Endocrine Abstracts

Background: The success of Minimally Invasive Parathyroidectomy (MIP) is closely linked to accurate preoperative localisation of a solitary parathyroid adenoma. Sestamibi/SPECT scan (SS) and ultrasonography (US) are the preferred imaging modalities although their accuracy varies considerably between different centres.

Aim: To assess the efficacy of SS and US in identifying a solitary parathyroid adenoma in patients with primary hyperparathyroidism (PHPT) at our centre.

Methods: A retrospective study based on demographic, biochemical and surgical details of patients with PHPT who underwent SS and US during a 5-year period. Imaging results were analysed on patients who were considered to have a confirmed solitary parathyroid adenoma as indicated by single adenoma on bilateral neck exploration or biochemical cure after MIP.

Results: Sixty-three patients had SS, 61 had US and 33 had surgery. Sixty-four percent were females, median age 68 years, median serum calcium 2.86 mmol/l and median serum PTH 15.26 pmol/l. SS identified a single adenoma in 35 (56%) patients, multigland disease in 7 (11%) and was normal in 21 (44%) patients. Corresponding figures for US were 35 (57%), 3 (5%) and 23 (38%). Positive and negative predictive value, sensitivity and specificity for SS in identifying a confirmed solitary adenoma were 80, 67, 86 and 55% and for US 73, 44, 76 and 40% respectively. Concordance between the two imaging studies was obtained in 37 (60%) patients although concordant imaging resulted in a minor increase in PPV to 83%.

Conclusion: Sestamib/SPECT and ultrasonography were individually highly effective in identifying a parathyroid adenoma at our centre which could allow the use of MIP in a higher proportion of patients with PHPT. Concordance between the two forms of imaging did not add significantly to the chances of detecting a solitary adenoma.