Hua Guo1, Xiaodong Ma1, Zhe Zhang1, Bida Zhang2, Chun Yuan1,3, Feng Huang4. 1. Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China. 2. Healthcare Department, Philips Research China, Shanghai, China. 3. Department of Radiology, University of Washington, Seattle, Washington, USA. 4. Philips Healthcare (Suzhou) Co., Ltd., Suzhou, China.
Abstract
PURPOSE: For multishot diffusion weighted imaging (DWI), one of the challenges is to remove phase variations induced by physiological motion among different shots. In this study, a new method is proposed to iteratively solve the phase errors and DWI images simultaneously, for navigator-free acquisitions. THEORY AND METHODS: Instead of solving phase errors and the image sequentially in the two-step parallel imaging, the proposed method, named POCS-enhanced Inherent Correction of motion-induced phase Errors (POCS-ICE), treats both the phase and DWI image as unknowns and solves them simultaneously. Multishot DWI with constant density spiral trajectory served as a specific example. Simulation and in vivo experiments were performed to evaluate the proposed method. RESULTS: POCS-ICE shows improved image quality in terms of higher SNR and fewer artifacts than the compared method, SENSE+CG. The improvement becomes more conspicuous as the number of shots increases. The convergence behavior of POCS-ICE was also shown to be more stable. CONCLUSION: POCS-ICE can inherently and reliably correct motion-induced phase errors in navigator-free multishot DWI, and it is easier to determine the stopping criterion without manual interventions. The improved spatial resolution and image resolvability are beneficial to study of brain microstructures and physiological features for neuroscience.
PURPOSE: For multishot diffusion weighted imaging (DWI), one of the challenges is to remove phase variations induced by physiological motion among different shots. In this study, a new method is proposed to iteratively solve the phase errors and DWI images simultaneously, for navigator-free acquisitions. THEORY AND METHODS: Instead of solving phase errors and the image sequentially in the two-step parallel imaging, the proposed method, named POCS-enhanced Inherent Correction of motion-induced phase Errors (POCS-ICE), treats both the phase and DWI image as unknowns and solves them simultaneously. Multishot DWI with constant density spiral trajectory served as a specific example. Simulation and in vivo experiments were performed to evaluate the proposed method. RESULTS: POCS-ICE shows improved image quality in terms of higher SNR and fewer artifacts than the compared method, SENSE+CG. The improvement becomes more conspicuous as the number of shots increases. The convergence behavior of POCS-ICE was also shown to be more stable. CONCLUSION: POCS-ICE can inherently and reliably correct motion-induced phase errors in navigator-free multishot DWI, and it is easier to determine the stopping criterion without manual interventions. The improved spatial resolution and image resolvability are beneficial to study of brain microstructures and physiological features for neuroscience.
Authors: Yuxin Hu; Evan G Levine; Qiyuan Tian; Catherine J Moran; Xiaole Wang; Valentina Taviani; Shreyas S Vasanawala; Jennifer A McNab; Bruce A Daniel; Brian L Hargreaves Journal: Magn Reson Med Date: 2018-10-22 Impact factor: 4.668
Authors: Yuxin Hu; Xiaole Wang; Qiyuan Tian; Grant Yang; Bruce Daniel; Jennifer McNab; Brian Hargreaves Journal: Magn Reson Med Date: 2019-10-08 Impact factor: 4.668