0 inhomogeneity. Since PASTA++ does not use a prepulse, it delivers fat suppression immune to B1- and T1-variation without increasing SAR.
2911. A Joint Estimation Method for Two-Point Water/fat Imaging with Regularized Field Map
Diego Hernando 1 , Peter Kellman 2 , Zhi-Pei Liang 1
1 Electrical and Computer Engineering, University of Illinois, Urbana, IL, United States; 2 National Institutes of Health, Bethesda, MD,
United States
Two-point methods for water/fat imaging are attractive because of their moderate acquisition time. In this work, we adapt a previously proposed joint
estimation approach for two-point acquisitions and demonstrate its performance using simulations, phantom results and in vivo data. The proposed method,
based on a regularized formulation and a graph cut solution, results in good noise properties and the ability to handle large B0 field inhomogeneities.
2912. Multiplex RARE Dixon: A Novel Multislice RARE Sequence Applied to Simultaneous Slice Fat-Water
Dixon Imaging
Kuan J. Lee 1 , Benjamin Zahneisen 1 , Jürgen Hennig 1 , Weigel Matthias 1 , Jochen Leupold 1
1 Medical Physics, University Hospital Freiburg, Freiburg, Baden-Württemberg, Germany
Multiplex RARE is a new sequence in which multiple slices are simultaneously excited and refocused in a spin-echo train. The echo trains are interleaved in
such a way that CPMG conditions are fulfilled at all times, and signals from slices can be separated, preventing aliasing. This work demonstrates how the
sequence may be used in a novel fat-water Dixon method, which enables fast volume coverage of multiple, simultaneously excited slices. The technique is
demonstrated in-vivo and compared with fTED, another fast Dixon method.