Proposed nomogram predicting neoplastic ampullary obstruction in patients with a suspected ampulla of Vater lesion on CT

Purpose: To stratify and weigh the computed tomography (CT) imaging and clinical features differentiating a neoplastic ampullary obstruction from a non-neoplastic ampullary obstruction and to develop a nomogram for estimating individualized risk of neoplastic potential in patients with a suspected ampulla of Vater (AOV) lesion on CT. Methods: 135 patients (92 non-neoplastic and 43 neoplastic) with a suspected ampullary obstruction on a CT scan between February 2015 and May 2019 were included after the exclusion criteria were applied. Significant imaging and clinical findings of the neoplastic lesions were assessed using univariate and multivariate logistic regression analyses. Based on the significant variables in the multivariate analysis, a nomogram was developed to predict neoplastic potential in patients suspected of ampullary obstruction. The area under the receiver operating characteristic curve (AUC) was used to assess the diagnostic value in the external validation cohort (36 non-neoplastic and 13 neoplastic). Results: The multivariate analysis revealed that the presence of an AOV mass (odds ratio (OR), 77.21; 95% confidence intervals (CI) 1.51–3950.38), AOV size > 12 mm (OR, 23.93; 95% CI 2.96–193.60), total bilirubin > 1.2 mg/dl (OR, 9.99; 95% CI 1.37–73.06) and age ≤ 63 years (OR, 7.52; 95% CI 1.33–42.48) were independent significant parameters that predicted a neoplastic lesion in the AOV. The AUC for the nomogram was 0.93 on the internal validation and 0.91 (95% CI 0.79–0.97) on the external validation. Conclusions: A nomogram using imaging and clinical findings was useful to estimate a neoplastic ampullary obstruction in patients with a suspected AOV lesion on CT and suggests a further evaluation.