Primary hyperparathyroidism (PHPT) refers to an intrinsic parathyroid gland abnormality that produces excessive secretion of parathyroid hormone. PHPT is diagnosed biochemically, and surgical excision of the abnormal parathyroid tissue represents the only definitive cure. Historically, the standard operative management of PHPT has been bilateral neck exploration (BNE). Minimally invasive parathyroidectomy (MIP) involves the targeted evaluation of parathyroid abnormality identified by preoperative imaging. MIP is associated with shorter operating times, shorter length of stay and lower costs. MIP has become the operation of choice in most centres, whereas BNE is reserved for patients with non-localising imaging results, suspected multiglandular disease (MGD), or failure to achieve cure with MIP. No universally accepted algorithm exists for preoperative localisation. Different imaging modalities have various advantages and disadvantages depending on the clinical scenario. Surgeon preference and available radiologic expertise may also factor in the decision-making.
Ultrasonography is a common first-line imaging modality for preoperative localisation. A meta-analysis of 19 studies found a pooled sensitivity of 76% and a pooled positive predictive value (PPV) of 93%. 99m-Technetium-sestamibi scintigraphy is another common first-line modality for preoperative localisation. A meta-analysis of nine studies found a pooled sensitivity of 63% and a pooled PPV of 90% for this technique.
However, up to 40% of parathyroid adenomas demonstrate rapid wash out of radiotracer and are very difficult to detect. Multiphase four-dimensional parathyroid computed tomography (CT) is an increasingly used preoperative localisation technique. Specific scenarios that favour four-dimensional CT include negative or discordant ultrasonography and sestamibi imaging results, suspected MGD and previous failed operations. The reported sensitivity of 4D CT for localisation is 92% and the PPV ranges from 88% to 94%. On the basis of available evidence, the authors have proposed an algorithm in which ultrasonography is the first-line test followed by the surgeon’s choice of 4D CT or sestamibi imaging when necessary and considering the clinical scenario.