The deep abdominal ultrasound transducer (DAX) increases the success rate and diagnostic accuracy of shear wave elastography for liver fibrosis assessment in patients with obesity-A prospective biopsy-controlled study

BACKGROUND: Obesity impacts the diagnostic accuracy of shear wave elastography (SWE). A deep abdominal ultrasound transducer (DAX) capable of point (pSWE) and two-dimensional (2D)-SWE has recently been introduced to address this issue.

METHODS: We performed a prospective study in a cohort of mostly patients with obesity undergoing liver biopsy with a high prevalence of metabolic dysfunction-associate steatotic liver disease (MASLD). Liver stiffness measurement (LSM) was measured using vibration-controlled transient elastography (VCTE), as well as pSWE and 2D SWE on the standard (5C1) and the DAX transducers.

RESULTS: We included 129 patients with paired LSM and liver biopsy: median age 44.0 years, 82 (63.6%) women, median BMI: 43.2 kg/m2. Histologic fibrosis stages: F0: N = 55 (42.6%), F1: N = 14 (10.9%), F2: N = 50 (38.8%), F3: N = 2 (1.6%), F4: N = 8 (6.2%). VCTE-LSM failed (N = 13) or were unreliable (IQR/median ≤30% in ≥7.1 kPa, N = 14) in 20.9% of patients. The Pearson correlation of reliable VCTE-LSM with both pSWE and 2D SWE was strong (all >0.78). The diagnostic accuracy for all LSM techniques was poor for significant fibrosis (≥F2, AUC: 0.54-0.63); however, it was good to excellent for advanced fibrosis (≥F3, AUC: 0.87-0.99) and cirrhosis (F4, AUC: 0.86-1.00). In intention-to-diagnose analysis, pSWE on DAX was significantly superior to VCTE-LSM.

CONCLUSIONS: pSWE- and 2D-SWE enable the non-invasive identification of advanced fibrosis and cirrhosis in patients with obese MASLD. The use of the DAX transducer for acoustic radiation force imaging (ARFI)-LSM avoids technical failures in an obese population and subsequently offers advantages over VCTE-LSM for the evaluation of fibrosis in an obese MASLD population at risk for fibrosis.