The Evaluation of Preoperative <sup>18</sup>F-FDG PET/CT in Patients with Endometrial Cancer and the Correlation Between PET Parameters and Postoperative Pathology Results

Objectives: Endometrial cancer (EC) is the most common gynecological malignancy.The 18 fluorine-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) is used for initial staging, evaluating treatment response, and detecting recurrence.This study aimed to investigate the diagnostic value of preoperative PET/CT in EC staging and determine the volumetric PET parameters that are accurate predictors of histopathological tumor characteristics.Methods: Preoperative PET/CT data of 66 patients with EC were retrospectively analyzed.Patients were divided into low and high-risk groups according to the European Society for Medical Oncology criteria.The maximum standardized uptake value (SUV max ), SUV mean , metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary lesion and pathological lymph nodes were noted.The International Federation of Gynecology and Obstetrics (FIGO) classifications, histopathology, the depth of myometrial invasion (MI), lymph node metastasis (LNM), cervical stromal invasion (CSI), and tumor sizes were noted. Results:The SUV max , TLG, and MTV values of high and low-risk groups were significantly different.TLG was the most useful parameter in differentiating risk groups.PET/CT had 90% sensitivity, 96.3% specificity, 81.8% positive predictive value, 98.1% negative predictive value, and 95.45% accuracy in assessing LNM.MTV and TLG values in patients with non-endometrioid pathology were higher than those with endometrioid.The SUV max , MTV, and TLG of patients with deep MI were higher than those with superficial MI.TLG values of patients with CSI were higher than those without CSI.Patients with LNM had higher MTV and TLG values than those without LNM.A significant difference was found in TLG, MTV, and SUV max values between patients with FIGO stage I-II and patients with FIGO stage III and above.Conclusion: SUV and volumetric parameters obtained from PET/CT, especially TLG, are strong predictors of tumor characteristics, such as MI and CSI, FIGO stages, and LNM, and are useful in noninvasively defining the risk groups in the preoperative period.