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Does fractional anisotropy have better noise immunity characteristics than relative anisotropy in diffusion tensor MRI? An analytical approach
Author(s) -
Hasan Khader M.,
Alexander Andrew L.,
Narayana Ponnada A.
Publication year - 2004
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.10682
Subject(s) - anisotropy , diffusion mri , fractional anisotropy , tensor (intrinsic definition) , scalar (mathematics) , monte carlo method , physics , nuclear magnetic resonance , noise (video) , noise immunity , imaging phantom , computational physics , statistical physics , mathematical analysis , mathematics , optics , medicine , statistics , computer science , magnetic resonance imaging , quantum mechanics , geometry , radiology , artificial intelligence , image (mathematics) , electronic circuit
Fractional anisotropy (FA) and relative anisotropy (RA) are the two most commonly used scalar measures of anisotropy in diffusion tensor (DT) MRI. While a few published studies have shown that FA has superior noise immunity relative to RA, no theoretical basis has been proposed to explain this behavior. In the current study, the diffusion tensor invariants were used to derive a simple analytical expression that directly relates RA and FA. An analysis based on that analytical expression demonstrated that the FA images have a higher signal‐to‐noise ratio (SNR) than RA for any value of tensor anisotropy RA or FA > 0. This theoretical behavior was verified using both Monte Carlo simulations and bootstrap analysis of DT‐MRI data acquired in a spherical water phantom and normal human subjects. Magn Reson Med 51:413–417, 2004. © 2004 Wiley‐Liss, Inc.