Basics of Chest X-ray Interpretation:
A Programmed Study
Acknowledgment is given to Leslie Muma, RN, MSN, NP for assistance in preparation of this learning module.
Description — The course is designed as an elective to give the advanced practice nurse, involved in the care of patients with cardiopulmonary problems, a basic introduction to the principles of chest x-ray interpretation. The course is in a self-programmed format whereby the student reviews chest films with accompanying case histories and answers. The chest films selected represent commonly occurring cardiopulmonary problems in the primary care setting and provide additional means by which nurses can correlate their knowledge of pathophysiology and cardiopulmonary physical assessment (theory and skills) with findings demonstrable on a chest x-ray.
Objectives:
• Identify cardiothoracic anatomical structures demonstrable on a chest film.
• Recognize a normal chest radiograph.
• Recognize and name the radiographic signs of atelectasis, consolidation, pneumothorax, pleural and pericardial effusions, and hyperinflation frequently seen in patients with cardiopulmonary disease.
• Correlate physical signs and symptoms of cardiopulmonary disease with chest radiographic findings.
Prerequisites:
• Graduate standing.
• Consent of instructor/department chair.
Course Requirements:
• Pre-test and Post-test of radiograph interpretation (instructor-administered).
Grading — Choice of letter grade or satisfactory/unsatisfactory. A satisfactory grade is obtained by achieving 80% or greater on the post-test. The post-test may be retaken as many times as necessary in order to achieve a passing grade.
Required Text:
Felson, B., Weinstein,A., & Spitz, H. (1965) Principles of Chest Roentogenology: A Programmed Text. Philadelphia: Saunders.
Novelline, R.A. (1997) Squires’s Fundamentals of Radiology. Cambridge: Harvard University Press.
Required Articles:
Zelfsky, M.N. (1977) A simplified approach to reading x-rays of the heart. Modern Medicine, October 30, 33-36.
Schapiro, R.l., & Musallam, J.J. (1977) A radiologic approach to disorders involving the interstitium of the lung. Heart & Lung, 6, 635-643.
Required Web Sites:
Basics of Chest X-ray Interpretation: A Programmed Study
http://www.nps.freeservers.com
Recommended Articles:
See list at end of syllabus (Appendix B).
Recommended Texts:
Elliott, J.A. (1987) Exercises in Chest X-ray Diagnosis. Oxford, England: Butterworth Heinemann.
Recommended Web Sites:
Chest X-ray
http://edcenter.med.cornell.edu
Teaching Files on the Radiology Links Page
Recommended Schedule for Chest X-ray Practicum:
This schedule is given to be used as a guideline to the practicum. The order of the films has been selected to build and reinforce prior learning. The material to be read may not follow exactly, but may be utilized as a reference. Although Novelline is lengthy at times, it has the best examples of films throughout the text. Felson and Basics of Chest X-ray Interpretation: A Programmed Study (BCI) are self-learning modules which you may use at your own pace.
Films
Novelline
Articles
Felson
BCI
1. Radiographic Anatomy Chapters 1, 2 , 3, 4 & 5 Zelfsky Chapters 1, 4, 5 Sections 1, 2, & 3 2. Interstitial Schapiro &Musallam Sections 1 & 4 3. Airway Chapter 5 & 6 Chapters 2 & 3 Section 1 4. Pulmonary Edema Chapters 7, 8, & 9 Sections 2 & 4 5. Pleura/Mediastinum Chapters 7, 8, & 9 Chapters 7 & 8 Sections 2, 3, & 4 6. Cardiac Chapter 10 and 17 Sections 2 & 3 7. Infection Chapter 5 & 6 Section 4 8. Iatrogenic Section 2 See Appendix A for Glossary of Terms. See Appendix C for Chest X-ray Workbook.
STANDARD FRONTAL CHEST RADIOGRAPH (Roentgenogram) — upright; PA or posterior Æ anterior (film in front of patient, beam behind at a distance of six feet; patient usually upright; distance of beam determines magnification and clarity or sharpness
• Place the films on the view box as though you were facing the patient with his left on your right side.
• An AP film, taken from the same distance (6') enlarges the shadow of the heart which is far anterior in the chest and makes the posterior ribs appear more horizontal.
• In a supine film, the diaphragm will be higher and the lung volumes less than in a standing patient.
STANDARD LATERAL CHEST RADIOGRAPH — left side of the chest against filmholder (cassette); beam from right at a distance of six feet; lesion located behind the left side of the heart or in the base of the lung are often invisible on the PA view because the heart or diaphragm shadow hides it; the left lateral will generally show such lesions; the left lateral is thus the customary lateral view as it is the best view to visualize lesions in the left thorax. Also, the heart is less magnified when it is closer to the film.
• Good for viewing area behind heart (retrosternal airspace — between the heart and sternum).
• Marked with a "R" or "L" according to whether the right or the left side of the patient was against the film — left lateral or right lateral.
To visualize a lesion in the left thorax, it is better to get a left lateral view.
To visualize a lesion in the right thorax, it is better to get a right lateral view.
A fundamental rule of roentgenography — Try to get the lesion as close to the film as possible.
PORTABLE CHEST X-RAYS — are AP views (anterior Æ posterior); preferably upright but may be supine, depending on patient's condition; taken with beam at distance of 36 inches Æ blurring and magnification
OTHER VIEWS:
Posteroanterior Oblique Views — patient at 45° angle to cassette and beam.
The tracheal bifurcation is best seen in an oblique view.
In bilateral involvement of the lungs (as by lymphoma involvement of the lower lungs), an oblique view avoids the superimposition of a lateral view.
Sometimes used in studying the heart or hila of the lungs; also in detailed study of the ribs.
The optimum degree of obliquity depends on the site of the lesion being studied and the information desired — it may have to be determined by fluoroscopy.
When we're too tired to think of whether we need a right or a left oblique we just take both obliques.
Left Anterior Oblique — Left Anterolateral Chest Next to Cassette
Right Anterior Oblique — Right Anterolateral Chest Next to Cassette
Decubitus Views — "decubitus" actually means "lying down;" made with the patient lying on his side and the x-ray beam horizontal (parallel) to the floor. Especially good to confirm air-fluid levels in the lung.
Cross-Table Lateral (Horizontal) Views — made with patient prone or supine and the beam horizontal to the floor.
Lordotic Views — formerly made in the upright AP position with the patient leaning backward at an angle of ~ 30° from the vertical which was very awkward; now made with the patient facing the film as for an upright PA view but the tube is elevated and angled downward 45°.
Projects the lung apices of the lungs below the clavicles and causes the ribs to project more horizontally.
Especially good for viewing the apices of the lungs, lesions that are partially obscured by ribs, or the right middle lobe or lingula of the left lung.
Expiratory Views — on expiration the lungs "cloud up" and the heart appears larger.
If the air on one side cannot be readily expelled, the lung on the obstructed side remains expanded and radiolucent on expiration.
Useful in detecting unilateral obstructive emphysema (as from a unilateral obstruction of a bronchus).
A pneumothorax always appears larger on expiration than on inspiration.
Since the thorax is smaller on expiration, the unchanged volume of pleural air spreads out in the smaller thoracic space.
Occasionally a small pneumothorax is only visible on expiration.
Bucky Films — made with a moving grid between the patient and the film which absorbs excess, scattered radiation.
Scattered radiation produces a hazy, unsharp image, or fog, and detracts from film clarity.
Used to delineate a thick pulmonary or pleural lesion, bony structures, or to more clearly see structures in an obese patient.
Bucky technique also used whenever the abdomen, spine, mediastinum, pelvis, or heavy long bones are studied.
Tomography (Laminagraphy)
An apparatus moves the tube and film synchronously in opposite directions; the adjustable fulcrum is set to the plane of the lesion to be studied; blurs structures in the planes above and below the level being studied.
Especially helpful in evaluating pulmonary nodules, demonstrating cavities, and depicting bronchial obstruction.
If you can't think of the exact name for a view, be descriptive or draw a picture (i.e., "Get me a cross-table view with the patient lying on his right side facing the tube.") or consult with the radiologist.
There are all sorts of ingenious projections and fascinating special procedures in the armamentarium of the radiologist.
DENSITIES Air < fat < liver < blood < muscle < bone < barium < lead.
• Air — least dense; most transparent or radiolucent; unobstructed beam or air-filled densities appear black
Lungs, gastric bubble, trachea, ? bifurcation of bronchi
• Fat — breasts
• Fluid — most of what you see; vessels, heart, diaphragm, soft tissues, mediastinal structures
• Mineral — most dense (or radiopaque) of body structures; mostly Ca++; bones (marrow is aerated), aortic calcifications such as the aortic knob, ? calcification of the coronary arteries, old granulomas; bullets, safety pins, etc.
• Structures which are perpendicular to the plane of the film appear as they were much more dense as the shadows represent the sum of the densities interposed between the beam source and the film. Learn to think in terms of those parts that are relatively parallel to the film and those that are roughly perpendicular to it. Think about it three-dimensionally.
• Thickness as well as composition determine radiodensity. The shadow cast by a thick mass of soft tissues will approach that of bone.
Section Two
PROCEDURE FOR INTERPRETATION OF CHEST FILMS
Develop a systematic approach and use it consistently.
(Usually external Æ internal.)
I. LABEL — Read the label on every film to verify the patient's name, age, and sex.
II. ORIENTATION — Identify the patient's right side, his position, and determine if he is rotated.
Symmetrical spacing of the clavicles and other structures on either side of the sternum; clavicles esp. will show whether or not patient is straight or rotated. Symmetry of the clavicles and ribs gives you assurance that no rotation is present. Even slight rotation is undesirable in a chest film as the heart and mediastinum are then radiography obliquely and their shadows appear enlarged and distorted.
III. QUALITY — In a film of good technical quality in a patient without gross cardiomegaly, you should be able to see the outlines of the vertebral bodies within the heart shadow; notice linearity of spine — is it straight?
IV. INTERPRETATION: the following should be identified:
A. Skeletal Structures — what you see of the bones is incidental as the technique used for chest films
has been designed for study of the lungs. Always compare for symmetry.
1. Scapulae — PA and lateral; are there two of each?
With hands on hips, palms out, and elbows forward the scapulae are rotated to the sides to prevent their superimposition upon the upper lung fields. Therefore only their medial margins are seen.
2. Humeri and Shoulder Joints — PA and lateral.
Little of the shoulder girdle and humerus will be seen in films of broad-chested individuals.
Coracoid is seen through the spine of the scapula because they superimpose.
Head of humerus and the acromium are also seen additively.
Are fractures or abnormal calcifications (dense white shadows) seen?
3. Clavicles — PA; symmetrical spacing on either side of sternum only if there is no rotation of the chest. Turned even a few degrees, the clavicles will exhibit a remarkable degree of asymmetry.
4. Ribs — count on every film to level of diaphragm.
Identify the first rib carefully by finding its anterior junction with the manubrium and following this rib backward to the spine. Then count down the posterior ribs.
Begin at the origin of the first rib at its junction with the first thoracic vertebra and trace each rib as far anteriorly as you can to the beginning of the radiolucent (and hence invisible) costal cartilage.
Interspaces are useful in identifying the location of a precise shadow and are named for the posterior rib above the interspace unless the anterior rib is specified as the marker.
# of ribs helps you determine how much lungs are inflated.
9 or more ribs = good inflation.
Transverse cardiac shadow smallest — used for measurement.
Lungs better filled with air; therefore relatively minor disease is seen better.
10 or more ribs = ? hyperinflated
Expiratory film — see < 9 ribs.
Diaphragm higher; lung bases less well seen; transverse diameter of heart is larger.
Minimal pneumothorax can be seen better. Also, obstructive emphysema.
Compare both sides for symmetry,
Note width of the intercostal spaces. Are they equal?
Are they continuous or is there a fracture?
Beam only "sees" what is parallel to it; anterior ribs are more perpendicular and thus not seen very well.
5. Spine — notice linearity — is it straight?
Spine and sternum are superimposed upon each other and upon the dense shadows of the mediastinal structures in the PA view.
Scoliosis may mask margin of RA; don't mistake for RA with mediastinal shift.
B. Soft Tissues — Symmetry of Density.
1. Chest wall (outside of lung fields).
2. Neck.
3. Mediastinum.
MEDIASTINAL STRUCTURES
Identify trachea — is it midline, not shifted?
Identify bifurcation and position.
Should not be able to follow airways any further out as they are very thin walled; if visible (air bronchogram sign) - ?? pulmonary edema.
4. Breasts — symmetrical in size, shape, position; nipples may possibly be visible.
Be sure to check whether there are two breasts.
The lung field under a missing breast will appear a little darker than the other lung field.
C. Diaphragm
1. Difference in the Level of the Hemidiaphragms
Right hemidiaphragm is normally a bit higher.
Impaired mobility of diaphragm — may be from paralysis of either phrenic nerve, disease in abdomen such as a subdiaphragmatic abscess, pleurisy, pulmonary infarction, etc.
2. Normal Position
Distance from gastric bubble (if it is visible) to diaphragm should be very small.
3. Shape of the Diaphragm.
4. Identification of Left and Right Diaphragms — lateral film.
5. Costophrenic Angles
Should be sharp and clear.
No fluid density should be visible.
6. Cardiophrenic angle should be fairly clear.
7. Inferior vena cava adds its own little shadow.
D. Heart and Great Vessels
Size of Heart — measure at widest point; compare to size of thorax; should be no more than 1/2
the width of the thorax. Using any handy piece of paper, determine the width of the heart. Then decide whether this width exceeds the distance from the midpoint (spine) to the inside of the rib cage (half the transthoracic diameter). Still more simply, you can measure from the midline to the right heart border and see whether that distance will fit into the piece of lung field to the left side of the heart.
Assessment of the cardiovascular anatomy includes assessment of heart and chamber size as well as the position and size of the great vessels.
1 = right brachiocephalic vessels
2 = ascending aorta and superimposed SVC
3 = right atrium (RA)
4 = inferior vena cava (IVC)
5 = left brachiocephalic vessels
6 = aortic knob/arch
7 = pulmonary trunk
8 = left atrial appendage (LA)
9 = left ventricle (LV)
Note: Normally concave slope between arcs 6 and 9 is often called the "cardiac waistline."
1. Left Atrial Border — PA and lateral views.
2. Left Ventricular Border — PA and lateral.
3. Right Ventricular Border — PA and lateral — anterior structures and border is not normally visualized.
4. Inferior Vena Cava.
5. Right Atrial Border — PA.
Scoliosis, if present, may mask border of the right atrium.
6. Superior Vena Cava — PA.
7. Ascending Aorta — PA and lateral.
8. Aortic Knob — position, calcification.
9. Main Pulmonary Artery — lateral.
10. Relative position of left and right main branches of pulmonary arteries — in relation to left and right main bronchi.
11. Esophagus — PA and lateral.
12. Note cardiac size — normal is 1/2 or less of the thoracic width on a PA film.
E. Lungs
1. Trachea and carina — PA and lateral.
2. Major bronchi — PA and lateral.
3. Pleura.
4. Left — upper and lower lobe representation — PA and lateral.
Major fissure on left — between ribs 6 and 8. Only one fissure.
Lingula (tongue-shaped) — area adjacent to LV; not a separate lobe.
5. Right — upper, middle, and lower lobe representation — PA and lateral.
Oblique or major fissure — T3 Æ T10.
6. Differences in density, upper and lower lung fields.
In a PA film the peripheral vasculature is normally seen out to the lateral one inch of the films and is more clearly delineated in the lower lobes than the apices.
Upright — most of perfusion goes to lower lungs so you should see it all the way out.
_ PAP Æ reversal of blood flow with enhancement of apical vascularity.
Older smoker and vasculature not visible all the way out = ? emphysema.
Younger person and not visible all the way out = ? pneumothorax.
Pneumothorax = about the only thing that can be diagnosed with absolute certainty with CXR.
7. Peripheral vasculature — follow it out as far as you can see it.
• Hilum (pl. = hila).
• Position — higher or lower.
• Symmetry
Lung fields — symmetry re: amount of density.
8. Silhouette Sign
2 densities that are alike with margins adjacent to each other — borders will be masked.
If margin is obliterated, whatever is masked and it has to be in the same plane.
Masking of RA — would be from R middle lobe.
Masking of posterior diaphragm — would be from R lower lobe.
Masking of LV — would be from L upper lobe (anterior).
Masking of descending aorta — would be from L lower lobe.
Masking of IVC and SVC — would be from R lower and middle lobes.
If you can see heart — comes from posterior.
9. Air Bronchogram Sign — "butterfly" distribution of the abnormal densities or an anatomic distribution of abnormal densities restricted to lobar or sublobar portions of the lung.
Temporally rapid (reckoned in days) changes in the appearance of the lung infiltrate.
Indicative of alveolar disease.
See airways out past bifurcation.
Air-filled airway superimposed on air-filled densities.
Demonstration of the air-filled bronchus as a radiolucent "tube" is dependent on its close association with alveoli that are fluid-filled rather than air-filled.
Two contrasting densities make it visible.
Airways OK, surround tissues not OK.
10. Kerley's Lines
Kerley's B Lines — short, thin horizontal lines at the periphery of the lung near the costophrenic angles; formed by thickening of the interlobular septa 2° to fibrosis (e.g., pneumoconiosis), fluid accumulation, or distended lymphatics-venules Kerley's A Lines — long, linear densities, more centrally located in the upper portions of the lungs near the hila; may be seen in interstitial lung disease and CHF; represent swollen lymphatic channels.
F. Iatrogenics
1. ECG leads
2. Endotracheal tube — positioning
3. CVP and PA lines
INTERPRETATION OF CHEST FILMS
I. Skeletal Structures
A. Scapulae
B. Humeri
C. Clavicles — symmetrical spacing on either side of sternum
D. Ribs
II. Soft Tissues — symmetry of density.
A. Chest wall
B. Neck
C. Mediastinum
Trachea — is it midline, not shifted.
Identify bifurcation and position.
Should not be able to follow airways any further out as they are very thin walled; if visible (air bronchogram sign) - ?? pulmonary edema.
D. Breasts — symmetrical in size, shape, position; nipples may ? be visible.
III. Diaphragm
A. Difference in the level of the hemidiaphragms.
B. Normal position.
C. Shape of the diaphragm.
D. Identification of left and right diaphragms — lateral.
E. Costophrenic angles.
IV. Heart and Great Vessels — Assessment of the cardiovascular anatomy includes assessment of heart and chamber size as well as the position and size of the great vessels.
A. Left atrial border — PA and lateral.
B. Left ventricular border — PA and lateral.
C. Right ventricular border — PA and lateral — anterior structures and border is not normally visualized.
D. Inferior vena cava.
E. Right atrial border — PA.
Scoliosis, if present, may mask border of RA.
F. Superior vena cava — PA.
G. Ascending aorta — PA and lateral.
H. Aortic knob — position, calcification.
Hypertension can cause a flat, almost absent aortic arch.
I. Main pulmonary artery — lateral.
J. Relative position of L and R main branches of pulmonary arteries — in relation to L & R main bronchi
K. Esophagus — PA and lateral
L. Cardiac Size — normal is 1/2 or less of the thoracic width on a PA film.
Simulation of cardiac enlargement — PA films made in expiration (high diaphragm Æ heart tilted upward bringing apex closer to the lateral chest wall + less flare of ribs which alters the apparent cardiothoracic ratio); also any abdominal distention (late pregnancy, ascites, intestinal obstruction) produces similar results; diaphragm also likely to be higher in supine views; portable chest films and other AP views place heart farther away from the film.
Rotation of the patient produces appearance of widening of the heart and mediastinal shadows.
Deformity of the thoracic cage — severe scoliosis; depressed sternum (pectus excavatum) usually displaces heart to the left + right heart border not visible.
Difference between heart volumes in systole and diastole usually not enough to affect rough estimate of the cardiothoracic ratio in adults.
Simulation of deceptively small heart — overdistention of the lungs for any reason (dyspneic patient with low diaphragm or emphysematous patient) compresses the heart and mediastinal structures from both sides and narrows their PA shadow.
Mediastinal disease, pulmonary disease, or any density (consolidation, effusions, true mediastinal shift) may render the dimensions of the heart unobtainable.
RADIOLOGIC SIGNS OF CARDIAC DISEASE
Posteroanterior Projection
• The upper right border is formed by the SVC and the lower cardiac border is formed by the RA. The left border has three well-defined segments: The uppermost is formed by the aortic arch, the main pulmonary artery lies immediately below the aortic knob, and the lower left cardiac border is formed by the LV and the apex. The LA appendage lies between the pulmonary artery segment and the LV and is usually not seen as a separate bulge.
Lateral Projection
• RV is the most anterior cardiac chamber and is in direct contact with the lower sternum.
There should be a clear space (lung tissue) between the sternum, the RV outflow tract, and the root of the pulmonary artery, but pectus excavatum as well as RV enlargement can impinge on this space.
The posterior cardiac border is made up of the LA above and the LV below.
1 = right brachiocephalic vessels
2 = ascending aorta and superimposed SVC
3 = right atrium (RA)
4 = inferior vena cava (IVC)
5 = left brachiocephalic vessels
6 = aortic arch
7 = pulmonary trunk
8 = left atrial appendage (LA)
9 = left ventricle (LV)
Technical Factors
• The heart appears larger on AP than PA views.
• Film during expiration — simulates pulmonary edema and the heart appears larger.
• One should check side markers for dextrocardia.
• One should check the clavicles for angulation.
• Overpenetrated films may miss heart failure.
Extracardiac Structures
• Rib notching indicates coarctation of the aorta. Rib notching = saucered erosions of the undersurface of the ribs where dilated intercostal arteries have developed as collateral pathways. Seldom present in children younger than 10. Other conditions such as neurofibromatosis can also cause rib notching.
• Pectus excavatum simulates cardiac enlargement by displacing heart to the left. Lateral view shows
depression of the sternum at the level of the heart. Ø AP dimension of the chest at heart level and the heart is displaced posteriorly (posterior margin behind the inferior vena cava).
• Straight back is a/w mitral valve prolapse and aortic insufficiency.
• Right-sided pleural effusion occurs with CHF.
Physiologic Analysis of the Pulmonary Vasculature — appearance of the hilar and pulmonary vessels is an excellent indicator of the physiologic state of the heart.
Congestive Heart Failure
• _ size, shapelessness of heart, + evidence of pulmonary venous engorgement — the vessels are seen to extend farther than normal into the lung field.
• Bronchi become "framed" in the interstitial fluid accumulating around them and, when seen end-on, appear as white rings. This is often called "peribronchial cuffing" and can be observed to decrease as the patient improves.
• Pleural effusion in cardiac failure may be bilateral or unilateral and is more frequent on the right.
• Lungs appear hazy and less radiolucent than normal because of retained water; lattice pattern.
• Kerley's B lines appear — short, horizontal white linear densities very close to the peripheral margin of the lung; have been proven to represent the thickened, edematous interlobular septa; also seen in lymphangitic spread of malignancies within the lung parenchyma and interstitial pulmonary disease.
• Rapid accumulation of fluid spills over into the alveoli and causes the development of alveolar (air-space) pulmonary edema.
Pulmonary edema Æ the so-called "bat-wing" appearance about both hila; superimposed shadowsof innumerable fluid-filled alveoli may cause disappearance of the vessels of the hilum; interstitial pulmonary edema Æ blurring of pulmonary vasculature; perihilar haze; may appear rapidly after sudden LV failure or it may be superimposed on the more gradual CXR findings of CHF.
Pulmonary edema can also occur in noncardiac conditions such as fluid overload, renal failure, heroin overdose, and inhalation injury or burns.
CXR findings can lag behind hemodynamic Ds but the following patterns can predict pulmonary artery wedge pressure:
• Grade 0: normal — PAWP < 12 mm Hg.
• Grade 1: pulmonary venous HTN, pulmonary vascular redistribution to the apices (venous markings Æ into the upper lobes), and loss of the right hilar angle — PAWP 12-19 mm Hg.
• Grade 2: interstitial edema (Kerley's B lines), hilar haze or blurriness, peribronchial vascular thickening — PAWP 20-25 mm Hg.
• Grade 3: generalized or perihilar alveolar edema — PAWP > 25 mm Hg.
• Distinguishing Between Cardiac Hypertrophy, Dilatation, and Pericardial
Effusion:
Plain films may show ventricular enlargement but do not differentiate between hypertrophy and dilatation.
If heart is decompensating, it will tend to shapelessness and extend to both the R and L in the PAview, suggesting either failure or pericardial effusion. A review of the patient's old films is probably the best way to assess development of cardiac enlargement, in and out of failure.
Sudden shapeless _ in size should suggest pericardial effusion.
Section Three
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Chamber Enlargement
• The echocardiogram is much more specific for identifying structural abnormalities and chamber enlargement. The echocardiogram also is very important for distinguishing hypertrophy from dilation and recognizing pericardial effusions.
AP View Lateral View
Ao Dil = Aortic Dilatation PA Dil = Pulmonary Artery Dilatation
Asc Ao = Ascending Aorta PA HTN-Dil = Pulmonary Artery Bulging due to
LAE = Left Atrial Enlargement Pulmonary Hypertension
LVE = Left Ventricular Enlargement RVE = Right Ventricular Enlargement
Enlargement of the Left Atrium
• CXR studies are most accurate in detecting enlargement of the LA compared to the other 3 chambers.
• LA = most posterior of the cardiac chambers and lies in the midline below the carina of the trachea and the mainstem bronchus.
• LA has 2 distinct components — a body and an appendage.
The body of the LA is centrally placed and does not form a border on the frontal view.
The LA atrial appendage is to the left of the body, immediately beneath the pulmonary artery segment, and above the LV.
• The most common findings are a double density of the right cardiac shadow, bulging the atrial appendage along the middle of the left cardiac border on the frontal view, and a posterior bulge of the upper cardiac border on the lateral view.
• LA enlargement may eventually extend it to the right so that its margin is visible along the right heart border, above the profile of the RA and overlapping it — the "double shadow" frequently referred to as a classic sign of LA enlargement.
• Straightening of the L heart border may be a normal finding; does not always signify increased LA size.
Filling in of the normally concave waistline may be due to fullness that is either posterior (as in LA dilatation) or anterior (as in any condition such as poststenotic dilatation in pulmonic stenosis, or dilatation due to PDA).
• LA enlargement in mitral disease cardiac enlargement — elevation of the L main bronchus just above the L 8th rib, double shadow along the R heart border, ? straightening of L heart border (? due to slight fullness of main pulmonary artery).
Enlargement of the Left Ventricle
• LV forms the apex of the heart on the frontal view.
• With dilation, the cardiac apex is displaced downward toward the diaphragm and to the left; shadow of aortic arch may be flattened.
• With hypertrophy, the apex becomes rounded.
• LV enlargement often a/w aortic stenosis and chronic HTN both of which may cause enlargement of the aorta.
• Lateral film — rounded posterior projection of LV; border of heart is extended posteriorly and low against the diaphragm.
Enlargement of the Right Side — more difficult to recognize.
• RA forms the right lateral cardiac border. The RV is normally an anterior midline chamber located directly behind the sternum.
• RA enlargement fills in the space behind the sternum.
• RV enlargement — enlarges in cor pulmonale and in pulmonic stenosis; CXR (PA) may be deceptively normal or show displacement of normal LV to the left.
Pulmonary artery often enlarged concomitantly.
May also see LV and LA enlargement if Lateral film — filling in of the lower part of the anterior clear space + flat posterior surface of the heart. Heart is not extended posteriorly.
Chest X-Ray Findings with Myocardial Dysfunction
• A large heart on CXR films supports the dx. of systolic myocardial dysfunction.
• A lateral view is often helpful to check for right-sided failure. If the space behind the sternum is filled in, right-sided heart failure and RV dilation are possible.
• Echocardiography is most useful for identifying enlargement of a specific chamber and separating dilation from hypertrophy.
• _ vascular markings in the upper lobes are 2° to increased filling pressure of ~ 13-18 mm Hg.
• Interstitial edema (Kerley's B lines) suggests a LV end-diastolic pressure of 19-25 mm Hg.
• Alveolar infiltrates (pulmonary edema) are consistent with a LVEDP > 25 mm Hg.
• Blunting of the margins is due to effusion.
• CXR can help rule in or out other causes of dyspnea such as pulmonary fibrosis or COPD.
Chest X-Ray Findings with Myocardial Ischemia
• Special x-ray imaging (fluoroscopy or CT) can demonstrate coronary artery calcification, but this is an uncertain marker. It has not had the test characteristics that were originally anticipated because calcification of the arterial walls is not necessarily a/w luminal occlusion, particularly in older individuals.
Chest X-Ray Findings with Valvular Dysfunction
• Signs of CHF and chamber enlargement can be detected using chest x-ray studies.
• Valvular calcification can sometimes be seen.
Chest X-Ray Findings with Poor Exercise Capacity
• Signs of pulmonary disease can suggest a noncardiac limitation to exercise and a large heart could suggest cardiac disease.
• Signs of CHF can offer the possibility of a cardiac cause for a change in exercise capacity.
Chest X-Ray Findings with Arrhythmias
• Films are of little use in the diagnosis of arrhythmias. However, finding problems that are often a/w arrhythmias, such as cardiac enlargement and lung disease, should alter one to the possibility of arrhythmias.
• The straight back syndrome or pectus excavatum was thought to be a/w with mitral valve prolapse and arrhythmias.
RADIOLOGIC SIGNS OF PULMONARY DISEASE
1. Trachea and carina — PA and lateral
2. Major bronchi — PA and lateral
3. Pleura
4. Left — upper and lower lobe representation — PA and lateral
5. Right — upper, middle, and lower lobe representation — PA and lateral
6. Differences in density, upper and lower lung fields — reason
7. Peripheral vasculature — in a PA film the peripheral vasculature is normally seen out to the lateral one inch of the films and is more clearly delineated in the lower lobes than the apices
8. Silhouette sign
9. Air bronchogram sign
10. Solitary Pulmonary Nodules
Well-circumscribed, approximately round lesion that is < 4-6 cm. in diameter on CXR.
By definition, it is completely surrounded by aerated lung.
AKA a "coin lesion."
Pulmonary masses are > 4-6 cm. in diameter.
Calcification of the lesion, absence of a history of tobacco use, and age < 35 years are important factors that strongly correlate with benign nodules.
Noncalcified lesions can be benign or malignant.
Even benign calcification does not exclude the presence of coincidental malignancy in adjacent tissue or the subsequent degeneration of a previously benign process into a malignant lesion.
Close observation with serial CXRs every 6 mo. for at least 2 years is prudent.
Cavitating lesions, lesions with multilobulated or spiculated contours, and lesions with shaggy or extremely irregular borders tend to be malignant.
Benign nodules tend to grow at either very slow or very rapid rates.
In contrast, malignant processes grow at steady, predictable, exponential rates.
The growth of a nodule is conventionally defined as the doubling time (time required for its volume to double) and corresponds to an increase in diameter by a factor of 1.26.
In general, doubling times > 16 months or < 1 month are associated with benign processes.
If a nodule has not increased in size over a 2-year period, the probability that it is benign is > 99%.
SIX COMMON PATTERNS OF CALCIFICATION IN SOLITARY PULMONARY NODULES
Adapted from: Webb, W. R. (1990). Radiologic evaluation of the solitary pulmonary nodule.
American Journal of Radiology, 154, 701-708.
----------------------------------------A -----------------B ----------------C --------------D -----------------E -------------------F----------------------------------
_______________________Diffuse_________ Central_______ Popcorn____ Laminar______ Stippled_______ Eccentric__________________
Concentric
The first four are almost always benign; the latter two may be benign or malignant.
RADIOLOGIC SIGNS OF ALVEOLAR LUNG DISEASE
• Hypersensitivity Pneumonitis (Extrinsic Allergic Alveolitis)
Perihilar haziness and peripheral alveolar infiltrates.
Chronic disease — abnormalities indistinguishable from fibrosing alveolitis are commonly found — reticulonodular parenchymal infiltrates, dense fibrotic areas, and decreased lung volumes.
Hilar adenopathy is not found.
Signs/Symptoms of Acute Exposure — fever, chills, anorexia, shortness of breath, dry cough; tachypnea, pyrexia, tachycardia, dry basilar inspiratory rales without rhonchi; occasionally, cyanosis or restlessness indicating hypoxemia.
Signs/Symptoms of Chronic Exposure — shortness of breath, mild fever, weight loss, fatigue, malaise, dry cough, dyspnea on exertion, tachypnea; above signs + ? cor pulmonale (neck vein distention, hepatojugular reflex, hepatomegaly, ankle edema, ascites, loud P2, increased RV activity with a parasternal lift and parasternal S4 gallop).