Influence of medication and PTH levels on detection of parathyroid adenomas with dual isotope parathyroid scintigraphy.

Localization of parathyroid adenomas is a crucial step to facilitate minimally invasive parathyroidectomy. In this study, we investigated sensitivity and positivity rate of SPECT-based dual isotope parathyroid scintigraphy in detecting parathyroid adenomas, and the effect of medication and parathyroid hormone (PTH)-level on detection of adenomas. Two hundred and thirty-seven patients with primary hyperparathyroidism undergoing dual isotope parathyroid scintigraphy with SPECT-CT in our centre between January 1st 2013 and December 31st 2017 were included in this retrospective study. Sensitivity and positivity rate for accurate location of parathyroid adenomas, based on histopathological findings after surgery and follow-up PTH and calcium, were calculated. The impact of pre-operative medication (thyroxin, calcium-antagonists, antacids, vitamin D, bisphosphonates and calcium) and PTH-levels between positive and negative scans was evaluated by using univariate and multivariate analysis, and a ROC analysis respectively. Overall patient-based sensitivity of scintigraphy for finding parathyroid adenomas was 72% for scintigraphy, with a positivity rate of 60%. No significant effect of investigated medication on positivity rate was found. PTH-level was significantly higher in patients with positive scintigraphy (median 96.3 ng/L vs 75.2 ng/L, P < 0.01). Optimum cut-off for detection of adenomas for PTH was 79.4 ng/L with a sensitivity of 67% and a specificity of 63%. In this retrospective cohort, sensitivity and positivity rate of dual-isotope SPECT-CT for parathyroid adenomas were in line with previous studies. No statistically significant influence of medication on positivity of scintigraphy was found, suggesting these medication types should not be stopped prior to scintigraphy. PTH level was no useful parameter to predict positivity of scintigraphic imaging. AJNMMI