The diagnostic value of ultrasound viscoelastic imaging for biliary and vascular complications after liver transplantation: a single-center retrospective study

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.