Author information
1
Liver Imaging Group, Department of Radiology, University of California, San Diego, 9500 Gilman Drive, San Diego, CA, 92093-0888, USA.
2
Computational and Applied Statistics Laboratory (CASL), San Diego Supercomputer Center (SDSC), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
3
Division of Epidemiology, Department of Family Medicine and Preventive Medicine, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
4
Liver Imaging Group, Department of Radiology, University of California, San Diego, 9500 Gilman Drive, San Diego, CA, 92093-0888, USA. csirlin@ucsd.edu.
Abstract
PURPOSE:
To determine the inter-reader agreement of magnetic resonance imaging proton density fat fraction (PDFF) and its longitudinal change in a clinical trial of adults with nonalcoholic steatohepatitis (NASH).
STUDY TYPE:
We performed a secondary analysis of a placebo-controlled randomized clinical trial of a bile acid sequestrant in 45 adults with NASH. A six-echo spoiled gradient-recalled-echo magnitude-based fat quantification technique was performed at 3 T. Three independent readers measured MRI-PDFF by placing one primary and two additional regions of interest (ROIs) in each segment at both time points. Cross-sectional agreement between the three readers was evaluated using intra-class correlation coefficients (ICCs) and coefficients of variation (CV). Additionally, we used Bland-Altman analyses to examine pairwise agreement between the three readers at baseline, end of treatment (EOT), and for longitudinal change.
RESULTS:
Using all ROIs by all readers, mean PDFF at baseline, at EOT, and mean change in PDFF was 16.1%, 16.0%, and 0.07%, respectively. The 27-ROI PDFF measurements had 0.998 ICC and 1.8% CV at baseline, 0.998 ICC and 1.8% CV at EOT, and 0.997 ICC for longitudinal change. The 9-ROI PDFF measurements had corresponding values of 0.997 and 2.6%, 0.996 and 2.4%, and 0.994. Using 27 ROIs, the magnitude of the bias between readers for whole-liver PDFF measurement ranged from 0.03% to 0.06% points at baseline, 0.01% to 0.07% points at EOT, and 0.01% to 0.02% points for longitudinal change.
CONCLUSION:
Inter-reader agreement for measuring whole-liver PDFF and its longitudinal change is high. 9-ROI measurements have only slightly lower agreement than 27-ROI measurements.