ChestChest X-ray Basic Interpretation

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Chest X-rays Basic Interpretation1-Normal & Variants2-Systematic Approach3-Heart & Pericardium4-Hilum5-Mediastinum6-Lungs7-Pleura8-Chest Wall9-Abdomen10-Support Devices

1-Normal & Variants :a) PA viewb) Vena azygos lobec) Pectus excavatumd) Lateral viewe) Lobar & segmental anatomy

1-Tracheal Air Column2-Carina3-1st Rib4-Scapula

5-Minor or Horizontal Fissure6-Right Hemidiaphram7-Left Hemidiaphram8-Ascending Aorta

9-Clavicle10-Superior Vena Cava Shadow

11-Region of Azygos Vein12-Right Pulmonary Artery13-Left Atrial Appendage14-Border of Right Atrium

15-Inferior Vena Cava16-Aortic Arch

17-Left Pulmonary Artery18-Border of Left Ventricle

19-Descending Aorta

1-Sternum2-Arm Soft Tissue

3-Tracheal Air Column4-Scapula

5-Ascending Aorta6-Aortic Arch

7-Descending Aorta8-Right Main Stem Bronchus9-Left Main Stem Bronchus10-Right Pulmonary Artery11-Left Pulmonary Artery

12-Horizontal or Minor Fissure13-Retrosternal Space

14-Left Ventricle15-Right Ventricle

16-Right Major or Oblique Fissure17-Thorasic Vertebrae

18-Left Atrium19-Inferrior Vena Cava

20-Diaphram

a) PA view :-On the PA chest-film it is important to examine all the

areas where the lung borders the diaphragm , the heart and other mediastinal structures

-At these borders lung-soft tissue interfaces are seen resulting in a :

1-Line or stripe 2-Silhouette-These lines and silhouettes are useful localizers of disease

, because they can be displaced or obscured with loss of the normal silhouette , this is called the silhouette sign

-The lines (strips) are :1-Paraspinal Line 2-The Paratracheal Line3-Para-aortic Line4-Anterior & Posterior Junction Lines5-Azygoesophageal Line or Recess

1-Paraspinal Line :-The paraspinal line may be displaced by a

paravertebral abscess , hemorrhage due to a fracture or extravertebral extension of a neoplasm

2-The Paratracheal Line :-Widening of the paratracheal line (> 2-3mm) may

be due to lymphadenopathy , pleural thickening , hemorrhage or fluid overload and heart failure

3-Para-aortic Line :-Displacement of the para-aortic line can be

due to elongation of the aorta , aneurysm , dissection and rupture

4-Anterior & Posterior Junction Lines :-Are formed where the upper lobes join

anteriorly and posteriorly , these are usually not well seen

5-Azygoesophageal Line or Recess :-The region inferior to the level of the azygos

vein arch in which the right lung forms an interface with the mediastinum between the heart anteriorly and vertebral column posteriorly , it is bordered on the left by the esophagus

-Deviation of the azygoesophageal line is caused by :

1-Hiatal hernia2-Esophageal disease (achalasia ,

scleroderma , carcinoma)3-Left atrial enlargement4-Subcarinal lymphadenopathy5-Bronchogenic cyst

Azygoesophageal recess , the blue arrow indicates the paraaortic line

Deviation of the azygoesophageal line on the PA-film , It is caused by a hiatal hernia

A hiatal hernia is the most common cause of displacement of the azygoesophageal line , notice the air within the hernia on the lateral view

Displacement of the upper part of the azygoesophageal line on the chest x-ray in the area below the carina , this is the result of massive lymphadenopathy in the subcarinal region , there are also nodes on the right of the trachea displacing the right paratracheal line

The azygoesophageal recess is displaced by lymph nodes that compress the left atrium

There is displacement of the azygoesophageal line both superiorly an inferiorly , there is an air-fluid level (arrow) , combined with the above this must be a dilated esophagus with residual fluid. , the final diagnosis was achalasia , the density on the left in the region of the lingula is the result from prior aspiration pneumonia

The AP-film shows a right paratracheal mass , the azygoesophageal recess is not identified, because it is displaced and parallels the border of the right atrium , the large round density in the left lung is the result of aspiration , notice the massive dilatation of the esophagus on the CT

-Silhouette Sign :*The loss of the normal silhouette of a

structure is called the silhouette sign *Recognition of this sign is useful in localizing

areas of airspace opacities , atelectasis or mass within the lung with the loss of these normal silhouettes on frontal chest radiographs being generally indicative of the site of pathology :

1-Right paratracheal stripe : right upper lobe2-Right heart border : right middle lobe or

medial right lower lobe3-Right hemidiaphragm : right lower lobe4-Aortic knuckle : left upper lobe5-Left heart border : lingula segments of the

left upper lobe6-Left hemidiaphragm or descending aorta :

left lower lobe

Silhouette sign in a consolidation located in the lingula (blue arrow) , the silhouette of the left heart border will still be visible in a consolidation in the left lower lobe (red arrow)

PA-film shows a silhouette sign of the left heart border , even without looking at the lateral film , we know that the pathology must be located anteriorly in the left lung , this was a consolidation due to a pneumonia caused by Sterptococcus pneumoniae

Consolidation which is located in the left lower lobe , there is a normal silhouette of the left heart border

RUL pneumonia

RML pneumonia

RLL pneumonia

-Sites of silhouette sign on the lateral chest radiograph include :

1-Posterior border of the heart +/- posterior left hemidiaphragm : left lower lobe

2-Anterior right hemidiaphragm : right middle lobe

3-Posterior right hemidiaphragm : right lower lobe

-On a normal lateral chest film the silhouette of the left diaphragm 2- can be seen from posterior up to where it is bordered by the heart, which has the same density (blue arrow).

-One should be able to follow the contour of the right diaphragm 1- from posterior all the way to anterior, because it is only bordered by the lung

-Here we cannot follow the contour of the right diaphragm all the way to posterior , which indicates that there is something of water-density in the right lower lobe (red arrow)

-On the PA-film there is a normal silhouette of the heart border , so the pathology is not in the anterior part of the chest which we already suspected by studying the lateral view

-What we see is actually the highest point of the right diaphragm which is anterior to the pneumonia in the right lower lobe , the pneumonia does not border the highest point of the diaphragm

b) Vena Azygos Lobe :-A common normal variant is the azygos

lobe (seen in less than 1% of patients)-The azygos lobe is created when a laterally

displaced azygos vein makes a deep fissure in the upper part of the lung

-On a chest film it is seen as a fine line that crosses the apex of the right lung

The azygos vein is seen as a thick structure within the azygos fissure

In some patients an extra joint is seen in the anterior part of the first rib at the point where the bone meets the calcified cartilageneous part (arrow) , this may simulate a lung mass

c) Pectus Excavatum :-Pectus excavatum is a congenital deformity of the

ribs and the sternum producing a concave appearance of the anterior chest wall

-In patients with a pectus excavatum the right heart border can be ill-defined but this is normal , it produces a silhouette sign and thus simulating a consolidation or atelectasis of the right middle lobe , the lateral view is helpful in such cases

d) Lateral View :-On a normal lateral view the contours of the heart are

visible and the IVC is seen entering the right atrium-The retrosternal space should be radiolucent since it only

contains air , any radio-opacity in this area is suspective of a process in the anterior mediastinum or upper lobes of the lung

As you go from superior to inferior over the vertebral bodies they should get darker, because usually there will be less soft tissue and more radiolucent lung tissue , if this is not the case , look carefully for pathology in the lower lobes

-The contours of the left and right diaphragm should be visible

-The right diaphragm should be visible all the way to the anterior chest wall (red arrow)

-Actually we see the interface between the air in the lungs and the soft tissue structures in the abdomen

-The left diaphragm can only be seen to a point where it borders the heart (blue arrow) , here the interface is lost , since the heart has the same density as the structures below the diaphragm

The left main pulmonary artery (in purple) passes over the left main bronchus and is higher than the right pulmonary artery (in blue) which passes in front of the right main bronchus

-In this case on the PA-view there is hilar enlargement , on the PA-view it is not clear whether this is due to dilated vessels or enlarged lymph nodes

-On the lateral view there are round structures in areas where you don't expect any vessels , so we can conclude that we are dealing with enlarged lymph nodes

-This patient has sarcoidosis , notice also the widening of the paratracheal line (or stripe) as a result of enlarged lymph nodes

On the lateral view spondylosis may mimick a lung mass , any density in the area of the vertebral bodies should lead you to the PA-film to look for spondylosis which is usually located on the right side (arrows) , on the left side the formation of osteophytes is hampered by the pulsations of the aorta

On the PA-view the superior mediastinum is widened , the lateral view is helpful in this case because it demonstrates a density in the retrosternal space.Now the differential diagnosis is limited to a mass in the anterior mediastinum (4 T's) , this was a Hodgkins lymphoma

-A common incidental finding in adults is a Bochdalek hernia which is due to a congenital defect in the posterior diaphragm (arrows) , in most cases it only contains retroperitoneal fat and is asymptomatic, but occasionally it may contain abdominal organs

-Large hernias are sometimes seen in neonates and can be complicated by pulmonary hypoplasia

-A hernia of Morgagni is also a congenital diaphragmatic hernia , but is less common , it is located anteriorly

e) Lobar & segmental anatomy :

Right Lung containing:-Upper Lobe: Apical Segment-Upper Lobe: Posterior Segment-Upper Lobe: Anterior Segment-Middle Lobe: Lateral Segment-Middle Lobe: Medial Segment-Lower Lobe: Anterior Basal Segment

Left Lung containing:-Upper Lobe: Apical Posterior

Segment-Upper Lobe : Anterior Segment-Upper Lobe: Lingula Superior

Segment-Upper Lobe: Lingula Inferior

Segment-Lower Lobe: Anteromedial Segment

*Interlobar Fissures :-The minor (horizontal) fissure separates the RUL

from the RML and is seen in both the frontal & lateral views as a fine horizontal line

-The major (oblique) fissures are seen only on the lateral radiographs as oblique lines :

a) On the right , the major fissure separates the RUL & RML from the RLL

b) On the left , the major fissure separates the LUL from the LLL

(A) Horizontal or Minor Fissure(B) Right Oblique or Major Fissure(C) Left Oblique or Major Fissure

2-Systematic Approach :-Use an inside-out approach from central to

peripheral-First the heart figure is evaluated , followed

by mediastinum and hili , subsequently the lungs , lung borders and finally the chest wall and abdomen are examined

-Hidden areas :There are some areas that need special

attention because pathology in these areas can easily be overlooked :

1-Apical zones2-Hilar zones3-Retrocardial zone4-Zone below the dome of diaphragm

Large lesion in the right lower lobe which is difficult to detect on the PA-film , unless when you give special attention to the hidden areas

Pneumonia which was hidden in the right lower lobe mainly below the level of the dome of the diaphragm (red arrow) , notice the increase in density on the lateral film in the lower vertebral region

Subtle increased density in the area behind the heart that needs special attention (blue arrow) , this was a lower lobe pneumonia

Small lung cancer is seen behind the left first rib , notice that is also seen on the lateral view in the retrosternal area

There is a subtle consolidation in the left lower lobe in the hidden area behind the heart , there is increased density over the lower vertebral region

3-Heart & Pericardium :a) Anatomyb) Cardiac incisurac) Pericardial effusiond) Calcificationse) Pericardial fat padf) Pericardial cyst

a) Anatomy :*PA View :1-Left Atrium :-Most posterior structure-Receives blood from the pulmonary veins that run

almost horizontally towards the left atrium-Left atrial appendage (in purple) can sometimes

be seen as a small outpouching just below the pulmonary trunk

-Enlargement of the left atrium results on the PA-view in outpouching of the upper heart contour on the right and an obtuse angle between the right and left main bronchus , on the lateral view bulging of the upper posterior contour will be seen

Left Atrial Enlargement

2-Right Atrium :-Receives blood from the inferior and

superior vena cava-Enlargement will cause an outpouching of

the right heart contour

3-Left Ventricle :-Situated to the left and posteriorly to the

right ventricle-Enlargement will result on the PA-view in

an increase of the heart size to the left and on the lateral view in bulging of the lower posterior contour

4-Right Ventricle :-Most anterior structure and is situated

behind the sternum-Enlargement will result on the PA-view in

an increase of the heart size to the left and can finally result in the left heart border being formed by the right ventricle

-On these chest films the heart is extremely dilated , notice that it is especially the right ventricle that is dilated, this is well seen on the lateral film (yellow arrow)

-There is a small aortic knob (blue arrow) while the pulmonary trunk and the right lower pulmonary artery are dilated

-All these findings are probably the result of a left-to-right shunt with subsequent development of pulmonary hypertension

RV Enlargement

*Lateral View :1-Left Atrium :-The upper posterior border of the heart is

formed by the left atrium-Enlargement will result in bulging of the

upper posterior contour

2-Left Ventricle :-Forms the lower posterior border-Enlargement will displace the contour more

posteriorly

3-Right Ventricle :-The lower retrosternal space is filled by the right

ventricle-Enlargement of the right ventricle will result in

more superior filling of this retrosternal space

-The location of the cardiac valves is best determined on the lateral radiograph , a line is drawn on the lateral radiograph from the carina to the cardiac apex

-The pulmonic and aortic valves generally sit above this line and the tricuspid and mitral valves sit below this line

-On this lateral view you can get a good impression of the enlargement of the left atrium

b) Cardiac incisura :-On the right side of the chest the lung will lie against the

anterior chest wall-On the left however the inferior part of the lung may not

reach the anterior chest wall since the heart or pericardial fat or effusion is situated there

-This causes a density on the anteroinferior side on the lateral view which can have many forms

-It is a normal finding which can be seen on many CXR and should not be mistaken for pathology in the lingula or middle lobe

At the level of the inferior part of the heart we can appreciate that the lower lobe of the right lung is seen more anteriorly compared to the left lower lobe

Cardiac pacemaker

c) Pericardial effusion :-Whenever we encounter a large heart figure , we

should always be aware of the possibility of pericardial effusion simulating a large heart

-On the chest x-ray it looks as if this patient has a dilated heart while on the CT it is clear that it is the pericardial effusion that is responsible for the enlarged heart figure

-Especially in patients who had recent cardiac surgery an enlargement of the heart figure can indicate pericardial bleeding

-CXR : patient who had valve replacement , notice the large heart size , there is redistribution of the pulmonary vessels which indicates heart failure

-The CT shows a large pericardial effusion

Patient with recent cardiac surgery had a change in the heart configuration and pericardial bleeding was suspected , CT shows a large pericardial effusion which is located posteriorly to the left ventricle (blue arrow) , the left ventricle id filled with contrast and is compressed (red arrow) , at surgery a large hematoma in the posterior part of the pericardium was found

d) Calcifications :-Detection of calcifications within the heart is

quite common-The most common are coronary artery

calcifications and valve calcifications

Pericardial calcifications which can be associated with constrictive pericarditis

In this case there are calcifications that look like pericardial calcifications but these are myocardial calcifications in an infarcted area of the left ventricle , notice that they follow the contour of the left ventricle

e) Pericardial fat pad :-Pericardial fat depositions are common-Sometimes a large fat pad can be seen

f) Pericardial cyst :-Pericardial cysts are connected to the

pericardium and usually contain clear fluid

Rounded density with a smooth border in the region of the right cardiophrenic angle that partially obscures the right border of the heart , pericardial cyst

4-Hilum :-The normal hilar shadow is for 99% composed of

vessels , pulmonary arteries and to a lesser extent veins

-The vessel margins are smooth and the vessels have branches

-The left pulmonary artery runs over the left main bronchus while the right pulmonary artery runs in front of the right main bronchus which is usually lower in position than the left main bronchus , hence the left hilum is higher than the right

The lower lobe arteries are coloured blue because they contain oxygen-poor blood , they have a more vertical orientation while the pulmonary veins run more horizontally towards the left atrium which is located below the level of the main pulmonary arteries

Both pulmonary arteries and veins can be identified on a lateral view and should not be mistaken for lymphadenopathy , sometimes the pulmonary veins can be very prominent , the left main pulmonary artery passes over the left main bronchus and is higher than the right pulmonary artery which passes in front of the right main bronchus

The lower lobe pulmonary arteries extend inferiorly from the hilum , they are described as little fingers, because each has the size of a little finger

Absence of the little finger on the right and on the lateral view the increased density over the lower vertebral column , there is a right lower lobe atelectasis , notice the abnormal right border of the heart , the right interlobar artery is not visible because it is not surrounded by aerated lung but by the collapsed lower lobe which is adjacent to the right atrium

-Normal hili are :*Normal in position , left higher than right*Equal density*Normal branching vessels-Hilar Enlargement :*Enlargement of the hili is usually due to

lymphadenopathy or enlarged vessels

*May be unilateral or bilateral : (caused by lymph node or pulmonary artery enlargement)

a) Unilateral :1-Infection : T.B. , viral , bacterial2-Tumor : lung ca , mets3-Vascular : pulmonary artery aneurysm , stenosis4-Other : Mediastinal mass extending into the

hilum , perihilar pneumonia (ill-defined +/- air bronchogram)

b) Bilateral :1-Sarcoidosis , silicosis2-Infection : T.B. , viral , bacterial3-Tumor : lymphoma , mets , lymphangitis

carcinomatosis4-Vascular : pulmonary artery hypertension

-Enlarged hilar shadow on both sides , this could be the result of enlarged vessels or enlarged lymph nodes , a very helpful finding in this case is the mass on the right of the trachea

-This is known as the 1-2-3 sign in sarcoidosis , i.e. enlargement of left hilum , right hilum and paratracheal

5-Mediastinum :The mediastinum can be divided into an anterior ,

middle and posterior compartment , each with it's own pathology

-Mediastinal lines or stripes are interfaces between the soft tissue of mediastinal structures and the lung , displacement of these lines is helpful in finding mediastinal pathology

-Azygoesophageal recess , see before

-Aortopulmonary window :The aortopulmonary window is the interface

below the aorta and above the pulmonary trunk and is concave or straight laterally

The AP-window is convex laterally due to a mass that fills the retrosternal space on the lateral view , on the CT a mass in the anterior mediastinum is seen , Hodgkins lymphoma

On the PA-film a mass is seen that fills the aortopulmonary window

6-Lungs :1-Consolidation2-Interstitial3-Nodules or masses4-Atelectasis5-Decreased density or lucencies

1-Consolidation :a) Etiologyb) X-ray Findingsc) Patterns

a) Etiology :-Consolidation is the result of replacement of

air in the alveoli by transudate , pus , blood , cells or other substances

-Pneumonia is by far the most common cause of consolidation

-The disease usually starts within the alveoli and spreads from one alveolus to another

1-Pneumonia2-Pulmonary Edema3-Pulmonary Hemorrhage4-Bronchoalveolar Carcinoma5-Alveolar Proteinosis

b) X-ray Findings :1-ill-defined homogeneous opacity obscuring

vessels2-Silhouette sign : loss of lung/soft tissue

interface3-Air-bronchogram4-Extension to the pleura or fissure but not

crossing it5-No volume loss

c) Patterns :1-Lobar Consolidation2-Diffuse Consolidation3-Multifocal Consolidation

1-Lobar Consolidation :-The most common presentation of consolidation

is lobar or segmental-The most common diagnosis is lobar pneumonia -Causes :a) Lobar Pneumoniab) BACc) Hemorrhage (contusion , infarction)d) Sequestration

Lobar Pneumonia

Hemorrhage Post Biopsy

Pulmonary Infarction

Pulmonary Sequestration (Notice the feeding artery that branches off from the aorta (blue arrow)

2-Diffuse Consolidation :-Causes :a) Pulmonary Edemab) Bronchopneumoniac) Bronchoalveolar Carcinoma

a) Pulmonary Edema :-The most common cause of diffuse

consolidation is pulmonary edema due to heart failure

CHF : bilateral perihilar consolidation with air bronchograms and ill-defined borders and increased heart size

Diffuse consolidation in bronchopneumonia , unlike lobar pneumonia which starts in the alveoli , bronchopneumonia starts in the airways as acute bronchitis , it will lead to multifocal ill-defined densities

c) Bronchoalveolar Carcinoma :-Consolidated form

Diffuse consolidation in BAC

-Batwing :A bilateral perihilar distribution of consolidation is

also called a Batwing distributionThe sparing of the periphery of the lung is

attributed to a better lymphatic drainage in this area

-It is most typical of pulmonary edema , both cardiogenic and non-cardiogenic

-Sometimes it is seen in bronchopneumonia

-Reverse Batwing :-Peripheral or subpleural consolidation is

called reverse Batwing distribution-It is frequently seen in chronic lung

disease , BAC , sarcoidosis , organizing pneumonia and eosinophilic pneumonia

3-Multifocal Consolidation :-Multifocal consolidations are also described

as multifocal ill-defined opacities or densities

-In most cases these are the result of airspace-consolidations due to bronchopneumonia

-Causes :1-Bronchopneumonia2-Vascular , septic emboli , Wegner’s

granulomatosis3-Bronchoalveolar carcinoma , lymphoma ,

metastases4-Sarcoidosis

Wegner’s granulomatosis , ill-defined densities in the right lung

2-Interstitial :a) Etiologyb) X-ray Findingsc) Interstitial Pneumonia : UCPd) Interstitial Pulmonary Edemae) Sarcoidosisf) Lymphangitis Carcinomatosis

a) Etiology :1-Interstitial Pneumonia2-Interstitial Fibrosis (Asbestosis)3-Interstitial pulmonary Edema4-Drug Induced5-Collagen Vascular Disease6-Radiation Induced7-With Adenopathy (Sarcoidosis or Lymphangitis

Carcinomatosis)

b) X-ray Findings :-On a CXR it can be very difficult to determine whether

there is interstitial lung disease and what kind of pattern we are dealing with

-On a CXR the most common pattern is reticular-The ground-glass pattern is frequently not detected on a

chest x-ray-The cystic pattern is also difficult to appreciate on a CXR ,

when the cysts have thick walls like in Langerhans cell histiocytosis or honeycombing , it frequently presents as a reticular pattern on a CXR , however sometimes an interstitial pattern can be seen and in many cases UIP can be suspected based on the x-ray findings

c) Interstitial Pneumonia : UCP-UIP is a histologic pattern of pulmonary

fibrosis-On CXR UIP manifests as a reticular

pattern particularly at the lung bases-A HRCT is needed to confirm the diagnosis

by demonstrating honeycombing

-The CXR demonstrates a reticular interstitial pattern with a preference at the lung bases , the HRCT demonstrates honeycombing and traction bronchiectasis

d) Interstitial Pulmonary Edema :-With congestive heart failure-Interstitial edema usually presents as

reticulation-Sometimes Kerley B lines are visible -Kerley B lines are 1-2 cm long horizontal

lines near the lateral pleuraSometimes the reticulation is more coarse ,

congestive heart failure

Interstitial edema and Kerley B lines in a patient with congestive heart failure , The CT shows the septal thickening

e) Sarcoidosis :-On a CXR sarcoidosis usually first presents

with hilar and mediastinal lymphadenopathy

-Parenchymal disease can present as consolidation or even as masses but the most common presentation is a fine nodules

Lymphadenopathy , this is known as the 1-2-3 sign in sarcoidosis , i.e. enlargement of left hilum , right hilum and paratracheal

Coarse reticulation

f) Lymphangitis Carcinomatosis :-Lymphangitis carcinomatosis also produces

a reticular pattern-It is best appreciated on HRCT-images

3-Nodules or masses :-See focal lung diseases

4-Atelectasis :a) Definitionb) X-ray Findingsc) Etiologyd) Patterns

a) Definition :-Atelectasis or lung-collapse is the result of

loss of air in a lung or part of the lung with subsequent volume loss due to airway obstruction or compression of the lung by pleural fluid or a pneumothorax

b) X-ray Findings :-Sharply-defined opacity obscuring vessels

without air-bronchogram-Volume loss resulting in displacement of

diaphragm , fissures , hila or mediastinum

c) Etiology :1-Resorptive (obstructive) atelectasis : -Bronchial carcinoma in smokers-Mucus plug in patients on mechanical ventilation

or asthmatics (ABPA)-Malpositioned endotracheal tube-Foreign body in children2-Passive (relaxation) atelectasis :-Pleural effusion , pneumothorax

d) Patterns :1-Lobar Atelectasis2-Total Atelectasis3-Round Atelectasis4-Plate-like Atelectasis5-Cicacitration Atelectasis

1-Lobar Atelectasis :a) Right upper lobe atelectasis b) Right middle lobe atelectasisc) Right lower lobe atelectasisd) Left upper lobe atelectasise) Left lower lobe atelectasis

-RUL collapse , triangular density , elevated right hilum with obliteration of the retrosternal clear space (arrow)

RUL collapse

-A common finding in atelectasis of the right upper lobe is tenting of the diaphragm (blue arrow)

-This patient had a centrally located lung carcinoma with metastases in both lungs (red arrows)

-RML collapse-Blurring of the right heart border

(silhouette sign)-Triangular density on the lateral

view as a result of collapse of the middle lobe

-Usually right middle lobe atelectasis does not result in noticable elevation of the right diaphragm

-A pectus excavatum can mimic a middle lobe atelectasis on a frontal view, but the lateral view should solve this problem

RML collapse

RLL collapse

RLL collapse

-LUL collapse-Minimal volume loss with

elevation of the left diaphragm

-Band of increased density in the retrosternal space, which is the collapsed left upper lobe

-Abnormal left hilum , i.e. possible obstructing mass

LUL Collapse

Atelectasis of the left upper lobe (blue arrow) , there is a centrally located mass which obstructs the left upper lobe bronchus (red arrow)

LUL collapse

LUL collapse

-There is an atelectasis of the left upper lobe , you would not expect the apical region to be this dark, but in fact this is caused by overinflation of the lower lobe which causes the superior segment to creep all the way up to the apical region , this is called the luft sichel sign

-Luft sichel means a sickle of air (blue arrow) , notice the bulging of the fissure on the lateral view , this is comparable to the Iin right upper lobe atelectasis and is suspective of a centrally obstructing mass

-There is a total collapse of the left upper lobe

-Notice the high position of the left hilum , there is only a subtle band of density projecting behind the sternum , this is the collapsed upper lobe

-In this case there is compensatory overinflation of the left lower lobe resulting in a normal position of the diaphragm and the mediastinum

-LLL collapse-There is a triangular density seen

through the cardiac shadow , this must be an abnormality located posterior to the heart , this is confirmed on the lateral view

-The contour of the left diaphragm is lost when you go from anterior to posterior , lower lobe atelectasis

-We cannot see the lower lobe vessels because they are surrounded by the atelectatic lobe

-Normally when you follow the thoracic spine form top to bottom , the lower region becomes less opaque

-Here we have the opposite (blue arrow)

LLL collapse

LLL collapse

2-Total Atelectasis :-Total collapse of the entire lung-A common cause of total atelectasis of a

lung is a ventilation tube that is positioned too deep and thus obstructing one of the main bronchi

-The CXR shows a nearly total opacification of the left hemithorax , this patient was known to have pleuritic carcinomatosis

-The left lung is almost completely compressed by the pleural fluid

-The compression of the lung by the loculated fluid collections is best seen on the CT-image (blue arrow)

-The CT-scan was performed, because the patient was suspected of having pulmonary emboli (red arrow)

3-Round Atelectasis :-Rounded atelectasis is frequently seen in patients

with a history of asbestos exposure -The typical findings of rounded atelectasis on CT

are :a) Pleural thickeningb) Pleural-based massc) Comet tail sign , vessels converge into the mass

in a curvilinear fashion

-The theory is that a local pleuritis causes the pleura to thicken and contract

-The underlying lung shrinks and atelectasis develops in a round configuration

-The distorted vessels appear to be pulled into the mass and resemble a comet tail

CXR lateral view there is a mass-like lesion that is pleural-based , the first impression is that this is a pleural lesion, CT was performed shows a lesion that originates in the lung , many would have a lung cancer on the top of their differential diagnostic list, however there is also some pleural thickening (red arrow) and vessels seem to swirl around the mass (blue arrows) , this is also described as the comet tail sign, whenever you see a pleural-based lesion that looks like a lung cancer , also consider the possibility of rounded atelectasis

CXR shows a density posteriorly in the left lower lobe, on the PA-film this looks like a mass or possibly a consolidation , on the lateral film however the boundaries seem to be sharp which is in favor of a mass , also notice that the pleura is thickened (red arrow) , although a peripheral lung cancer is on top of our list , we now also consider the possibility of rounded atelectasis, CT shows the typical features of a rounded atelectasis , there is an oval mass , pleural thickening and a comet tail sign (arrow) , this lesion did not change in a two-year follow up

4-Plate-like Atelectasis :-Plate-like atelectasis is a common finding on CXR

and detected almost every day-They are characterized by linear shadows of

increased density at the lung bases-They are usually horizontal , measure 1-3 mm in

thickness and are only a few cm long-In most cases these findings have no clinical

significance and are seen in smokers and elderly

5-Cicacitration Atelectasis :-Atelectasis can be the result of fibrosis of

lung tissue-This is seen after radiotherapy and in

chronic infection , especially TB

Patient who was treated with radiotherapy for lung cancer, notice the increased density of the lung tissue and the volume loss

Patient with atelectasis of the right upper lobe as a result of TB , notice the deviation of the trachea

5-Decreased density or lucencies :-Cavity or cyst-See cavitary lung lesions and cystic lung

lesions

7-Pleura :a) Pleural Fluidb) Pneumothoraxc) Pleural Opacities

a) Pleural Fluid :-It takes about 200-300 ml of fluid before it

comes visible on an CXR-About 5 liters of pleural fluid are present

when there is total opacification of the hemithorax

Total opacification of the right hemithorax in a patient with pleuritis carcinomatosa on both sides

Pleural fluid may become encysted , here we see fluid entrapped within the fissure , this can sometimes give the impression of a mass and is called vanishing tumor

b) Pneumothorax :-Causes :1-Spontaneous : subpleural bleb2-Lung disease : COPD , asthma , cystic

disease (LAM , langerhans CH )3-Trauma : biopsy , central line , mechanical

ventilation , cocaine , marijuana

The retracted visceral pleura is seen (blue arrow) which indicates that there is a pneumothorax There is a horizontal line visible (yellow arrow) , normally there are no straight lines in the human body unless when there is an air-fluid level , this means that there is a hydro-pneumothorax , when a pneumothorax is small , this air-fluid level can be the only key to the diagnosis of a pneumothorax

There is a hydropneumothorax , notice the air-fluid level (blue arrow) here is a lung cyst in the upper lobe (red arrow) , so we can assume that the pneumothorax has something to do with a cystic lung disease

Deep sulcus sign , it represents lucency of the lateral costophrenic angle extending toward the hypochondrium , patient in the ICU who is on mechanical ventilation , there was an acute exacerbation of the dyspnea , there is a deep sulcus sign on the left , notice that the left hemidiaphragm is depressed , this is an important finding since it indicates a tension pneumothorax

Obvious skin folds , not a pneumothorax

c) Pleural Opacities :-May be single or multiple :a) Single pleural opacity :1-Fluid collection :-Loculated pleural effusion , organizing empyema ,

hematoma2-Tumor :-Mesothelioma , mets , neural tumor , lipoma ,

solitary fibrous tumor of the pleura

b) Multiple pleural opacities :1-Pleural plaques :-Asbestos related2-Fluid collection :-Loculated pleural effusion3-Tumor :-Mesothelioma , mets , neural tumors ,

splenosis

Pleural plaques , CXR shows multiple irregular opacities , some of these opacities are clearly bordering the chest wall (red arrows) , asbestos related pleural plaques are usually bilateral and extensive & covering the dome of the diaphragm

Unilateral pleural calcifications are usually due to : infection (TB) , empyema & hemorrhagic

Pleural hematoma , patient who had a pleural opacity after a chest trauma , it was believed to be a hematoma and resolved spontaneously

8-Chest Wall :-The most common identified chest wall

abnormalities are old rib fractures-The second most common chest wall

abnormalities that we see on a CXR are metastases in vertebral bodies and ribs

The CXR shows many rib deformities due to old fractures

When a rib fracture heals , the callus formation may create a mass-like appearance (blue arrow) , notice the large lung volume and the enlarged pulmonary vessels , probably we are dealing with pulmonary arterial hypertension in a patient with COPD

Ribs mets , expansile mass in the posterior rib on the right

9-Abdomen :-Air under diaphragm-This finding indicates a bowel perforation

unless when the patient had recent abdominal surgery and there is still some air left in the abdomen which can stay there for several days

Air under diaphragm , there is another subtle finding in the left upper lobe , a subtle density projecting over the first rib , hidden area , proved to be a lung carcinoma

Patient with free abdominal air , notice the very thin regular line which is the diaphragm (arrow)

10-Support Devices :a) Endotracheal Tubeb) Nasogastric Tubec) Central Venous Catheterd) Chest Drains

a) Endotracheal Tube :-The endotracheal tube tip should be

approximately 4-6 cm above the carina with the neck in neutral alignment

-Direct intubation of either the RT or LT mainstream bronchus (RT mainstream bronchus far more common, more vertically orientated than the left main bronchus) is an emergent finding than can cause complete atelectasis of the un-intubated lung

Tracheobronchial anatomy, the trachea is located on the right side of the aortic knuckle and slightly to the right of the midline, the carina is the point at which the lower edge of left and right main bronchi meet

Tracheostomy Tube

-Complications :1-ET tube misplaced at carina 2-ET tube misplaced in right main bronchus 3-ET tube misplacement with lung collapse4-Barotrauma (Complications of mechanical

ventilation such as pneumothorax, pneumomediastinum and surgical emphysema may be visible on a chest X-ray)

This ET tube tip is incorrectly located at the level of the carina and nearly enters the right main bronchus, although both lungs are currently ventilated there is a risk of intubation of a single bronchus on extension of the neck

The ET tube has entered the right main bronchus

RT mainstream bronchus intubation , CXR shows the endotracheal tube terminating in the RT mainstream bronchus (yellow arrow) , a few centimeters distal to the carina (red arrow)

The ET tube is within the right main bronchus, the tube and its cuff occlude the orifice of the left main bronchus which is not visible, consequently the left lung is not ventilated and has collapsed

The ET tube tip is adequately positioned, 5 cm above the carina, surgical emphysema is readily visible in the soft tissues of the neck on the right, pneumomediastinum (gas in the soft tissues of the mediastinum) is often more difficult to identify, in this image the mediastinum is outlined by a thin white line (arrowheads), this line is the mediastinal pleura which is separated from the mediastinum by gas, these are the typical appearances of pneumomediastinum

b) Nasogastric Tube :-A correctly positioned nasogastric tube passes vertically

down the esophagus into the stomach, as the esophagus is not visible on a plain chest X-ray, it is essential to have an understanding of its anatomical position in relation to other visible structures

-The esophagus passes posteriorly and slightly to the left side of the trachea, the esophagus is located immediately to the right of the aortic knuckle, from this level the esophagus passes down in the midline to the level of the gastro-oesophageal junction which is at the level of the diaphragm

Correct NG tube position-Check the tube passes vertically in the midline, or near the

midline, below the level of the carina (red ring)-The tube MUST NOT follow the course of the right or left

main bronchi-Check the tube continues vertically in the midline down to

the level of the diaphragm where it passes through the gastro-oesophageal junction (orange ring)

-The tip of the tube (green ring) must be visible below the diaphragm and on the left side of the abdomen 10 cm or more beyond the gastro-oesophageal junction

-Complications :1-NG tube misplacement, Looped2-NG tube in right main bronchus3-Tube misplacement in proximal stomach4-Tube misplacement in duodenum

NG tube misplacement (Looped), the tube passes below the level of the carina and does not follow the course of the right or left bronchi, the tube is, therefore, in the esophagus and has not been inhaled, the tube is looped back on itself so its tip is located in the upper esophagus

NG tube in right main bronchus

Tube misplacement in proximal stomach

Tube misplacement in duodenum

c) Central Venous Catheter :-Positioning the tip of a CVC within the superior vena cava

(SVC) at or just above the level of the carina is generally considered acceptable for most short-term uses, such as fluid administration or monitoring of central venous pressure, ideally the distal end of a CVC should be orientated vertically within the SVC

-CVC placed for the purpose of long term chemotherapy may be placed more inferiorly at the cavo-atrial junction, the junction of the SVC and right atrium (RA)

-Catheters used for hemodialysis may be placed at the cavo-atrial junction or even in the RA itself

Superior vena cava (SVC) anatomy-The internal jugular and subclavian veins

join to form the brachiocephalic veins (asterisks)

-The brachiocephalic veins (also known as the innominate veins) join to form the SVC

-The SVC is located to the right side of the mediastinum above and below the level of the carina

The internal jugular and subclavian veins join to form the brachiocephalic veins (asterisks), the brachiocephalic veins (also known as the innominate veins) join to form the SVC, the SVC is located to the right side of the mediastinum above and below the level of the carina

-The lower part of the SVC is surrounded by the pericardial reflection; this is where the upper pericardium folds back on itself to form a sac

-Positioning a CVC tip within the SVC and below the level of the pericardial reflection is associated with a small risk of pericardial tamponade

-Neither the SVC nor the pericardial reflection are visible on a chest X-ray

-As the carina is a visible structure, which is located above the level of the pericardial reflection, it can be used as an anatomical landmark to help determine the level of a CVC tip within the SVC and above the pericardial reflection

The pericardial reflection is located below the level of the carina, the cavo-atrial junction is located approximately the height of two vertebral bodies below the level of the carina

Right-sided catheters-CVCs are most commonly inserted via the

right internal jugular vein, right internal jugular catheters are positioned on the right side of the neck, and pass vertically from a position above the clavicle

-Catheters inserted into the subclavian vein pass below the clavicle and then curve into the SVC

Right internal jugular vein catheter, the catheter is orientated vertically, the tip is projected over the anatomical location of the SVC - approximately 1.5 cm above the level of the carina, this is an ideal position for right-sided catheters for fluid administration and venous pressure monitoring, but not for long-term chemotherapy or dialysis

Right subclavian vein catheter, the catheter passes below the level of the clavicle, the distal catheter is orientated vertically, the tip is located 1 cm above the level of the carina

Left-sided catheters-Left-sided catheters approach the SVC at a

shallow angle such that they may abut the right lateral wall of the SVC

-They may need to be inserted further so the distal end obtains a vertical orientation

-This may mean locating the tip below the level of the carina, in this position the risk of vessel wall erosion is reduced, but with a small increased risk of pericardial tamponade

Left subclavian vein catheter, this left subclavian catheter is located with its tip below the level of the carina, positioning the tube vertically avoids abutment of the tip against the right lateral wall of the SVC

Long-term catheters-Catheters which are used for long-term

administration of chemotherapy drugs (inserted either from the right or left) are usually positioned more inferiorly, at the level of the cavo-atrial junction

Long term catheter-PICC line, this peripherally inserted central catheter (PICC) is correctly located with its tip at the level of the cavo-atrial junction - approximately the height of two vertebral bodies below the level of the carina, this is often considered a preferable location for long-term catheters

-Complications :a) Immediate complications :-Complications such as pneumothorax and surgical

emphysema may arise from traumatic placementb) The X-ray may also be used to identify incorrect

positioning (If catheters are not inserted far enough they may be located in the jugular, subclavian, or brachiocephalic veins, catheters inserted too far may enter the right atrium) and, therefore, help reduce the risk of delayed complications such as pericardial tamponade or vessel wall erosion

Iatrogenic pneumothorax, this right subclavian catheter is adequately positioned with its tip in the superior vena cava, positioning was complicated by pneumothorax due to pleural injury

CVC in left brachiocephalic vein, the tip of this catheter is projected over the left brachiocephalic vein rather than the SVC (superior vena cava)

Catheter in right atrium, this peripherally inserted central catheter (PICC) was aimed to be inserted with its tip at the level of the cavo-atrial junction (the height of two vertebral bodies below the carina), the PICC has been inserted too far with its tip in the right atrium (RA)

Horizontal positioning in SVC, catheters placed via a left-sided approach are prone to being positioned nearly horizontally rather than vertically within the SVC, catheters which contact the lateral wall of the SVC in this way may cause vessel erosion if positioned long term, and should therefore be placed so the tip is orientated vertically

Internal jugular catheter-misplaced, CV catheters may take an incorrect course and end with their tip in completely the wrong place, this left internal jugular catheter has entered the left subclavian vein, the catheter needs to be repositioned, note also the ET tube, the external cardiac monitoring wire, and the lung shadowing - due to pulmonary edema in this case

d) Chest Drains :-A pleural effusion or a pneumothorax can be

treated by positioning a tube into the pleural cavity

-Chest drains are usually inserted through the chest wall in the mid-axillary line

-For treatment of a pneumothorax the tube tip is aimed towards the upper pleural cavity and for treatment of a pleural effusion towards the lower part of the pleural cavity

Chest drain-treatment for pneumothorax-To drain a pneumothorax the tube is aimed

superiorly towards the apex of the pleural cavity

Chest drain-treatment for pneumothorax, a large chest drain is positioned with its tip pointing superiorly within the pleural cavity

Chest drain-close up, chest drains are variable in design, this tube has a radio-opaque tip and a marker strip along the edge, gaps in the marker indicate the position of holes in the side of the tube

Chest drain-treatment for pleural effusion-To drain a pleural effusion the tube tip is

ideally located towards the lower part of the pleural cavity

Chest drain-treatment for pleural effusion, the tube is appropriately placed towards the lower part of the pleural cavity

-Complications :1-Iatrogenic pneumothorax :-Traumatic placement of a chest drain inserted to

treat a pleural effusion, can lead to lung injury and formation of a pneumothorax

2-Surgical emphysema :-Surgical emphysema may result from incorrect

tube positioning such that the end is located within soft tissues of the chest wall, this may also occur if the tube becomes displaced following correct tube placement

Iatrogenic pneumothorax, this chest drain was placed to treat a pleural effusion, the effusion, which was very large, has been nearly completely drained leaving only a relatively small volume of residual fluid, injury to the lung at the time of drain insertion has led to formation of a large pneumothorax

Surgical emphysema, this chest drain is located within soft tissues of the chest wall, there is a pneumothorax (asterisks) and widespread surgical emphysema over the left chest wall