Four-Dimensional Computed Tomography Scan Utility in Parathyroidectomy for Primary Hyperparathyroidism With Low Baseline Intact Parathyroid Hormone

Objectives/Hypothesis: The prevalence of multiglandular disease (MGD) of the parathyroid has been reported to be higher in patients with primary hyperparathyroidism and low baseline intact parathyroid hormone (PTH) levels (<100 pg/mL). Low baseline PTH is associated with lower localization rate and positive predictive value with both preoperative sestamibi and ultrasound. This study sought to evaluate our experience with four-dimensional computed tomography (4D-CT) for the localization of abnormal parathyroid glands, including MGD, in patients with low baseline intact PTH (LBiPTH). Study Design: A single institution case series. Methods: A case series of patients with primary hyperparathyroidism with low baseline PTH or an inconclusive sestamibi, who underwent surgery with a single surgeon from April 2012 to June 2015 following 4D-CT to help with abnormal gland localization. Results: We identified 14 patients who underwent a 4D-CT in the setting of primary hyperparathyroidism and LBiPTH. A sestamibi scan had been ordered in 71% and was inconclusive in all cases. No ultrasound was performed. In all patients, 4D-CT was 84.6% sensitive in localizing abnormal glands, yielding a positive predictive value of 91.7%. Overall, 42.9% of patients had evidence of MGD, and 4D-CT detected 83.3% of MGD cases. A focused unilateral exploration was performed in 28.6% of cases, and a four-gland exploration was performed in all remaining patients. Conclusions: In patients with hypercalcemia and LBiPTH, with higher likelihood of MGD and of inconclusive results on sestamibi, 4D-CT may be a superior modality for localizing smaller adenoma or multiple hypercellular glands. This may allow for improved interpretation of intraoperative PTH results, and in a minority of cases, a focused parathyroid exploration.