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Optimization of b-value schemes for estimation of the diffusion coefficient and the perfusion fraction with segmented intravoxel incoherent motion model fitting

Journal article
Authors Oscar Jalnefjord
Mikael Montelius
Göran Starck
Maria Ljungberg
Published in Magnetic Resonance in Medicine
Volume 82
Issue 4
Pages 1541-1552
ISSN 0740-3194
Publication year 2019
Published at Institute of Clinical Sciences, Department of Radiation Physics
Pages 1541-1552
Language en
Keywords Cramer-Rao lower bound, diffusion-weighted imaging, error propagation, experiment design, IVIM, MRI, adult, article, clinical article, controlled study, diffusion coefficient, diffusion weighted imaging, female, human, human experiment, in vivo study, liver, male, motion, perfusion, simulation, theoretical study, uncertainty, volunteer
Subject categories Radiological physics


Purpose: Intravoxel incoherent motion (IVIM) modeling for estimation of the diffusion coefficient (D) and perfusion fraction (f) is increasingly popular, but no consensus on standard protocols exists. This study provides a framework for optimization of b-value schemes for reduced estimation uncertainty of D and f from segmented model fitting. Theory: Analytical expressions for uncertainties of D and f from segmented model fitting were derived as Cramer-Rao lower bounds (CRLBs). Methods: Optimized b-value schemes were obtained for 3 to 12 acquisitions and in the limit of infinitely many acquisitions through constrained minimization of the CRLBs, with b-values constrained to be 0 or 200 to 800 s/mm2. The optimized b-value scheme with eight acquisitions was compared with b-values linearly distributed in the allowed range using simulations and in vivo liver data from seven healthy volunteers. Results: All optimized b-value schemes contained exactly three unique b-values regardless of the total number of acquisitions (0, 200, and 800 s/mm2) with repeated acquisitions distributed approximately as 1:2:2. Compared with linearly distributed b-values, the variability of estimates of D and f was reduced by approximately 30% as seen both in simulations and in repeated in vivo measurements. Conclusion: The uncertainty of IVIM D and f estimates can be reduced by the use of optimized b-value schemes. © 2019 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine

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