Radioiodide imaging of pertechnetate ''hot'' solitary thyroid nodules

In 5,100 consecutive patients having pertechnetate thyroid images, 96 were noted to have solitary ''hot'' nodules (1.9%). Each was reimaged (by 2 months) with I-123 sodium iodide (I-131 in 1 case). In 84 of the 96 cases (88%), the nodules were also ''hot'' on the radioiodide images. Seven of these cases were biopsied; all were follicular adenomas. In 9 cases, the solitary radiotechnetium ''hot'' nodules were not delineated on the radioiodide images; hence, 8% of the cases had areas that would not have been noted if radioiodide was the sole imaging agent. Of the 9 ''nondelineated'' nodules, 3 were biopsied. One was reported as being normal (adequate tissue removal), one was a follicular adenoma, and one was a folicular adenoma with a focus of metastatic tumor from an undetermined site (there were other metastases in the lungs and mediastinum). Hence, the 3 biopsied areas showed benign thyroid tissue (with one metastatic site). In 3 cases (4%) the pertechnetate ''hot'' nodule was ''cold'' on the radioiodide study. Two of these were biopsied. One was a follicular carcinoma, while the second was a follicular adenoma with pleomorphic Hurthle cells. The authors conclude that, in this series, 88% of the ''hot'' pertechnetate thyroid solitary nodules were also ''hot'' to radioiodide; all those biopsied were nonmalignant. In 8% of the cases, the pertechnetate ''hot'' areas were not delineated on the radioiodide images. Biopsies in this group showed nonmalignant lesions (although one had a metastatic area). In 3 cases with pertechnetate ''hot'', but radioiodide cold areas, 2 were biopsied and showed malignant or premalignant elements