Sirlin, Claude B.

Background: Accurate identification of patients with metabolic dysfunction–associated steatohepatitis (MASH) at risk of disease progression (at-risk MASH) is critical for guiding resmetirom and semaglutide therapy. Inconsistent definitions of at-risk MASH complicate clinical risk classification and comparisons across studies. This study aimed to standardize the definition of at-risk MASH and propose optimized MRE-based liver stiffness (LS-MRE) cutoffs to improve noninvasive risk stratification and better guide pharmacotherapy. Methods: In this prospective study, 413 patients with suspected or diagnosed MASLD from two medical centers underwent liver biopsy and MRE. Results: A simplified definition of at-risk MASH (MASH with fibrosis stage≥2) identified a broader group of patients requiring clinical attention than a stricter definition requiring NAFLD Activity Score≥4 with ≥1 point in steatosis, inflammation, and ballooning (n=122 vs. 77). LS-MRE alone showed the highest diagnostic accuracy for identifying at-risk MASH using the simplified definition (AUC 0.91 [0.87, 0.95]) and cirrhosis (AUC 0.93 [0.88, 0.99]), compared with FIB-4 and individual laboratory parameters (AST, ALT, and platelet count) ( p <0.01 for all, paired DeLong tests). Optimized LS-MRE cutoffs (2.8–6.4 kPa) captured 25 additional biopsy-proven pharmacotherapy candidates (28% of all eligible patients) compared to AASLD guidelines–recommended cutoffs (3.1–4.4 kPa), improving sensitivity (80% vs. 50%) with acceptable specificity (73% vs. 88%). Conclusions: A simplified definition of at-risk MASH enables broader identification of treatment candidates. LS-MRE demonstrates excellent diagnostic performance and improves noninvasive risk stratification when paired with optimized cutoffs. These findings support the use of MRE to guide resmetirom and semaglutide eligibility and improve access to emerging therapies.

Compared with two-dimensional MR elastography (MRE), three-dimensional MRE demonstrated better test-retest repeatability, between–field-strength reproducibility, and between-day reproducibility at 3 T for measurement of liver stiffness in adults with severe obesity but failed more frequently.

Ezetimibe inhibits intestinal cholesterol absorption and lowers low‐density lipoprotein cholesterol. Uncontrolled studies have suggested that it reduces liver fat as estimated by ultrasound in nonalcoholic steatohepatitis (NASH). Therefore, we aimed to examine the efficacy of ezetimibe versus placebo in reducing liver fat by the magnetic resonance imaging‐derived proton density‐fat fraction (MRI‐PDFF) and liver histology in patients with biopsy‐proven NASH. In this randomized, double‐blind, placebo‐controlled trial, 50 patients with biopsy‐proven NASH were randomized to either ezetimibe 10 mg orally daily or placebo for 24 weeks. The primary outcome was a change in liver fat as measured by MRI‐PDFF in colocalized regions of interest within each of the nine liver segments. Novel assessment by two‐dimensional and three‐dimensional magnetic resonance elastography was also performed. Ezetimibe was not significantly better than placebo at reducing liver fat as measured by MRI‐PDFF (mean difference between the ezetimibe and placebo arms ‐1.3%, P = 0.4). Compared to baseline, however, end‐of‐treatment MRI‐PDFF was significantly lower in the ezetimibe arm (15%‐11.6%, P < 0.016) but not in the placebo arm (18.5%‐16.4%, P = 0.15). There were no significant differences in histologic response rates, serum alanine aminotransferase and aspartate aminotransferase levels, or longitudinal changes in two‐dimensional and three‐dimensional magnetic resonance elastography‐derived liver stiffness between the ezetimibe and placebo arms. Compared to histologic nonresponders (25/35), histologic responders (10/35) had a significantly greater reduction in MRI‐PDFF (‐4.35 ± 4.9% versus ‐0.30 ± 4.1%, P < 0.019). Conclusions : Ezetimibe did not significantly reduce liver fat in NASH. This trial demonstrates the application of colocalization of MRI‐PDFF‐derived fat maps and magnetic resonance elastography‐derived stiffness maps of the liver before and after treatment to noninvasively assess treatment response in NASH. (H epatology 2015;61:1239–1250)