10. Systematic ApproachSystematic Approach
Lung Fields and Hila
– Hilum
Pulmonary arteries
Pulmonary veins
– Lungs
Linear and fine nodular
shadows of pulmonary
vessels
– Blood vessels
– 40% obscured by other
tissue
11. Systematic ApproachSystematic Approach
Diaphragm and
Pleural Surfaces
– Diaphragm
Dome-shaped
Costophrenic angles
– Normal pleural is not
visible
– Interlobar fissures
12. Systematic ApproachSystematic Approach
Mediastinum and
Heart
– Heart size on PA
– Right side
Inferior vena cava
Right atrium
Ascending aorta
Superior vena cava
13. Systematic ApproachSystematic Approach
Mediastinum and
Heart
– Left side
Left ventricle
Left atrium
Pulmonary artery
Aortic arch
Subclavian artery and
vein
16. Lung AnatomyLung Anatomy
Trachea
Carina
Right and Left Pulmonary
Bronchi
Secondary Bronchi
Tertiary Bronchi
Bronchioles
Alveolar Duct
Alveoli
17. Lung AnatomyLung Anatomy
Right Lung
– Superior lobe
– Middle lobe
– Inferior lobe
Left Lung
– Superior lobe
– Inferior lobe
18. Lung Anatomy on Chest X-rayLung Anatomy on Chest X-ray
PA View:
– Extensive overlap
– Lower lobes extend
high
Lateral View:
– Extent of lower lobes
19.
20. Lung Anatomy on Chest X-rayLung Anatomy on Chest X-ray
The right upper lobe
(RUL) occupies the upper
1/3 of the right lung.
Posteriorly, the RUL is
adjacent to the first 3 to 5
ribs.
Anteriorly, the RUL
extends inferiorly as far as
the 4th right anterior rib
21. Lung Anatomy onLung Anatomy on
CXRCXR
The right middle lobe
is typically the
smallest of the three,
and appears triangular
in shape, being
narrowest near the
hilum
22. Lung Anatomy onLung Anatomy on
CXRCXR
The right lower lobe is the
largest of all three lobes,
separated from the others by
the major fissure.
Posteriorly, the RLL extend
as far superiorly as the 6th
thoracic vertebral body, and
extends inferiorly to the
diaphragm.
Review of the lateral plain
film surprisingly shows the
superior extent of the RLL.
23. Lung Anatomy on Chest X-rayLung Anatomy on Chest X-ray
These lobes can be separated
from one another by two
fissures.
The minor fissure separates
the RUL from the RML, and
thus represents the visceral
pleural surfaces of both of
these lobes.
Oriented obliquely, the
major fissure extends
posteriorly and superiorly
approximately to the level of
the T4 vertebral body.
24. LEFT Lung AnatomyLEFT Lung Anatomy
on CXRon CXR
The lobar architecture
of the left lung is
slightly different than
the right.
Because there is no
defined left minor
fissure, there are only
two lobes on the left;
the left upper &
lower lobes
25. Lung Anatomy on Chest X-rayLung Anatomy on Chest X-ray
Left lower
lobes
27. LAT VIEW-CXRLAT VIEW-CXR
These two lobes are
separated by a major
fissure, identical to that
seen on the right side,
although often slightly
more inferior in location.
The portion of the left
lung that corresponds
anatomically to the right
middle lobe is
incorporated into the left
upper lobe.
28. THE CXRTHE CXR
PA View:
1. Aortic arch
2. Pulmonary trunk
3. Left atrial appendage
4. Left ventricle
5. Right atrium
6. Superior vena cava
7. Right hemidiaphragm
8. Left hemidiaphragm
9. Horizontal fissure
29. Normal CXR-LATNormal CXR-LAT
Lateral View:
1. Oblique fissure
2. Horizontal fissure
3. Thoracic spine and
retrocardiac space
4. Retrosternal space
5. Retratracheal space
30. The Silhouette SignThe Silhouette Sign
An intra-thoracic radio-
opacity, if in anatomic
contact with a border of
heart or aorta, will obscure
that border. An intra-
thoracic lesion not
anatomically contiguous
with a border or a normal
structure will not
obliterate that border.
33. Liquid DensityLiquid Density
Liquid density Increased air density
Generalized Localized
Diffuse alveolar
Diffuse interstitial
Mixed
Vascular
Infiltrate
Consolidation
Cavitation
Mass
Congestion
Atelectasis
Localized airway obstruction
Diffuse airway obstruction
Emphysema
Bulla
34. ConsolidationConsolidation
Lobar consolidation:
– Alveolar space filled with
inflammatory exudate
– Interstitium and architecture
remain intact
– The airway is patent
– Radiologically:
A density corresponding to a
segment or lobe
Airbronchogram, and
No significant loss of lung
volume
35. AtelectasisAtelectasis
Loss of air
Obstructive atelectasis:
– No ventilation to the lobe beyond
obstruction
– Radiologically:
Density corresponding to
a segment or lobe
Significant loss of volume
Compensatory
hyperinflation of normal
lungs
36. Stages of Evaluating anStages of Evaluating an
AbnormalityAbnormality
1. Identification of abnormal shadows
2. Localization of lesion
3. Identification of pathological process
4. Identification of etiology
5. Confirmation of clinical suspicion
40. A single, 3cm relatively thick-walled cavity is noted in the left
midlung. This finding is most typical of squamous cell
carcinoma (SCC). One-third of SCC masses show cavitation
54. COPD: Decrease in heart diameter, flattening of the diaphragm,
and increase in the size of the retrosternal air space. In addition the
upper lobes will become hyperlucent due to destruction of the lung
tissue.
57. Pseudotumor: fluid has filled the fissure creating a density that
resembles a tumor (arrow). Fluid and soft tissue are indistinguishable
on plain film. Further analysis, however, reveals a classic pleural
effusion in the right pleura. Note the right lateral gutter is blunted and
the right lateral diaphragm is obscured.
60. Pneumonia: a large pneumoniac consolidation in the right
lower lobe. Knowledge of lobar and segmental anatomy is
important in identifying the location of the infection
63. CHF: accentuated interstitial markings, Kerley B lines,
and an enlarged heart. Normally indistinct upper lobe
vessels are prominent but are also masked by
interstitial edema.
99. THANK U FOR YOUR KINDTHANK U FOR YOUR KIND
ATTENTIONATTENTION
Notas do Editor
In the United States, chest x-rays are routinely obtained for hospitalized adults. Pulmonary specialists will almost never provide a consultation without having seen a chest x-ray. In under developed countries chest x-rays are obtained very selectively and physicians rely mostly on physical exam and history for diagnosis. Physical examination of the chest has inherent limitations. Lesions located in the mediastinum, interstitium, and in the center of the lung are rarely picked up by physical exam. Ease of availability of chest x-ray has made many physicians avoid time consuming physical exam which in most cases fails to reveal all of the problems. As a result, physicians have lost the skill of physical exam. Just as physical examination has limitations, chest x-ray also has limitations, and it should be recognized that a normal chest x-ray does not rule out pulmonary problems. Interstitial, airway and pulmonary vascular disease in certain cases cannot be recognized by chest x-ray while it is easily evident on physical exam, e.g. asthmatics can have normal chest x-rays. Physical exam and chest x-ray provide a compliment of any information and they are not mutually exclusive. Physical exam in general is good for acute illness, while chest x-ray is better for chronic illness.
Overexposure causes a film to be too dark. Under these circumstances, the thoracic spine, mediastinal structures, and retrocardiac areas are well seen, but small nodules and the fine structures in the lung cannot be seen.
Underexposure causes the film to be quite white. This is a major problem for adequate interpretation. It will make small pulmonary blood vessels appear prominent and may lead you to think that there are generalized infiltrates when none is really present.
The major difference between male and female chest x-rays is caused by differences in the amount of breast tissue. Breast tissue absorbs some of the x-ray beam, essentially causing underexposure of the tissues in the path. This is not a problem if the inferior aspect of the breasts is above the hemidiaphragms.
Chest x-rays on ambulatory patients are usually done with the patient’s chest up against the film holder. The x-ray tube is behind the patient, and the beam passes from the back and exits in front of the chest. This is referred to as a PA (posterior to anterior) projection. If the patient is lying down, it is standard practice to take an AP (anterior to posterior) chest x-ray.
For interpretive purposes, the main difference is that the heart will be magnified on an AP projection. This is because in the AP projection the heart is farther from the film and the x-ray beam diverges as it goes farther from the tube.
The amount of inspiration is greater in an upright film, which allows for spreading of the pulmonary vessels and allowing clearer visualization. Another reason for preferring upright films is that small pleural effusions tend to run down into the normally deep costophrenic angles.
A patient lying down is unable to take a full inspiration; the liver and abdominal contents are pushing up on the lungs and heart, and the result is that the pulmonary vessels are crowded. On a supine film, the standard AP projection combined with the cephalic push of the abdominal contents will make a normal heart appear large.
The degree of inspiration is important not only for assessing the quality and limitations of the examination but also for diagnosing different diseases.
When standing, most adults can easily take an inspiration that brings the domes of the hemidiaphragms down to the kevel of the tenth posterior ribs.
When sitting down, often the level is between the eighth and tenth ribs.
If the radiograph has the domes of the diaphragms at the seventh posterior ribs, the chest should be considered hypoinflated, and you need to be very careful before diagnosing basilar pneumonia or cardiomegaly.
First, inspect the BONY FRAMEWORK of the chestYou should be able to count and number the ribs, inspect the capulae, humeri and shoulders, and clavicles, and seethe diaphragms overlying the posterior aspects of the 10th or 11th ribs (in a normal adult)> The spine and sternum are generally difficult to visualize in detail on standard PA films due to overlying shadows.
Next, inspect the soft the SOFT TISSUES that overlie the thoracic cageNote the breast shadows,supraclavicular areas, axillae, and tissues along the sides of the chest.
Examine the LUNG FIELDS and HILAThe hilum ("lung root") is the shadow of pulmonary artery and vein adjacent the heart shadow.Normal lung markings are the linear and fine nodular shadows of pulmonary vessels.Abnormalities in the lung fields are marked by excessive radiolucency, excessive radiopacity, or opacified areas.
Next, examine the DIAPHRAGM and PLEURAL SURFACESDiaphragmatic images in the lung bases are dense, radiopaque shadows made principally by the liver on the left and the spleen on the right.The normal pleura is not visible on the chest x-ray, except where two layers come together to form the interlobar fissures.
Finally, examine the MEDIASTINUM and and HEARTDisplacement of the mediastinum is an important clue to disease in on or the other hemithorax.On the PA chest film, the normal right heart and mediastinal border is made up (from bottom to top) of the 1) inferior vena cava; 2) the right atrium; 3)ascending aorta; and 4) superior vena cava. The normal left heart and mediastinal border consists (from bottom to top) of the 1) left ventricle; 2) left atrium; 3)pulmonary artery; 4) aortic arch; and 5) subclavian artery and vein
The normal left heart and mediastinal border consists (from bottom to top) of the 1) left ventricle; 2) left atrium; 3)pulmonary artery; 4) aortic arch; and 5) subclavian artery and vein
The right upper lobe (RUL) occupies the upper 1/3 of the right lung. Posteriorly, the RUL is adjacent to the first three to five ribs. Anteriorly, the RUL extends inferiorly as far as the 4th right anterior rib.
The right middle lobe is typically the smallest of the three, and appears triangular in shape, being narrowest near the hilum.
Posteriorly, the RLL extend as far superiorly as the 6th thoracic vertebral body, and extends inferiorly to the diaphragm. Review of the lateral plain film surprisingly shows the superior extent of the RLL; there is considerable overlap between the more anterosuperiorly located RUL and the RLL. Similarly, the deep posterior gutters extend considerably inferiorly; with full inspiration, the lower lobe can extend may as low as L2, becoming superimposed over the upper poles of the kidneys.
Grossly, these lobes can be separated from one another by two fissures which anatomically correspond to the visceral pleural surfaces of those lobes from which they are formed. The minor fissure separates the RUL from the RML, and thus represents the visceral pleural surfaces of both of these lobes. The minor fissure is oriented horizontally, extending ventrally from the chest wall, and extending posteriorly to meet the major fissure. Generally, the location of the minor fissure is approximately at the level of the fourth vertebral body and crosses the right sixth rib in the midaxillary line. The right major fissure is more expansive in size than the minor fissure, separating the right upper and middle lobes from the larger right lower lobe. Oriented obliquely, the major fissure extends posteriorly and superiorly approximately to the level of the fourth vertebral body. The major fissure extends anteroinferiorly, intersecting the diaphragm at the anterior cardiophrenic angle
The lobar architecture of the left lung is slightly different than the right. Because there is no defined left minor fissure, there are only two lobes on the left; left upper
and left lower lobes
These two lobes are separated by a major fissure, identical to that seen on the right side, although often slightly more inferior in location. The portion of the left lung that corresponds anatomically to the right middle lobe is incorporated into the left upper lobe.
It is important to understand that in most individuals, interlobar fissures are usually not completely formed; in some individuals there may be complete absence of a fissure thus losing the demarcation between lobes on gross examination.
In general, fissures are not readily identifiable on plain films, with only small portions typically visualized at best. This is because fissures which are composed of only two layers of visceral pleura, may not present a significant radiographic interface and will not produce a shadow. However, if there is fluid within the pleural space or if the visceral pleura is thickened, fissures may be seen in their entirety.
Each tissue reacts to injury in a predictable fashion. Multiple etiology can evoke a similar pathological reaction. Let us just exam the pathological process that can occur in the lung. Lung injury or pathological states can be either a generalized or localized process.
Consolidation: In the lobar consolidation, a lobe is involved. The alveolar space is filled with inflammatory exudate made up of WBC, bacteria, plasma, and debris. In Pneumococcal pneumonia, the most common cause for lobar consolidation, the lobe goes through red hepatization and gray hepatization stage. In the stage of resolution, some secretions can be in the airway. The interstitium and architecture of the lung remain intact and complete recovery occurs. The lobe swells up initially and may shrink slightly later if there is significant secretions in the airway causing some obstruction. The airway is patent.
Radiologically this transcribes to:
1. a density corresponding to a segment or lobe
2. airbronchogram, and
3. no significant loss of lung volume.
Atelectasis: Atelectasis means loss of air. In absorptive Atelectasis there is an obstructive lesion on the bronchus. There is no ventilation to the lobe beyond the obstruction. Gradually the air gets absorbed by pulmonary circulation. The involved lobe eventually is devoid of air and becomes atelectatic.
Radiologic criteria for absorptive Atelectasis is
1. a density corresponding to a segment or lobe,
2. significant signs of loss of volume, and
3. compensatory hyperinflation of normal lungs.
STAGES OF EVALUATING AN ABNORMALITY:
In reading chest x-rays, I recommend that you do it in 4 steps:
Step: 1. Identify the abnormal shadows
2. Anatomically localize the lesion
3. Identify pathological process
4. Identify the etiology
Step 1: Identification of abnormal shadows
You have to know what is normal before you recognize abnormalities. Let us identify the normal structures in the thorax (heart, aorta, pulmonary artery, lung fields, costophrenic angles, diaphragm, trachea, etc.).
Which lung is larger?
Which diaphragm is higher and why?
What is the normal size of the heart?
What is the normal size and shape of the aorta?
You need to know normal and variations before you can detect and recognize abnormal shadows on chest x-ray.