E2411. Parathyroid Gland Imaging
  1. Hye Jeong Choi; Bundang CHA Hospital
Normal parathyroid glands are very small and not usually identified by most imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), sestamibi scintigraphy, or ultrasound. Recently, many authors have reported ultrasound features of normal parathyroid glands based on the intraoperative ultrasonographic exam. In clinical practice, parathyroid lesions are easily misdiagnosed as thyroid gland or lymph node. Fine needle aspiration with washout parathyroid hormone is generally accepted for accurate diagnosis for parathyroid lesion.

Educational Goals / Teaching Points
Review of normal parathyroid imaging features, choice of appropriate imaging modality in clinical practice of hyperparathyroidism, understand pros and cons of fine needle aspiration with washout parathyroid hormone, differentiation of parathyroid adenoma from parathyroid carcinoma, and patient selection for minimal invasive treatment for parathyroid disease.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Normal parathyroid glands showed homogeneously oval and hyperechoic features on ultrasound imaging. The cause of hyperechogenicity is based on its pathologic backgrounds such as rich lipocytes and loose connective tissue. For evaluation of primary hyperparathyroidism, the mainstays of imaging are 99mTc sestamibi scintigraphy for parathyroid localization and ectopia and ultrasound for anatomic relationship. Fine-needle aspiration with washout parathyroid hormone is a very sensitive and specific modality for the identification of parathyroid adenoma, it has a limited value. It can induce lesion disruption, seeding along the needle tract, and fibrotic reaction that cause recurrent laryngeal nerve injury. Four-dimensional CT can provide detailed anatomic information and can help differentiate adenoma from other mimickers. Because of the rarity of parathyroid carcinoma, there were few reports focused on the differentiation between parathyroid adenoma and parathyroid carcinoma. Indistinct and infiltrative borders and heterogeneous echotexture are significantly different between the two disease entities. The conventional treatment for patients with primary hyperparathyroidism is open surgery. However, for some patients with risks associated with the surgery or anesthesia, nonsurgical treatment modalities have been developed to treat such patients. Ethanol ablation and radiofrequency ablation have been suggested alternative treatments.

Case-based approaches are essential for parathyroid gland disease.