Multimodality imaging of the parathyroid glands in primary hyperparathyroidism

Primary hyperparathyroidism is a common endocrine disorder, affecting approximately 1 in 500 women and 1 in 2,000 men. Surgical removal of the hyperfunctioning parathyroid gland is the primary curative treatment. The last decade has witnessed the development of minimally invasive parathyroidectomy, which is based on the fact that the vast majority of cases are caused by single adenomas. However, the success of this technique relies on accurate preoperative localisation of the parathyroid lesions. The imaging modalities used vary at different institutions according to local expertise and availability, but include high resolution ultrasound, radionuclide studies, computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasound and 99mTc sestamibi scintigraphy, particularly when complemented by single photon emission computed tomography (SPECT), are currently the imaging techniques of choice for preoperative localisation of parathyroid adenomas; a combination of the two methods further improves the sensitivity and accuracy of detection. CT is less commonly used for preoperative localisation and usually reserved for cases of failed parathyroidectomy, for the detection of suspected ectopic glands. MRI appears to be useful in patients with persistent or recurrent hyperparathyroidism, who have previously undergone surgery. Cross-sectional imaging is also useful in cases where the findings at sonography and scintigraphy are discordant. SPECT/CT appears promising, but further studies are needed to evaluate its role in preoperative localisation.