Chest X-ray Evaluation of Cardiac Patients Dr Awadhesh Kumar Sharma,
Wilhelm Conrad Roentgen (1845 - 1923)"I did not think I investigated...It seemed at firsta new kind of invisible light. It was clearlysomething new something unrecorded...There ismuch to do, and I am busy, very busy" Wilhelm Conrad Röntgen(First observer of X-rays made on 8 Nov 1895)
INTRODUCTION The discovery of X-rays by W.C.Roentgen,the german physicist on November 8,1895 ,was a crucially important landmark in the advancement of medical knowledge. The cardiopulmonary images help us to understand the anatomy, physiology and pathophysiology of the heart and blood vessels because of the excellent contrast between the lungs filled with air and the opaque silhouette of the heart and vessels filled with blood.
With careful evaluation, it yields a large amount of anatomic and physiologic information, but it is difficult and sometimes even impossible to extract the information that it contains. The major variables that determine what can be learned from the chest x-ray include the technical factors (miliamperage [mA], kilo voltage [kV], exposure duration) used in obtaining the radiographs, patient specific factors (e.g., body habitus, age, physiologic status, ability to stand and to take and hold a deep breath), and the training, experience, and focus of the interpreter. The aims of my todays seminar are to review how chest radiographs are obtained, present a basic approach to their interpretation, and discuss and illustrate common and characteristic findings relevant to cardiovascular disease in adults.
Technical Considerations The usual chest radiograph consists of a frontal and a lateral view. The frontal view is a postero anterior (PA) view, with the patient standing with the chest toward the recording medium and the back to the x-ray tube. The lateral view is also taken with the patient standing, with the left side toward the film. For both, the x-ray tube is positioned at a distance of 6 feet from the film. This is termed a 6-foot SID (source-image distance). At 6 feet distance the focal length of X-rays gives maximum resolution with less irradiation. The beam is near parallel without divergence and distortions.
X-rays are blocked from the film or other recording medium to varying degrees by various structures, leading to shades of gray that allow discrimination between the heart, which is fluid-filled and relatively impervious to x-rays, and the air- filled lung parenchyma, which blocks few x-rays. The exposure that the patient receives is a function of the strength and duration of the current applied to the x-ray tube (or, more precisely and accurately, of the number, strength and duration of the x-ray photons produced—the mA, kV, and milliseconds), size of the focal spot, distance from the tube to the patient, and degree to which the x-rays are blocked and scattered within the patient.
Most patient exposure is not a result of the x-rays that penetrate, but rather those that interact with tissues and are slowed and changed, and in the process deposit residual energy in tissue. This process is what is broadly referred to as scatter. Patients who are very thin will require an inherently lower x- ray dose to achieve diagnostically satisfactory deposition of x- ray photons on an imaging medium, and will have less energy deposition within the body. In patients who are obese, a higher x-ray dose will be necessary to penetrate the patient and produce a diagnostic exposure. The increased soft tissue in these patients also causes more dispersion of the x-ray beam and results in a higher dose.
There are several additional practical considerations that relate to the physics of chest radiographs. The standard chest radiograph is obtained with deep inspiration and the patient facing the film. If patients are unable to stand, chest radiographs are generally obtained with the patients chest toward the tube and the back toward the film, the antero- posterior (AP) position. With the standard PA view, the heart appears smaller and its size and contour are more accurately depicted than on an AP view, because the heart is closer to the recording medium. With AP views, as with portable films, there is resultant greater divergence of x-rays because the heart lies relatively anteriorly (and so is farther from the film) .
X-ray film is close to the heart in PA view,hence further magnification is avoided.In AP view ,the film isover the posterior chest and away from the heart,resulting in 5-10% magnification of heart shadow hence apparent cardiomegaly.
X-ray chest PA view if taken in expiration, gives a false impression of cardiomegaly, widening of aorta and prominent pulmonary arteries .This is the importance of taking X-ray chest held in deep inspiration- the criteria for it is being able to see ten posterior ribs and/or six anterior ribs.
X-ray chest PA viewshowing effects ofexpiration. There ispseudo cardiomegalyand aorta becomesprominent.
Properly exposed chest film PA view held in inspiration
Portable radiographs Portable radiographs are invariably taken as AP views and the SID is less than 6 feet, of necessity, because of the nature of the portable x-ray machine and also because of the usual position of the patient, sitting or lying in a bed. Most portable x-ray units do not have generators sufficiently strong to be able to produce x-rays that will penetrate a patient adequately and expose the film from 6 feet. Space constraints and the patients position are additional hurdles.
For all these reasons, the inherent resolution is poorer with portable radiographs, making them less accurate and useful. Also because of the lower available energy with portable x-ray units and the longer exposure time necessary to compensate, radiation exposure to the patient is greater than with a standard PA film. Portable films are most useful for answering relatively simple mechanical questions, such as whether the pacemaker or automated implantable cardioverter-defibrillator (ICD) is properly positioned , whether the endotracheal tube is in the correct location, and whether the mediastinum is midline. They are generally not good at providing physiologic or complex anatomic information.
Image Recording and Radiation Exposure Until the turn of the last century, all chest radiographs were recorded on high-resolution x-ray film. With optimal technique and a cooperative patient who can hold a deep inspiration, the result is a study that clearly and accurately depicts very small structures, such as the contour of small pulmonary arteries. This has changed as the digital age has come to imaging. With the advent of digital radiography (DR), a filmless form of radiography, chest radiographs are increasingly stored on digital media.
DR, is the direct recording of images by digital means, without analog-to-digital conversion. The most common is flat plate technology for reasons of resolution, usefulness and, in the long term, cost. It involves the use of an image-sensing plate that directly converts the incident photons into a digital signal. DR is truly “filmless”; and the classic chest radiograph relies on film that is exposed and developed.
Radiation Hazards The radiation exposure to the patient should always be kept in mind when any x-ray study is ordered or performed. The complexity of diagnostic radiation in the general population limits obtaining clear answers. However, a real concern is that ionizing radiation at cumulative diagnostic doses may be teratogenic and may, over decades, cause cancers. The radiation necessary for PA and lateral chest films is usually minimal in terms of radiation effects, in both the dose of a single study (generally <1 mSv) and the cumulative dose of repeated chest x-rays. In pregnant women and children, radiation exposure is always a concern because of the long latency period for radiation- induced cancer.
The contribution from conventional imaging procedures, such as chest x-rays, is small, but the precise relationships between individual exposures and cumulative effect are not known. Despite this, and despite the lack of clarity of the relationship between diagnostic level radiation and cancer, it is always wise to limit the amount of radiation as much as possible. Consequently, each chest film should be ordered with care. Whether the dose is actually decreased with digital imaging remains an open question, because digital systems continue to evolve rapidly.
Normal Chest Radiograph Interpreting standard PA and lateral chest radiographs is a daunting task. The amount of information present is huge, and there are countless relevant variables. It is imperative to have a systematic and standardized approach, based first on an assessment of anatomy, then of physiology, and finally of pathology. Any approach must be based on an understanding of what is normal and must include an evaluation of the soft tissues, bones and joints, pleura, lungs and major airways, pulmonary vascularity, mediastinum and its contents, and heart and its chambers specifically, as well as the areas seen below the diaphragm and above the thorax. In the standard PA chest study, the overall heart diameter is normally less than half the transverse diameter of the thorax . The heart overlies the thoracic spine, roughly 75% to the left of the spine and 25% to the right. The mediastinum is narrow superiorly, and normally the descending aorta can be defined from the arch to the dome of the diaphragm, on the left. The pulmonary hila are seen below the aortic arch, slightly higher on the left than the right.
On the lateral film , the left main pulmonary artery can be seen coursing superiorly and posteriorly compared with the right. On both frontal and lateral views, the ascending aorta (aortic root) is normally obscured by the main pulmonary artery and both atria. The location of the pulmonary outflow tract is usually clear on the lateral film. On the normal chest film, it is not usually possible to define individual cardiac chambers. It is imperative, however, to know their normal position and to examine the film to determine whether the size and location of each chamber and the great vessels are within the normal range. On the PA view, the right contour of the mediastinum contains the right atrium and the ascending aorta and superior vena cava (SVC). If the azygous vein is enlarged, secondary to right heart failure or SVC obstruction , it may also be visible. The right ventricle, as is clear from cross-sectional imaging , is located partially overlying the left ventricle on both frontal and lateral views.
The left atrium is located just inferior to the left pulmonary hilum. In normal individuals, there is a concavity at this level, which is the location of the left atrial appendage. The atrium constitutes the upper portion of the posterior contour of the heart on the lateral film but cannot normally be differentiated from the left ventricle. The left ventricle constitutes the prominent, rounded apex of the heart on the frontal view and the sloping inferior portion of the mediastinum on the lateral view . The apex is often not clearly delineated for a reason related to x-ray attenuation. The heart is distinguishable from the lungs because it contains water density blood rather than air. Because blood attenuates x-rays to a greater extent than air, the heart appears relatively white (although less so than calcium-containing bones) and the lungs relatively black (less so than the edges of the film, where there is only air and no interposed tissue).
Chest X-ray PA view: Normal. Structuresforming right and left borders of the heart
Chest X-ray PA viewStructures forming anterior and posteriorborders of the heart
A fat pad of varying thickness surrounds the apex of the heart . Fat has a density greater than that of air and marginally less than that of blood. As it covers the ventricular apex, the fat pad is relatively thick and dense. As it thins out toward the left lateral chest wall, it is progressively less dense; hence, the hazy, poorly marginated appearance of the apex. Similarly, a fat pad may be seen on the lateral chest film as a wedge-shaped density overlying the anterior aspect of the left ventricle. The pericardial sac cannot normally be defined . The borders of the cardiac silhouette are normally moderately but not completely sharp in contour. Even though the exposure time for a chest x-ray is very short (less than 100 milliseconds), there is usually sufficient cardiac motion to cause minor haziness of the silhouette. If a portion of the heart border does not move, as in the case of a left ventricular aneurysm, the border may be unusually sharp . The aortic arch, however, is usually visible, as the aorta courses posteriorly and is surrounded by air. Most of the descending aorta is also visible. The position and the size of each can be easily evaluated using the frontal and lateral views.
Lungs and Pulmonary Vasculature Lung size varies as a function of inspiratory effort, age, body habitus, water content, and intrinsic pathologic processes. For example, because lung distensibility decreases with age, the lungs normally appear subtly but progressively smaller as patients age, even with maximal inspiratory effort. As lung size decreases, the heart appears relatively slightly larger, although in adults the heart does not exceed half the transverse diameter of the chest in a good-quality PA film unless there is true cardiomegaly. Also, with increasing left ventricular dysfunction, interstitial fluid in the lungs increases and lung compliance, and therefore expansion as seen on a chest x-ray, decreases. With the presence of chronic obstructive pulmonary disease, with or without bullae, the lungs appear larger and blacker, the diaphragms may appear flattened, and the relative heart size, even in the presence of heart failure, decreases. The heart often appears small or normal in size, even in the presence of cardiac dysfunction .
In normal subjects, pulmonary vascularity has a predictable pattern. Pulmonary arteries are usually easily visible centrally in the hila and progressively less so more peripherally. Centrally, the main right and left pulmonary arteries are difficult to quantify unless they are grossly enlarged, because they lie within the mediastinum . If the lung is thought of in three zones, the major arteries are central; the clearly distinguishable midsized pulmonary arteries (third and fourth order branches) are in the middle zone, and the small arteries and arterioles that are normally below the limit of resolution are in the outer zone. The visible small and midsized arteries (midzone) have sharp, clearly definable margins. As noted, this is because of the sharp border between water density and air density structures. In the standard, standing frontal (PA) chest film, the arteries in the lower zone are larger than those in the upper zone, at an equal distance from the hila. This is because of the effect of gravity on the normal, low-pressure lung circulation. That is, gravity leads to slightly greater intravascular volume at the lung bases than in the upper zones.
This effect of gravity on the distribution of normal intravascular lung volume is reflected in a normal perfusion lung scan. Because the radionuclide is generally administered with the patient supine, there is a greater concentration posteriorly than anteriorly, as confirmed in the count rates. If the patient is sitting or standing when the radionuclide is injected, the count rate is greater at the lung base than at the apices.
Evaluating the Chest Radiograph in Heart Disease There is no single best way to read a chest film. A systematic approach to the evaluation of a chest radiograph is imperative to distinguish normal from abnormal and to define the underlying pathology and pathophysiology. The first step is to define which type of film is being evaluated—PA and lateral, PA alone, or AP view (either portable or one obtained in the AP view because the patient is unable to stand). The next step is to determine whether prior films are available for comparison. Many abnormalities are put into appropriate perspective by determining whether they are new. Common examples are a prominent aortic arch, visible major fissure related to prior inflammatory process, or widened superior mediastinum related to aortic ectasia , substernal thyroid, or enlarged azygous vein .
Any system should incorporate a routine that includes a deliberate attempt to look at areas that are easily ignored. These include the thoracic spine, neck (for masses and tracheal position), costophrenic angles, lung apices, retrocardiac space, and retrosternal space. Looking at these areas enables definition of mediastinal position and cardiac and aortic situs and the presence of pleural effusions, scarring, or diaphragmatic elevation. It is logical to evaluate the lung fields next. This should involve a careful search for infiltrates or masses, even when the primary concern is cardiovascular abnormalities. The logic is that many people with coronary artery disease have a history of tobacco abuse and are thus at increased risk for lung malignancies. Cardiovascular disease states cause various and complex changes in the appearance of the chest radiograph. The overall size of the cardiac silhouette, its position, and the location of the ascending and descending aorta must be specifically evaluated.
Dextrocardia and a right descending aorta are rare, particularly in adults, but are easy to check for and are important to recognize because of their association with congenital cardiac and abdominal situs abnormalities. It is also important to look at the site and position of the stomach. This information can be used to differentiate between a high diaphragm and a pleural effusion . Cardiomegaly, accurately judged by the heart diameter exceeding half the diameter of the thorax on a PA film, is a common but nonspecific finding.It is probably most often seen as a result of ischemic cardiomyopathy following one or more myocardial infarctions.
CARDIOMEGALY IN X-RAY CHEST(PA VIEW) Trans cardiac diameter is measured as follows- Mark a mid-vertical line along the spinous process. Draw a horizontal line from the vertical line to the maximum convexity in the right cardiac border. Draw another horizontal line from the vertical line to the maximum convexity in the left cardiac border Line A+B=Transcardiac diameter Transthoracic diameter at the level of inner border of ninth rib.
Cardiothoracic ratio=TCD/TTD Normally cardiothoracic ratio is 33%- 50%(0.33-0.50). Any increase in transcardiac diameter more then 2 cm,is significant if earlier X-rays are available for comparison. In old age and emphysema, transcardiac diameter of 15 cm or more is taken as cardiomegaly irrespective of CT ratio.
Evaluation of the pulmonary vascular pattern is difficult and imprecise but very important. As noted, the pattern varies with the patients position (erect versus supine) and is altered substantially by underlying pulmonary disease. It is best to define pulmonary vascularity by looking at the middle zone of the lungs (i.e., the third of the lungs between the hilar region and peripheral region laterally) and comparing a region in the upper portion of the lungs with a region in the lower portion, at equal distances from the hilum. Vessels should be larger in the lower lung but sharply marginated in the upper and lower zones. In normal individuals, the vessels taper and bifurcate and are difficult to define in the outer third of the lung. They normally become too small to be seen near the pleura Two distinct patterns of abnormality are recognizable. When pulmonary arterial flow is increased, as in patients with a high-output state (e.g., pregnancy, severe anemia as in sickle cell disease, hyperthyroidism) or left-to-right shunt, the pulmonary vessels are seen more prominently than usual in the periphery of the lung.
They are uniformly enlarged and can be traced almost to the pleura, but their margins remain clear. In contrast, in patients with elevated pulmonary venous pressure, the vessel borders become hazy, the lower zone vessels constrict and the upper zone vessels enlarge, and vessels become visible farther toward the pleura, in the outer third of the lungs
Larry Elliots grading of Pulmonary Venous Hypertension
Grade-1pulmonary venoushypertension-The upper lobeveins becomesmore prominentthan the lowerlobe veins-cephalisation
Grade-2 pulmonary venous hypertension- Kerleys lines are due to interlobular septal thickening due to lymphatic and venous drainage. Kerleys A lines-Horizontal linear shadows towards the hilum. Kerleys B lines-Horizontal and linear shadows towards the costophrenic angle. Kerleys C lines-Crisscross between A and B.
Chest X-ray PA view of 40year old male with grade-IIpulmonary venoushypertension-Top panel shows typicalfeatures of pulmonaryvenous hypertension withKerleys lines andinterstitial oedema.Bottom panel shows X-rays of the same patient 4hours after treatment withdiuretics.
Right Atrium Right atrial enlargement is essentially never isolated except in the presence of congenital tricuspid atresia or Ebstein anomaly. Both are rarely encountered, even in the pediatric age group. The right atrium may dilate in the presence of pulmonary hypertension or tricuspid regurgitation, but right ventricular dilation usually predominates and prevents definition of the atrium. The right atrial contour blends with that of the SVC, right main pulmonary artery, and right ventricle.
Radiological features S/O Right atrial enlargement in PA view Right cardiac border becomes more convex and elongated. It forms more then 50% of right cardiac border. Distance from mid-vertical line to the maximum convexity in the right border is more then 5cm in adults and more then 4cm in children which results in cardiomegaly. Right atrial border extends beyond three intercostal spaces. Dilation of superior vena cava.
Right atrial enlargement in LAO view Normally in LAO view, upper half of anterior cardiac border is formed by right atrium and lower half by right ventricle. When right atrium enlarges the upper anterior cardiac border becomes squared giving a box like appearance. LAO is the best view to visualise right atrial enlargement.
Right atrialenlargement in apatient withrheumatic mitralstenosis. There isleft atrialenlargement andmitralisation too,of heart.
Right Ventricle The classic signs of right ventricular enlargement are a boot-shaped heart and filling in of the retrosternal air space.The former is caused by transverse displacement of the apex of the right ventricle as it dilates. In adults, it is rare for the right ventricle to dilate without left ventricular dilation, so this boot shape is not often obvious. It is most commonly seen as an isolated finding in congenital heart disease, typically in tetralogy of Fallot. As the right ventricle dilates, it expands superiorly as well as laterally and posteriorly, explaining the well-marginated increase in density in the retrosternal airspace. The classic teaching is that in a lateral chest radiograph in normal patients, the soft tissue density is confined to less than one third of the distance from the suprasternal notch to the tip of the xephoid. If the soft tissue fills in by more than one third, in the absence of other explanations, it is a reliable indication of right ventricular enlargement.
Right ventricularenlargementPA view-Roundedand elevated apexfrom the left domeof the diaphragmRight lateral view-Obliteration ofretrosternal space
Chest radiographs of a 59-year-old woman with a history of rheumatic heart disease andmitral stenosis. a, PA view demonstrates enlarged cardiac silhouette, with suggestion of adouble density seen through the heart (left atrial enlargement), prominent convexity of theleft atrial appendage (small arrow), and slightly elevated cardiac apex (large arrow),suggestive of right ventricular (rather than left ventricular) enlargement. there is significantelevation of the pulmonary venous pressures.B, The lateral view confirms marked right ventricular (arrow) and left atrial (small arrows)enlargement. note filling in of the retrosternal airspace. la = left atrium; lv = left ventricle.
Left Atrium Several classic signs define left atrial enlargement- The first is dilation of the left atrial appendage, seen as a focal convexity where there is normally a concavity between the left main pulmonary artery and left border of the left ventricle on the frontal view . Second, because of its location, as the left atrium enlarges, it elevates the left main stem bronchus. In so doing, it widens the angle of the carina,normal being 45-75 degrees. Third, with marked left atrial enlargement, a double density can be seen on the frontal view because the left atrium projects laterally toward the right and posteriorly, and the discrete outline of the blood-filled left atrium is surrounded by air-filled lung . Finally, on the lateral film, left atrial enlargement appears as a focal, posteriorly directed bulge .
Chest X-ray PA view of two patients withvarying degree of leftatrial enlargement in rheumatic mitral stenosis
Left Ventricle Left ventricular enlargement is characterized by a prominent, downwardly directed contour of the apex, as distinguished from the transverse displacement seen with right ventricular enlargement. On the PA film, the overall cardiac contour is also usually enlarged, although this is a nonspecific finding. It may also be seen inferiorly, pushing the gastric bubble . Such left ventricular enlargement is an illustration of findings that lie outside the usual confines of the chest and another example of the value of looking at the entire chest radiograph. Focal left ventricular enlargement in adults is most commonly seen in the presence of aortic insufficiency (with aortic root dilation; or mitral regurgitation (with left atrial dilation. In contrast, because aortic stenosis is characterized by left ventricular hypertrophy rather than dilation, the left ventricle is dilated on the chest film only when aortic stenosis is accompanied by left ventricular failure.
Chest radiographs of a 63-year-old man with chronic aortic regurgitation. A, PA view shows downward displacement of the apex (arrow), suggestive of left ventricular enlargement. There is prominence andenlargement of the ascending aorta, creating a convex right border of the mediastinum. B, Lateral viewshows prominent left ventricular enlargement (arrowheads). The aortic root is markedly enlarged in the retrosternal airspace but is separate from the sternum (in contrast to findings in right ventricular enlargement).
Pulmonary Arteries The main pulmonary artery can appear abnormal in many clinical settings. In the presence of pulmonic stenosis, the main pulmonary artery and left pulmonary artery dilate . This dilation is thought to be caused by the jet effect on the vessel wall of the blood flow through the stenotic valve, coupled with the anatomy. That is, the main pulmonary artery continues straight into the left main pulmonary artery but the right comes off at a fairly sharp angle and is not generally affected by the jet from the stenotic valve. This enlargement can be seen with a prominent left hilum on the frontal view and a prominent pulmonary outflow tract on the lateral view. It is important to remember that the pulmonic valve lies more superiorly in the outflow tract and more anteriorly than the aortic valve .
Chest radiographs of a 56-year-old asymptomatic woman with incidentally discovered pulmonic stenosis. A, PA view shows marked enlargement of the main pulmonary trunk extending into the left main pulmonary artery (arrow). B, Lateral view confirms prominence of thepulmonary outflow tract and main and left pulmonary arteries (arrows).
Aorta The most commonly seen abnormality of the aorta is dilation, and the way the aorta dilates is a function of the underlying pathology . It is often possible to define the pathology by a combination of the pattern of dilation and associated cardiac abnormalities. On the frontal chest radiograph, aortic dilation appears as a prominence to the right of the middle mediastinum . There is also a prominence in the anterior mediastinum on the lateral view, behind and superior to the pulmonary outflow tract. Dilation of the aortic root is seen in the presence of aortic valve disease (both stenosis and regurgitation) but more frequently has other causes, such as long-term, poorly controlled systemic hypertension or generalized atherosclerosis with ectasia.
Chest radiographs of a 65-year-old woman with severe aortic stenosis. A, Frontalview shows a prominent aortic root, to the right of the midline (arrowheads). Note absence of cardiomegaly and presence of normal pulmonary vascular pattern. B, Lateral view demonstrates calcification of the aortic valve leaflets (arrows), suggestive of a bicuspid valve. There is a prominent, mildly dilated aortic root (arrowheads).
Pleura and Pericardium The pleura and pericardium also require systematic evaluation. The pericardium is rarely distinctly definable on plain films of the chest.There are two situations, however, in which it can be seen; in the presence of a large pericardial effusion, the visceral and parietal pericardium separate. Because there is a fat pad associated with each, it is sometimes possible to make out two parallel lucent lines (i.e., fat) on the lateral film, usually in the area of the cardiac apex, with density (fluid) between them. CMRI, echocardiography, and CT, however, are all far more reliable for defining a pericardial effusion Nonetheless, if the cardiac silhouette is enlarged on the chest radiograph, it is important to look for specific explanations. Although cardiac dilation and valvular disease are more common causes, the presence of an unsuspected effusion is worth considering. Typically, the cardiac silhouette has a water bottle shape in the presence of a pericardial effusion, but this shape is not in itself diagnostic.
Pericardial effusion Cardiomegaly Cardio phrenic angles become more and more acute. Narrow vascular pedicle Marked change in cardiac silhouette in decubitus position is very diagnostic.
Pleural and pericardial calcification Pleural and pericardial calcification can occur, but are often not obvious . Pericardial calcification is associated with a history of pericarditis. Although there are multiple causes, tuberculosis and various viruses are the most common. Such calcification is usually thin and linear and follows the contour of the pericardium. Because the calcification is thin, it is often seen only on one view. Myocardial calcification secondary to a large myocardial infarction with transmural necrosis is rare but can generally be distinguished from pericardial calcification. It tends to appear thicker, more focal, and less consistent with the outer contour of the heart. Pleural calcification is easily distinguishable from pericardial calcification and is essentially pathognomonic for asbestos exposure. It is associated with a high risk of malignant mesothelioma but is not diagnostic of this type of tumor.
Chest radiographs of a 45-year-old man with calcific pericarditis. A, PA view is essentially normal. B, Lateral view demonstrates thin, irregular calcification of pericardium around the left ventricular contour.
Chest radiograph showing marked pericardial calcification in a patient with constrictive pericarditis.
Cardiac valves calcificationCalcified cardiac valvesChest PA viewAortic valve will be at the level ofT6-T7 overlying the midline area.Mitral valve will be at T8 level awayfrom the midline in the paravertebralregion.Lateral viewAortic calcification is above animaginary line from left bronchus toRV apex and mitral calcification isbelow the line.
Rheumatic valvular heart diseases Rheumatic Mitral Stenosis X-ray chest PA view The typical mitralisation. Less prominent aortic knuckle. Obliteration of pulmonary bay due to prominent main and left pulmonary arteries. Prominent left atrial appendage. Straightening of convex contour of left ventricular border due to hypoplasia and hypovolumia.
Top panel showsmitralisation.Bottom panelshows grossenlargement ofmain pulmonaryartery, left atria andleft atrialappendage dilationand rightventricularenlargement.
Congenital heart diseases-Acyanotic Without a shunt Pulmonary valvular stenosis The radiological features are- Pulmonary oligaemia Post-stenotic dilatation of main pulmonary artery Right ventricular enlargement Right atrial enlargrment
Primary pulmonary hypertension X-ray chest PA view Moderate to marked enlargement of main pulmonary artery and its proximal branches. Peripheral pulmonary arteries are diminished and pruned resulting in clear peripheral lung fields. Absence of pulmonary venous hypertension. Small and inconspicuous ascending aorta Right ventricular and right atrial enlargement Absent left atrial enlargement
Congenital heart diseases-Acyanotic With a shunt Shunt at atrial level Shunt at ventricular level Shunt at aorto pulmonary level Pulmonary plethora is common in all left to right shunts.
Atrial septal defect Ostium secundum ASD Enlargement of RV,RA and LA. Left ventricle is hypovolaemic and hypoplastic. Right pulmonary artery is more prominent than left pulmonary artery giving the radiological sign of jug-handle appearance. Ostium primum ASDLeft ventricular enlargement in addition to the radiological features of OS –ASD.
VSD All four chambers are involved. The ascending aorta is inconspicuous. Both pulmonary arteries are equally prominent.
Patent Ductus Arteriosus All the four chambers are involved. Prominent ascending aorta. There may be speck of calcium when PDA is calcified.It is comma shaped between aortic knuckle and main pulmonary artery and is known as Cap of Zin. Both pulmonary arteries are equally dilated.
Congenital cyanotic heart diseases Increased pulmonary arterial blood flow Complete transposition of great arteries(d-TGA) Absent thymic shadow Narrow vascular pedicle Increased CT ratio with egg lying on its side appearance Pulmonary plethora
Truncus Arteriosus All four chambers are dilated with pulmonary plethora. In one – third of cases right aortic arch is present.
TAPVC Supracardiac type is the commonest and will have a distinctive figure of 8 or snowman silhouette or cottage loaf.The upper portion of figure of 8 is formed by the dilated left vertical vein and right superior vena cava.The lower portion consists of dilated right atrium and right ventricle.
Decreased pulmonary arterial blood flow Tetralogy of Fallot No cardiomegaly Uplifted apex-boot shaped or coeur en sabot appearance Pulmonary oligaemia Dilated ascending aorta with right aortic arch in 25% of cases Bilateral reticular formation due to bronchopulmonary collaterals Unilateral rib notching after BT shunt
Ebstein anomaly of the tricuspid valve Cardiomegaly with dilated right atrium and right ventricular infundibulum accounts for the box like silhouette with normal or decreased pulmonary blood flow,resembling pericardial effusion.
Coarction of aorta Three sign on chest X-ray E sign or reverse 3 sign in barium swallow Rib notching of 3rd to 8th posterior ribs along its lower border usually after the age of 9 years
Cardiac malpositionSitus solitus Situs inversus totalis
Implantable Devices and Other Postsurgical Findings A final important and broad area concerns the chest radiograph following surgery or other procedures. In these situations, it is crucial to recognize devices that have been implanted and changes that may occur. Among the most common are various valve prostheses, pacemakers and ICDs, intra- aortic counterpulsation balloons , and ventricular assist devices . There are also clear changes that occur after surgery, such as the presence of clips on the side branches of saphenous veins used for coronary artery bypass grafting and retrosternal blurring and effusions Some of these findings may be temporary, such as lines and tubes associated with surgery and effusions. Pacemakers and ICDs present specific questions . The first is whether the leads are intact and the second is the position of the tips. Although course and tip position are generally confirmed fluoroscopically at the time of placement, malposition can occur. If there are two leads, the tips should generally be in the anterolateral wall of the right atrium and apex of the right ventricle.
If the leads are not positioned in this way, the reasons should be carefully determined. That is, are they positioned because of error or anatomic variants (e.g., a persistent left SVC that empties into the coronary sinus and then the right atrium or because the lead belongs in the coronary sinus. Additionally, the position of the wires and of valve prostheses can help in the definition of specific chamber enlargement
AV sequential pacemaker in right infra clavicular subcutaneous pocket. J shaped atrial lead is seen in right atrial appendage.Tip of ventricular lead is in right ventricular apex.
Biventricular pacing. Atrial lead is in right atrium; right ventricular lead is in RV apex, left ventricular lead is introduced through coronary sinus to pace left ventricular epicardium.
Conclusion Chest radiographs provide a wealth of physiologic and anatomic information. As such, they play a central role in the evaluation and management of patients with a wide variety of cardiovascular and other disorders. The radiation dose inherent in obtaining x-rays should always be considered. Portable chest films should be used as infrequently as possible because the information they provide is limited and may even be misleading (e.g., in defining cardiomegaly or in ruling out a pneumothorax or effusion). Standard 6-foot frontal and lateral chest x-rays, on the other hand, are almost always of value. Whether recorded conventionally or digitally, if they are evaluated carefully using a systematic approach and, whenever possible, compared with prior chest radiographs, it is hard to overstate their importance.