Dual-tracer 99mTc-sestamibi/ 123I imaging in primary hyperparathyroidism.

Abstract

Surgery is the only curative treatment for primary hyperparathyroidism (PHPT). Preoperative imaging is always recommended. ^99mTc-sestamibi scintigraphy is often used in combination with neck ultrasonography as first-line imaging. ^99mTc-sestamibi scintigraphy plays a major role in depicting ectopic parathyroid lesions, as well as in guiding a targeted, minimally invasive parathyroidectomy (MIP). Detecting multiple gland disease (MGD) is important to reduce the risks of surgical failure or unplanned conversion to bilateral surgery. However, the ability to recognize MGD varies greatly depending on the ^99mTc-sestamibi imaging protocol that is used. Dual-tracer ^99mTc-sestamibi/¹²³I highly improves MGD detection compared to single-tracer "dual-phase" ^99mTc-sestamibi imaging. It can thus improve patient selection for MIP. The main requirements for successful dual-tracer imaging are: 1) to acquire ^99mTc-sestamibi and 123-iodine images simultaneously, thus avoiding motion artifacts on subtraction images; to use neck pinhole imaging, in addition to planar imaging, to improve resolution and MGD detection; to follow with dual-tracer SPECT/CT imaging to better define anatomic position of detected parathyroid lesions. If dual-tracer ^99mTc-sestamibi/¹²³I and neck ultrasonography are negative or inconclusive, the second-line imaging in our practice is ¹⁸F-fluorocholine PET/CT. The CT component of ¹⁸F-fluorocholine PET/CT is performed as non-enhanced acquisition plus a contrast-enhanced arterial phase acquisition, to minimize the risk from false-positives due to choline uptake in inflammatory lymph nodes. We use the same strategy of first-line dual-tracer ^99mTc-sestamibi/¹²³I plus neck ultrasonography, followed if necessary by second-line contrast-enhanced ¹⁸F-fluorocholine PET/CT, in patients requiring reoperation for persistent or recurrent PHPT. Additional localization techniques are now rarely necessary.