Ultrasound of the thyroid gland is a visualizing method of examination that reflects the location of the endocrine gland, its size, structure, anatomical features, the presence of diffuse and focal changes, the state of blood flow. It is used in the diagnosis of cysts, adenomas, malignant tumors, thyrotoxicosis, thyroiditis. Depending on the research tasks, a standard ultrasound of the thyroid gland or its combination with ultrasound examination of blood vessels is prescribed.
Ultrasound of the thyroid gland refers to procedures that do not require special training. It is not recommended to eat food for several hours before the examination in order to avoid a gag reflex when pressing the sensor on the gland area.
When performing ultrasound of the thyroid gland, its general characteristics are evaluated: location, size, structure, echogenicity, contours, condition of the lobes and isthmus. The presence and nature of diffuse changes, for example, inflammatory process or fibrosis, features of focal formations (number of nodes, their localization, size, structure) are determined. Dopplerography of thyroid vessels reflects the speed of blood flow in the lower thyroid arteries, patency of veins and arteries.
A normal thyroid gland in an adult has a length from 4 to 4.8 cm, a width from 1 to 1.8 cm, a thickness of 0.8-1.6 cm, a weight of 15-25 g, a volume of 18-23 ml. Excess of average indicators is sometimes found in women in the first half of the menstrual cycle and in people who smoke. Ultrasound reveals the following diseases:
- Diffuse toxic goiter. In Graves’ disease, an increase in the size of the gland, hypoechoicity of glandular tissue, and the presence of hyperechoic areas are diagnosed. Hyperechoic elements look like a few small and thin linear structures.
- Nodular goiter. Ultrasound determines various types of nodular goiter: nodular colloidal goiter, follicular adenoma, solitary cyst, malignant tumors. The key signs are the heterogeneous echo structure of the focus, its reduced echogenicity (more often). With adenoma and cyst, the node is clearly outlined, the boundaries are even, there is a hypoechoic vascular contour. In cancer, there is no restrictive rim, the borders are uneven, the contours are indistinct, regional lymph nodes are often enlarged.
- Autoimmune thyroiditis. With Hashimoto’s thyroiditis, it is possible to increase the gland (hypertrophic form), decrease it (atrophic form) or maintain normal volume. There is an uneven decrease in echogenicity, diffuse heterogeneity of parenchyma with alternating hypoechoic zones of various sizes, evenly or unevenly distributed in the tissue. A bumpy deformation of the contour of the posterior surface of the organ is characteristic.
- Thyrotoxicosis. In patients with thyrotoxicosis, the echogenicity of the gland is uniformly reduced, the echostructure is more often homogeneous, the blood supply is enhanced. It is possible to identify nodular/multi-nodular goiter – foci with altered heterogeneous echogenicity.
Ultrasound examination of the thyroid gland is one of the components of the diagnosis of endocrine diseases. The results obtained complement the information obtained by an endocrinologist during a survey, palpation of the gland, and a study of the level of hormones in the blood.
The advantages of thyroid ultrasound are accessibility, safety and informativeness. If necessary, the procedure can be carried out repeatedly. The absence of contraindications allows using this type of diagnosis for the examination of newborns and infants, pregnant women, elderly patients. Ultrasound navigation is indispensable when conducting a thyroid biopsy. Compared to other imaging methods such as MRI, CT and thyroid scintigraphy, ultrasound has a low cost. The use of ultrasound in the diagnosis of diseases has a number of limitations: it does not allow to assess the severity of the autoimmune process, to identify malignant degeneration of neoplasms.