TRADITIONAL POSTER - ismrm

1615. 3D PROPELLER-Based Diffusion Weighted Imaging with Improved Robustness to Motion
Eric Aboussouan 1 , Jim Pipe 1
1 Barrow Neurological Institute, Phoenix, AZ, United States
Poster Sessions
The previously described ROTOR (Radially Oriented Tri-Dimensionally Organized Readouts) pulse sequence allows 3D DWI with high SNR efficiency
and lower SAR compared to DW FSE and reduced off-resonance artifacts and improved 3D phase correction compared to DW EPI. This work describes
improvements in the pulse sequence and reconstruction scheme allowing greater robustness to motion. Blades are made wider by combining odd and even
non-CPMG echoes and are gridded off-center to effectively reflect the linear component of the motion phase.
1616. Multi-Shot SENSE DWI at 7T
Ha-Kyu Jeong 1,2 , Adam W. Anderson 1,2 , John C. Gore 1,2
1 Vanderbilt University Institute of Imaging Science, Nashville, TN, United States; 2 Department of Radiology and Radiological
Sciences, Vanderbilt University, Nashville, TN, United States
We developed a simple reconstruction method for multi-shot SENSE diffusion weighted data using an interleaved EPI sequence. The reconstruction was
done independently for each column of the image by combining image unwrapping and phase corrections. To estimate shot-to-shot phase variations due to
subject motion during diffusion encoding, a 2-D navigator-echo acquisition was used following the image-echo acquisition. Both of the echo acquisitions
were SENSE accelerated reducing scan duration, susceptibility and T2* effects. Our reconstruction method and pulse sequence produced diffusion weighted
images free of ghost artifacts at 7 Tesla.
1617. Whole-Blade PROPELLER DWI
Chu-Yu Lee 1 , Zhiqiang Li 2 , Eric Aboussouan 1 , Josef P. Debbins, 1,3 , James G. Pipe 3
1 Electrical Engineering, Arizona State University, Tempe, AZ, United States; 2 GE Healthcare, Waukesha, WI, United States; 3 Keller
Center for Imaging Innovation, Barrow Neurological Institute, Phoenix
PROPELLER [1] is a variant of multi-shot FSE technique, providing a high-resolution DWI with excellent immunity to off-resonance. Its self-navigated
nature around the center of K-space also allows for motion correction. The odd/even echo phase inconsistencies in the non-CPMG echo train were addressed
using the ¡§split-blade¡¨ method [2], where the blade width was reduced by a factor of two, making the motion-related phase more difficult to remove [3].
Thus, this work applied the ¡§whole blade¡¨ method [3] to create wider blades for robustly removing the motion-induced phase. The proposed scheme added
the reference blade (only for b=0) to effectively remove the coil phase of odd/even echoes. This reference blade can also be used for GRAPPA kernel
training for parallel imaging to further widen the blade width and reduce the scan time.
1618. High Resolution 3D Multi-Slab Multi-Shot Spin Echo Diffusion-Weighted Imaging
Anh Tu Van 1 , Dimitrios C. Karampinos 2 , Bradley P. Sutton 3,4
1 Electrical and Computer Engineering, University of Illinois, Urbana, IL, United States; 2 Radiology and Biomedical Imaging,
University of California, San Francisco, CA, United States; 3 Bioengineering, University of Illinois, Urbana, IL, United States;
4 Beckman Institute, University of Illinois, Urbana, IL, United States
High isotropic resolution diffusion-weighted imaging is required in order to reduce partial volume effects in the estimation of diffusion metrics. In the
present work, a novel high resolution 3D spin echo diffusion-weighted acquisition strategy is proposed. The acquisition is time efficient, fairly immune to
gross motion and pulsation effects, and has a simple diffusion-weighted signal model. High quality, high resolution (1.88 x 1.88 x 1.88 mm3) diffusionweighted
images, FA maps, color-coded FA maps (13 directions) with whole brain coverage were achieved within a reasonable scan time.
1619. Isotropic Resolution in Diffusion Weighted Imaging Using 3D Multi-Slab, Multi-Echo Echo Planar
Imaging
Mathias Engström 1,2 , Anders Nordell 1,2 , Magnus Mårtensson 1,2 , Bo Nordell 1 , Roland Bammer 3 , Stefan
Skare, 2,3
1 Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden; 2 Karolinska MR Research Center, Karolinska
Institute, Stockholm, Sweden; 3 Radiology, Stanford University, Stanford, CA, United States
A new readout strategy for 3D-DWI is proposed using EPI and multi-slab encoding, with the purpose of achieve sharp and thin slice profiles.
1620. Improved 3-Dimensional Reconstruction of Diffusion Data Using Overlapping Slices
Rita G. Nunes 1 , Joseph V. Hajnal 1
1 Robert Steiner MRI Unit, Imaging Sciences Department, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College
London, London, United Kingdom
As Diffusion-Weighted images are inherently very sensitive to motion, full brain coverage is achieved by imaging multiple 2D single shot slices. However,
as most fiber tracts in the brain have a 3-dimensional structure, ensuring that the anatomy is fully sampled along all three dimensions is likely to be
important. Conventionally, the same slice prescription is used for all diffusion sensitization directions. We demonstrate that by using overlapping slices
and/or combining slices acquired along orthogonal directions higher fidelity anisotropy maps can be reconstructed. Using this type of geometry should also
increase data robustness in the presence of more severe subject motion.
1621. Diffusion Weighted Turbo-STEAM ZOOM Imaging of the Lumbar Spine
Patrick Hiepe 1 , Karl-Heinz Herrmann 2 , Christian Ros 2 , Jürgen R. Reichenbach 2
1 Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital , Jena, Germany; 2 Medical
Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany
So far, most clinical DWI applications have relied on EPI although DWI EPI is limited by susceptibility artifacts. STEAM MRI with robust turbo-FLASH
readout is a fast imaging technique with subsecond measurement times. This robustness is traded against SNR by using a less signal efficient acquisition
technique. To achieve maximum efficiency of the turbo-STEAM sequences a reduced number of PE lines is necessary. An effective way is to utilize the