Abstract
BACKGROUND: Postoperative biliary and vascular complications (including stenosis, thrombosis, and occlusion) after liver transplantation (LT) can impair graft function, increase reoperation needs, and elevate patient mortality, significantly affecting long-term survival. The clinical reference standards magnetic resonance cholangiopancreatography (MRCP) for biliary complications is expensive and time-consuming, while computed tomography angiography (CTA) for vascular complication involves ionizing radiation and allergic reaction to contrast agents, limiting their repeated use during follow-up. Ultrasound viscoelastic imaging (UVI), an affordable, non-invasive technique, could be an effective alternative. This study aims to assess the clinical value of UVI in auxiliary diagnosis of biliary and vascular complications post-LT. METHODS: Between June 2024 and August 2025, 141 LT patients who underwent UVI were retrospectively analyzed, including 25 with repeated examinations (intervals of 1-4 weeks). UVI parameters included Young's modulus, viscosity, and dispersion coefficients. MRCP and CTA served as reference standards for biliary and vascular complications, respectively. Statistical analysis was performed using SPSS 27.0 (P < 0.05). Independent t-tests or non-parametric tests were applied, and generalized estimating equations (GEE) was used for patients with multiple UVI measurements. RESULTS: Among 116 patients with a single UVI, mean Young's modulus, viscosity, and dispersion values were 12.30 ± 6.41 kPa, 2.3 ± 0.9 Pa·s, and 5.25 ± 1.81 m/s/kHz, respectively. Patients with biliary complications (n = 52) showed significantly higher viscoelastic values than those without (n = 64). In vascular complications (n = 10), only minimum viscosity differed significantly from controls. In patients with repeated UVI, GEE analysis revealed significant temporal changes in elasticity, viscosity, and dispersion parameters after liver transplantation (all P < 0.001). Significant time-complication interactions were identified for biliary complications and for most vascular parameters, suggesting distinct longitudinal patterns between patients with and without complications. CONCLUSIONS: Viscoelasticity values increased in the presence of biliary and vascular complications, likely due to hemodynamic abnormalities and tissue inflammation. These findings suggest that UVI can be a valuable tool for monitoring biliary and vascular complications after LT, providing non-invasive, reliable, and repeated assessments of graft health.