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Purpose: We aimed to investigate the potential of [68Ga]Ga-FAPI-04 PET/CT as an alternative diagnostic and theranostic tool in well-differentiated NETs refractory to [177Lu]Lu-DOTATATE therapy. Methods: Patients who received at least two cycles of [177Lu]Lu-DOTATATE therapy for metastatic NETs and progressed under treatment were included. All patients had performed [68Ga]Ga-DOTATATE and [68Ga]Ga-FAPI-04 PET/CT within 3 weeks. The number of PET-positive lesions related to NETs and tumor sites was documented. Mann-Whitney U and chi-square tests were used to compare SUVmax levels of tracers and the number of detected metastases. Results: Twelve patients (7 male, 5 female) who met the eligibility criteria were included in the study. Ten patients had grade 1–2 NET of various origins, and two had paraganglioma and pheochromocytoma. One hundred ninety-eight of 230 lesions (86%) were SSTR positive with a median SUVmax of 16.6 (2.2–76.5), and 88 of 230 lesions (38.2%) were [68Ga]Ga-FAPI-04 positive with a median SUVmax of 5.1 (2.3–21). Median SUVmax level and detected number of tumors were significantly higher in [68Ga]Ga-DOTATATE PET/CT (p=<0.001). [68Ga]Ga-FAPI-04 PET/CT was completely (n:2) or almost completely (n:3) negative in 5 (42%) patients. Two (17%) patients had flip-flop SSTR/FAPI uptake in tumors. In four patients (33%), tumor uptake or the number of PET-positive lesions was inferior in [68Ga]Ga-FAPI-04 PET/CT. In only one patient (8%), tumor uptakes were higher in [68Ga]Ga-FAPI-04 PET/CT. Low-dose [177Lu]Lu-FAPI-46 dosimetry was performed on the FAPI-dominant patient; absorbed radiation doses per GBq were 1.26 Gy, 0.36 Gy, 0.32 Gy, and 0.2 Gy for kidneys, liver, spleen, and total body, respectively. The mean absorbed dose per GBq was 0.33 Gy for liver mass and 0.41 Gy for metastatic lymph nodes. Conclusion: Our preliminary results demonstrated that [68Ga]Ga-FAPI-04 PET/CT mainly failed in well-differentiated NETs refractory to [177Lu]Lu-DOTATATE therapy and had a limited role as an alternative diagnostic or theranostic agent. Further investigations with a larger patient population are required to determine the impact of [68Ga]Ga-FAPI-04 PET/CT on NETs. [ABSTRACT FROM AUTHOR]

Objective: We aimed to examine the relationship between tumor marker (Cancer Antigen 15-3 [CA15-3] and Carcinoembryonic Antigen [CEA]) positivity and metabolic (standardized uptake value [SUV]) and volume-based (metabolic tumor volume [MTV] and total lesion glycolysis [TLG]) 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) parameters of the primary tumor and lymph node., Material and Methods: Our study group consisted of 91 female patients, who underwent PET/CT between January 2018 and December 2019 in our clinic with a diagnosis of breast cancer. These patients had no distant metastasis or supraclavicular and internal mammarian lymph node metastasis. MTV, TLG, and SUVmax values were obtained from the primary breast lesion and axillary lymph nodes., Results: The mean age of the patients, who participated in the study, was 52,19±14,57, and the median values of the primary tumor MTV, TLG, and total MTV values were found to be statistically significantly higher in those who were CEA positive compared to those who were CEA negative. The median SUVmax value of the axillary lymph node was found to be statistically significantly higher in those who were CEA positive compared to those who were CEA negative (p: 0.004). There was no statistically significant difference between the other parameters., Conclusion: There was a statistically significant correlation between CEA positivity in preoperative primary breast cancer and primary tumor volume MTV, TLG, and total MTV values, which are volume-based PET parameters. CEA positivity evaluation may indicate increased tumor load in preoperative., Key Words: Breast Cancer, CEA, CA 15-3, MTV, TLG, FDG PET/CT.

Aim: In this study, we aimed to investigate the roles of volume based 18F-FDG PET/CT parameters, CA19-9 levels, and complete blood count parameters in predicting survival in patients with unresectable and/or metastatic pancreatic ductal adenocarcinoma., Materials and Method: Fifty-seven pancreatic cancer patients who were followed in University of Health Sciences Gazi Yasargil Training and Research Hospital between January 2017 and June 2020, declined surgical treatment and/or radiation therapy or had medically inoperable, unresectable, or metastatic disease, and received chemotherapy were included in the study. 18F-FDG PET/CT images of patients were evaluated and calculated metabolic tumor volume (MTV) and total lesion glycolysis (TLG) parameters were compared with CA19-9 levels and complete blood count parameters. Patients were assessed in two groups as survivors and non-survivors., Results: Total MTV and total TLG on 18F-FDG PET/CT were significantly higher among non-survivors than survivors (p: 0.023 and 0.034, respectively). Multivariate Cox regression analysis revealed that TLG higher than 46 g/ml.cm3, MTV higher than 11.02 cm3 (OR 0.987, 95%CI 0.976-0.999, p:0.029 and OR 0.246, 95%CI 0.089- 0.685, p: 0.007, respectively) and elevated MPV (OR:0.785, 95% CI 0,574-0.976, p:0.042) were independent prognostic factors for predicting mortality., Conclusion: TLG >46 g/ml.cm3 and MTV >11.02 cm3 in 18F-FDG PET/CT and elevated MPV in complete blood count are independent prognostic factors for predicting mortality in patients with unresectable or metastatic pancreatic cancer who are treated with chemotherapy., Key Words: Pancreatic cancer, Metabolic tumor volume, Total lesion glycolysis, Mean platelet volume.

At present a large number of the renal transplantations are being performed from the deceased donors. The success of these transplantations depends on the viability of the deceased donor kidneys. The aim of this study was to investigate the reliability of scintigraphic estimation of function of deceased donor kidneys by comparing the histopathologic and scintigraphic findings. Ten rats were included in the study (2-3 months old, 250-300 g, all male). Control scintigraphy was performed to all the rats by injection of 37 MBq Tc-99m DTPA from the tail vein in a dynamic manner. Brain death of the rats was achieved by inflation of a Fogartys catheter in the cranial cavity. Immediately, after brain death confirmation, dynamic renal scintigraphy was performed with the same parameters of control scintigraphy. In the comparison of scintigraphies obtained in the before and just after brain death period, there was impairment of tubular functions, concentration and excretion functions in the postbrain death period. In the immediate postbrain death period, there was a significant elevation in the glomerular filtration rate and time to maximum concentration values. In the histopathological evaluation of the kidney samples in the postbrain death period, there were definitive findings of tubular impairment. Dynamic renal scintigraphy also demonstrated definite impairment of tubular system and tubular functions in the deceased donor kidneys. This could explain the reason of the increased frequency of acute tubular necrosis seen among deceased donor kidneys.