In this radiology lecture, we review the ultrasound appearance of parathyroid adenoma! Key teaching points include: * Benign tumor of the parathyroid glands * Most common cause of primary hyperparathyroidism: Elevated serum calcium and parathyroid hormone (PTH) levels * Ultrasound: Solid, homogeneous and very hypoechoic. Oval or bean-shaped, long axis oriented craniocaudal. Hypervascular. Majority posterior and inferior to thyroid. Hyperechoic line often separates adenoma from adjacent thyroid. Atypical features: Cystic degeneration, calcification. * Tc-99m sestamibi: Radiotracer uptake persisting on delayed 2-hour images. Taken up by both thyroid and parathyroid tissue, but washes out more rapidly from thyroid. Greater than 90% predictive value for preoperative localization of parathyroid adenoma. SPECT aids with anatomic localization * Ectopic locations in up to 5%: Lower neck, mediastinum, retrotracheal/retroesophageal, carotid sheath and intrathyroidal (typically more homogeneous than thyroid nodules and have a linear interface with gland) * Larger adenomas can be multilobulated * “Polar vessel” sign: Enlarged feeding artery or draining vein terminating at parathyroid adenoma To learn more about the Samsung RS85 Prestige ultrasound system, please visit: https://www.bostonimaging.com/rs85-prestige-ultrasound-system-4 Click the YouTube Community tab or follow on social media for bonus teaching material posted throughout the week! Spotify: https://spoti.fi/462r0F2 Instagram: https://www.instagram.com/Radquarters/ Facebook: https://www.facebook.com/Radquarters/ X (Twitter): https://twitter.com/Radquarters Reddit: https://www.reddit.com/user/radiologistHQ/