Research: MRE has Excellent Technical Performance in Patients with High BMI

The following poster was presented at The Liver Meeting® in early November 2019, hosted by the American Association for the Study of Liver Diseases (AASLD). The research examined the success rate of MR Elastography exams in 1,056 patients with a mean body mass index (BMI) of 32. The success rate of MRE in this patient population was 97%. This important research continues to demonstrate that MRE can be a highly useful tool for diagnosing and staging liver fibrosis in patient populations were obesity is highly prevalent, such as non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH).

LIVER STIFFNESS USING MR ELASTOGRAPHY HAS HIGH TECHNICAL SUCCESS RATE IN NAFLD PATIENTS WITH HIGH BMI

Kay Pepin1, Jeremy Heilman1, Bogdan Dzyubak1, Tolga Gidener2, Joseph Larson3, Terry M Therneau2, Richard Ehman1, Alina M. Allen4 and Meng Yin1, (1)Radiology, Mayo Clinic, (2)Mayo Clinic, (3)Mayo Clinic Rochester, (4) Gastroenterology and Hepatology, Mayo Clinic

Background: Obesity is a known risk factor for nonalcoholic fatty liver disease (NAFLD), where prevalence may exceed 90% in obese patients undergoing bariatric surgery Liver biopsy remains the gold standard in hepatic fibrosis staging, however it is invasive, subject to sampling errors, and lower success rate with high body mass index (BMI) There is a clinical need for reliable and accurate biomarkers in patients with high BMI Transient elastography provides liver stiffness (LS) measurements, however has been limited by a high technical failure rate (5-40%) in individuals with high BMI (>30 kg/m2) Magnetic resonance elastography (MRE) is highly reliable, reproducible, and accurate for the assessment of LS for fibrosis staging. Our purpose was to determine the technical success of MRE in patients with high BMI

Methods: We identified patients diagnosed with NAFLD, received an MRE exam between 2007 and 2019, and had a recorded BMI at the time of MRE LS was calculated as the mean across regions of interest (ROIs) on 4 MRE slices From 2007-2012, ROIs were manually drawn by an experienced reader From 2012-2019, ROIs were calculated using an automatic liver elasticity calculation (ALEC) and reviewed by an experienced reader. Technical success of MRE was defined as the ability to draw ROIs with a minimum of 500 pixels and calculate LS

Results: 1056 patients were identified (48% male) with1195 exams. Median age: 58 years, range [4, 93]. Median BMI: 32, [15,63]. Technical success of MRE occurred in 1167 exams (97%). Technical success did not vary by BMI category: BMI<20, 95.5%; 20≤BMI<30, 97.6%; 30≤BMI<40, 97.8%; 40≤BMI<50, 97.8%; BMI≥50, 97.1%. Mean LS in this NAFLD cohort was 3.9 kPa, [1.6, 17.5]. Mean LS did not vary by BMI category: BMI≤20, LS = 3.9 kPa; 20≤BMI<30, LS = 3.8 kPa; 30≤BMI<40, LS = 3.9 kPa; 40≤BMI<50, LS = 4.1 kPa; BMI≥50, LS = 4.1 kPa. High BMI (BMI≥30) was not associated with an elevated LS; 3 3 kPa vs 3 1 for BMI<30 kPa Reasons for technical failure were not recorded, but could include claustrophobia, inability to hold breath for acquisition, patient motion, iron overload, or inadequate shear wave penetration In our experience, tightening the belt that straps down the passive driver can improve the results, especially in patients with large BMI

Conclusion: Liver stiffness quantified by MRE has a high technical success rate of 97% in patients with high BMI and can be utilized for staging of liver fibrosis in this high-risk patient population.