Diagnostic performance of dual phase 99mTc-MIBI planar and SPECT/CT scintigraphy in primary hyperparathyroidism

Abstract

Background: Primary hyperparathyroidism (PHPT) is an endocrine disorder characterized by excessive parathyroid hormone secretion, resulting in hypercalcemia. For the reason that Para-thyroidectomy (PTx) is the most effective treatment for PHPT, precise preoperative localization of the abnormal parathyroid gland(s) is required. Aim: The purpose of this study was to assess the diagnostic performance of 99m Tc-MIBI SPECT/CT scintigraphy in the management of patients with suspected parathyroid adenoma/hyperplasia. Patients and Methods: Thirty patients were prospectively imaged using 99m Tc-MIBI dual phase scan. Early (15 min. after I.V tracer injection) and delayed (120 min. after I.V tracer injection) images were obtained. SPECT/CT images were obtained at both imaging time points. Additionally, 99m Tc-pertechntate was done after delayed imaging. We relied upon the clinical/imaging validation and histopathology whenever available as the gold standard. Results: Twenty two females and 8 males with a mean age of 29 ± 14.3 years (range; 5-55 years) were enrolled in this study. On a per patient basis, 11 subjects were positive for one or more parathyroid lesions while the remaining 19 proved negative. Out of the 11 positive cases, nine had single adenoma (3 were right inferior, 1 was right superior, 2 were left superior, 2 were left inferior and 1 was ectopic in the mediastinum); one had two adenomas and the other had three adenomas. Early planar imaging detected 8 true positive and 19 true negative cases, giving sensitivity of 72.7% and specificity of 100%. Delayed planar imaging identified 9 and 19 true positive and true negative lesions respectively, giving sensitivity of 81.8% and specificity of 100%. Both early and delayed SPECT/CT imaging revealed 10 true positive and 17 true negative lesions yielding 100 sensitivity and specificity. Conclusion: Hybrid SPECT/CT improves preoperative localization of parathyroid lesions, provides important additional clinical information especially in the setting of ectopic lesions, and shows slightly superior results compared to dual-phase planar imaging.