Removal of evidential motion-contaminated and poorly fitted image data improves IVIM diffusion MRI parameter scan–rescan reproducibility

摘要

Background It has been reported that intravoxel incoherent motion (IVIM) diffusion magnetic resonance imaging (MRI) scan–rescan reproducibility is unsatisfactory. Purpose To study IVIM MRI parameter reproducibility for liver parenchyma after the removal of motion-contaminated and/or poorly fitted image data. Material and Methods Eighteen healthy volunteers had liver scans twice in 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 images were acquired with a 3-T scanner using respiratory-triggered echo-planar sequence and 16 b-values (0–800 s/mm~(2)). Measurement was performed on the right liver with segment-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. Results With a total 54 examinations, six did not satisfy inclusion criteria, leading to a success rate of 89%, and 14 volunteers were finally included for the repeatability/reproducibility study. A total of 3–10 slices per examination (mean?=?5.3 slices, median?=?5 slices) were utilized for analysis. Using threshold b-value?=?80?s/mm~(2), the coefficient of variation and within-subject coefficient of variation for repeatability were 2.86% and 3.36% for D_(slow), 3.81% and 4.24% for perfusion fraction (PF), 18.16% and 24.88% for D_(fast); and those for reproducibility were 2.48% and 3.24% for D_(slow), 4.91% and 5.38% for PF, and 21.18% and 30.89% for D_(fast). Conclusion Removal of motion-contaminated and/or poorly fitted image data improves IVIM parameter reproducibility.