Determinants of Tc-99m sestamibi SPECT scan sensitivity in primary hyperparathyroidism

Abstract: Background: The aim of this study was to evaluate the influence of patient and adenoma characteristics on 99mTc–methoxy isobutyl isonitrile (MIBI) scan performance in individuals diagnosed with primary hyperparathyroidism (PHP). Methods: Records of patients undergoing parathyroidectomy for PHP over 6 years at a single center were reviewed. Results: The overall true-positive (TP) rate for 99mTc-MIBI scans was 56%. Adenomas sized 1.9 to 3.5 cm were more likely to have TP scans than 0.3-cm to 1.8-cm adenomas (74% vs 40%, P < .001). Preoperative ionized calcium levels between 1.49 and 1.72 mmol/L were more likely to have TPs than levels between 1.27 and 1.48 mmol/L (65% vs 47%, P < .05). No single class of medication was shown to significantly effect TP rates. A decrease in TP rate was observed for larger adenomas in patients on ≥1 medication (74% vs 65%, P = .05). Conclusions: In PHP, 99mTc-MIBI scan positivity is most related to adenoma size and preoperative ionized calcium level. [Copyright &y& Elsevier]