Quantitative comparison of technetium-99m tetrofosmin and thallium-201 images of the thyroid and abnormal parathyroid glands

The: aim of the study was to quantitatively compare the scintigraphic images of the thyroid and abnormal parathyroid glands obtained with technetium-99m tetrofosmin and thallium-201 in patients with hyperparathyroidism. Forty-six patients with hyperparathyroidism underwent Tl-201 (74 MBq), Tc-99m-pertechnetate (74 MBq) and Tc-99m-tetrofosmin (555-740 MBq) scintigraphy in a single session. Image analysis included the computation of the thyroid/background ratio in the whole study population and the parathyroid/background ratio, parathyroid/thyroid ratio and diagnostic sensitivity in 17 patients who underwent parathyroid surgery. The pertechnetate subtraction technique was used. Tl-201 and Tc-99m-tetrofosmin showed a similar thyroid/background ratio (1.79+/-0.41 and 1.81+/-0.47, respectively, P=NS); however, Tc-99m-tetrofosmin showed a higher parathyroid/background ratio than Tl-201 (2.06+/-0.54 vs 1.79+/- 0.50, P=0.007). Despite the superior quality of Tc-99m-tetrofosmin images, both tracers showed identical sensitivity in detecting enlarged parathyroid glands in patients with primary hyperparathyroidism (89%) and in those with secondary hyperparathyroidism (50%).