ORIGINAL RESEARCH n GASTROINTESTINAL IMAGING 418 radiology.rsna.org n Radiology: Volume 283: Number 2—May 2017 1 From the Departments of Radiology (J.C., M.Y., K.J.G., R.L.E.), Gastroenterology (J.A.T.), and Anatomic Pathology (T.C.S.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; and Echosens, Paris, France (J.O., V.M., L.S.). Received April 13, 2016; revision requested May 26; revision received July 20; accepted August 23; final version accepted September 13. Address correspondence to R.L.E. (e-mail: ehman.richard@mayo.edu). Supported by National Institute of Biomedical Imaging and Bioengineering (grants EB 001981, EB 10393, and EB 017197). q RSNA, 2016 Purpose: To evaluate the diagnostic performance and examination success rate of magnetic resonance (MR) elastography and vibration-controlled transient elastography (VCTE) in the detection of hepatic fibrosis in patients with severe to morbid obesity. Materials and Methods: This prospective and HIPAA-compliant study was approved by the institutional review board. A total of 111 patients (71 women, 40 men) participated. Written informed con- sent was obtained from all patients. Patients underwent MR elastography with two readers and VCTE with three observers to acquire liver stiffness measurements for liver fibrosis assessment. The results were compared with those from liver biopsy. Each pathology specimen was evaluated by two hepatopathologists according to the METAVIR scor- ing system or Brunt classification when appropriate. All imaging observers were blinded to the biopsy results, and all hepatopathologists were blinded to the imaging results. Examination success rate, interobserver agreement, and diagnostic accuracy for fibrosis detection were assessed. Results: In this obese patient population (mean body mass index = 40.3 kg/m 2 ; 95% confidence interval [CI]: 38.7 kg/m 2 , 41.8 kg/m 2 ]), the examination success rate was 95.8% (92 of 96 patients) for MR elastography and 81.3% (78 of 96 pa- tients) or 88.5% (85 of 96 patients) for VCTE. Interobserver agreement was higher with MR elastography than with bi- opsy (intraclass correlation coefficient, 0.95 vs 0.89). In pa- tients with successful MR elastography and VCTE examina- tions (excluding unreliable VCTE examinations), both MR elastography and VCTE had excellent diagnostic accuracy in the detection of clinically significant hepatic fibrosis (stage F2–F4) (mean area under the curve: 0.93 [95% CI: 0.85, 0.97] vs 0.91 [95% CI: 0.83, 0.96]; P = .551). Conclusion: In this obese patient population, both MR elastography and VCTE had excellent diagnostic performance for as- sessing hepatic fibrosis; MR elastography was more tech- nically reliable than VCTE and had a higher interobserver agreement than liver biopsy. q RSNA, 2016 Online supplemental material is available for this article. Jun Chen, PhD Meng Yin, PhD Jayant A. Talwalkar, MD Jennifer Oudry, PhD Kevin J. Glaser, PhD Thomas C. Smyrk, MD Véronique Miette, PhD Laurent Sandrin, PhD Richard L. Ehman, MD Diagnostic Performance of MR Elastography and Vibration-controlled Transient Elastography in the Detection of Hepatic Fibrosis in Patients with Severe to Morbid Obesity 1 An earlier incorrect version of this article appeared online. This article was corrected on January 25, 2017. This copy is for personal use only. To order printed copies, contact reprints@rsna.org