Abstract:

Objective To investigate the clinical value of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) dual-head coincidence imaging in metastasis of differentiated thyroid cancer with positive thyroglobulin (Tg) and negative ¹³¹I scan. Methods Thirty-five patients with differentiated thyroid cancer and positive Tg and negative ¹³¹I whole-body scan after thyroidectomy were included. ¹⁸F-FDG dual-head coincidence imaging was performed in all the patients for the detection of metastatic lesions. The ¹⁸F-FDG imaging results were compared with pathological findings or results of continuous follow-up by Tg and other imaging modalities such as B ultrasound, CT and MRI. The sensitivity, specificity, accuracy and positive diagnosis value of ¹⁸F-FDG dual-head coincidence imaging in patients with differentiated thyroid cancer and positive Tg and negative ¹³¹I scan were obtained. Results Twenty-seven patients with metastatic differentiated thyroid cancer were confirmed by pathological examinations or continuous follow-up. The sensitivity, specificity, accuracy and positive diagnosis value of ¹⁸F-FDG dual-head coincidence imaging were 81.5%（22/27）, 75.0%（6/8）, 80.0%（28/35) and 91.7%（22/24) respectively. ¹⁸F-FDG dual-head coincidence imaging was well in line with pathological examinations and continuous follow-up in diagnosis of metastatic lesions in differentiated thyroid cancer with positive Tg and negative ¹³¹I scan (κ=0.499, P=0.006). Conclusion ¹⁸F-FDG dual-head coincidence imaging plays an important role in the diagnosis of differentiated thyroid cancer with positive Tg and negative ¹³¹I scan.

Key words: differentiated thyroid cancer, ¹⁸F-fluorodeoxyglucose dual-head coincidence, thyroglobulin, ¹³¹I