Predictors of accuracy in preoperative parathyroid adenoma localization using ultrasound and Tc-99 m-Sestamibi: A 4-quadrant analysis ★

PurposeTo compare the accuracy of preoperative parathyroid adenoma localization in patients with primary hyperparathyroidism (pHPT) due to a single adenoma using a detailed 4-quadrant analysis and to identify patient and tumor characteristics associated with accurate preoperative localization.Materials and MethodsRetrospective review of 203 patients who underwent parathyroidectomy for pHPT due to a single adenoma between 2008 and 2011. Results from preoperative ultrasound and Tc-99 m-sestamibi were compared to operative findings to determine accuracy of localization studies. Associations between clinicopathologic features and accurate preoperative adenoma localization were evaluated.ResultsUltrasound was performed on 198 patients, sestamibi on 177 patients, and both on 172 patients. Accurate localization occurred significantly more often for ultrasound than sestamibi (63% vs. 41%, P < 0.001). For ultrasound, accurate localization was found in patients with larger or heavier adenomas, those with adenomas located inferiorly, patients not having a reoperative procedure, and patients with higher post-operative serum calcium levels. For sestamibi, greater adenoma size or weight, adenomas located inferiorly, and patients with associated thyroid cancer on pathology were most predictive of accurate preoperative localization.ConclusionsOur results provide evidence that ultrasound is more accurate in localizing parathyroid adenomas in patients with pHPT due to a single adenoma when compared to sestamibi scan using 4-quadrant location analysis and may be the preferred preoperative imaging modality in these patients. No significant preoperative patient factors were associated with accurate localization by ultrasound or sestamibi, but adenoma size, weight, and location in an inferior position were predictive of accurate preoperative localization.