Degree of bile-duct dilatation in liver-transplanted patients with biliary stricture: a magnetic resonance cholangiography-based study.

PURPOSE: This study assessed whether the degree of bile-duct dilatation in liver-transplanted patients is correlated with the time from intervention and the type of underlying biliary stricture. METHODS AND MATERIALS: Fifty-seven 3D magnetic resonance cholangiograms (MRCs) performed on 42 liver-transplanted patients were retrospectively evaluated. Diameter was measured at the level of the extrahepatic bile duct (EBD), right hepatic duct (RHD), left hepatic duct (LHD), anterior and posterior right hepatic ducts (aRHD, pRHD) and left lateral and medial ducts (LLD, LMD). Data were stratified according to the type of biliary stricture (all types, anastomotic, ischaemic-like, mixed) and compared, on a per-examination basis: (a) between two groups based on time from transplantation using a 1-year threshold (nonlongitudinal analysis); (b) among 26 repeated examinations on 11 patients (longitudinal analysis); (c) among different stricture groups. RESULTS: The biliary tree was slightly dilated within 1 year from transplantation (2.9±1.3 to 6.1±3.2 mm). In general, nonlongitudinal analysis showed minimally larger duct size after 1 year (mean +1.4±0.5 mm) despite significant differences at most sites of measurement considering all types of strictures (p<0.01; Mann-Whitney U test). Longitudinal analysis showed diameter increase over time, although without statistically significant differences (p>0.01; Kruskal-Wallis test). No significant difference in bile-duct size was observed when comparing types of stricture (p>0.01; Kruskal-Wallis test). CONCLUSIONS: Biliary dilatation after liver transplantation is mild and develops slowly regardless of the underlying type of stricture, possibly in relation to graft properties. MRC has a potential role as first-line imaging modality for a reliable assessment of biliary dilatation and the presence of a stricture.