Differentiating between benign and malignant ampullary strictures: a prediction model using a nomogram based on CT imaging and clinical findings.

OBJECTIVES: To construct a predictive nomogram for differentiating malignant from benign ampullary strictures using contrast-enhanced computed tomography (CT) findings combined with clinical findings. METHODS: In this retrospective study, 152 patients with ampullary stricture (98 benign and 54 malignant) who underwent contrast-enhanced CT were included. Various imaging findings of the ampulla, bile duct, main pancreatic duct, and periampullary area were evaluated and clinical findings including the presence of jaundice, carbohydrate antigen 19-9 level, and history of cholecystectomy were collected. Among them, statistically significant findings were identified using univariable and multivariable logistic regression analyses. A nomogram was constructed to differentiate benign and malignant ampullary strictures and was internally validated. RESULTS: Multivariable analysis revealed that jaundice (odds ratio [OR]: 17.33, p < 0.001), presence of an ampullary mass (OR: 24.40, p < 0.001), non-similar enhancement of the ampulla to the duodenum (OR: 31.96, p = 0.003), and proportional dilatation of the bile duct (OR: 7.98, p = 0.001) were independent significant factors for predicting the malignant ampullary stricture, and were used to construct a nomogram. Among them, non-similar enhancement of the ampulla to the duodenum showed the highest OR and predictor point on the nomogram. The calibration plots showed excellent agreement between the predicted probabilities and the actual rates of malignant ampullary strictures, on internal validation. CONCLUSIONS: Combination of clinical and imaging findings could aid in predicting malignant ampullary strictures using significant findings of jaundice, presence of ampullary mass, non-similar enhancement of the ampulla to the duodenum, and proportional dilatation of the bile duct. KEY POINTS: • The presence of jaundice, ampullary mass, non-similar enhancement of the ampulla, and proportional bile duct dilatation were significant findings for predicting malignant ampullary strictures. • Non-similar enhancement of the ampulla to the duodenum was a significant feature with the highest odds ratio for differentiating benign and malignant ampullary strictures. • The nomogram constructed using contrast-enhanced computed tomography imaging and clinical findings could aid in predicting malignant ampullary strictures.