Abstract: Objective To summarize both direct and indirect imaging characteristics of cholangiocarcinoma as revealed by MRI And CT scans. Methods Data were retrospectively collected and analyzed from 62 cholangiocarcinoma resection cases at the Fifth Medical Center of PLA General Hospital, spanning from March 2019 to October 2022. These patients had undergone either MR Or CT dynamic enhancement scans within 1 week prior to their surgery. The imaging sequences and dynamic enhancement scan features were meticulously analyzed, with the prevalence of each distinct radiologic sign observed in these patients being quantified. Results In this study of 62 cholangiocarcinoma patients, lesion sizes ranged from 0.8 to 8.9cm in the longest dimension.,MRI analysis revealed varid signal intensities: on T1WI, lesions exhibited high signal in 4 cases, isointense signal in 2, low signal in 36, and heterogeneous signal in 1. On T2WI, 35cases showed high signals, 3 isointense, 3 low signal, and 2 heterogeneous. Diffusion-weighted imaging(DWI) identified high signal in 40 cases and isointense signal in 3. Enhancement patterins included pronounced enhancement in 19 cases, mild in 17, absent in 6, rapid in-and out in.19, continuous 24 and delayed in 11. CT imaging revealed isodensity in 2 cases, slightly hyperdense in 3 and slightly hypodense in 14. Enhancement patterns on CT were mild in,12 cases, marked in 4, and absent in 3. In the portal venous phases, 7 patients presented with slightly hyperdense lesions, 7 with slightly hypodense, 4 with hyperdense, and 1 with isodense lesions. Additonal findings included 10 cases with slightly hyperdense lesions, 5 with slightly hypodense, 2 with isodense, and 2 with hyperdense. Indirect signs of cholangiocarcinoma, such as biliary dilation, were noted in 47 of the 62 patients. This included 38 cases of mild dilation, 3 moderate, 4 severe with soft vine appearance, and 2 showing earthworm-like dilation. Conclusion Delayed and continuous enhancement patterns, along with biliary duct dilatation, are identified as hallmark direct and indirect signs in MRI And CT imaging for the diagnosis of bile duct carcinoma. These imaging features play a crucial role in differentiating bile duct carcinoma from other hepatic pathologies, underscoring their diagnostic significance in clinical radiology.

Key words: Cholangiocarcinoma, MR, CT, Bile duct dilatation