title: POCS-enhanced inherent correction of motion-induced phase errors (POCS-ICE) for high-resolution multishot diffusion MRI.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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: Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China.
authors: Hua
authors: H
authors: Guo
authors: Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China.
authors: Xiaodong
authors: X
authors: Ma
authors: Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China.
authors: Zhe
authors: Z
authors: Zhang
authors: Healthcare Department, Philips Research China, Shanghai, China.
authors: Bida
authors: B
authors: Zhang
authors: Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, China.|Department of Radiology, University of Washington, Seattle, Washington, USA.
authors: Chun
authors: C
authors: Yuan
authors: Philips Healthcare (Suzhou) Co., Ltd., Suzhou, China.
authors: Feng
authors: F
authors: Huang
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D009038:Motion; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
keywords: POCS-ICE; SENSE+CG; diffusion weighted imaging; multishot diffusion imaging; navigator-free