Products & Solutions News & Events Financial services Our commitment About GE Healthcare World-Wide

Medcyclopaedia Home E-learning Library Lexical Index Lexical Topics Glossary Face-a-Case Textbook of Radiology Preface W.C Roentgen and the discovery of X-rays Radiology in an international perspective Radiophysics Modalities and methods Radiology worldwide – the WHO approach Digital imaging Contrast media in diagnostic radiology Interventional radiology The brain The head and neck Modalities Temporal bone The nose, paranasal sinuses and the facial skeleton Nasopharynx Oral cavity and the oropharynx Salivary glands Larynx Neck Thyroid and parathyroid glands Dental radiology The Spine Muskoskeletal radiology Paediatric musculoskeletal radiology Pedriatic radiology Pediatric neuroradiology Breast imaging The lungs and mediastinum The heart The peripheral vessels The lymphatic system The gastrointestinal tract The liver, biliary tract, pancreas and spleen The acute abdomen The genitourinary system Obstetric imaging Tropical diseases Radiology in AIDS Textbook of Radiology (e-paper)Medical Imaging Made Easy Downloads MedcyclOasis About Medcyclopaedia Contact Us

MedcycloPoll
Did you get the help you required from Medcyclopaedia™ during today's visit?

Yes
		(84.6%)
No
		(10.9%)
Undecided
		(4.5%)

You must be logged on to vote.
Please log in or register.

help advanced search

Printer-friendly version

The head and neck

Thyroid and parathyroid glands

Technique

Nuclear medicine studies using iodine isotopes is used to study the size, location and function of the thyroid gland, as well as, demonstrate intraglandular lesions. Ultrasound has higher diagnostic yield than computed tomography to demonstrate and characterize small adenomas in both the thyroid and the parathyroid glands. Ultrasound can also differentiate between cyst and solid tumors seen as cold nodules on isotope studies. Intrathoracic extension of thyroid tumors or goiter is better demonstrated by computed tomography or magnetic resonance imaging.

Anatomy

Because of its high iodine content the normal thyroid gland can be seen as hyperdense tissue easily separated from the surrounding structures even without contrast enhancement. The triangle shaped lobes on both sides of the trachea are connected anteriorly by the isthmus. The internal jugular veins and the common carotid arteries are found adjacent to the thyroid lobes (Fig 25 d). The four parathyroid glands can normally not be visualized by cross sectional imaging. The glands are located in association with each pole of the thyroid lobes in the angle between the common carotid artery and the oesophagus.

Pathology

It is not possible to differentiate between benign thyroid adenomas and malignant nodules with any imaging method. Ultrasound and nuclear medicine studies are still the most useful to evaluate an enlarged thyroid gland. In hyperparathyroidism ultrasound is the primary method to localise a parathyroid expansion. If the ultrasound and radionuclide examination of the neck is negative computed tomography or magnetic resonance imaging can be used to assess for adenomas in the upper mediastinum. In previously operated cases with persistent or recurring hyperparathyroidism ultrasound, radionuclide and cross sectional imaging can be supplemented by selective venous sampling and digital subtraction angiography. Two studies should be positive to confidently identify recurrent adenoma or hyperplasia unless one positive study appears absolutely definitive.

Sven G. Larsson and Anthony A. Mancuso