Medical expert of the article
New publications
X-ray anatomy of the thyroid gland
Last reviewed: 19.10.2021
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
The thyroid gland is located in the anterior region of the neck in front of the trachea. It has a horseshoe shape with concavity facing posteriorly, and consists of two unequal parts, which are connected by an isthmus. Sometimes there are additional thyroid glands (on the neck, in the root of the tongue, in the chest cavity), which can be detected with the help of radiation methods, especially in scintigraphy.
The usual radiographs do not produce a clear image of the thyroid gland because of its small size and insignificant differences in density compared to surrounding tissues. On computer and magnetic resonance tomograms of the iron appears quite clearly: its lobes and isthmus are visible, having even rounded contours. The gland tissue is uniform, its density, determined with densitometry. Reaches about 100 HU. The relation of the gland to the trachea and the blood vessels of the neck is well seen.
The main methods of visualization of the thyroid gland are ultrasound scanning and scintigraphy.
To conduct an ultrasound study does not require special training, it can be performed many times, the study has no contraindications and is not accompanied by complications. It is carried out on devices operating in real time, with special sensors with an ultrasound frequency of about 5-7 MHz.
For the purpose of comprehensive research, a series of longitudinal and transverse sonograms is produced. Normally, the thyroid gland is excreted as a formation with a homogeneous fine-grained structure. Its natural markers are trachea and common carotid arteries. On the longitudinal sonogram, both lobes of the gland and an isthmus between them are visible up to a thickness of 0.8 cm. Each share has the shape of an oval. Ahead of her skin and subcutaneous fat tissue, and posterior - a common carotid artery or thyroid hryash. When transverse scanning of iron is defined as a symmetrically located with respect to the median line formation, each part of which forms an oval. Between the lobes, linear echostructures are visible-a mapping of the laryngeal cartilage. On the transverse scannograms, the thyroid cartilage, which determines two linear structures that form an obtuse angle, is also noticeable. Behind and slightly lateral from each lobe of the thyroid gland are rounded echo-negative figures corresponding to the common carotid artery and lateral to the jugular vein. Anterior and lateral to the lobes of the gland, you can see oval, fine-meshed structures of the sternocleidomastoid muscles.
Radionuclide investigation of the thyroid gland is carried out after preliminary preparation of the patient. Preparation consists in the exclusion of substances blocking the gland (food products and medicinal substances containing iodine and bromine). In addition, the patient should report to the radionuclide laboratory on an empty stomach. The image of the gland is obtained by intravenous injection of 80-100 MBq of 99mTc pertechnetate.
Normally, a scintigram outlines the outline of the entire thyroid gland in the form of a butterfly. The right and left lobes and isthmus are visible. The size of the right lobe is usually somewhat larger than the left one: 3-6 cm in length and 2-3 cm in width. The outer contours of the gland are convex. The density of the image is higher in the central parts of the lobes, since there is more mass of glandular tissue, and to the periphery it decreases. There are numerous variations in the size of the lobe of the gland and in the mapping of the isthmus. The pyramidal share, which extends from the isthmus to the top, is rarely seen.