X-ray of the sternum in 2 projections

A chest x-ray is usually taken for diagnostic purposes, but a focused visualization of the flat sternum in the middle of its anterior wall - a sternum x-ray - may be required.

Indications for the procedure

Indications for a chest x-ray include:

• fracture of the sternumassociated with injuries, including with intense compression on the  chest  during cardiopulmonary resuscitation;
• postoperative divergence (nonunion) of the sternum - after sternotomy during coronary artery bypass grafting;
• chest deformities -  funnel chest , cleft sternum,  Poland's syndrome ;
• developmental anomaly in the form of the absence of the lower part of the sternum (xiphoid process) - axiphoidia;
• syndrome of the anterior chest wall - rib-sternal syndrome (inflammation of the rib-sternal joints);
• suspicion of chondro- or osteosarcoma of the sternum.

What does a chest x-ray show? On an x-ray , the sternum  (sternum) - the handle (manubrium sterni) starting below the jugular notch, the body (corpus sterni) and the xiphoid process (processus xiphoideus) - is visible along the spine without superposition of the vertebrae, and cortical contours of the bone are also visible above the shadow of the heart; sternoclavicular joints (articulatio sternoclavicularis) are also visualized.

Preparation

Preparation, as with any x-ray of bone structures, is limited to the fact that the patient must remove all metal-containing accessories - wherever they are.[1]

The positioning or positioning of the patient during chest x-ray is made according to the Atlas of x-ray positions and depends on the x-ray positioning, that is, on the projection in which a given bone is to be taken.

Technique of the chest x-ray

According to the standard, an x-ray of the sternum is taken in 2 projections: in the lateral (lateral) and anterior oblique.

X-ray of the sternum in the lateral projection - the most informative in cases of fracture of the sternum and determining the degree of displacement, as well as the detection of metastases - is carried out in the vertical position of the patient (sitting or standing). In this case, one of the sides of the patient's chest should be adjacent to the X-ray cassette, his hands should be brought behind his back, taking his shoulders back (so that the chest moves forward), and his chin is raised. At the command of the radiologist, the patient needs to hold his breath for a few seconds.

If severe pain prevents the patient from taking this position, a parallel thin stream of radiation (collimation) is used, which allows a satisfactory image to be obtained. In severe injuries, the procedure is carried out lying down - on the side or on the back, changing the focus of the x-ray beam accordingly.

Often, the lateral view is complemented by a right anterior oblique view, in which the patient leans forward 15-25°, and the central beam is directed perpendicular to the film - just to the left of the spinal column, midway between the jugular notch and the xiphoid process. In the presence of a severe injury, an x-ray is performed lying down - in the left posterior oblique projection.

X-ray signs of a fracture of the sternum

Chest radiographs are usually the first imaging in patients with suspected sternal trauma. The anteroposterior radiograph has been shown to have only 50% sensitivity for detecting sternal fractures. The lateral radiograph increases sensitivity and is usually diagnostic since most sternum fractures are transverse and any displacement occurs in the sagittal plane. 

And their x-ray sign is the appearance of dark gaps on a light background of a flat sternum, which is a reflection of the lines of fractures. Convincing confirmation of the fracture is the displacement of fragments visible on the picture. [2]

To date, CT is recognized as the preferred imaging method for suspected sternal fracture, which, in addition to demonstrating a violation of the integrity of the bone, is able to show possible retrosternal hematomas and soft tissue edema.

Chest deformity on x-ray

With a funnel-shaped deformity of the chest (Pectus excatum), an x-ray in a lateral projection shows penetration (deflection) of the sternum into the mediastinum; often there is an anterior deflection of the thoracic spine (kyphosis), torsion of the sternum in the axial plane and a noticeable increase in its thickness.

In addition, the assessment of the state of the mediastinal organs, bones and connective tissues of the chest is carried out using ultrasound and computed tomography.

Among the radiological signs of the keeled chest (Pectus carinatum) is chondrogladiolar or chondromanubria protrusion of the sternum. In the first case, its middle and lower parts protrude anteriorly, in the second case, the protrusion of the sternum handle occurs (known as the Currarino-Silverman syndrome).

In patients with Poland's syndrome of the II degree, the deformation of the sternum on the X-ray is visible in the form of its small lateral turn, which is much more pronounced in the IV degree of deformation.

X-ray signs of sarcoma of the sternum

On X-ray, osteosarcoma of the sternum looks like a formation with uneven edges that does not have clear boundaries, consisting of bone and soft tissues with areas of osteolytic destruction (destruction of the medullary and cortical layers of bone tissue), calcification (calcification zones), as well as the inclusion of osteoid matrix (secreted by osteoblasts). Unmineralized proteins).

On the pictures in the lateral projection, the result of the tumor periosteal reaction can be visualized - the mineralization of the chondroid matrix (periosteum) in the form of bone protrusions (which experts call spicules).

On the subject of their localization, the nature of bone destruction, matrix mineralization, periosteal reaction and the associated soft tissue component. However, when evaluating tumors of flat bones, especially the sternum, X-ray has limitations: the lesion may not be fully projected due to the overlap of the surrounding lungs. Lateral radiographs can help, especially in distinguishing between intrathoracic and extrathoracic lesions. Plain radiography is of limited use for diagnosing small lesions, as well as for assessing intrathoracic extent, which requires the use of cross-sectional images. [3]

And the method of choice for instrumental diagnosis of lesions of the sternum is computed tomography (CT). And for the local determination of the stage of the sarcoma of the sternum (assessment of its intraosseous spread and soft tissue damage), MRI is used.

Contraindications to the procedure

Radiography is contraindicated in severe conditions of patients, in the acute phase of infectious diseases and internal bleeding, in pregnant and lactating women.

In children under 15 years of age, x-rays should be replaced by ultrasonography (ultrasound) or MRI if possible.