When should preoperative parathyroid localization studies be performed?
An experienced parathyroid surgeon does not require preoperative localization prior to an initial bilateral neck exploration and will have a surgical success rate of > 95%. However, about 85% of patients with primary HPT have a single parathyroid adenoma, and therefore, preoperative imaging is commonly performed. If an adenoma is localized, then a focused parathyroidectomy (also known as minimally invasive parathyroidectomy ) can be performed. Ultrasonography and 99m technetium sestamibi scanning are the most common modalities utilized, but high-resolution CT with intravenous contrast, commonly referred to as a “4-D CT,” is increasingly being used. Advantages of ultrasonography are its low cost, absence of ionizing radiation, and ability to evaluate for concomitant thyroid pathology. Sestamibi scanning and CT are more costly and entail radiation exposure but may have improved sensitivity compared with ultrasonography. Centers vary as to which modality is used preferentially. Patients with a prior history of neck surgery and certainly all patients with persistent or recurrent hyperparathyroidism should undergo preoperative localization studies prior to planned reexploration. Parathyroid venous sampling with or without arteriography may be useful in select situations of persistent or recurrent hyperparathyroidism when other modalities have failed to localize the abnormal gland.