A pilot study in PROMETHEUS: MRI Proton density fat fraction is feasible in morbidly obese patients and results equivalent to liver biopsy

Background: The PROMETHEUS study is a prospective cohort study that extensively characterize morbidly obese persons (BMI > 35 kg/m3) aiming to detect, grade and follow non-alcoholic fatty liver disease (NAFLD). Methods: 52/600 participants are included. All underwent liver biopsy and transient elastography with controlled attenuation parameter (CAP) using XL or M probe to quantify steatosis. The liver biopsies were evaluated semi-quantitatively on a standard H&E-stain and fat content estimated to the nearest 10% interval. Twenty were further offered steatosis evaluation using proton density fat fraction (PDFF) — a single-breath-hold MRI sequence using a GE healthcare 1,5-T scanner. Aims: Assess MRI feasibility in our morbidly obese cohort and examine accordance between liver fat content at liver biopsy, CAP and PDFF. Results: Fourteen patients accepted MRI-PDFF. Six (30%) declined (claustrophobia or problems with prolonged supination). None were excluded due to limitations of size or weight. We could confirm an excellent accordance between liver fat content measured by biopsy and PDFF (Person r=0.8, p<0.0001). But not between PDFF and CAP (Person r=0.2, p=0.5). Conclusion: MRI-PDFF fat quantification using MRI was feasible in the 2/3 who accepted the scan; and results were equivalent to those obtained by biopsy, but not CAP.