Showing posts with label chest x ray. Show all posts
Showing posts with label chest x ray. Show all posts

The “BIG RIB SIGN” and “VERTICAL DISPLACEMENT SIGN” In Lateral Chest X Ray.

Pulmonary Medicine Blog By Dr Deepu

The “BIG RIB SIGN” and “VERTICAL DISPLACEMENT SIGN”- To Differentiate The Right and Left Ribs on Lateral Chest Radiographs

Today I would like to share with you two important signs in Chest X Ray- The Big Rib Sign and Vertical Displacement Sign.

Diseases of the ribs and diaphragm are often identified only at lateral chest radiography. Therefore, it is important to use a reliable technique for differentiating the right and left ribs. Two techniques—the “big rib” sign and the “vertical displacement “sign—can be used to localize the right and left ribs at lateral chest radiography. Conventially lateral radiographs are taken with left side near the film. But lateral view can be obtained as Right or left  as per clinicians request, then the principle remains the same but only the magnified sides change .

The big rib sign is a technique that exploits the difference in magnification between the right and left sides on lateral chest radiographs.



The side of the rib cage farther from the film is magnified more than the side closer to the film. On a well-positioned left lateral chest radiograph, the right ribs appear larger than the left ribs . This difference in rib size is more easily detected posteriorly where the x-ray beam is tangential to the ribs but can be appreciated at all corresponding points along the curvature of the two ribs. In addition, rotating the patient may enhance or reduce the magnification effect because, with such rotation, the x-ray beam is transmitted through different portions of the ribs, which are thin medially and thick laterally. In a left lateral projection, when the posterior portions of the right and left ribs appear comparable in size, the hemidiaphragm traceable to the most anterior ribs is the right hemidiaphragm. Otherwise, the significantly larger ribs are the right ribs, which are farther from the film.

The big rib sign is very useful but is not perfect because the magnification difference between the right and left ribs is only 10%. For example, if the width of a rib is 5 mm, the observed difference between sides is only 0.5 mm, which is not always sufficient to enable differentiation of the two sides. Furthermore, the big rib sign is not applicable when the posterior ribs are superimposed.

Another Sign is the vertical displacement sign, which is an easy, reliable, and precise method for differentiating the right and left ribs on lateral radiographs .

 The vertical displacement sign is based primarily on the vertical divergence of the x-ray beam rather than on the magnification of the ribs. Because the right rib cage is farther from the film, the projection of the right ribs on a lateral radiograph will fan out and diverge in a vertical direction to a greater degree than that of the left ribs. Thus, the right side can be distinguished from the left by the vertical displacement of the paired ribs.

The vertical displacement sign is usually applicable even when the posterior ribs are partially superimposed. It is usually possible to identify which rib is higher or lower even when they overlap. The vertical displacement sign can be used as an alternative when the big rib sign is not applicable.

Also Read

Air Bronchogram Sign.


The ‘Dark Bronchus’ Sign


reference:
1. http://pubs.rsna.org/doi/pdf/10.1148/radiographics.19.1.g99ja02105
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BASICS OF CHEST X RAY-PART 5, THE HILUM AND MEDIASTINUM

Hello, Welcome to the fifth part of chest Xray Reading, today we shall know about the hilum and mediastinum
spare time to go through the other posts on chest X ray
Here are the links

The Part 2 has over a lakh views, please go through it.


Hilum
The normal hilar shadow is for 99% composed of vessels - pulmonary arteries and to a lesser extent veins .

The vessel margins are smooth and the vessels have branches.
The left hilum should never be lower than the right hilum.

The left pulmonary artery runs over the left main bronchus, while the right pulmonary artery runs in front of the right main bronchus, which is usually lower in position than the left main bronchus.
Hence the left hilum is higher than the right.
Only in a minority of cases the right hilus is at the same level as the left, but never higher.
In this illustration the lower lobe arteries are coloured blue because they contain oxygen-poor blood.
They have a more vertical orientation, while the pulmonary veins run more horizontally towards the left atrium, which is located below the level of the main pulmonary arteries.
Both pulmonary arteries and veins can be identified on a lateral view and should not be mistaken for lymphadenopathy

Sometimes the pulmonary veins can be very prominent.
The left main pulmonary artery passes over the left main bronchus and is higher than the right pulmonary artery which passes in front of the right main bronchus.

These images are thick slab sagittal reconstructions of a chest-ct to get a better view of the hilar structures.
The lower lobe pulmonary arteries extend inferiorly from the hilum.

They are described as little fingers, because each has the size of a little finger .
On the right side the little finger will be visible in 94% of normal CXRs and on the left side in 62% of normals.
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Study the CXR of a 70-year old male who fell from the stairs and has severe pain on the right flank..
Notice on the PA-film the absence of the little finger on the right and on the lateral view the increased density over the lower vertebral column.
What is your diagnosis?
There is a right lower lobe atelectasis.
Notice the abnormal right border of the heart.
The right interlobar artery is not visible, because it is not surrounded by aerated lung but by the collapsed lower lobe, which is adjacent to the right atrium.

On a follow-up chest film the atelectasis has resolved.
We assume that the atelectasis was a result of post-traumatic poor ventilation with mucus plugging.
Notice the reappearance of the right little finger (red arrow) and the normal right heart border (blue arrow).

Hilar enlargement

The table summarizes the causes of hilar enlargement.


Normal hili are:
    Normal in position - left higher than right
    Equal density
    Normal branching vessels
Enlargement of the hili is usually due to lymphadenopathy or enlarged vessels.
In this case there is an enlarged hilar shadow on both sides.

This could be the result of enlarged vessels or enlarged lymph nodes.
A very helpful finding in this case is the mass on the right of the trachea.
This is known as the 1-2-3 sign in sarcoidosis, i.e. enlargement of left hilum, right hilum and paratracheal.
Here some more examples of sarcoidosis.

    Lymphadenopathy and groundglass appearance of the lungs
    Lymphadenopathy, 1-2-3 sign
    Bulky lymphadenopathy
    1-2-3 sign
    Nodular lung pattern, no lymphadenopathy
    Hilar and paratracheal lymphadenopathy

Mediastinum


Here is just a brief overview of Mediastinal masses.
The mediastinum can be divided into an anterior, middle and posterior compartment, each with it's own pathology.



Mediastinal lines



Mediastinal lines or stripes are interfaces between the soft tissue of mediastinal structures and the lung.
Displacement of these lines is helpful in finding mediastinal pathology, as we have discussed above.
Azygoesophageal recess



The most important mediastinal line to look for is the azygoesophageal line, which borders the azygoesophageal recess.



 This line is visible on most frontal CXRs.
The causes of displacement of this line are summarized in the table.
A hiatal hernia is the most common cause of displacement of the azygoesophageal line.
Notice the air within the hernia on the lateral view.

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Another common cause of displacement of the azygoesophageal line is subcarinal lymphadenopathy.

Notice the displacement of the upper part of the azygoesophageal line on the chest x-ray in the area below the carina.
This is the result of massive lymphadenopathy in the subcarinal region (station 7).
There are also nodes on the right of the trachea displacing the right paratracheal line.
On the PET we can appreciate the massive lymphadenopathy far better than on the CXR.



There are also lymphomas in the neck.
this is an important finding, since these nodes are accessible for biopsy.
Continue with images of CT and ultrasound.
Here we see a CT-image.


The azygoesophageal recess is displaced by lymph nodes that compress the left atrium.
The final diagnosis of small cel lungcancer was made through a biopsy of a lymphnode in the neck.
First study the chest x-ray.

Then continue reading.
Notice the following:
    There is displacement of the azygoesophageal line both superiorly an inferiorly.
    There is an air-fluid level (arrow).
    Combined with the above this must be a dilated esophagus with residual fluid. The final diagnosis was achalasia.
    The density on the left in the region of the lingula is the result from prior aspiration pneumonia.
Here we have a prior CXR of this patient.



The AP-film shows a right paratracheal mass.
The azygoesophageal recess is not identified, because it is displaced and parallels the border of the right atrium.
The large round density in the left lung is the result of aspiration.
Notice the massive dilatation of the esophagus on the CT.
Aortopulmonary window

The aortopulmonary window is the interface below the aorta and above the pulmonary trunk and is concave or straight laterally.
Here the AP-window is convex laterally due to a mass that fills the retrosternal space on the lateral view.


On the CT-images a mass in the anterior mediastinum is seen.




Final diagnosis: Hodgkins lymphoma.
Here another case.


On the PA-film a mass is seen that fills the aortopulmonary window.

The PET better demonstrates the extent of the lymphnode metastases in this patient.
Final diagnosis: small cell lungcarcinoma.
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BASICS OF CHEST X RAY-PART 4, THE HEART AND PERICARDIUM



This is the fourth Post in the series Chest X Ray Interpretation. I personally suggest to read the other three posts before proceeding

 1

    Heart and Pericardium
    On a chest film only the outer contours of the heart are seen.
    In many cases we can only tell whether the heart figure is normal or enlarged and it will be difficult to say anything about the different heart compartments.

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     However it can be helpful to know where the different compartments are situated.
    Left Atrium
        Most posterior structure.
        Receives blood from the pulmonary veins that run almost horizontally towards the left atrium.
        Left atrial appendage (in purple) can sometimes be seen as a small outpouching just below the pulmonary trunk.
        Enlargement of the left atrium results on the PA-view in outpouching of the upper heart contour on the right and an obtuse angle between the right and left main bronchus. On the lateral view bulging of the upper posterior contour will be seen.

    Right Atrium
        Receives blood from the inferior and superior vena cava.
        Enlargement will cause an outpouching of the right heart contour.

    Left Ventricle
        Situated to the left and posteriorly to the right ventricle.
        Enlargement will result on the PA-view in an increase of the heart size to the left and on the lateral view in bulging of the lower posterior contour.

    Right Ventricle
        Most anterior structure and is situated behind the sternum.
        Enlargement will result on the PA-view in an increase of the heart size to the left and can finally result in the left heart border being formed by the right ventricle.
    Left Atrium
        The upper posterior border of the heart is formed by the left atrium.
        Enlargement will result in bulging of the upper posterior contour

    Left Ventricle
        Forms the lower posterior border.
        Enlargement will displace the contour more posteriorly.

    Right Ventricle
        The lower retrosternal space is filled by the right ventricle.
        Enlargement of the right ventricle will result in more superior filling of this retrosternal space.

    Left Atrium enlargement
    This is a patient with longstanding mitral valve disease and mitral valve replacement.
    Extreme dilatation of the left atrium has resulted in bulging of the contours (blue and black arrows).

    Right ventricle enlargement
    First study the PA and lateral chest film and then continue reading.

    On these chest films the heart is extremely dilated.
    Notice that it is especially the right ventricle that is dilated. This is well seen on the lateral film (yellow arrow).

    There is a small aortic knob (blue arrow), while the pulmonary trunk and the right lower pulmonary artery are dilated.
    All these findings are probably the result of a left-to-right shunt with subsequent development of pulmonary hypertension.
    The location of the cardiac valves
    is best determined on the lateral radiograph.
    A line is drawn on the lateral radiograph from the carina to the cardiac apex.
    The pulmonic and aortic valves generally sit above this line and the tricuspid and mitral valves sit below this line .

    On this lateral view you can get a good impression of the enlargement of the left atrium.

    Cardiac incisura
    On the right side of the chest the lung will lie against the anterior chest wall.
    On the left however the inferior part of the lung may not reach the anterior chest wall, since the heart or pericardial fat or effusion is situated there.
    This causes a density on the anteroinferior side on the lateral view which can have many forms.
    It is a normal finding, which can be seen on many chest x-rays and should not be mistaken for pathology in the lingula or middle lobe.

    The explanation for the cardiac incisura is seen on this CT-image.
    At the level of the inferior part of the heart we can appreciate that the lower lobe of the right lung is seen more anteriorly compared to the left lower lobe.

    Pacemaker
    There are different types of cardiac pacemakers.
    Here we see a pacemaker with one lead in the right atrium and another in the right ventricle.

    A third lead is seen, which is guided through the coronary sinus towards the left ventricle.
    This is done in patients with asynchrone ventricular contractions.
    Pacing both ventricles at the same time will lead to synchrone contractions and a better cardiac output.


    Pericardial effusion
    Whenever we encounter a large heart figure, we should always be aware of the possibility of pericardial effusion simulating a large heart.

    On the chest x-ray it looks as if this patient has a dilated heart while on the CT it is clear, that it is the pericardial effusion that is responsible for the enlarged heart figure.
    Especially in patients who had recent cardiac surgery an enlargement of the heart figure can indicate pericardial bleeding.

    This patient had a change in the heart configuration and pericardial bleeding was suspected.
    Ultrasound demonstrated only a minimal pericardial effusion.
    Continue with the CT.

    There is a large pericardial effusion, which is located posteriorly to the left ventricle (blue arrow).
    The left ventricle id filled with contrast and is compressed (red arrow).
    At surgery a large hematoma in the posterior part of the pericardium was found.

    Notice that on the anterior side there is only a minimal collection of pericardial fluid, which explains why the ultrasound examination underestimated the amount of pericardial fluid.

    Here another patient who had valve-replacement.

    Notice the large heart size.
    There is redistribution of the pulmonary vessels which indicates heart failure.

    Continue with the CT.
      

    The CT-image shows a large pericardial effusion.

    Always compare these post-operative chest films with the pre-operative ones.

    Calcifications

    Detection of calcifications within the heart is quite common.
    The most common are coronary artery calcifications and valve calcifications.

    Here we see pericardial calcifications which can be associated with constrictive pericarditis.
    In this case there are calcifications that look like pericardial calcifications,
    but these are myocardial calcifications in an infarcted area of the left ventricle.

    Notice that they follow the contour of the left ventricle.

    Pericardial fatpad

    Pericardial fat depositions are common.
    Sometimes a large fat pad can be seen (figure).

    Necrosis of the fat pad has pathologic features similar to fat necrosis in epiploic appendagitis.
    It is an uncommon benign condition, that manifests as acute pleuritic chest pain in previously healthy persons.

    Pericardial cyst     
       
                                                                                                                 

     Pericardial cysts are connected to the pericardium and usually contain clear fluid.
    The majority of pericardial cysts arise in the anterior cardiophrenic angle, more frequently on the rightside, but they can be seen as high as the pericardial recesses at the level of the proximal aorta and pulmonary arteries .
    Most patients are asymptomatic.
    On the chest x-ray it seems as if there is a elevated left hemidiaphragm.
    On CT however there is a cyst connected to the pericardium

    suggested reading



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