Magnetic resonance elastography is as accurate as liver biopsy for liver fibrosis staging

Background Liver MR elastography (MRE) is available for the noninvasive assessment of liver fibrosis; however, no previous studies have compared the diagnostic ability of MRE with that of liver biopsy. Purpose To compare the diagnostic accuracy of liver fibrosis staging between MRE‐based methods and liver biopsy using the resected liver specimens as the reference standard. Study Type A retrospective study at a single institution. Population In all, 200 patients who underwent preoperative MRE and subsequent surgical liver resection were included in this study. Data from 80 patients were used to estimate cutoff and distributions of liver stiffness values measured by MRE for each liver fibrosis stage (F0–F4, METAVIR system). In the remaining 120 patients, liver biopsy specimens were obtained from the resected liver tissues using a standard biopsy needle. Field Strength/Sequence 2D liver MRE with gradient‐echo based sequence on a 1.5 or 3T scanner was used. Assessment Two radiologists independently measured the liver stiffness value on MRE and two types of MRE‐based methods (threshold and Bayesian prediction method) were applied. Two pathologists evaluated all biopsy samples independently to stage liver fibrosis. Surgically resected whole tissue specimens were used as the reference standard. Statistical Tests The accuracy for liver fibrosis staging was compared between liver biopsy and MRE‐based methods with a modified McNemar's test. Results Accurate fibrosis staging was achieved in 53.3% (64/120) and 59.1% (71/120) of patients using MRE with threshold and Bayesian methods, respectively, and in 51.6% (62/120) with liver biopsy. Accuracies of MRE‐based methods for diagnoses of ≥F2 (90–91% [108–9/120]), ≥F3 (79–81% [95–97/120]), and F4 (82–85% [98–102/120]) were statistically equivalent to those of liver biopsy (≥F2, 79% [95/120], P ≤ 0.01; ≥F3, 88% [105/120], P ≤ 0.006; and F4, 82% [99/120], P ≤ 0.017). Data Conclusion MRE can be an alternative to liver biopsy for fibrosis staging. Level of Evidence: 3. Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1268–1275.