Technetium 99m-MIBI-SPECT: A highly sensitive diagnostic tool for localization of parathyroid adenomas.

BACKGROUND

The aim of this study was to assess the value of technetium 99m-MIBI scintigraphy using the single photon emission computed tomography (SPECT) technique for preoperative localization of smaller (</= 1 g) parathyroid adenomas.

METHODS

A total of 92 patients (34 men, 58 women; mean age, 60 +/- 13 years) with an established diagnosis of primary hyperparathyroidism and nondiagnostic ultrasonography (inclusion criteria) were scanned preoperatively. After a thyroid examination to check for other possible radionuclide-accumulating thyroid diseases, a planar technetium 99m-pertechnetate/technetium 99m-MIBI subtraction scintigraphy (15 minutes post injection) and tomographic images (120 minutes post injection) were acquired after intravenous injection of 740 MBq of technetium 99m-MIBI and using a 3-head gamma camera (Picker Prism 3000). Sensitivity was defined by the ability to predict the correct site of a parathyroid adenoma.

RESULTS

All patients had parathyroid adenomas </= 1 g (53 patients, 0.5 -1.0 g; 39 patients, < 0.5 g). Correct localization of parathyroid adenomas to one side or the other was achieved in 87% of the patients using planar technetium 99m-pertechnetate/technetium 99m-MIBI subtraction scintigraphy. Sensitivity was increased to 95% by supplementary use of the SPECT technique and a 3-D display (volume-rendered reprojection for visualization). There was technetium 99m-MIBI accumulation in 11 benign thyroid nodes, but none of the healthy parathyroid glands were shown on the scan.

CONCLUSIONS

This study indicates that technetium 99m-MIBI parathyroid scintigraphy is a sensitive and specific tool for topographic localization even of small parathyroid adenomas, especially with the use of SPECT. This method could help to improve the efficiency of parathyroidectomy (eg, by making unilateral exploration sufficient).