Fluorine-18 fluorodeoxyglucose positron emission tomography in thyroid cancer: results of a multicentre study

The aim of this multicentre study was to evaluate the clinical significance of fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in differentiated thyroid carcinoma and to compare the results with both i odine-131 whole-body scintigraphy (WBS) and technetium-99m 2-methoxyisobuty lisonitrile (MIBI) or thallium-201 chloride (Tl) scintigraphy, Whole-body P ET imaging using FDG was performed in 222 patients: 134 with papillary rumo urs, 80 with follicular rumours and 8 with mixed-cell type tumours. Finally , for each case an overall clinical evaluation was done including histology , cytology, thyroglobulin level, ultrasonography, computed tomography and s ubsequent clinical course, to allow a comparison with functional imaging re sults. Sensitivity of FDG-PET was 75% and 85% for the whole patient group ( n=222) and the group with negative radioiodine scan (n=166), respectively. Specificity was 90% in the whole patient group. Sensitivity and specificity of WBS were 50% and 99%, respectively. When the results of FDG-PET and WBS were considered in combination, tumour tissue was missed in only 7%. Sensi tivity and specificity of MIBI/Tl were 53% and 92%, respectively (n=117). W e conclude that FDG-PET is a sensitive method in the follow-up of thyroid c ancer which should be considered in all patients suffering from differentia ted thyroid cancer with suspected recurrence and/or metastases, and particu larly in those with elevated thyroglobulin values and negative WBS.