[Diagnosis of hyperparathyroidism]

To preoperatively localize enlarged parathyroid glands in patients with hyperparathyroidism (HPT).

Besides clinical and biochemical workup, high-resolution ultrasonography (US) is the most commonly used imaging method.Additionally,Tc-99m-MIBI scintigraphy in subtraction or biphasic technique, computed tomography (CT) and magnetic resonance imaging (MRI) are used.

US fails to detect a minimum of 10% of enlarged parathyroid glands,most commonly due to ectopic location, or difficult examination conditions, such as nodular goiter or previous surgery. If attempted US localization is unsuccessful, multiphase scintigraphy, using Tc-99m-sestamibi, can help to locate ectopic adenomas in the mediastinum. With SPECT, ademomas can be found which escape detection on planar scans due to their small size. With combined use of US and scintigraphy, a correct localization of parathyroid adenomas is possible in up to 90%. CT and MRI are of limited value due to their low specificity.

For newly diagnosed hyperparathyroidism, high-resolution US is the method of choice for localizing parathyroid adenomas. If ultrasound fails to detect a lesion, Tc-99m-MIBI scintigraphy is recommended. In patients scheduled for re-operation for recurrent or persistent HPT, a preoperative detection of a parathyroid adenoma should be attempted whenever possible, in order to minimize the extent of surgery. The role of CT or MRI is mainly to help to better anatomically localize a suspected adenoma previously detected with scintigraphy.