Mediastinal ultrasound: what is it?
Ultrasonography of the mediastinum is an ultrasound examination of anatomical and topographical features and macrostructure of organs located in the middle section of the thoracic cavity. Most often, the study is performed by transthoracic access, but it is possible to carry out a transesophageal or endobronchial echoscanization. The ultrasound of the mediastinum is used to recognize volumetric formations, inflammatory processes of this anatomical region, assessment of the state of the lymph nodes. In the mediastinum there are vital organs (heart, large airways, main vessels, etc.), so a quick and accurate non-invasive examination of this area is of invaluable diagnostic significance.
The ultrasound of the mediastinum is a method of ultrasound imaging of the mediastinal space. The complex of mediastinal organs includes the thymus and the fatty tissue replacing it with age, the aortic arch, the heart and the surrounding pericardium, the bifurcation of the trachea and the main bronchi, the thoracic esophagus, the ERW, the lymphatic duct, the mediastinal lymph nodes, the large nerve trunks. The pathology of the mediastinum organs is usually detected when performing a chest X-ray. If necessary, X-rays of UCP with contrasting esophagus are used. Diagnostic methods for selection and differential diagnosis are ultrasound, CT, PET and MRI of the mediastinum. Less often resort to invasive techniques – pneumomediastinography, mediastinoscopy.
In a number of the listed methods of ultrasound of the mediastinum in Moscow takes one of the leading positions. Advantages of ultrasonography are non-invasiveness, high resolving power, harmlessness and accessibility. Undoubted advantages of ultrasound of the mediastinum are its mobility and low price. At the present time most ultrasound scanners are equipped with ultrasound scanners, and any ultrasound diagnostician who has been trained can perform the research.
Mediastinum for a long time was considered difficult to access for ultrasound imaging due to its spatial arrangement in the chest and little informative because of the reflection of ultrasonic signals by air pulmonary tissue. However, the improvement of ultrasound devices, as well as the accumulation of practical experience, made it possible to study the echosemiotics of the mediastinal organs and to develop convenient scanning algorithms.
Historically, the earliest method of echoscanning is transthoracic ultrasound of the mediastinum. Later, with the development of intracavitary ultrasound, the diagnostic capabilities of ultrasound of the mediastinum expanded due to the introduction into clinical practice of esophageal and endobronchial approaches. The basic principles and approaches for transthoracic ultrasound of the mediastinum were developed in 1990 by K. Wernecke; He also proposed a technique for the study and described the echographic pattern in normal and with various mediastinum lesions. K. Wernecke identified 8 areas available for transthoracic echoscanning:
- nadaortal region located above the aortic arch;
- aortopulmonary window located between the aorta and the pulmonary artery trunk, the left branch of the LA and the left main bronchus;
- right paratracheal area, located at the front and sides of the trachea;
- the prevascular region located posterior to the sternum, between it and the ascending aorta, the ERW, and the pulmonary artery trunk;
- the pericardial region located in front and on the sides of the heart;
- sub-bifurcation region located under the bifurcation of the trachea and above the left atrium;
- the paravertebral region located on the sides of the spinal column;
- posterior mediastinum – the space located between a back surface of heart and thoracal department of a backbone.
The most informative ultrasound of the mediastinum for the location of mediastinal tumors (thymoma, retrosternal cyst, mediastinal cysts, abdomino-mediastinal lumpomas, lymphomas, coelomic cysts of the pericardium, mediastinal lung cancer, etc.); detection of affected mediastinal lymph nodes in sarcoidosis, lymphogranulomatosis and tuberculosis of VGLU; inflammatory changes in mediastinal tissue during mediastinitis; damage to the lymphatic duct.
Endobronchial and transesophageal (transesophageal) ultrasound examination of the mediastinum significantly improve the quality of visualization and the accuracy of diagnosis. Endobronchial access extends the diagnostic capabilities of endoscopy by examining the peribronchial and para-esophageal areas. In addition, endosonography allows for an extra-bronchial fine-needle puncture-aspiration biopsy of volumetric mediastinal formations in real time.
In recent years, intraoperative ultrasound sonography has been increasingly used in thoracic surgery. Even with a small amount of the surgical wound with the help of the intraoperative sensor, it is possible to examine the deep mediastinal divisions, make sure of the operability of the process, determine the fit of the tumor to large vessels and other vital organs. Contraindications for performing transeophageal or endobronchial ultrasound are life-threatening arrhythmias, heart failure, acute or subacute myocardial ischemia, severe coagulopathies, critical hypoxemia.
Method of conducting
Preparation for transthoracic ultrasound of the mediastinum is not required. Before scanning to the chest, a conductive gel is applied. It is necessary that the skin of this area is intact, they do not have purulent-inflammatory foci.
For echoscanning of intrathoracic anatomical structures, suprasternal (suprahornal), parasternal (pericarred), intercostal and subcostal (sub-ribbed) approaches are used. From the suprasternal access, the thoracic aorta, the superior hollow vein, the pulmonary artery are visualized. The fatty tissue of the mediastinum, lymph nodes, heart, thymus gland is parsed. Of the intercostal spaces, soft tissues, ribs, parietal pleura, lung surface, pleural sinuses are normally visible. From the xiphoid process of the sternum, the right cardio diaphragmatic angle is clearly visible. From the subcostal access, the dome of the diaphragm, the liver and the spleen, serving as a guide for ultrasound diagnosis, are identified.
Endoscopic ultrasound of the mediastinum is performed under local anesthesia after preliminary premedication or under intravenous sedation. 6 hours before the study, food and water are excluded. The equipment is additionally equipped with a gastroscopy or bronchoscope equipped with a special endoscopic sensor. During the study, constant cardiac monitoring and pulse oximetry, blood pressure monitoring are performed. If the diagnostic procedure was followed by a biopsy, within a few days the patient can mark hemoptysis, feel chest pain.
Cost of ultrasound of mediastinum in the United States
Ultrasound examination of the mediastinum organs is a safe, fast, low-cost and effective method for diagnosing a number of diseases of organs located in the mediastinal space. The price of ultrasound in the mediastinum in Moscow is affected by the kind of procedure. Transesophageal and transbronchial ultrasound are more accurate and, at the same time, more labor-intensive methods, which affects their cost. In addition, using these techniques, medications are used for sedation, premedication or local anesthesia, which additionally increases the price of the study.