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Thyroid ultrasound
Medical expert of the article
Last reviewed: 06.07.2025
Where to do thyroid ultrasound and why is it necessary to undergo regular preventive examinations of this organ? The thyroid gland is part of the endocrine system, diseases or disorders of its functioning negatively affect the work of the whole organism. Ultrasound diagnostics allows to detect foci of pathologies in time and conduct treatment.
Thyroid ultrasound technique
Thyroid vascularization can be assessed using color flow and pulse Doppler. Depending on the clinical task (diffuse or focal thyroid disease), the purpose of the study may be a quantitative assessment of thyroid vascularization or determination of its vascular structure.
Pulsed wave Doppler is used to measure peak systolic velocity and flow volume in the thyroid arteries. The inferior thyroid artery merges posteriorly with the common carotid artery. The apex of the confluence appears as a cross-section of the vessel by the common carotid artery on the longitudinal scan. The transducer is then rotated to visualize the ascending portion of the inferior thyroid artery, and the Doppler sample volume is placed within this segment. The superior thyroid artery, located medial to the common carotid artery in the upper pole of the thyroid gland, is visualized on a slightly modified longitudinal scan. It is easily detected by its opposite direction of blood flow to the common carotid artery. Peak systolic velocity (PSV) in the thyroid vessels is normally 25 cm/sec, and blood flow volume is 6 mL/min per vessel.
Diffuse thyroid disease can be identified by placing a color zone over the area being examined. This allows a semiquantitative assessment of parenchymal blood flow. Standard settings allow consistency to be compared between individuals and within the same patient. This cannot be achieved by examining with different machines or with different settings. Each ultrasound technician must have experience with a particular machine before assessing the degree of increased blood flow.
Diffuse hypervascularization in the acute stage of Graves' disease is well expressed and can be considered pathognomonic for this disease. Average peak systolic velocities are more than 100 cm/s, blood flow volume is more than 150 ml/min. Increased blood flow in the gland persists even when the euthyroid state is achieved with the help of drug therapy, and disappears only with time.
Hashimoto's thyroiditis has a similar picture in B-mode. The color mode with sensitive settings shows increased blood flow, but it is less pronounced than in acute Graves' disease.
In de Quervain's thyroiditis, the inflammation does not affect the entire thyroid gland, but it is infiltrated with the appearance of a heterogeneous picture. Ultrasound examination reveals a disordered picture with the presence of hyperechoic and hypoechoic areas.
Nodular hyperplasia is characterized by the presence of hyperechoic and isoechoic nodes. A hypoechoic rim (halo) is often determined, but unlike focal thyroid lesions, it does not indicate malignancy. The halo does not always correspond to the annular hypervascular pattern. In some cases, such a pattern occurs in the absence of a halo in B-mode. Although most adenomas have annular hypervascularization, this symptom is nonspecific, since it can be observed both in nodular hyperplasia and in cancer.
Most thyroid cancers are hypoechoic with peripheral and central hypervascularization. In order to judge the suspicion of malignancy, ultrasound signs of malignancy should be interpreted in combination with radionuclide examination data ("cold focus") and the clinical picture.
Critical assessment
The standard method of examining patients with suspected head and neck tumors is CT, which allows both to detect the tumor and to assess the state of regional lymph nodes. However, with CT, the only criteria that allow differential diagnostics between benign and malignant processes are the size of the node and possible enhancement in the form of a rim after the introduction of a contrast agent. If the size of the node is within the limits of a questionable value, CT should be supplemented with an ultrasound examination, which allows obtaining more criteria for comparative analysis.
Ultrasound is effective for staging malignant lymphoma. The disadvantage is that the results, unlike CT, are not as easy to document. In addition, ultrasound cannot assess the condition of the lymphoid tissue in the Valdeyra ring, which can swell in systemic diseases of the lymphatic system and cause potentially dangerous narrowing of the pharynx.
Color duplex sonography does not provide precise information on the functional state of thyroid nodules and for differential diagnosis between benign and malignant processes. In this regard, color duplex sonography does not complement fine-needle aspiration biopsy or radionuclide examination. In diffuse thyroid diseases, especially Graves' disease, color duplex sonography can help assess inflammatory activity and, in combination with laboratory data, is suitable for diagnosis and monitoring.
Ultrasound scanning of the thyroid gland is performed during pregnancy, with unexplained weight fluctuations, irritability and negative symptoms from the cardiovascular system. During the examination, the doctor determines the shape and location of the organ, the size and volume of the lobes, the structure, the presence of neoplasms and blood supply. The ultrasound conclusion is not a diagnosis, but only information for the endocrinologist. As a rule, this procedure is accompanied by a blood test for hormone levels and an examination of the entire body.
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