Liver stiffness measurement reliability and main determinants of point shear-wave elastography in patients with chronic liver disease

Background: Liver stiffness (LS) measured by transient elastography (TE) accurately predicts the severity of chronic liver diseases (CLD). Point quantification shear-wave elastography (pSWE) is a new technique incorporated into a conventional ultrasound system for measuring LS. We evaluated pSWE feasibility, reproducibility and diagnostic accuracy in consecutively recruited CLD patients who concomitantly underwent TE and liver biopsy. Aim: To evaluate pSWE feasibility, reproducibility and diagnostic accuracy in consecutively recruited CLD patients who concomitantly underwent TE and liver biopsy. Methods: Over 2 years 186 CLD patients (116 males, 132 viral hepatitis) consecutively underwent pSWE (10 valid measurements by ElastPQ) blindly performed by two raters. A further operator performed TE. Inter-observer agreement for pSWE was analysed by intraclass correlation coefficient (ICC) and correlated with histological liver fibrosis (METAVIR). Main determinants of pSWE were investigated by linear regression model. Results: Three hundred and seventy-two (100%) reliable measurements were obtained by pSWE and 184 by TE (99%). LS was 8.1 ± 4.5 kPa for pSWE with the first rater and 8.0 ± 4.2 kPa with the second one vs. 8.8 ± 3.6 kPa for TE. pSWE ICC was 0.89 (95% CI 0.85‒0.91), not influenced by age, sex, BMI, liver enzymes, liver aetiology. ICC increased over time with year 1 at 0.86 and 95% CI 0.81–0.90 vs. year 2 at 0.92 and 95% CI 0.87–0.95. Liver fibrosis was the only independent determinant of LS on pSWE. The AUROCs for diagnosing F ≥ 2, F ≥ 3 and F = 4 were 0.77, 0.85 and 0.88 for pSWE vs. 0.81, 0.88 and 0.94 for TE. After 1-year training they were 0.86, 0.94 and 0.91. Conclusion: Point quantification shear-wave elastography reliably and reproducibly evaluates liver stiffness, matching transient elastography for accuracy after a 1-year learning curve or 130 examinations.