Magnetic resonance elastography predicts advanced fibrosis in patients with nonalcoholic fatty liver disease: a prospective study

Abstract

Retrospective studies have shown that two-dimensional magnetic resonance elastography (2D-MRE), a novel MR method for assessment of liver stiffness, correlates with advanced fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). Prospective data on diagnostic accuracy of 2D-MRE in the detection of advanced fibrosis in NAFLD are needed. The aim of this study is to prospectively assess the diagnostic accuracy of 2D-MRE, a noninvasive imaging biomarker, in predicting advanced fibrosis (stage 3 or 4) in well-characterized patients with biopsy-proven NAFLD. This is a cross-sectional analysis of a prospective study including 117 consecutive patients (56% women) with biopsy-proven NAFLD who underwent a standardized research visit: history, exam, liver biopsy assessment (using the nonalcoholic steatohepatitis Clinical Research Network histological scoring system), and 2D-MRE from 2011 to 2013. The radiologist and pathologist were blinded to clinical and pathology/imaging data, respectively. Receiver operating characteristics (ROCs) were examined to assess the diagnostic test performance of 2D-MRE in predicting advanced fibrosis. The mean (± standard deviation) of age and body mass index was 50.1 (± 13.4) years and 32.4 (± 5.0) kg/m(2), respectively. The median time interval between biopsy and 2D-MRE was 45 days (interquartile range: 50 days). The number of patients with fibrosis stages 0, 1, 2, 3, and 4 was 43, 39, 13, 12, and 10, respectively. The area under the ROC curve for 2D-MRE discriminating advanced fibrosis (stage 3-4) from stage 0-2 fibrosis was 0.924 (P < 0.0001). A threshold of >3.63 kPa had a sensitivity of 0.86 (95% confidence interval [CI]: 0.65-0.97), specificity of 0.91 (95% CI: 0.83-0.96), positive predictive value of 0.68 (95% CI: 0.48-0.84), and negative predictive value of 0.97 (95% CI: 0.91-0.99).

Conclusions: MRE is accurate in predicting advanced fibrosis and may be utilized for noninvasive diagnosis of advanced fibrosis in patients with NAFLD.

Fig 1

Diagnostic accuracy of MRE for advanced fibrosis. AUROC for the detection of advanced fibrosis in patients with biopsy-proven NAFLD is shown, and a two-tailed P value is provided. TPR, true-positive rate; FPR, false-positive rate.

Fig 2

Distribution of fibrosis and MRE readings for the entire cohort. A box plot of individual stages of fibrosis (stage 0, 1, 2, 3, and 4) is shown on the x-axis, and the respective 2D-MRE reading on the y-axis is shown for the entire cohort stratified by fibrosis stage.

Fig 3

MRE stiffness maps of 5 patients with NAFLD and different stages of liver fibrosis. Shown are MRE stiffness maps in 5 patients with NAFLD. These maps depict the spatial distribution of stiffness (in kPa) within the liver (outlined in white). As shown in the color lookup table at the right, the stiffness values range from near zero (dark purple) to 8 kPa (red). The histology-determined liver fibrosis stage is shown at the top of each stiffness map, and the MRE-determined mean liver stiffness is shown at the bottom of each image. Notice that the stiffness values are greater in patients with more-advanced fibrosis.