MRI system scoring for differentiation of malignant versus benign stricture of the common bile duct

The purpose of this study was to evaluate the ability of magnetic resonance imaging (MRI) to differentiate between malignant and benign strictures of the common bile duct by using a scoring system.MRI scans of 34 patients with indeterminate biliary stricture on prior imaging were reviewed; non-enhanced MRI, magnetic resonance cholangiopancreatography (MRCP), diffusion weighted imaging, and contrastenhanced MRIs were considered for analysis.Ten radiologic findings were significant for malignancy: luminal irregularity, post-contrast conspicuity, high signal intensity on diffusion weighted MRI, luminal stenosis asymmetry, T2-weighted MRI signal intensity, indistinct outer border, abrupt stenosis, bile duct dilatation  12.5 mm, stenosis length  10.5 mm, and wall thickness  4.5 mm.Since none of these findings was pathognomonic for malignancy, a simple system scoring based on statistically significant findings was developed, where each of the above findings counts for one point.A score of 6 or higher was found only in patients with a malignant stricture of the common bile duct; 70% of patients with a benign stenosis had a score of 1, or 2, and all patients with benign lesions had scores of less than 5.This MRI scoring system can assist in the differential diagnosis of common bile duct stricture with high accuracy; to be widely applicable, the MRI score needs to be validated in a prospective patient population.