IVIM parameters have good scan-rescan reproducibility when evidential motion contaminated and poorly fitted image data are removed

Abstract

BackgroundIntravoxel Incoherent Motion (IVIM) diffusion MRI is a promising technique for liver pathology evaluation, but this techniques scan-rescan reproducibility has been reported to be unsatisfactory.\n\nObjectiveTo understand whether IVIM MRI parameters for liver parenchyma can be good after removal of motion contaminated and/or poorly fitted image data.\n\nMaterial and MethodsEighteen healthy volunteers had liver scanned twice at the same session to assess scan-rescan repeatability, and again in another session after an average interval of 13 days to assess reproducibility. Diffusion weighted image were acquired with a 3T scanner using respiratory-triggered echo-planar sequence and 16 b-values (0 to 800 s/mm2). Measurement was performed on the right liver with segmented-unconstrained least square fitting. Image series with evidential anatomical mismatch, apparent artifacts, and poorly fitted signal intensity vs. b-value curve were excluded. A minimum of three slices was deemed necessary for IVIM parameter estimation of a liver.\n\nResultsWith total 54 examinations, 6 scans did not satisfy inclusion criteria, leading to a success rate of 89%; and 14 volunteers were finally included. With each scan a mean of 5.3 slices (range: 3-10 slices) were utilized for analysis. Using threshold b-value=80s/mm2, the coefficient of variation and within-subject coefficient of variation for repeatability and reproducibility were: 2.86% and 4.24% for Dslow, 3.81% and 4.24%, for PF, 18.16% and 24.88% for Dfast; and those for reproducibility were 2.48% and 3.24% for Dslow; 4.91% and 5.38% for PF; 21.18% and 30.89% for Dfast.\n\nConclusionIVIM parameter scan-rescan reproducibility can be potentially good.