Quantitative estimation of 67Ga citrate in hypofunctioning thyroid nodules

Quantitation of 67Ga citrate activity was performed in 11 subjects who underwent surgery for nonfunctioning, cold thyroid nodules. Radioactivity was measured in blood and in excised nodular and paranodular tissue at approximately 48 hours after the injection. Eight subjects were histologically benign, nonfunctioning nodules had no significant concentration of Ga. Their nodular/blood activity ratio was 1.6. In two patients with thyroid cancer, a higher activity was observed (mean 4.5/1). One patient with Hashimoto's thyroiditis also revealed a high concentration of Ga (5.3/1). Findings suggest that 67Ga citrate has a lesser affinity for benign cold nodules than for malignant and inflammatory lesions. More clinical experience is necessary before the significance of these observations can be assessed.