Detection of common bile duct stones before laparoscopic cholecystectomy

Purpose: To assess the diagnostic value of MR cholangiography (MRC) for detecting common bile duct (CBD) stones in candidates for laparoscopic cholecystectomy (LC). Material and Methods: A series of 95 selected patients with gallstones and suspected CBD lithiasis (abnormal serum liver tests and/or CBD size greater than or equal to6.5 mm at US) were referred to our institution for MRC, before LC. MRC was performed on a 0.5 T magnet through a non-breath-hold, respiratory-triggered, fat-suppressed, thin-slab, heavily T2-weighted fast spin-echo sequence and through a breath-hold, thick-slab, single-shot T2-weighted sequence in the coronal plane. Axial T1- and T2-weighted sequences were first obtained. Two observers in conference reviewed source images and maximum intensity projections to determine the presence or absence of choledocholithiasis. MR findings were compared with endoscopic retrograde cholangiography and intraoperative cholangiography (IOC); IOC was always performed during LC. Results: CBD calculi (single or multiple) were identified in 41 out of 95 patients (43%). Two false-positive and 4 false-negative cases were found on MRC. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MRC for choledocholithiasis were 90%, 96%, 94%, 95%, and 93%, respectively. Conclusion: MRC is a highly effective diagnostic modality for evaluation of patients with risk factors for CBD stones prior to LC.