3-T MRI of the biliary tract variations

Abstract

The gallbladder and the biliary tract are structures in close connection with the adjacent organs and may show a number of variations and anomalies. It is therefore important for surgical purposes to know their anatomy and variations in detail. Various methods are used in the imaging of the variations of the biliary tract and its pathologies, including ultrasonography, computed tomography; direct cholangiographic methods like endoscopic retrograde cholangiopancreatography, percutaneous transhepatic cholangiography, intravenous cholangiography and T-tube cholangiography, as well as indirect methods like magnetic resonance cholangiopancreatography (MRCP) or cholescintigraphy. The aim of this study is to investigate the frequency of the anatomic variations of the biliary tract using 3-T MRCP and to compare the findings with the data in the literature. For the purposes of this study, patients who underwent MRCP at our hospital (Dicle University Hospital) between November 2009 and February 2012 were investigated retrospectively. A total of 590 patients (between 6 and 88 years of age; mean age: 51 ± 9 years) were included in the study. The MRCP imaging was carried out with an magnetic resonance imaging (MRI) device supplied with 3-T magnetic power and by obtaining T2-weighted images through the single-shot fast spin echo technique using the standard body coil. The axial and coronal source images and the reformatted images were evaluated together in terms of the possible anatomic variations. Among the 590 patients included in the study, of 233 (39.5 %) showed anatomic variations at different levels in the intra- and extrahepatic biliary tracts. Among these variations, a right posterior hepatic duct insertion to the left hepatic duct at the level of the bifurcation has been observed in 71 patients (12.1 %), trifurcation was observed in 30 patients (5.1 %) and insertion into the main hepatic duct at the proximal aspect of the cystic duct was observed in 18 patients (3.1 %). At the level of the cystic duct, medial insertion of the cystic duct was viewed in 58 patients (9.8 %), distal medial insertion was seen in 40 patients (6.8 %), a short cystic duct was detected in 10 patients (1.7 %), pancreatobiliary junction anomaly was viewed in two patients (0.4 %) and duplicate anatomic variations have been observed in 42 patients (7.2 %). MRCP studies conducted using 3-T MRI devices may reveal similar or greater numbers of variations when compared to the existing MRCP studies in the literature. 3-T MRI shows a couple of variations. Pointing out these anatomical variations before the surgical intervention may prevent possible iatrogenic traumas. Donors with unsuitable variations for liver transplant may be spotted out at an early phase through the MRCP and certain operations with a high morbidity rate may thus be avoided.