Objective: To evaluate the effect that thyroid-related factors have on the preoperative localization of parathyroid adenomas.
Methods: This retrospective study included adult patients who were referred for further evaluation of primary hyperparathyroidism between December 2005 and October 2009 at a teaching and research hospital in Turkey. High-frequency ultrasonography and sestamibi scintigraphy (MIBI) were performed in all patients. Surgical procedure involved focal or bilateral exploration on the basis of concordant or discordant imaging studies. Selection of patients for minimally invasive parathyroidectomy was made based on the presence or absence of a single parathyroid adenoma detected by both ultrasonography and MIBI scan. Patients with negative or discordant imaging studies and a concomitant thyroid nodule underwent bilateral neck exploration.
Results: Two hundred and forty-eight patients with primary hyperparathyroidism who underwent parathyroidectomy were included in the study. Parathyroid gland abnormalities were successfully detected preoperatively by ultrasonography in 231 patients and by MIBI scan in 152 patients. When used together, ultrasonography and MIBI scan were unsuccessful in detecting an abnormality in 11 cases. MIBI scan visualized a lesion in 6 cases that remained undiagnosed by ultrasonography. Fifty-six of 85 patients with lesions detected by ultrasonography, but not by MIBI scan, had thyroid nodules. The frequency of thyroid nodules was higher in the 96 patients in whom a MIBI scan could visualize a parathyroid lesion than in the 152 patients in whom MIBI scan was successful (P = .004). No difference was observed regarding ipsilateral thyroid lobe involvement or nodule volume. Parathyroid adenomas were significantly smaller in patients with negative MIBI scans (P<.001).
Conclusion: Our results suggest that ultrasonography is more sensitive than MIBI scan in the detection of parathyroid adenomas, particularly in the presence of small parathyroid adenomas or other thyroid related-factors.