O160 The utility of pre-operative localisation scans (ultrasound and Tc99M Sestamibi) for primary hyperparathyroidism is limited in up to 40% of the patients

Abstract

Abstract Introduction The aim of this study was to evaluate the diagnostic accuracy of pre-operative localisation scans for primary hyperparathyroidism (PHPT). Methods Patients with PHPT had pre-operative localisation scans; ultrasound (US) and Tc99m Sestamibi and were operated between 12/2020 and 12/2022. Patients with persistent/recurrence PHPT post-operatively were excluded. Results 97 patients with PHPT were included. The mean age was 60 (SD:13) years old. The male/female ratio was 1:4.4. The mean hospital stay was 1.1 days (SD:0.3). 94 and 91 patients had US and Tc99m Sestamibi scans respectively while 88 patients had both scans. There was 1 patient with an ectopic mediastinal parathyroid adenoma. On the histopathology, 72 patients had single-gland disease, 13 patients had 2 abnormal parathyroid glands, 9 patients had 4-gland hyperplasia. The diagnostic accuracy, sensitivity, specificity, Positive Predictive Value and negative predictive value of US scan was 62% (95%CI: 51-72%), 64% (95%CI: 53-74%), 20% (95%CI: 0.51-72%), 93% (95%CI: 90-96%) and 3% (95%CI: 0.5-16%), respectively. In 9 patients the US missed other/extra pathologic glands. The diagnostic accuracy, sensitivity and Positive Predictive Value of Tc99m Sestamibi scan was 63% (95%CI: 53-73%), 65% (95%CI: 54-75%) and 97% (95%CI: 97-97%) respectively. In 8 patients the Tc99m Sestamibi missed other/extra pathologic glands. Conclusion Parathyroid pathology in primary hyperparathyroidism is complex and the diagnostic accuracy of pre-operative localisation scans (ultrasound and Tc99m Sestamibi) is limited in up to 40%. The presence of negative pre-operative localisation scans should not be an obstacle to offering the patient a curative parathyroidectomy.