COMPARISON OF TECHNETIUM-99M-MIBI, TECHNETIUM-99M-TETROFOSMIN, ULTRASOUND AND MRI FOR LOCALIZATION OF ABNORMAL PARATHYROID-GLANDS

Abnormal parathyroid tissue can be identified by radionuclide imaging with either Tc-99m-MIBI or Tc-99m-tetrofosmin. This study compared the relative sensitivity of these two gents to localize parathyroid hyper plasia and adenoma. Methods: Twenty patients with primary (n = 9) or s econdary (n = 11) hyperparathyroidism were studied with Tc-99m-MIBI an d Tc-99m-tetrofosmin parathyroid imaging, ultrasonography and MRI. Rad ionuclide images of the neck were acquired 10 min and 2-3 hr after rad iopharmaceutical injection. The images were visually evaluated for abn ormal focal areas of increased tracer localization in the neck and med iastinum. A parathyroid gland/normal thyroid tissue activity ratio (re ferred to as the P/T uptake ratio) was calculated for each positive sc an. Results: Of the 46 parathyroid glands surgically explored, the ove rall sensitivity and specificity of MIBI imaging were 83% and 83% (38/ 46); tetrofosmin imaging 87% and 83% (40/46); ultrasonography 78% and 40% (36/46); and MRI 80% and 60% (37/46), respectively, Both radiophar maceuticals performed well in the nine patients found to have adenoma. The sensitivity and specificity of MIBI imaging were 100% and 100% (9 /9); tetrofosmin imaging 100% and 100% (9/9); ultrasonography 78% and 67% (7/9); and MRI 100% and 100% (9/9), respectively. In the 37 glands with hyperplasia, MIBI imaging had a sensitivity of 78% and specifici ty of 75%; tetrofosmin imaging 84% and 75%; ultrasonography 78% and 43 %; and MRI 73% and 60%, respectively. Conclusion: All imaging techniqu es localized abnormal parathyroid glands. The radiotracers have equal sensitivity for the localization of abnormal parathyroid glands. The s ensitivity of these tracers was high as compared to ultrasonography or MRI.