Liver shear wave elastography using a mechanical index exceeding regulatory limits is safe and effective

Metabolic dysfunction-associated steatotic liver disease affects 1 in 3 people worldwide. Ultrasound shear wave elastography (SWE) in obese patients, the target population for testing, is hampered by beam attenuation, leading to unreliable liver fibrosis quantification.

We assess the safety and efficacy of increased push mechanical index (IPMI) above U.S. Food and Drug Administration limits to improve SWE.

This single-center prospective trial (July 2023-April 2024) (NCT05792423) enrolled healthy adults stratified by body mass index (BMI). Participants underwent conventional push pulse (mechanical index [MI] 1.4) and IPMI (MI 2.5) SWE (GE Healthcare LOGIQ E10) performed by 1 of 3 sonographers and serial liver function testing (LFT) before and up to 7 days after imaging. Liver injury was defined as increased serum alanine transaminase (ALT), aspartate aminotransferase (AST), or alkaline phosphatase (ALP) (non-inferiority margins: AST 7.5 U/L, ALT 12 U/L, ALP 17.5 U/L). Secondary endpoints included SWE variability and measurement number.

Twenty-two analyzable participants (mean age 39.6 ± 16.3 years; 15 women) had normal BMI (6), overweight (6), class 1 obesity (7), and class 2 obesity (3). Conventional shear wave speed was 1.34 ± 0.21 m/s, and IPMI yielded 1.36 ± 0.20 m/s (velocities ≤ 1.34 m/s indicate minimal or no fibrosis). The mean [95% CI] LFT change from baseline to day 1 was 1) AST: -0.86 [-2.34, 0.61], P = .24, 2) ALT: 0.32 [-1.04, 1.68], P = .63, 3) ALP: 1.73 [-1.02, 4.47], P = .21. The upper 95% CI for all biomarkers met non-inferiority criteria. Mean IPMI interquartile range (IQR) to median ratio decreased 0.019 (29.2% relative reduction) (P = .01) with 0.68 [IQR: 0.0.75] (P = .058), fewer average attempts.

IPMI SWE in healthy volunteers did not cause injury and reduced measurement variability. IPMI SWE should be developed to improve examination quality and reliability in obese patients.