Comparison of 18F-AIF-NOTA-PRGD2 and 18F-FDG uptake in lymph node metastasis of differentiated thyroid cancer.

UNLABELLED: A widespread application of integrin αvβ3 imaging has been emerging in both pre-clinical and clinical studies. But few studies reported its value as compared with 18F-FDG PET, especially for differentiated thyroid cancer (DTC). In this study, we compared the tracer uptake of 18F-AIF-NOTA-PRGD2 and 18F-FDG in lymph node metastasis of DTC to evaluate 18F-AIF-NOTA-PRGD2 as compared with 18F-FDG.

METHODS: 20 DTC patients with presumptive lymph node metastasis were examined with 18F-AIF-NOTA-PRGD2 and 18F-FDG PET/CT. 16 patients undergoing fine needle aspiration biopsy (FNAB) were evaluated by cytology results. For lesions without FNAB, the findings of clinical staging procedures served as the standard of reference (including neck ultrasound and serum thyroglobulin).

RESULTS: A total of 39 presumptive lymph node metastases were visualized on PET/CT images. 35 lesions were confirmed as malignant by FNAB and other clinical findings. The mean 18F-AIF-NOTA-PRGD2 in radioactive iodine-refractory (RAIR) lesions and benign lesions were 2.5±0.9 and 2.8±0.9 respectively. The mean SUV for 18F-FDG in all malignant lesions was 4.5±1.6 while in benign lesions it was 3.3±1.2. For all malignant lesions, the mean SUV for 18F-FDG was significantly higher than that for 18F-AIF-NOTA-PRGD2 (P<0.05). No significant correlation was found between the SUVs of 18F-AIF-NOTA-PRGD2 and 18F-FDG for 35 lesions (r = 0.114, P = 0.515). Moreover, 15 lesions of which the diameter larger than 1.5 cm had higher 18F-AIF-NOTA-PRGD2 uptake as compared with the lesions smaller than 1.5 cm.

CONCLUSION: Although most lymph node metastases of DTC showed abnormal uptake of 18F-AIF-NOTA-PRGD2, its diagnostic value was inferior to 18F-FDG. No correlation was found between the uptake of 18F-AIF-NOTA-PRGD2 and 18F-FDG, which may suggest the two tracers provide complementary information in DTC lesions.