PT  - JOURNAL ARTICLE
AU  - Badia O. Helal
AU  - Pascal Merlet
AU  - Marie-Elisabeth Toubert
AU  - Brigitte Franc
AU  - Claire Schvartz
AU  - Halène Gauthier-Koelesnikov
AU  - Alain Prigent
AU  - André Syrota
TI  - Clinical Impact of <sup>18</sup>F-FDG PET in Thyroid Carcinoma Patients with Elevated Thyroglobulin Levels and Negative <sup>131</sup>I Scanning Results After Therapy
DP  - 2001 Oct 01
TA  - Journal of Nuclear Medicine
PG  - 1464--1469
VI  - 42
IP  - 10
4099  - http://jnm.snmjournals.org/content/42/10/1464.short
4100  - http://jnm.snmjournals.org/content/42/10/1464.full
SO  - J Nucl Med2001 Oct 01; 42
AB  - 18F-FDG PET has been shown to effectively detect differentiated thyroid carcinoma (DTC) metastases with impaired iodine-trapping ability. This article evaluates the potential contribution of FDG PET in the follow-up of patients with differentiated thyroid carcinoma, elevated thyroglobulin (Tg) levels, and negative whole-body scan results obtained after high doses of 131I. Methods: We prospectively assessed the ability of FDG to detect metastases in 37 DTC patients who had undergone total thyroidectomy and radioactive ablation and presented with persistent disease, as assessed from elevated Tg levels and negative results of whole-body scans performed after therapeutic doses of 131I. Additional conventional imaging procedures were performed to detect residual disease, and the patients were divided into 2 groups: group 1, with positive conventional imaging findings (n = 10), and group 2, with negative conventional imaging findings (n = 27). Results: FDG PET showed positive findings in 28 patients and accurately localized tumor sites in 89% of them. In group 1, FDG PET confirmed 17 of 18 previously known tumor sites and detected 11 additional sites. In group 2, FDG PET findings were positive in 19 of 27 patients with no previously detected metastases. PET was effective for both low- and high-stage tumors. The FDG data led to a change in the clinical management of 29 of 37 patients with further surgical resection in 23 patients, 14 of whom achieved disease-free status, and external radiation therapy in 4 patients. Conclusion: FDG PET is able to detect metastases undetected by 131I posttherapy whole-body scanning in patients with elevated Tg levels. It should be proposed as a first-line investigation in patients with persistent disease but negative findings on 131I whole-body scans after treatment.