HAS DOUBLE-PHASE MIBI SCINTIGRAPHY USEFULNESS IN THE DIAGNOSIS OF HYPERPARATHYROIDISM

The usefulness of double-phase parathyroid technetium-99m-MIBI scintig raphy for the detection of hyperplastic parathyroid tissue has been de scribed. The aim of the present study was to establish the effectivene ss of this new technique in the morphological and functional assessmen t of parathyroid glands in patients with different types of hyperparat hyroidism. We performed 99mTc-MIBI scintigraphy (MIBI) and neck ultras onography in 38 patients with primary (n = 16) or secondary (n = 22) h yperparathyroidism. All patients underwent surgical neck exploration, removing a total of 84 parathyroid glands. Before and after surgery, b lood intact parathyroid hormone (iPTH) was measured peripherally and i n both the right and left internal jugular veins. In patients with pri mary hyperparathyroidism, ultrasonography showed one enlarged gland in 11 cases (69%), while MIBI was positive in 15 (94%) (including two ec topic glands). The sensitivity of MIBI (93%) was greater than that of ultrasonography (68%), with a similar specificity (100 and 97%, respec tively). In patients with secondary hyperparathyroidism, there was a d iscrepancy between both imaging modalities in 29 glands (33%). The sen sitivity of both techniques was similar (41 and 54%, respectively), wi th the same specificity (89%). There were more difficulties in detecti ng the upper than the lower pathological glands. MIBI reflected more a ccurately the functionality of the glands, and ultrasonography has a b etter correlation with the volume and weight. In conclusion, Tc-99m-MI BI scintigraphy is a good technique to identify parathyroid hyperfunct ioning tissue in cases of primary hyperparathyroidism and to detect ec topic glands, but it does not give significantly better results than c onventional ultrasonography in patients with secondary hyperparathyroi dism.