EVALUATION OF THYROID-NODULES FOR MALIGNANCY USING TC-99(M)-SESTAMIBI

Tc-99(m)-sestamibi (Tc-99(m)-MIBI) is used for myocardial perfusion im aging but has also been reported to localize in tumours. The usual thy roid scanning radionuclide is Tc-99(m)-pertechnetate. Altogether, 161 patients with clinically solitary thyroid nodules had both Tc-99(m)-MI BI and Tc-99(m)-pertechnetate thyroid scans, with the nodules being re ported as cold, warm or hot. Fine-needle aspiration cytology (FNAC) an d surgery were performed in those patients who consented to these proc edures. Of 131 patients who had FNAC, only 58 proceeded to surgery. In the surgically treated group, 14 of 58 (24%) were confirmed to have t hyroid cancer, whereas 44 of 58 (76%) had benign lesions. The 14 cance rous nodules were cold on the Tc-99(m)-pertechnetate scan, whereas wit h Tc-99(m)-MIBI 11 were warm and 3 were either cold or hot nodules. Of the 44 benign lesions, 18 were cold, 9 were warm and 17 were hot nodu les. In those 131 patients who had FNAC, the cytology was reported as benign in 120 of the nodules and malignant in 11. The three false-nega tive cytologies were reported as follicular adenomas. The benign lesio ns noted on FNAC and surgery were thyroiditis, adenomas and haemorrhag ic or colloid cysts. The results from the 58 surgically treated patien ts suggest that the warm nodules would need surgery, whereas the cold and hot nodules are unlikely to be malignant. The overall sensitivitiy of the Tc-99(m)-MIBI scan was 79% and the specificity 80%, with the w arm nodule on Tc-99(m)-MIBI scan having a positive predictive value of 55% and a negative predictive value of 92%.