Parathyroid Scintigraphy in Primary and Secondary Hyperparathyroidism: Accuracy of Preoperative Localisation Using Combined Imaging Techniques

Full Article

HT Tam, YH Wong, SK Cheung, WT Ngai, PT Choi

Hong Kong J Radiol 2010;13:59-67

Objective: To evaluate the accuracy of preoperative parathyroid scintigraphy for lesion localisation in primary and secondary hyperparathyroidism.

Methods: The archives of 3 regional Hong Kong hospitals extending over a 12-month period were retrospectively reviewed for parathyroid scintigraphies in subjects who underwent subsequent first-time parathyroidectomy. Scintigraphic techniques comprised early- and late-phase 99mTc-sestamibi planar imaging (100% of studies), emission computed tomography (97%), and supplementary 99mTc-pertechnetate thyroid imaging (13%). Images were re-interpreted by applying a scoring scale to different lesional locations. Accuracies were determined by operative and histological findings.

Results: This series was based on 19 patients with primary hyperparathyroidismlesions (23 lesions) and 19 with secondary hyperparathyroidism associated with chronic renal failure (70 lesions). The frequencies of primary lesions in left upper, left lower, right upper, right lower, and ectopic positions were 13%, 30%, 9%, 44%, and 4% respectively; corresponding figures for secondary lesions were 24%, 24%, 26%, 23%, and 3%. The sensitivity, specificity, positive predictive, and negative predictive values of scintigraphy for locating primary lesions were 91%, 99%, 96%, and 97% respectively; and for secondary lesions corresponding figures were 74%, 84%, 93%, and 54%. The corresponding overall results for all lesions were 79%, 95%, 94%, and 82%.

Conclusions: Preoperative scintigraphy for localising hyperfunctioning parathyroids has a better accuracy in primary than secondary hyperparathyroidism (97% vs. 77%). Primary lesions have a preponderance for lower positions (74%) and may be subjected to scintigraphy-guided minimally invasive parathyroidectomy. The lower sensitivity (74%) and negative predictive value (54%) for secondary lesions render scintigraphy less helpful in secondary hyperparathyroidism, except on rare occasions to locate ectopic lesions.