^99mTcO₄^-/^99mTc-MIBI dual-tracer scintigraphy for preoperative localization of parathyroid adenomas

To investigate the accuracy of dual-tracer scintigraphy for locating parathyroid adenomas in patients with primary hyperparathyroidism (PHPT).

We reviewed 268 patients with PHPT. All patients underwent technetium-99m pertechnetate (^99mTcO₄^-) scintigraphy and technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) dual-tracer scintigraphy of the thyroid and parathyroid glands, respectively. ^99mTcO₄^- planar scintigraphy was carried out initially followed by dual-phase ^99mTc-MIBI single-photon emission computed tomography (SPECT)/CT the next day. The findings were combined and interpreted. Individual ^99mTc-MIBI and dual-tracer scintigraphy were both analyzed. The sensitivity, specificity, and accuracy were determined in relation to surgical findings. The average interval between scan and surgery was 13 days.

The positive and negative predictive values of ^99mTc-MIBI SPECT/CT were 92.0% and 71.3%, respectively, and the sensitivity, specificity, and accuracy were 88.3%, 79.2%, and 85.8%, respectively. The positive and negative predictive values of dual-tracer scintigraphy were 96.3% and 82.3%, respectively, and the sensitivity, specificity, and accuracy were 92.9%, 90.3%, and 92.2%, respectively. Youden's index for dual-tracer scintigraphy and ^99mTc-MIBI SPECT/CT were 0.83 and 0.63, respectively.

These finding suggest that ^99mTcO₄^- and ^99mTc-MIBI dual-tracer scintigraphy is more accurate than other scintigraphy methods for detecting parathyroid adenoma, and may thus be the most suitable imaging technique in patients with PHPT.