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Noise correction for the exact determination of apparent diffusion coefficients at low SNR
Author(s) -
Dietrich Olaf,
Heiland Sabine,
Sartor Klaus
Publication year - 2001
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 - 10.1002/1522-2594(200103)45:3<448::aid-mrm1059>3.0.co;2-w
Subject(s) - noise (video) , weighting , intensity (physics) , diffusion , gaussian noise , gaussian , signal (programming language) , signal to noise ratio (imaging) , magnitude (astronomy) , diffusion mri , distribution (mathematics) , mathematics , nuclear magnetic resonance , algorithm , physics , statistics , computer science , optics , image (mathematics) , mathematical analysis , artificial intelligence , acoustics , magnetic resonance imaging , medicine , radiology , quantum mechanics , astronomy , thermodynamics , programming language
Noise in MR image data increases the mean signal intensity of image regions due to the usually performed magnitude reconstruction. Diffusion‐weighted imaging (DWI) is especially affected by high noise levels for several reasons, and a decreasing SNR at increasing diffusion weighting causes systematic errors when calculating apparent diffusion coefficients (ADCs). Two different methods are presented to correct biased signal intensities due to the presence of complex noise: 1) with Gaussian intensity distribution, and 2) with arbitrary intensity distribution. The performance of the correction schemes is demonstrated by numerical simulations and DWI measurements on two different MR systems with different noise characteristics. These experiments show that noise significantly influences the determination of ADCs. Applying the proposed correction schemes reduced the bias of the determined ADC to less than 10% of the bias without correction. Magn Reson Med 45:448–453, 2001. © 2001 Wiley‐Liss, Inc.