Thyroid scanning & the significance of the solitary cold nodule

Since thyroid scanning was introduced in Singapore in 1968 there has been progressive increase in the demand for these scans. 215 patients comprising 153 females and 62 males were scanned in 1976 using 131I. The solitary nodule was the commonest condition referred for scans (60%) and next was the multinodular goitre 919%). Other indications for scan included postthyroidectomy cases, aberrant thyroids, retrosternal goitres, thyrotoxicosis and metastases from thyroid carcinoma. 73 cases of solitary cold nodules were discovered and 43 of these were operated on. 7 of these were found to be malignant, giving an incidence of 16%. The incidence of malignancy in the cold nodule varies in the reported literature. By itself the 131I scan cannot diagnose malignancy but is it a useful supplementary test in addition to the clinical and other investigations.