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

The aim of this study was to evaluate the clinical use of fluorine-18 fluor odeoxyglucose positron emission tomography (FDG-PET) in medullary thyroid c ancer MTC on the basis of comparison with findings obtained using indium-11 1 pentetreotide (SMS), pentavalent technetium-99m dimercaptosuccinic acid ( DMSA), technetium-99m sestamibi (MIBI), computed tomography (CT) and magnet ic resonance imaging (MRI). One hundred FDG-PET examinations in 85 patients (40 males, 45 females) with elevated tumour marker levels and/or pathologi cal findings on other imaging methods were evaluated retrospectively. Eight y-two patients were examined after total thyroidectomy, and the remaining t hree patients prior to surgery. Overall, 181 lesions could be identified wi th at least one of the imaging techniques. Fifty-five lesions were confirme d histologically. FDG-PET detected 123 of 181 sites, which is a lesion dete ction probability of 68%. In the 55 cases with histological confirmation, w e found 32 true positive, 3 false positive, 11 true negative and 9 false ne gative lesions using FDG-PET, resulting in a sensitivity of 78% and a speci ficity of 79%. Sensitivity and specificity were, respectively, 25% and 92% for SMS, 33% and 78% for DMSA, 25% and 100% for MIBI, 50% and 20% for CT an d 82% and 67% for MRI. Compared with morphological techniques and functiona l imaging methods with single-photon emitters, FDG-PET showed the highest l esion detection probability for MTC tissue, with a high sensitivity and spe cificity. It is concluded that FDG-PET is a useful method in the staging an d follow-up of MTC.