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Signal‐to‐noise, resolution, and bias function analysis of asymmetric sampling with zero‐padded magnitude ft reconstruction
Author(s) -
Hurst Gregory C.,
Hua Jianmin,
Simonetti Orlando P.,
Duerk Jeffrey L.
Publication year - 1992
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.1910270206
Subject(s) - asymmetry , sampling (signal processing) , distortion (music) , magnitude (astronomy) , mathematics , resolution (logic) , voxel , noise (video) , image resolution , nyquist frequency , window function , zero crossing , spatial frequency , nuclear magnetic resonance , physics , optics , statistics , artificial intelligence , image (mathematics) , computer science , computer vision , spectral density , amplifier , optoelectronics , cmos , quantum mechanics , astronomy , detector , filter (signal processing) , voltage
This report describes NMR image effects due to sampling asymmetry when using zero‐padded magnitude FT reconstruction. With this method, the MTF is not flat over the spatial frequency passband, so resolution cannot be accurately described by a single variable such as voxel size. At small to moderate asymmetry, shortened (reduced window duration) asymmetry provides increased S/N and decreased resolution, whereas shifted (constant window duration) asymmetry yields essentially constant S/N with simultaneously increased and decreased resolution. A bias function expression describes image distortion due to sampling in terms separable from the imaged object. The analyses are consistent with previous descriptions of perceived image differences related to data asymmetry.