Suchandrima Banerjee1, Dwight G Nishimura2, Ajit Shankaranarayanan1, Emine Ulku Saritas3,4. 1. Global MR Applications & Workflow, GE Healthcare, Menlo Park, California, USA. 2. Department of Electrical Engineering, Stanford University, Stanford, California, USA. 3. Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey. 4. National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey.
Abstract
PURPOSE: Reduced field-of-view (rFOV) diffusion-weighted imaging (DWI) using 2D echo-planar radiofrequency (2DRF) excitation has been widely and successfully applied in clinical settings. The purpose of this work is to further improve its clinical utility by overcoming slice coverage limitations without any scan time penalty while providing robust fat suppression. THEORY AND METHODS: During multislice imaging with 2DRF pulses, periodic sidelobes in the slice direction cause partial saturation, limiting the slice coverage. In this work, a tilting of the excitation plane is proposed to push the sidelobes out of the imaging section while preserving robust fat suppression. The 2DRF pulse is designed using Shinnar-Le Roux algorithm on a rotated excitation k-space. The performance of the method is validated via simulations, phantom experiments, and high in-plane resolution in vivo DWI of the spinal cord. RESULTS: Results show that rFOV DWI using the tilted 2DRF pulse provides increased signal-to-noise ratio, extended coverage, and robust fat suppression, without any scan time penalty. CONCLUSION: Using a tilted 2DRF excitation, a high-resolution rFOV DWI method with robust fat suppression and unrestricted slice coverage is presented. This method will be beneficial in clinical applications needing large slice coverage, for example, axial imaging of the spine, prostate, or breast. Magn Reson Med 76:1668-1676, 2016.
PURPOSE: Reduced field-of-view (rFOV) diffusion-weighted imaging (DWI) using 2D echo-planar radiofrequency (2DRF) excitation has been widely and successfully applied in clinical settings. The purpose of this work is to further improve its clinical utility by overcoming slice coverage limitations without any scan time penalty while providing robust fat suppression. THEORY AND METHODS: During multislice imaging with 2DRF pulses, periodic sidelobes in the slice direction cause partial saturation, limiting the slice coverage. In this work, a tilting of the excitation plane is proposed to push the sidelobes out of the imaging section while preserving robust fat suppression. The 2DRF pulse is designed using Shinnar-Le Roux algorithm on a rotated excitation k-space. The performance of the method is validated via simulations, phantom experiments, and high in-plane resolution in vivo DWI of the spinal cord. RESULTS: Results show that rFOV DWI using the tilted 2DRF pulse provides increased signal-to-noise ratio, extended coverage, and robust fat suppression, without any scan time penalty. CONCLUSION: Using a tilted 2DRF excitation, a high-resolution rFOV DWI method with robust fat suppression and unrestricted slice coverage is presented. This method will be beneficial in clinical applications needing large slice coverage, for example, axial imaging of the spine, prostate, or breast. Magn Reson Med 76:1668-1676, 2016.
Authors: Amita Shukla-Dave; Nancy A Obuchowski; Thomas L Chenevert; Sachin Jambawalikar; Lawrence H Schwartz; Dariya Malyarenko; Wei Huang; Susan M Noworolski; Robert J Young; Mark S Shiroishi; Harrison Kim; Catherine Coolens; Hendrik Laue; Caroline Chung; Mark Rosen; Michael Boss; Edward F Jackson Journal: J Magn Reson Imaging Date: 2018-11-19 Impact factor: 5.119
Authors: Yi Sui; Shivaram P Arunachalam; Arvin Arani; Joshua D Trzasko; Phillip M Young; James F Glockner; Kevin J Glaser; David S Lake; Kiaran P McGee; Armando Manduca; Phillip J Rossman; Richard L Ehman; Philip A Araoz Journal: Magn Reson Med Date: 2017-12-01 Impact factor: 4.668