Accuracy of MR imaging-estimated proton density fat fraction for classification of dichotomized histologic steatosis grades in nonalcoholic fatty liver disease - PubMed (original) (raw)

. 2015 Feb;274(2):416-25.

doi: 10.1148/radiol.14140754. Epub 2014 Sep 22.

Ajinkya Desai, Gavin Hamilton, Tanya Wolfson, Anthony Gamst, Jessica Lam, Lisa Clark, Jonathan Hooker, Tanya Chavez, Brandon D Ang, Michael S Middleton, Michael Peterson, Rohit Loomba, Claude B Sirlin

Affiliations

Accuracy of MR imaging-estimated proton density fat fraction for classification of dichotomized histologic steatosis grades in nonalcoholic fatty liver disease

An Tang et al. Radiology. 2015 Feb.

Abstract

Purpose: To evaluate the diagnostic performance of previously proposed high-specificity magnetic resonance (MR) imaging-estimated proton density fat fraction (PDFF) thresholds for diagnosis of steatosis grade 1 or higher (PDFF threshold of 6.4%), grade 2 or higher (PDFF threshold of 17.4%), and grade 3 (PDFF threshold of 22.1%) by using histologic findings as a reference in an independent cohort of adults known to have or suspected of having nonalcoholic fatty liver disease (NAFLD).

Materials and methods: This prospective, cross-sectional, institutional review board-approved, HIPAA-compliant single-center study was conducted in an independent cohort of 89 adults known to have or suspected of having NAFLD who underwent contemporaneous liver biopsy. MR imaging PDFF was estimated at 3 T by using magnitude-based low-flip-angle multiecho gradient-recalled-echo imaging with T2* correction and multipeak modeling. Steatosis was graded histologically (grades 0, 1, 2, and 3, according to the Nonalcoholic Steatohepatitis Clinical Research Network scoring system). Sensitivity, specificity, and binomial confidence intervals were calculated for the proposed MR imaging PDFF thresholds.

Results: The proposed MR imaging PDFF threshold of 6.4% to diagnose grade 1 or higher steatosis had 86% sensitivity (71 of 83 patients; 95% confidence interval [CI]: 76, 92) and 83% specificity (five of six patients; 95% CI: 36, 100). The threshold of 17.4% to diagnose grade 2 or higher steatosis had 64% sensitivity (28 of 44 patients; 95% CI: 48, 78) and 96% specificity (43 of 45 patients; 95% CI: 85, 100). The threshold of 22.1% to diagnose grade 3 steatosis had 71% sensitivity (10 of 14 patients; 95% CI: 42, 92) and 92% specificity (69 of 75 patients; 95% CI: 83, 97).

Conclusion: In an independent cohort of adults known to have or suspected of having NAFLD, the previously proposed MR imaging PDFF thresholds provided moderate to high sensitivity and high specificity for diagnosis of grade 1 or higher, grade 2 or higher, and grade 3 steatosis. Prospective multicenter studies are now needed to further validate these high-specificity thresholds.

© RSNA, 2014.

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Figures

Figure 1:

Figure 1:

Scatterplot shows MR imaging–estimated PDFF (mean of nine segments) versus near-continuous steatosis score (mean of two readings) according to proportion of hepatocytes with macrovesicular steatosis. Points are colored according to steatosis grade. NASH CRN–derived thresholds are shown on the y-axis.

Figure 2:

Figure 2:

MR imaging PDFF maps in, A, a 30-year-old man with grade 0 steatosis, B, a 48-year-old woman with grade 1 steatosis, C, a 42-year-old woman with grade 2 steatosis, and, D, a 54-year old woman with grade 3 steatosis. One representative section acquired in the liver is shown for each subject. All maps were generated by using the same PDFF dynamic range (see scale bar at right). Overlaid on each Figure part is the mean PDFF calculated from ROIs placed in each liver segment.

Figure 3:

Figure 3:

Scatterplot of MR imaging–estimated PDFF versus near-continuous steatosis score (mean of two readings) is shown, according to the time interval between MR imaging and liver biopsy. No significant effect of the time interval between MR imaging and biopsy was observed on the relationship between MR imaging–estimated PDFF and steatosis.

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