title: Improving image quality for skipped phase encoding and edge deghosting (SPEED) by exploiting several sparsifying transforms.
abstract: OBJECTIVE
  To improve the image quality of skipped phase encoding and edge deghosting (SPEED) by exploiting several sparsifying transforms.
  
  
  METHODS
  The SPEED technique uses a skipped phase encoding (PE) step to accelerate MRI scan. Previously, a difference transform (DT) along PE direction is used to obtain sparse ghosted-edge maps, which were modeled by a double layer ghost model and was then deghosted by a least square error solution. In this work, it is hypothesized that enhanced sparsity, and thus improved image quality may be achievable with other sparsifying transforms, including discrete wavelet transform (DWT), discrete cosine transform (DCT), DWT combined with DT, and DCT combined with DT.
  
  
  RESULTS
  For images of human subjects, SPEED with DWT or DCT can yield higher image quality than DT only, especially for those images with low contrast. Reconstruction error can be further reduced if DWT or DCT are combined with DT.
  
  
  CONCLUSIONS
  Image sparsity can be enhanced with more advanced transforms, leading to higher reconstruction quality in SPEED imaging that is desirable for practical MRI applications.
authors.affiliation: Key Lab for IOT and Information Fusion Technology of Zhejiang, Hangzhou Dianzi University, Hangzhou, Zhejiang, People's Republic of China.
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Jin
authors.affiliation: Department of Fetal Monitoring, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
authors.forename: Haihui
authors.initials: H
authors.lastname: Ye
authors.affiliation: Collaborative Innovation Center for Brain Science and the Key Laboratory for Biomedical Engineering of Education Ministry of China, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
authors.forename: Yiping P
authors.initials: YP
authors.lastname: Du
authors.affiliation: Department of Radiology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Qing-San
authors.initials: QS
authors.lastname: Xiang
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging; D003198:Computer Simulation; D003287:Contrast Media / Q000737:chemistry; D005583:Fourier Analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D016018:Least-Squares Analysis; D008279:Magnetic Resonance Imaging; D015233:Models, Statistical; D009991:Oscillometry; D019047:Phantoms, Imaging; D012984:Software; D058067:Wavelet Analysis
chemical_list: D003287:Contrast Media
keywords: SPEED; difference transform; discrete cosine transform; discrete wavelet transform; fast imaging; sparsifying transform