 Several modalities have been employed for localization such as ultrasound US, computed tomography CT, and magnetic resonance imaging MRI. The sensitivity of ultrasound for the preoperative detection of parathyroid adenomas has been reported to be 65-90 1. There are however, limitations to US. Because of the sonolucent appearance of parathyroid adenomas, it is impossible to distinguish an ectopic cervical parathyroid adenoma from a pathologic lymph node. Furthermore, mediastinal parathyroid adenomas are difficult, if not impossible to visualize due to acoustic shadowing from the sternum and clavicles 2. Also, this method is very operator-dependent. MRI has a slightly higher sensitivity of 62.5-94 while CT has a poor sensitivity of only 40-44 1. 