Comparison among sonography, double-tracer subtraction scintigraphy, and double-phase scintigraphy in the detection of parathyroid lesions.

OBJECTIVE: This study prospectively evaluated the sensitivity of high-resolution sonography compared with double-tracer 201Tl-99mTc scintigraphy (Tl-Tc) subtractive scintigraphy and double-phase 99mTc-sestamibi (Tc-MIBI) scintigraphy prior to surgery in the assessment of patients with primary hyperparathyroidism in a geographic region where areas of endemic thyroid goiter are present. SUBJECTS AND METHODS: Sonography and scintigraphy were used as first-step imaging procedures in 73 patients with primary hyperparathyroidism. In 30 (41%) of 73 cases, we found an association with a thyroid abnormality. We compared sonography with double-tracer Tl-Tc scintigraphy in 41 cases, with Tc-MIBI scintigraphy in 22 other cases, and with both scintigraphic studies in 10 other cases.
RESULTS: Surgery demonstrated 68 solitary parathyroid lesions (66 adenomas, one hyperplasia, and one carcinoma), two adenomas in two patients, and multiple hyperplastic glands in two patients for a total of seven lesions. In one case no abnormal parathyroid gland was found. Overall sensitivity of sonography, Tl-Tc, and Tc-MIBI scintigraphy was 85%, 62%, and 82%, respectively. In patients with concomitant thyroid disease, the sensitivity of sonography, dual-tracer Tl-Tc, and Tc-MIBI was 77%, 67%, and 80%, respectively.
CONCLUSION: Our study proves that sonography and scintigraphy are equally able to detect parathyroid lesions before surgery in patients with concomitant thyroid diseases. In patients without thyroid abnormalities, detection rates of sonography and Tc-MIBI do not show any statistical difference, and the detection rate of Tl-Tc is significantly inferior to that of sonography. Sonography alone should be used as the first step for localization of abnormal parathyroid glands prior to surgery, and Tc-MIBI scintigraphy should be used as the second step when sonography is negative.