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Objective In this study, we aimed to evaluate the diagnostic sensitivities of 68 Ga-FAPI-04 PET/CT and 18 F-FDG PET/CT in the primary tumor, and nodal, peritoneal and distant organ metastases of primary and recurrent gastric adenocarcinoma (GAc) with patient and lesionbased comparison. Materials and methodTwenty-one patients with histopathologically proven newly diagnosed or recurrent GAc who underwent 18 F-FDG and 68 Ga-FAPI-04 imaging were included in the study. Both imaging techniques were evaluated visually according to the intensity of organbased uptake. SUVmax and tumor-to-background ratio (TBR) values obtained from primary tumor/relapse and metastatic organs were compared statistically.Results 68 Ga-FAPI-04 uptake was positive in all 15 newly diagnosed patients, while two patients among them who had mucinous and signet ring cell carcinoma did not exhibit 18 F-FDG uptake. The sensitivity and specificity of 68 Ga-FAPI-04 PET/CT in detecting primary gastric were 100%, while the sensitivity and specificity of 18 F-FDG were 86.6 and 100%, respectively. 68 Ga-FAPI-04 imaging revealed diffuse stomach uptake in seven patients, while 18 F-FDG could only show two of them. The sensitivity and specificity of in-patient-based detection of lymph node metastases were 100 and 95.2%, respectively, while these values were 71.4 and 93.7%, respectively, for 18 F-FDG. For peritoneal involvement 68 Ga-FAPI-04 had a sensitivity and specificity of 100%, whereas 18 F-FDG had a sensitivity of 40% and a specificity of 100%.Conclusion 68 Ga-FAPI-04 PET/CT is an imaging modality with the potential of yielding more sensitive and specific findings 18 F-FDG PET/CT. This modality may help avoid invasive diagnostic procedures that may be frequently required in GAc.

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68Ga-FAPI (fibroblast activation protein-specific inhibitor) PET/CT was performed in a 56-year-old man with multiple liver masses, which were confirmed grade 2 well-differentiated neuroendocrine tumors with liver Tru-Cut biopsy. With 68Ga-DOTATE PET/CT, primary tumor in the pancreas, multiple metastases in the liver and metastatic portocaval lymph node were detected. In 68Ga-FAPI PET/CT imaging performed for comparison, it was seen that metastatic lesions in the liver were distinguished much better because of low background activity, and the primary tumor and metastatic lymph node were clearly selected. This case suggested that FAPI-bounded radionuclides may be useful in the evaluation and targeted therapy of neuroendocrine tumors.

68Ga–fibroblast activation protein–specific inhibitor (FAPI)-04 PET/CT was performed in a 49-year-old woman diagnosed with breast cancer. In PET/CT imaging, intense 68Ga-FAPI uptake was observed in the primary tumor, axillary lymph nodes, and also in the thyroid gland, whereas pathological 18F-FDG uptake was not observed in the thyroid gland. On thyroid ultrasonography, parenchyma was heterogeneous, and an area of focal thyroiditis was observed in the superior part of the right lobe. Biochemical parameters were found to be consistent with thyroiditis. This case shows that FAPI uptake in the thyroid gland may be associated with thyroiditis and should be evaluated clinically.

Amaç: Bu çalışmanın amacı primer tümörlerde ve metastatik lezyonlarda 18 F-floro-2-deoksi-glukoz ( 18 F-FDG) tutulum paternlerini değerlendirmek ve ayrıca mide kanserinin (MK) evrelemesinde pozitron emisyon tomografi/bilgisayarlı tomografi'nin (PET/BT) tanısal katkısını değerlendirmektir. Yöntem: Çalışmaya toplam 341 MK hastası dahil edildi. Primer evreleme 18 F-FDG PET/BT görüntüleme ile yapıldı. 18 F-FDG PET/BT görüntülemeden elde edilen primer tümöre ait maksimum standart tutulum (SUV max ) MK alt tipleri arasında karşılaştırıldı. Bulgular: Üç yüz otuz dokuz hastaya ait primer tümörün ortalama SUV max değeri 12,9±8,6 idi. En yüksek ortalama SUV max , medüller alt tip MK'li hastalarda (17,8±9,9), en düşük ortalama SUV max (9,7±7,6), taşlı yüzük hücreli mide kanserinde (TYHMK) görüldü. Ortalama SUV max , adenokarsinom (AK) grubunda TYHMK grubundan istatistiksel olarak daha yüksek bulundu (p<0,001). Daha yüksek SUV max değerleri, AK'li hastalarda ileri yaşla (yaş ≥60) ve artan tümör büyüklüğü (>3 cm) ile istatistiksel olarak anlamlı derecede ilişkili bulundu (p=0,03). Primer tümör SUV max , bölgesel lenf nodu (RLN) pozitif olan hastalarda AK ve TYHMK gruplarındaki RLN negatiflerden anlamlı Öz Objectives: The aim of this study was to evaluate 18 F-fluoro-2-deoxy-glucose (FDG) uptake patterns in primary tumors and metastatic lesions, and also to assess the diagnostic contribution of positron emission tomography/computed tomography (PET/CT) in the initial staging of gastric cancer (GC). Methods: The total number of 341 patients with GC were included in this study. All 18 F-FDG PET/CT imagings were performed for initial staging. The maximum standardized uptake value (SUV max ) of primary tumor, obtained from 18 F-FDG PET/CT imaging was compared between subtypes of GC. Results: Mean SUV max of 339 patients' primary tumor was 12.9±8.6. The highest mean SUV max was detected in patients with medullary subtype GC (17.8±9.9) while the lowest mean SUV max (9.7±7.6) was seen in signet ring cell carcinoma (SRCC). The primary mean SUV max was found statistically higher in adenocarcinoma (AC) group than SRCC group (p<0.001). Higher SUV max values were found statistically significantly correlated with advanced age (aged ≥60) and increased tumor size (>3 cm) in patients with AC (p=0.03). Primary tumor SUV max was found statistically higher in regional lymph node (RLN) positive patients than in RLN negative patients in AC and SRCC groups (p<0.001 and p=0.012, respectivelly). Also, in patients with SRCC, SUV max was significantly higher in the distant metastatic group than in the group without metastasis (p=0.025). Conclusion: Increased primary tumor SUV max was associated with some of clinical parameters such as age and RLN metastasis in patients with AC. However, there was no relationship between distant metastatic state and primary tumor 18 F-FDG uptake in AC. However, high SUV max of primary tumor in SRCC was associated with regional and distant metastasis, and primary tumor 18 F-FDG uptake may be a prognostic value for this su...

Objectives: This study aimed to compare the metabolic parameters obtained from 18 fluorine-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) and gallium-68 ( 68 Ga)-prostate-specific membrane antigen (PSMA) PET/CT and investigate the relationship between serum alpha-fetoprotein and PET scan parameters in patients with hepatocellular carcinoma. Methods: Fourteen patients were recruited after dynamic magnetic resonance imaging (MRI) of the upper abdomen, and 18 F-FDG and 68 Ga-PSMA PET/CT imaging studies were conducted. Regions of interest (ROIs) were drawn from lesion-free liver tissue, abdominal aorta (A), and right medial gluteal muscle (G) for the background activity. Maximum standard uptake value (SUV max ) of these regions were compared with the SUV max of primary tumor (T). Results: On visual assessment, five patients (36%) experienced low 18 F-FDG uptake in the primary lesion, three patients (21%) experienced moderate uptake, and six patients (43%) experienced high uptake. However, only one patient (7%) showed low 68 Ga-PSMA uptake, two patients (14%) showed moderate uptake, and 11 patients (79%) showed high uptake. Four patients with a low 18 F-FDG uptake showed high 68 Ga-PSMA uptake, while one patient exhibited low uptake with both 18 F-FDG and 68 Ga-PSMA. The number of lesions on 68 Ga-PSMA PET/CT and MRI was significantly higher than 18 F-FDG PET/CT (p=0.042 and 0.026, respectively). T/A and T/G values were significantly higher in 68 Ga-PSMA than 18 F-FDG (p=0.002 and 0.002, respectively). Conclusion: 68 Ga-PSMA PET/CT is superior to 18 F-FDG PET/CT in the staging of hepatocellular carcinoma. High 68 Ga-PSMA uptake could be promising for PSMA-targeted radionuclide treatments.

Objective. The aim of this study is to investigate the uptake of 68Ga-FAPI-04 in normal tissues and calculate standardized uptake values (SUVs) for various organs in the body. Methods. A total of 49 patients who underwent 68Ga-FAPI-04 PET/CT were included in our study. The following organs were identified on CT images: brain, parotid, and submandibular glands, palatine tonsils, thyroid, lymph nodes (if present), breasts, lungs, thymus, left ventricle walls, mediastinal blood pool, vertebral bone marrow, liver, spleen, pancreas, stomach, small and large intestines, adrenal glands, kidneys, uterus, testes, and prostate. Median, minimum, and maximum values (max) and average (avg) values of standard uptake value (SUV) of tissues and organs were calculated. Results. The accumulation of 68Ga-FAPI in normal organs showed variations. The cerebral/cerebellar cortex exhibited no 68Ga-FAPI uptake, while the scalp showed low uptake. Low uptake was also observed in the lung parenchyma, esophagus, left ventricle walls, nipple, and glandular breast tissue. In the abdominopelvic area, the pancreas exhibited low uptake, which was higher in the tail region. Low uptake was observed in the renal cortex. Intense 68Ga-FAPI uptake was observed throughout the uterus, which was higher in the corpus. There was no uptake of 68Ga-FAPI in the bone cortex and medulla. Conclusion. We determined the physiological uptake and SUVmax of FAPI-04 in different tissues and organs and created a guide for researchers.