@article {Pryma1260, author = {Daniel A. Pryma and Heiko Sch{\"o}der and Mithat G{\"o}nen and Richard J. Robbins and Steven M. Larson and Henry W.D. Yeung}, title = {Diagnostic Accuracy and Prognostic Value of 18F-FDG PET in H{\"u}rthle Cell Thyroid Cancer Patients}, volume = {47}, number = {8}, pages = {1260--1266}, year = {2006}, publisher = {Society of Nuclear Medicine}, abstract = {H{\"u}rthle cell carcinoma is an uncommon and occasionally aggressive differentiated thyroid cancer associated with increased mortality compared with other differentiated thyroid malignancies. Because it generally has lower iodine avidity, 18F-FDG PET has been suggested as a more accurate imaging modality. However, there is limited information with regard to the true diagnostic accuracy and prognostic value of 18F-FDG PET in this disease. Methods: All patients with H{\"u}rthle cell thyroid cancer who underwent their first 18F-FDG PET scan between May 1996 and February 2003 were identified retrospectively. 18F-FDG PET scans were reviewed and compared with all available imaging studies, including CT, ultrasound, and radioiodine scintigraphy (RIS). Abnormal 18F-FDG uptake was assessed visually and by measuring the maximum standardized uptake value (SUVmax) of the most intense lesion. Clinical follow-up for at least 1 y or until death was required for inclusion. Results: Forty-four patients met inclusion criteria. The median follow-up was 2.9 y. There were 24 positive and 20 negative 18F-FDG PET scans with 1 false-positive and 1 false-negative study, resulting in a diagnostic sensitivity of 95.8\% and a specificity of 95\%. In 5 of 11 patients who had both positive CT and 18F-FDG PET findings, 18F-FDG PET revealed additional sites of disease. Furthermore, 18F-FDG PET correctly classified as negative 3 patients with false-positive CT findings. In 3 of 6 patients with positive RIS, 18F-FDG PET revealed additional sites of metastatic disease. Ten patients with positive 18F-FDG PET had negative RIS. Only 1 patient with negative 18F-FDG PET had positive RIS. The SUVmax also provided prognostic information: In a stepwise fashion, each increase in intensity by SUVmax unit was associated with a 6\% increase in mortality (P \< 0.001). The 5-y overall survival in patients with SUVmax \< 10 was 92\%; it declined to 64\% in those with SUVmax \> 10 (P \< 0.01). Conclusion: 18F-FDG PET has excellent diagnostic accuracy in H{\"u}rthle cell thyroid cancer patients, improving on CT and RIS. Intense 18F-FDG uptake in lesions is an indicator of a poor prognosis. Our data suggest that all patients with H{\"u}rthle cell thyroid cancer should undergo 18F-FDG PET as part of their initial postoperative staging and periodically to screen for occult recurrence, particularly in patients with elevated serum thyroglobulin.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/47/8/1260}, eprint = {https://jnm.snmjournals.org/content/47/8/1260.full.pdf}, journal = {Journal of Nuclear Medicine} }