Diagnostic value of the choledochal sphericity index in the diagnosis of obstructive cholestasis using magnetic resonance cholangiopancreatography

Background and study aims: Dilatation of common bile duct (CBD) is the first sign in the diagnosis of obstructive jaundice. On magnetic resonance cholangiopancreatography (MRCP), the measurement of the CBD diameter is commonly performed on the widest part of the duct, and the long axis diameter is used in clinical practice. It is aimed to investigate the role of long axis, short axis and sphericity index (SI) of CBD in the diagnosis of obstructive cholestasis.

Patients and methods: MRCP images of 68 patients who had a bile duct diameter of ≥6 mm were retrospectively evaluated. The cases with a direct bilirubin value ?0.4 mg/dl were determined to be cholestasis. Using the curved planar images, the long and short axis measurements were obtained from the widest portion of the bile duct in the transverse section and SI were obtained by calculating the ratio of the long axis over short axis. Short axis, long axis and SI was compared between cholestatic and non-cholestatic group.

Results: The mean age of the patients was 58.97 ± 17.84. Long axis, short axis, and SI showed statistically significant difference between groups (p=0.034, p=0.001, and p=0.014, respectively). Sensitivity and specificity were 60.7% and 80% for long axis, %53.6 and 82.5% for short axis, 65% and 71.4% for SI, respectively.

Conclusions: In addition to the long axis measurement, evaluation of the short axis measurement and calculation of the SI on MRCP examination will help exclude physiological dilatation in the suspicion of cholestasis.

Keywords: Obstructive cholestasis, MRCP, common bile duct, jaundice.