The use of computed tomography as a first-line imaging modality in patients with primary hyperparathyroidism

Background: The success of minimally invasive parathyroidectomy (MIP) relies on accurate localization of the abnormal parathyroid glands. Concordant findings on ultrasound (US) and ^99mTc-scintigraphy (sestamibi) are currently considered the ‘gold standard’. Computed tomography (CT) has also recently been used in preoperative planning. We sought to assess the accuracy of CT for localization of abnormal parathyroid glands in such patients. Methods: An audit of 75 patients with primary hyperparathyroidism (PHPT) who underwent neck US and CT between 2017 and 2019 at our center as their first-line imaging. Results: All 75 patients underwent US and CT and 54 (72.0%) also had sestamibi. CT alone identified a potential target in all patients, of which the location was correct in 63 (84.0%). The overall combined sensitivity of US and CT was 88% (95% CI 78–94) and was higher than the combined sensitivity of US and sestamibi (65% [95% CI 53–76]; p< 0.001). Twenty-one patients (28.0%) had an ectopic gland, and the sensitivity of US and CT was 86% (95% CI 64–96) versus US and sestamibi (57% [95% CI 34–77]; p= 0.016). For adenomas < 1.0 g (n= 36; 48%), the accuracy of CT was 81% (95% CI 64–91) compared with 62% (95% CI 44–77) for US and sestamibi (p= 0.04). The correct preoperative diagnosis of multiglandular disease (n= 9; 12%) seemed to be the most difficult, with similar accuracy for US and sestamibi (40% [95% CI 14–73]) and US and CT (50% [95% CI 20–80]) (p> 0.99). Conclusion: The combination of US and CT was able to correctly identify the location of the abnormal parathyroid in 88% of patients and, in comparison with US and sestamibi, had better diagnostic accuracy, especially for smaller and ectopic adenomas. This finding suggests that US and CT could be considered as a first-line imaging modality in patients with PHPT considered for MIP.