Risk stratification of gallbladder polyps (1-2 cm) for surgical intervention with 18F-FDG PET/CT.

Abstract

We assessed the value of (18)F-FDG uptake in the gallbladder polyp (GP) in risk stratification for surgical intervention and the optimal cutoff level of the parameters derived from GP (18)F-FDG uptake for differentiating malignant from benign etiologies in a select, homogeneous group of patients with 1- to 2-cm GPs. Fifty patients with 1- to 2-cm GPs incidentally found on the CT portion of PET/CT were retrospectively analyzed. All patients had histologic diagnoses. GP (18)F-FDG activity was visually scored positive (≥liver) or negative (<liver). Maximal standardized uptake value of the GP (SUVgp) and ratio of SUVgp to mean SUV of the liver (GP/L ratio) were also measured. Univariate and multivariate logistic regression analyses were performed to determine the utility of patient and clinical variables--that is, sex, age, gallstone, polyp size, and three (18)F-FDG-related parameters in risk stratification. Twenty GPs were classified as malignant and 30 as benign. Multivariate analyses showed that the age and all parameters (visual criteria, SUVgp, and GP/L) related to (18)F-FDG uptake were significant risk factors, with the GP/L being the most significant. The sex, size of GPs, and presence of concurrent gallstones were found to be insignificant. (18)F-FDG uptake in a GP is a strong risk factor that can be used to determine the necessity of surgical intervention more effectively than other known risk factors. However, all criteria derived from (18)F-FDG uptake presented in this series may be applicable to the assessment of 1- to 2-cm GPs.