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Performance of sampling density‐weighted and postfiltered density‐adapted projection reconstruction in sodium magnetic resonance imaging
Author(s) -
Konstandin Simon,
Nagel Armin M.
Publication year - 2013
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.24255
Subject(s) - apodization , sampling (signal processing) , projection (relational algebra) , iterative reconstruction , physics , noise (video) , signal to noise ratio (imaging) , nuclear magnetic resonance , mathematics , optics , algorithm , computer science , artificial intelligence , image (mathematics) , detector
Sampling density‐weighted apodization projection reconstruction sequences are evaluated for three‐dimensional radial imaging. The readout gradients of the sampling density‐weighted apodization sequence are designed such that the locally averaged sampling density matches a Hamming filter function. This technique is compared with density‐adapted projection reconstruction with nonfiltered and postfiltered image reconstruction. Sampling density‐weighted apodization theoretically allows for a 1.28‐fold higher signal‐to‐noise ratio compared with postfiltered density‐adapted projection reconstruction sequences, if T 2 *decay is negligible compared with the readout duration T RO . Simulations of the point‐spread functions are performed for monoexponential and biexponential decay to investigate the effects of T 2 *decay on the performance of the different sequences. Postfiltered density‐adapted projection reconstruction performs superior to sampling density‐weighted apodization for large T RO / T 2 *ratios [>1.36 (monoexponential decay); >0.35 (biexponential decay with T 2 s * / T 2 f *= 10)], if signal‐to‐noise ratio of point‐like objects is considered. In conclusion, it depends on the readout parameters, the T 2 *relaxation times, and the dimensions of the subject which of both sequences is most suitable. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.