Showing posts sorted by date for query BASICS OF HRCT INTERPRETATION-PART 2- RETICULAR PATTERN. Sort by relevance Show all posts
Showing posts sorted by date for query BASICS OF HRCT INTERPRETATION-PART 2- RETICULAR PATTERN. Sort by relevance Show all posts

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

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    Basics of Chest X Ray Part 3- systematic approach, silhouette sign and Hidden areas in chest Xray

    This is the third post in the series, this post deals with the systematic interpretation and analysis of X-ray Chest with special emphasis on silhouette sign and hidden areas of the lung.

    Whenever you review a chest x-ray, always use a systematic approach.
    We use an inside-out approach from central to peripheral.

    First the heart figure is evaluated, followed by mediastinum and hili.
    Subsequently the lungs, lungborders and finally the chest wall and abdomen are examined.
    You have to know the normal anatomy and variants.

    Find subtle abnormalities by using the sihouette sign and mediastinal lines.
    Once you see an abnormality use a pattern approach to come up with the most likely diagnosis and differential diagnosis.
    Old films
    It is extremely important to always compare with old films, as we will demonstrate in this case.
    Actually someone said that the most important radiograph is the old film, since it gives you so much information.
    For instance a lung mass, which hasn't changed in many years is not a lung cancer.
    First study the chest films.
    Then continue.
    Based on the CXR that you just saw, you could have made the diagnosis of congestive heart failure, but the findings are very subtle.
    However once you compare it to the old film, things become more obvious and you will be much more confident in your diagnosis:
    1.     The size of the heart is slightly increased compared to the old film.
    2.     The pulmonary vessels are slightly increased in diameter indicating increased pulmonary pressure.
    3.     There are subtle interstitial markings as a result of interstitial edema.
    4.     There is pleural fluid bilaterally. Notice that the inferior border of the lower lobes has changed in position.
    All these findings indicate the presence of heart failure.

    Silhouette sign

    This is a very important sign. It enables us to find subtle pathology and to locate it within the chest.
    The loss of the normal silhouette of a structure is called the silhouette sign.
    Here an example to explain the silhouette sign:
    The heart is located anteriorly in the chest and it is bordered by the lingula of the left lung.
    The difference in density between the heart and the air in the lung enables us to see the silhouette of the left ventricle.
    When there is something in the lingula with the same 'water density' as the heart, the normal silhouette will be lost (blue arrow).



     When there is a pneumonia in the left lower lobe, which is located more posteriorly in the chest, the left ventricle will still be bordered by air in the lingula and we will still see the silhouette of the heart (red arrow).
    The PA-film shows a silhouette sign of the left heart border.

    Even without looking at the lateral film, we know, that the pathology must be located anteriorly in the left lung.
    This was a consolidation due to a pneumonia caused by Sterptococcus pneumoniae.
    Here we see a consolidation which is located in the left lower lobe.
    There is a normal silhouette of the left heart border.
    On this lateral film there is too much density over the lower part of the spine.

    By only looking at the interfaces of the left and right diaphragm on the lateral film, it is possible to tell on which side the pathology is located.
    First study the lateral film.
    Then continue.
    On a normal lateral chest film the silhouette of the left diaphragm 2- can be seen from posterior up to where it is bordered by the heart, which has the same density (blue arrow).

    One should be able to follow the contour of the right diaphragm -1- from posterior all the way to anterior, because it is only bordered by the lung.
    Here we cannot follow the contour of the right diaphragm all the way to posterior, which indicates that there is something of water-density in the right lower lobe (red arrow).
    On the PA-film there is a normal silhouette of the heart border,
    so the pathology is not in the anterior part of the chest, which we already suspected by studying the lateral view.
    Why do we still see the silhouette of the right diaphragm on the PA-film?
    What we see is actually the highest point of the right diaphragm, which is anterior to the pneumonia in the right lower lobe.
    The pneumonia does not border the highest point of the diaphragm.

    Hidden areas
    There are some areas that need special attention, because pathology in these areas can easily be overlooked:
    • apical zones
    • hilar zones
    • retrocardial zone
    • zone below the dome of diaphragm
    These areas are also known as the hidden areas.
    Notice that there is quite some lung volume below the dome of the diaphragm, which will need your attention (arrow)
    Here an example of a large lesion in the right lower lobe,
    which is difficult to detect on the PA-film, unless when you give special attention to the hidden areas.
    Here a pneumonia which was hidden in the right lower lobe mainly below the level of the dome of the diaphragm (red arrow).

    Notice the increase in density on the lateral film in the lower vertebral region.
    You may have to enlarge the image to get a better view.
    First study the CXR.

    Notice the subtle increased density in the area behind the heart that needs special attention (blue arrow).
    This was a lower lobe pneumonia.
    First study the CXR.

    We know that in some cases there is an extra joint in the anterior part of the first rib which may simulate a mass.
    However this is also a hidden area where it can be difficult to detect a mass.
    In this case a small lung cancer is seen behind the left first rib.
    Notice that is is also seen on the lateral view in the retrosternal area.
    Continue with the PET-CT.

    The PET-CT demonstrates the tumor (arrow) which has already spread to the bone and liver.


    The diagnosis was made by a biopsy of an osteeolytic metastasis in the iliac bone.
    First study the CXRs.

    There is a subtle consolidation in the left lower lobe in the hidden area behind the heart.

    Again there is increased density over the lower vertrebral region.

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