The usefulness of the dynamic phase in pertechnetate thyroid imaging for solitary hypofunctioning nodules

One hundred patients, each with a solitary thyroid nodule detected by clinical palpation, underwent three-phase Tc-99m pertechnetate thyroid imaging. The degree of perfusion of the thyroid nodule was classified as hypoperfused, euperfused, or hyperperfused compared to the remainder of the gland by a consensus of three nuclear medicine physicians. The nodules were subsequently biopsied, and the degree of perfusion of the nodules was correlated with their histologic diagnosis. Twenty-two nodules were classified as hyperperfused, 64 as euperfused, and 14 as hypoperfused. Malignancy rates of the hyperperfused, euperfused, and hypoperfused nodules were 36%, 31% and 0%, respectively. This seems to indicate that malignant thyroid nodules demonstrate a degree of perfusion at least equal to or greater than the rest of the thyroid gland. Conversely, none of the hypoperfused nodules was found to be malignant. The perfusion phase of thyroid imaging may provide useful clinical information regarding possible malignancy of a thyroid nodule.