RÉSUMÉ
OBJECTIVE: We aimed to evaluate the gallium-68-labeled fibroblast-activation protein inhibitor (68Ga-FAPI) positron emission tomography/computed tomography (PET/CT) in localizing papillary thyroid carcinoma (PTC) foci in patients with biochemical relapse. Papillary thyroid carcinoma has achieved biochemical recovery after appropriate treatment and had biochemical relapse in the last follow-up were included in this retrospective study. Gallium-68-FAPI and fluorine-18-fluorodeoxyglucose (68F-FDG) PET/CT were performed to detect recurrence foci. SUBJECTS AND METHODS: Biochemically relapsed patients who underwent total thyroidectomy and were diagnosed with pathologically differentiated thyroid cancer were included in our study. Gallium-68-FAPI and 18F-FDG PET/CT imaging methods were used to determine the focus of metastasis or recurrence in all patients. RESULTS: Among 29 patients enrolled to the study, pathological subgroups were papillary (n=26) and poorly differentiated (n=3) PTC. Anti-thyroglobulin (TG) antibody positivity were noted in 5 of the patients, while all 29 of them were TG positive and had been consist of three groups as follows: 2-10ng/mL (n=4), 11-300ng/mL (n=14), 301ng/mL and above (n=11). Recurrence was detected in 72.4% (n=21) and 86% (n=25) of the patients via 18F-FDG and 68Ga-FAPI, respectively. Accuracy of detection noted as 100% (5/5), 75% (3/4), and 92.9% (13/14) in groups with the anti-TG antibody positivity, TG levels of 2-10ng/mL and 11-300ng/mL, respectively, when the two imaging modalities were utilized together. Furthermore, accuracy of 68Ga-FAPI was 100% (11/11) in the group with TG levels of 301ng/mL and above, whereas accuracy of 18F-FDG was 81.8% (9/11). Lastly, median maximum standardized uptake value (SUVmax) of recurrent lesions detected by the 68Ga-FAPI (median SUVmax: 6.0) were statistically higher than the ones detected by the 18F-FDG (median SUVmax: 3.7) (P=0.002). CONCLUSION: In recurrent PTC especially in case of higher TG levels, 68Ga-FAPI can be used in patients with inconclusive 18F-FDG findings.
Sujet(s)
Quinoléines , Tumeurs de la thyroïde , Humains , Tomographie par émission de positons couplée à la tomodensitométrie/méthodes , Fluorodésoxyglucose F18 , Cancer papillaire de la thyroïde/imagerie diagnostique , Radio-isotopes du gallium , Études rétrospectives , Récidive tumorale locale/imagerie diagnostique , Tumeurs de la thyroïde/anatomopathologieRÉSUMÉ
PURPOSE: In this study, we aimed to investigate the utilization of 68Ga-FAPI PET/CT in comparison to 18FDG PET/CT to evaluate the peritoneal involvement of the gastrointestinal malignancies alongside primary lesions and other metastatic foci. PROCEDURES: A total of 37 patients with various gastrointestinal malignancies with accompanying peritoneal involvement who underwent 68Ga-FAPI PET/CT and 18FDG PET/CT imaging between September 2020 and June 2021 were included in this retrospective study. SUVmax values of 68Ga-FAPI and 18FDG were compared according to lesion locations. Also, the lesion localization ability of both imaging was compared in patient basis. RESULTS: Of the 37 patients with peritoneal involvement (23 males and 14 females; median age, 62.8 ± 12.7 years), 35.1% (n = 13) had colorectal cancer, 37.8% (n = 14) gastric cancer, and 27.0% (n = 10) pancreaticobiliary cancer. While 45.9% of them were operated, the remaining did not have surgery. The mean time interval between two studies was 3.2 days (range: 2-6 days). The mean SUVmax value of peritoneal metastases (p < 0.001) was significantly higher with 68Ga-FAPI PET/CT compared to that with 18FDG PET/CT, as in primary lesions (p < 0.001), lymph node metastases (p = 0.006), liver metastases (p = 0.002), and bone metastases (p = 0.018). A total of 185 lesions was detected in the initial assessment with 18FDG PET/CT. Of the total lesions detected with 18FDG PET/CT, 5 of them were evaluated as benign lesions with 68Ga-FAPI PET/CT also in accordance with the reference standard. In addition to 180 lesions detected with 18FDG PET/CT, a total of 37 additional malignant lesions, 12 of which were peritoneal metastases, were detected with 68Ga-FAPI PET/CT. CONCLUSION: 68Ga-FAPI PET/CT was determined to be superior to 18FDG PET/CT in terms of detection of peritoneal involvement with high image quality as well as primary tumor and other metastatic foci. Consequently, 68Ga-FAPI PET/CT can be used as a complementary imaging modality especially for inconclusive 18FDG findings due to the lack of accuracy of 18FDG PET/CT in some of the metastatic regions, especially in the liver.
