The Role of ¹⁸F-FDG PET/CT in the Evaluation of Peritoneal Thickening of Undetermined Origin.

The aim of this study was to assess the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for the differentiation of peritoneal thickening of undetermined origin. This retrospective study included 103 patients (44 men and 59 women, age 59.2 ± 14.8 years) who had undergone 18F-FDG PET/CT for the evaluation of peritoneal thickening of undetermined origin. All 18F-FDG PET/CT images were visually interpreted, and the maximal standardized uptake values (SUVmax) were measured. We compared the role of 18F-FDGPET/CT with that of CT alone in detecting peritoneal thickening of undetermined origin. We also compared the differences between malignant and tuberculous peritoneal thickening in PET/CT parameters and clinical characteristics. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy in detecting the primary cause of the peritoneal thickening were 76.2%, 78.9%, 94.1%, 42.9%, and 81.2%, respectively, for 18F-FDG PET/CT, and 58.3%, 84.2%, 94.2%, 31.4%, and 63.1%, respectively, for CT imaging. Malignant peritoneal thickening had significantly higher SUVmax than nontuberculous benign peritoneal thickening. However, tuberculous peritoneal thickening also had a high SUVmax. There were some factors that were significantly different between patients with tuberculous peritoneal thickening and those with malignant peritoneal thickening in our study; these included age, pattern of peritoneal thickening, and presence of ascites. 18F-FDG PET/CT is useful for detecting the underlying cause of peritoneal thickening. Special attention should be paid to peritoneal tuberculosis, which has a high SUVmax and may mimic malignant peritoneal thickening. Multiple PET/CT parameters which were different in patients with tuberculous and malignant causes could be taken into consideration to make the differential diagnosis.