Comparison of (18)F-AIF-NOTA-PRGD2 and (18)F-FDG Uptake in Lymph Node Metastasis of Differentiated Thyroid Cancer

A widespread application of integrin α(v)β(3) imaging has been emerging in both pre-clinical and clinical studies. But few studies reported its value as compared with (18)F-FDG PET, especially for differentiated thyroid cancer (DTC). In this study, we compared the tracer uptake of (18)F-AIF-NOTA-PRGD2 and (18)F-FDG in lymph node metastasis of DTC to evaluate (18)F-AIF-NOTA-PRGD2 as compared with (18)F-FDG. METHODS: 20 DTC patients with presumptive lymph node metastasis were examined with (18)F-AIF-NOTA-PRGD2 and (18)F-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 (18)F-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 (18)F-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 (18)F-FDG was significantly higher than that for (18)F-AIF-NOTA-PRGD2 (P<0.05). No significant correlation was found between the SUVs of (18)F-AIF-NOTA-PRGD2 and (18)F-FDG for 35 lesions (r = 0.114, P = 0.515). Moreover, 15 lesions of which the diameter larger than 1.5cm had higher (18)F-AIF-NOTA-PRGD2 uptake as compared with the lesions smaller than 1.5cm. CONCLUSION: Although most lymph node metastases of DTC showed abnormal uptake of (18)F-AIF-NOTA-PRGD2, its diagnostic value was inferior to (18)F-FDG. No correlation was found between the uptake of (18)F-AIF-NOTA-PRGD2 and (18)F-FDG, which may suggest the two tracers provide complementary information in DTC lesions.