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UNFOLD using a temporal subtraction and spectral energy comparison technique
Author(s) -
Wu Yijing,
Jeong EunKee,
Parker Dennis L.,
Alexander Andrew L.
Publication year - 2002
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.10247
Subject(s) - computer science , filter (signal processing) , subtraction , energy (signal processing) , temporal resolution , imaging phantom , background subtraction , spectral density , computer vision , artificial intelligence , contrast (vision) , optics , physics , mathematics , pixel , telecommunications , arithmetic , quantum mechanics
In dynamic MRI, several methods have been demonstrated to increase acquisition speed by decreasing the number of sequential phase encodings. The UNFOLD technique interleaves the measurements of k ‐space, reconstructs aliased images from each k ‐space interleaf, and applies a temporal low‐pass filter to obtain the nonaliased images. However, low‐pass filter resolution of the nonaliased images fails if there is overlap between the spatially aliased temporal spectra. In this study a subtraction method was used to remove the static portion of the image. The aliased and nonaliased dynamic portions are then resolved by comparing the temporal energy of bands in the power spectrum. This method was combined with the 3D 2×2 UNFOLD (a factor of 2 interleaves in two directions) technique. The combination resulted in a factor of 4 improvement in acquisition speed. Application of this method to a time‐resolved, contrast‐enhanced flow phantom study is presented. Magn Reson Med 48:559–564, 2002. © 2002 Wiley‐Liss, Inc.