Background: The aim of this study was to investigate the relationship between volumetric data obtained from staging ⁶⁸Ga-prostate-specific membrane antigen (PSMA) PET computerized tomography (CT) images with prostate-specific antigen (PSA), risk groups, Gleason Grade (GG) groups and presence of metastasis. Methods: We performed a retrospective analysis of ⁶⁸Ga-PSMA PET-CT images from 88 patients undergoing initial staging of prostate adenocarcinoma between January 2015 and September 2018. Images were evaluated in LIFEx software; PSMA involvement above the background activity in prostate gland, lymph node and other distant metastases was plotted with 40% SUVmax threshold, SUVmax, PSMA tumor volume (PSMA-TV) and total lesion PSMA (TL-PSMA) values were obtained. Results: In all patients, there was a moderate correlation between PSA and PSMA-tumor volume whole-body (PSMA-TVwb) (P < 0.001, r = 0.580) and a high correlation between total lesion-PSMAwb (TL-PSMAwb) (P < 0.001, r = 0.636). Prostate PSMA-TV (PSMA-TVp) and TL-PSMA (PSMA-TVp) values were different in local and locally advanced/metastatic patients (P = 0.020 and 0.006, respectively). PSMA-TVp and TL-PSMAp values were significantly different in low-moderate and high-risk patients (P = 0.003 and <0.001, respectively), and in patients with and without metastasis (P = 0.008 and 3 (P = 0.030, 0.002, <0.001 and <0.001, respectively). Conclusion: Pretreatment ⁶⁸Ga-PSMA PET/CT volumetric parameters provides unique data to use in the clinical decision-making process of patients with adenocarcinoma of the prostate.

Endometrial cancer (EC) is the most common gynecological malignancy. The ¹⁸fluorine-fluorodeoxyglucose (¹⁸F-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. 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. 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. 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.

The scan demonstrated multiple linear and patchy hypermetabolic lesions in skeletal muscles, mimicking the coat of a tiger, and was referred to as “a tiger man” sign. A 38-year-old man was admitted to our hospital with weakness, shortness of breath, and muscle pain. A CT scan showed a mass in the anterior mediastinum. ¹⁸F-FDG PET/CT was performed to evaluate the mass with a preliminary diagnosis of thymoma; heterogeneous ¹⁸F-FDG uptake in the mediastinal mass and tiger man findings in skeletal muscles were observed in PET/CT images.