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This PA (posterior-anterior) radiograph of a normal female shows symmetric soft tissue breast shadows and the stomach bubble under the left hemidiaphragm. The right hemidiaphragm is generally slightly higher than the left, being pushed upward by the presence of the liver.
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Normal female 1
This PA (posterior-anterior) radiograph of a normal female shows symmetric soft tissue breast shadows and the stomach bubble under the left hemidiaphragm. The right hemidiaphragm is generally slightly higher than the left, being pushed upward by the presence of the liver. Methodical examination of the x-ray includes examining the soft tissues and bony structures. Note that the ladder-like horizontal configuration of the posterior ribs tends to dominate the visual structure while the anterior ribs are fainter and appear to cross the posterior shadows and angle upward.
The V-shaped position of the clavicles indicates that the patient is positioned with the shoulders and arms elevated. The central densities in the mediastinum show the dark vertical tube of the trachea with projections of the spinous processes of the thoracic vertebra seen through the tracheal air column. The bifurcation of the trachea into the left and right mainstem bronchi occur at the carina which is located at the lower portion of the aortic knob. The left mainstem bronchus angulates somewhat more horizontally than the vertically right mainstem bronchus. The horizontal width of the heart normally occupies less than one half of the width of the overall thorax and the vertical line that descends from the aortic knob is created by the posterior descending aorta. The hilar vascular markings are composed of the vertically oriented pulmonary artery subdivisions while the more horizontally oriented vascular structures represent the pulmonary veins directed toward the left atrium. Small air-containing elipses within the hilae are smaller bronchi seen end on. Click the Nuclear ERNA (equilibrium radionuclide angiogram) to view the dynamic contraction of the ventricle filled with radioactive blood pool using the agent technetium-99m. The nuclear study allows calculation of the left ventricular ejection fraction which is an index of ventricular function normally above 65%.
Cardiac findings, normal heart size NOTES: |
Normal heart size
The cardiac silhouette is the most prominent central feature of the chest x-ray and it produces a familiar gourd shape with the apex of the left ventricle located just behind the left chest nipple. The inferior left ventricle wall lies on the left diaphragm and the superior base of the heart shows the aortic knob lying just to the left of the spine. A linear line descending from it, lying to the left of the spine, represents the lateral edge of the descending aorta. A normal cardiac silhouette is defined by the lower cross diameter of the heart from its right atrial boundary to the left ventricle apex occupying no more than one half the internal thoracic diameter. The right ventricular outflow tract (RVOT) at its junction with the left main pulmonary artery is concave. Note that the right hemidiaphragm is higher than the left because of the presence of the liver and not due to the weight of the heart since the same relationship occurs with dextrocardia.
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Forced expiration film
Findings of apparent cardiomegaly and pulmonary vascular congestion must be viewed in the light of possibility of a poor inspiratory effort. This is determined by noting the level of the diaphragm relative to the posterior ribs. With the high diaphragms characteristic of a forced expiration, it is natural that pulmonary vascular markings will be more crowded and may give the appearance of congestion but the lungs will lack Kerley B lines or bronchial cuffing. The heart lies more horizontal and thus may appear enlarged. This situation commonly occurs in anteroposterior (AP) films common in Emergency Rooms.
This radiograph demonstrates the effect of a forced expiration on the density and vascular pattern of the lung fields. With much of the air forced from the lungs, the diaphragms are higher and vascular pattern much more crowded and thus appearing more dense than normal. The heart becomes more horizontal and therefore appears larger than normal. Without considering the effect of this expiratory effort it is possible to confuse this image with congestive failure and cardiomegaly. Click the button to view the same patient properly imaged in inspiration. The striking change in lung opacity and heart size could make one aware of the importance of careful radiographic technique.
Image finding: Enlarged heart
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Enlarged heart size
When the horizontal diameter of the lower cardiac silhouette well exceeds one half of the internal diameter of the thorax, cardiomegaly is diagnosed. It is wise to assess the depth of the inspiration by noting whether the diaphragm lies lower than the ninth or tenth rib posteriorly as it should if there is an adequate inspiratory effort. Cardiomegaly may result from enlargement of the cardiac chambers but also from fluid accumulating in the pericardium. Further evaluation includes observation of the pulmonary vasculature and assessment of possible pulmonary vascular congestion which would be most consistent with cardiac failure. Assessment of left ventricular function and pericardial contents can be easily defined by echocardiography.
Image finding: Value of lateral views
The value of the lateral view
The PA (postero-anterior) radiograph at first appears to provide reassuring evidence that the tip of the pacemaker lies in the right ventricular apex. The slightly thickened metal tip of the pacemaker is seen just lateral to the border of the descending aorta near the diaphragm. The value of a lateral radiograph is best exemplified (click the "Lateral X-ray"button located on the right side of the main screen) when the course of the pacemaker wire is followed inferior and is found to lie well posterior to the expected position of the right ventricular cavity. The only course which this wire can occupy is if the tip of the catheter lies within the coronary sinus which is entered in the right atrium just proximal to the tricuspid valve and is the major draining coronary vein in the atrio-ventricular groove emptying into the lower right atrium. The pacer wire would have to be withdrawn and placed properly at the right ventricular apex.
Image finding: Pacemaker placement
COMMENTS
The position of the normal pacemaker takes a characteristic course when examined on both anterior and lateral views. On the anterior view the tip of the pacer should be visible just to the left of the spine but not all the way to the apex of the left ventricle at the cardiac border.
The lateral film should show the tip in the cardiac silhouette anteriorly rather than posteriorly in the lower part of the heart.
Image finding: Loss of cardiac border NOTES: |
Loss of cardiac border
Pneumonic infiltration of the lingula increases the density lung immediately adjacent to the left cardiac border. The presence of two areas of similar soft tissue density results in a loss of the conventional sharp boundary to the heart. The radiographic appearance of a sharp boundary at the left cardiac border would still be present if the lung density were located posterior to the heart, say in the left lower lobe. Loss of cardiac border on the left implicates the adjacent lung segment which is the lingula and loss of the border on the right would implicate the right middle lobe. Thus the finding allows for a certain degree of segment specificity in determining which area of the lung is involved.
Coronary stenosis
COMMENTS
This case exemplifies an acute occlusion of the right coronary artery - click the "Pre angiogram" button. After thrombolysis of the clot, the proximal obstruction was dilated by balloon angioplasty - click on "Post angiogram". Though flow was restored to the coronary, a discrete moderate stenosis is still present in mid-coronary. It was subsequently successfully dilated by balloon angioplasty.
Coronary clot
COMMENTS
Sequential right coronary artery (RCA) angiograms ("1", "2" and "3") showing diagnosis and treatment of a patient whose acute coronary syndrome was caused by a clot at the site of a high - grade stenosis in the proximal right coronary. Angio "1" shows the clot as a void in the contrast. Angio "2" shows balloon angioplasty of the stenosis. Angio "3" shows placement of an intra-coronary stent with complete restoration of lumen patency and flow.
Image finding: Normal chest PA film
Normal lungs
Findings to be observed in normal lungs include vascular markings composed primarily of the vertically oriented pulmonary artery segments and the horizontally directed pulmonary veins toward the left atrium. The gradual decrease in size of the vessels as they branch peripherally should be noted. Close to the hilar structures the smaller bronchials seen as thin walled darker circles. Edematous thickening of these bronchial walls are one of the earliest findings of congestive failure.
The normal hilum
Findings related to the hila include the observation of the general progressive branching pattern that can be expected from the pulmonary arteries, a concave right ventricular outflow tract segment, and absence of any elipsoidal densities that might represent hilar adenopathy. Other observations that can be made if the hila are enlarged include noting rapid tapering in cases of pulmonary hypertension or localized truncation of part of the pulmonary artery segment as can occur with some larger pulmonary emboli.
mage finding: Normal chest PA film, case 2
Erect posterior-anterior ("PA") chest radiograph
PA images commonly show significant differences from AP (antero-posterior) films particularly in relation to the proportional size of the mediastinum. The PA position places the heart and upper mediastinum closer to the film with greater distance to the exposing Xray tube (generally 72 inches) making the Xrays more parallel as they enter the body and avoiding disproportional enlargement of anterior vs. posterior structures.
The effects of gravity have visible effects on the pulmonary vasculature since the pulmonary artery pressures are low (~25 mm Hg. in systole and ~12 mm Hg. in diastole) and the vessel walls are soft and compliant. The upper lung arterial vessels in upright posture, being well above cardiac chamber level, are usually much less prominent than the lower lobe vessels which are at or below cardiac chamber level.
An indication of elevated pulmonary artery pressure during cardiac congestive failure is a visible shift of blood with a filling out of the upper lobe vessels on the upright frontal film which indicates a generalized increase in the central pulmonary artery pressure.
Anterior-posterior supine radiograph
On a supine frontal Xray of the chest there are significant differences in the appearance of normal pulmonary vasculature and mediastinum. The closer distance of the exposing Xray tube (often only 40 inches from the film cassette) makes the Xrays more diverging and disproportionally enlarges the appearance of structures that are farther from the film (the anterior body structures such as the ascending aorta).
Although the pulmonary artery pressures are low (~25 mm Hg. in systole and ~12 mm Hg. in diastole) and the vessel walls are soft and compliant, the upper lung arterial vessels and the lower lobe vessels are now at the same level as the cardiac chambers. Thus the supine film can be expected to show upper pulmonary artery vessels as equally prominent to those in the lower lung, a finding that differs significantly from upright posture but should not be confused with congestive failure.
Pulmonary angiogram, arterial
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Arterial angiogram
Angiograms are created by injecting an iodine solution into the bloodstream. Iodine was chosen because it is a high atomic weight material which differentially attenuates x-rays but is nonetheless well tolerated by the body (it is mostly excreted in the urine). When a catheter is threaded into the pulmonary artery and an iodinated solution ejected from its tip, the pulmonary arteries are quickly first opacified showing a relatively vertically oriented branching pattern, originating at the hilum. Normal arteries progressively reduce in diameter after multiple branches.
Using a catheter inserted by an intravenous route through the right atrium and ventricle and then upward into the main pulmonary artery, 40 cc. of iodinated contrast fluid is injected to opacify the pulmonary arteries bilaterally. Note the vertical orientation of the major vessels and how they branch and gradually taper.
Pulmonary angiogram, venous
Venous angiogram An angiogram is created by injecting an iodine solution into the bloodstream of the pulmonary artery through a catheter. The pulmonary arteries are first opacified, then as the iodine solution collects in the pulmonary venous structures (now, of course containing oxygenated blood having passed through the lung alveoli), the anatomy of these veins is revealed. The pulmonary veins lie somewhat more horizontal than the arteries and coalesce centrally toward the left atrium. Using a catheter inserted by an intravenous route through the right atrium and ventricle and then upward into the main pulmonary artery, 40 cc. of iodinated contrast fluid is injected. The opacification first fills the pulmonary arteries bilaterally but over the next few seconds washes into and opacifies the pulmonary venous tree. Note that compared to the vertical orientation of the arteries, the venous drainage is more horizontal gathering toward the left atrium.
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