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Accelerating MRI by skipped phase encoding and edge deghosting (SPEED)
Author(s) -
Xiang QingSan
Publication year - 2005
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20453
Subject(s) - aliasing , filter (signal processing) , encoding (memory) , enhanced data rates for gsm evolution , computer science , phase (matter) , algorithm , artifact (error) , signal (programming language) , noise (video) , acceleration , minification , k space , artificial intelligence , fourier transform , computer vision , mathematics , physics , image (mathematics) , mathematical analysis , classical mechanics , quantum mechanics , programming language
A fast imaging method called skipped phase encoding and edge deghosting (SPEED) is introduced. The k ‐space is sparsely sampled into three interleaved datasets, each with a skip‐size N and a relative shift in phase encoding (PE). These datasets are separately reconstructed by 2DFT and edge‐enhanced by a differential filter in the PE direction, resulting in edge maps with phase‐shifted aliasing ghosts. The sparseness of edges reduces the chance of ghost overlapping. Typical ghosted‐edge maps can be adequately modeled with only two dominating ghost layers that are resolved from a set of three equations using least‐square error minimization, yielding N ghost maps of different orders that can be registered and averaged into a single deghosted‐edge map for noise and artifact reduction. Finally, the deghosted‐edge map is transformed into a deghosted image by an inverse filter. A few central k ‐space lines are collected without PE skip to aid the inverse filtering. SPEED has been demonstrated by in vivo data to reduce scan time considerably without noticeable artifacts. It has various potential applications, such as MR angiography (MRA), where the signal itself is sparse. As an independent method, SPEED can be combined with other fast imaging methods for further acceleration. Magn Reson Med 53:1112–1117, 2005. © 2005 Wiley‐Liss, Inc.