• Hua Guo, Xiaodong Ma, Zhe Zhang, Bida Zhang, Chun Yuan, and Feng Huang.
• Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China.
• Magn Reson Med. 2016 Jan 1; 75 (1): 169-80.

PurposeFor 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 MethodsInstead 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.ResultsPOCS-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.ConclusionPOCS-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.© 2015 Wiley Periodicals, Inc.

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