Objective: To describe the imaging characteristics of common bile duct stones on magnetic resonance cholangiopancreatography (MRCP) and compare the detection rates of ultrasonography and MRCP in patients with stones confirmed by endoscopic retrograde cholangiopancreatography (ERCP).
Methods: A retrospective study was conducted on 48 patients at Vinmec Times City from 2022 to 2025. All patients underwent ultrasonography, MRCP, and ERCP. As all patients were ERCP-positive, the study assessed detection rates rather than specificity, predictive values, or overall diagnostic accuracy.
Results: Ultrasonography detected stones in 27/48 patients (56.3%; 95% CI: 42.3–69.3%), compared with 47/48 (97.9%; 95% CI: 89.1–99.6%) for MRCP, representing a 41.6-percentage-point difference (McNemar test, p<0.001). Among MRCP-positive cases, 61.7% had a single stone, 70.2% were located at the pancreatic level, 83.0% measured ≤10 mm, and 95.7% showed low signal intensity on T2-weighted images.
Conclusion: MRCP had a significantly higher stone detection rate than ultrasonography in patients with ERCP-confirmed choledocholithiasis. These findings do not represent full diagnostic accuracy and require validation in a broader population with suspected choledocholithiasis.