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Optimization of b ‐value distribution for four mathematical models of prostate cancer diffusion‐weighted imaging using b values up to 2000 s/mm 2 : Simulation and repeatability study
Author(s) -
Merisaari Harri,
Jambor Ivan
Publication year - 2015
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.25310
Subject(s) - kurtosis , repeatability , nuclear medicine , diffusion mri , mathematics , prostate cancer , distribution (mathematics) , nuclear magnetic resonance , statistics , magnetic resonance imaging , physics , medicine , cancer , mathematical analysis , radiology
Purpose To find optimal b ‐value distributions for monoexponential, stretched exponential, kurtosis, and biexponential models of prostate cancer (PCa) diffusion‐weighted imaging (DWI) using simulations and repeated DWI examinations. Methods Simulations aiming to minimize estimation accuracy error were performed. Ten PCa patients underwent in total four repeated 3‐tesla DWI examinations using 12 equally spaced b values (0–2000 s/mm 2 ). Normalized mean signal intensities of regions‐of‐interest placed in normal tissue and PCa were fitted. In total, 210 different b ‐value combinations consisting of six b values, 0 and 100 s/mm 2 included in every b ‐value distribution, were evaluated in terms of accuracy and repeatability. Results The simulations and in vivo DWI data suggest the optimal b ‐value distribution for the monoexponential model consists of four to five equally distributed b values in the range of 0 to 1200 s/mm 2 . The parameters of the stretched exponential and kurtosis models are best estimated using five to seven b values in the ranges of 300 to 700 and close to 2000 s/mm 2 , in addition to low b value. B ‐value distribution consisting of eight to 10 b values in the ranges of 0 to 100, 800 to 1200, and 1800 to 2000 s/mm 2 is the preferred method for estimation of the biexponential model parameters of PCa DWI. Conclusion The optimized b ‐value distributions demonstrated improved estimation accuracy and repeatability of DWI signal decay‐derived parameters. Magn Reson Med 73:1954–1969, 2015. © 2014 Wiley Periodicals, Inc.