ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Scientific Session • Diffusion Acquisition

Thursday 4 June 2015

Constitution Hall 107

16:00 - 18:00


Rita G. Nunes, D. Phil., David A. Porter, Ph.D.

16:00 0952.   Framework for comparing relative SNR and SNR efficiency of diffusion weighted sequences in neuro-imaging
Benjamin Fürsich1,2, Tim Sprenger1,2, Axel Haase1, and Marion I. Menzel2
1IMETUM, Technical University, Munich, Bavaria, Germany, 2GE Global Research, Munich, Germany

Different diffusion weighted sequences, including 2D DW-EPI, 2D simultaneous multi-slice EPI, 3D multi-slab EPI and an parameter optimized 3D DW-SSFP, were theoretically compared in terms of relative SNR and SNR efficiency concerning a complete brain scan. Therefore, an optimization of 3D DW-SSFP parameters was performed using an analytic model provided by Freed et al.. The analysis depicts 3D multi-slab EPI as the method of choice for highly efficient neuro-imaging at higher resolutions.

16:12 0953.   B1 insensitive zoomed FOV imaging
Zhigang Wu1, Jing Zhang1, Wenxin Fang1, and Feng Huang1
1Philips Healthcare (Suzhou), Suzhou, China

The goal of this work is to provide a new tilted algorithm for zoomed FOV DWI with improved image uniformity, and validate it on 1.5T system. It uses a different titled excitation k-space trajectory, which is also blipped at slice direction, but just tilts the PE direction gradients. It does not increase the k-space step at PE direction, so it has no influence on the sub-pulse bandwidth. It moderates the requirements for hardware components compared with rFOV. We called it iZoom (Improved Zoom FOV imaging).

16:24 0954.   
High Resolution DTI using Dual-density Spiral for Efficient Sampling and Reduced Off-resonance Artifacts
Xiaodong Ma1, Zhe Zhang1, Hui Zhang1, Bida Zhang2, Sheng Fang3, and Hua Guo1
1Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, 2Healthcare Department, Philips Research China, Shanghai, China, 3Institute of nuclear and new energy technology, Tsinghua University, Beijing, China

While variable density spiral (VDS) has been used to generate high resolution diffusion tensor imaging, it has low sampling efficiency and severe off-resonance artifacts caused by prolonged readout duration. To solve this, a more efficient trajectory, dual-density spiral (DDS), was proposed to replace VDS in DTI. In vivo results show that DDS can improve the sampling efficiency and reduce off-resonance blurring compared to VDS. Besides, it can correct the motion-induced phase errors more effectively since a larger full-sampling region and thus higher resolution navigator can be provided.

16:36 0955.   High-Resolution Single-Shot Spiral Imaging using Magnetic Field Monitoring and its Application to Diffusion Weighted MRI - permission withheld
Bertram J. Wilm1,2, Christoph Barmet1,2, Simon Gross1, Lars Kasper1, Johanna Vannesjo1, Maximilian Haeberlin1, Benjamin Dietrich1, David Brunner1, Thomas Schmid1, and Klaas P. Pruessmann1
1Institute for Biomedical Engineering, University & ETH, Zurich, Zurich, Switzerland, 2Skope Magnetic Resonance Technologies, Zurich, Zurich, Switzerland

Despite its great potential, single-shot spiral MRI is so far not used in clinical practice due to its sensitivity to any encoding deficiencies. We address this problem by applying magnetic field monitoring and demonstrate the benefit for high resolution diffusion imaging. The accurate and consistent encoding information retrieved from magnetic field monitoring data resulted in a strongly improved image quality and achieves image congruence among DW data without image co-registration. The high SNR efficiency and the motion robustness make this sequence ideal for its use for diffusion imaging in clinical practice and research.

16:48 0956.   
How to suppress the contribution from pseudo-diffusion in oscillating gradient diffusion MRI
Dan Wu1 and Jiangyang Zhang2
1Biomedical Engineering, Johns Hopkins University School of Medicine, BALTIMORE, Maryland, United States, 2Radiology, Johns Hopkins University School of Medicine, Maryland, United States

Oscillating gradient spin-echo (OGSE) diffusion MRI is useful to probe tissue microstructures at ultra-short diffusion times, and its applications on clinical MR systems are gradually emerging. However, OGSE diffusion measurements are commonly acquired at relatively low b-values due to gradient constraints, and such measurements contain contributions from perfusion related pseudo-diffusion. In this study, we showed the OGSE signals are sensitive to pseudo-diffusion at low b-values, and proposed to use pulsed and oscillating gradient on orthogonal directions to suppress the contributions from pseudo-diffusion. The hybrid sequence may be useful for future applications of OGSE diffusion MRI on clinical scanners.

17:00 0957.   Double Oscillating Diffusion Encoding (DODE) augments microscopic anisotropy contrast
Noam Shemesh1, Andrada Ianuş2, Daniel C Alexander2, and Ivana Drobnjak2
1Champalimaud Neuroscience Programme, Champalimaud Center for the Unknown, Lisbon, Portugal, 2Center for Medical Image Computing, Department of Computer Science, University College London, London, United Kingdom

Double-Diffusion-Encoding (DDE) MRI methodologies (e.g., double-Pulsed-Field-Gradient (dPFG) or Double-Wave-Vector (DWV)) rely on characteristic amplitude modulations that quantify microscopic anisotropy in highly heterogeneous systems. Here, we present Double-Oscillating-Diffusion-Encoding (DODE), and show that it can enhance DDE’s contrast, thereby providing increased sensitivity towards underlying microstructures. Simulations of DODE at long mixing times using the MISST framework reveal that low frequency oscillations enhance DDE’s contrast in randomly oriented anisotropic pores when compared to experiments in the long diffusion time / short diffusion gradient duration regime. These flexible DODE sequences show much potential for future applications.

17:12 0958.   Single-Spin Echo Multiband Diffusion Imaging with Slice Select Gradient Reversal
Matthew J. Middione1, Hua Wu2, Robert F. Dougherty2, Kangrong Zhu3, Adam B. Kerr3, and John M. Pauly3
1Applied Sciences Laboratory West, GE Healthcare, Meno Park, CA, United States, 2CNI, Stanford University, Stanford, CA, United States, 3Electrical Engineering, Stanford University, Stanford, CA, United States

Echo planar imaging (EPI), especially single shot EPI, is the method of choice for diffusion MRI (dMRI) due to its short scan time and motion insensitivity. However, it is sensitive to chemical-shift artifacts due to the low bandwidth in the phase-encoding direction, which requires the use of efficient fat suppression. Herein we analyze the effects of removing chemical shift artifacts with different fat saturation and suppression techniques for single-spin-echo, dual-spin-echo, and multiband imaging. We propose a single-spin-echo dMRI sequence using multiband imaging and slice select gradient reversal to provide efficient fat suppression, comparable SNR, and reduced scan time.

17:24 0959.   
Diffusion-Weighted Readout-Segmented EPI Using PINS Simultaneous Multislice Imaging
Peter J Koopmans1, Robert Frost1, David A Porter2, Wenchuan Wu1, Peter Jezzard1, Karla L Miller1, and Markus Barth3
1FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Institute for Medical Image Computing, Fraunhofer MEVIS, Bremen, Germany, 3Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia

Diffusion-weighted, readout-segmented echo-planar imaging is a technique that can produce higher resolution diffusion images than conventional single-shot approaches but is very slow. We accelerated it using simultaneous multislice methods and by using partial Fourier in the segmentation dimension. Results are shown with 133 whole-brain volumes of 1 mm isotropic, acquired in 45 minutes.

17:36 0960.   
Correction of 3D motion induced artifacts in multi-shot diffusion imaging using projection onto convex sets based multiplexed sensitivity-encoding MRI (POCSMUSE)
Mei-Lan Chu1,2, Shayan Guhaniyogi1, Hing-Chiu Chang1, and Nan-kuei Chen1
1Brain Imaging and Analysis Center, Duke University Medical Center, Durham, North Carolina, United States, 2Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan

A new POCSMUSE method is developed to produce high-quality and artifact-free multi-shot DTI data in the presence of large-scale intrascan subject motion, using coil sensitivity profiles, in-plane and through-plane position measures, and segment-specific signal variations as constraints. The developed method can effectively remove artifacts originating from both in-plane and through-plane motion in multi-shot DTI data, and is generally compatible with different types of sampling trajectories

17:48 0961.   Efficient Large Scale Motion Compensation for Multi-Shot Diffusion-Weighted Imaging
Zhongbiao Xu1, Zhigang Wu2, Wufan Chen1, Yanqiu Feng1, Feng Huang2, Wenxing Fang2, and Jing Zhang2
1Guangdong Provincial Key Laborary of Medical Image Processing, School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China, 2Philips Healthcare (Suzhou) CO.LTD, Suzhou, Jiangsu, China

In this work, we extend multiplexed sensitivity-encoding (MUSE) to address the issues related to shot-to-shot large-scale motion. Our method groups shots into clusters, reconstructs each cluster with MUSE by taking advantage of the same magnitude property inside each cluster, and corrects the inter-shot motion by image registration techniques. The proposed can robustly deliver high quality image even when there is large scale inter-shot motion.