Hyperfunctional parathyroid glands with 99mTc-MIBI scan: semiquantitative analysis correlated with histologic...

The purpose of this study was to correlate the semiquantitative analysis of 99mTc-methoxyisobutyl isonitrile (MIBI) scan with histologic findings of hyperfunctional parathyroid glands.

Early and delayed cervical images of MIBI scans were reviewed in 31 patients who eventually underwent parathyroidectomies because of biochemically suspected hyperparathyroidism ([HPT], primary, n = 13; secondary, n = 18). The sensitivity of a scan for localizing the diseased glands was determined by comparing scan findings with pathologic findings, which were considered the gold standard. The average ratio of parathyroid-to-thyroid (P/T) count was compared between glands with large and small areas of whole gland, chief cell, oxyphil cell or cellular components. The mean areas of whole gland, chief cells and oxyphil cells were also compared between glands detected by MIBI scan and those that the scan missed.

There were 99 resected lesions, including 9 parathyroid adenomas and 61 hyperplastic parathyroids. The sensitivity for localizing the diseased glands in patients with primary HPT (91%) was higher than that in patients with secondary HPT (83%). Significantly greater average P/T counts ratio on both early and delayed images was observed in the diseased glands with greater areas of whole gland, chief cells, oxyphil cells or cellular components. Fifty-nine MIBI-positive glands had significantly greater average areas of whole gland (P < 0.001) and chief cell (P = 0.002) than did 11 MIBI-negative glands.

The uptake of MIBI in hyperfunctional parathyroid is dependent on gland size and the amount of cellular components, chief cells and oxyphil cells. However, the amount of oxyphil cells does not clearly affect the results of MIBI parathyroid scintigraphy, because it is small in most hyperfunctional glands.