Fig. 12.6: Black and white areas in X-ray.

Criteria of well-penetrated chest X-ray:

A well-penetrated X-ray is one where the thoracic vertebrae are just visible through the heart shadow,

but bony details of spine are not usually seen.

Overpenetrated radiograph (Fig. 12.7) Underpenetrated radiograph (Fig. 12.8)

Fig. 12.7: Overpenetrated radiograph. Fig. 12.8: Underpenetrated radiograph.

In this radiograph, all thoracic vertebrae visible

through the heart shadow.

Lung field darker than normal; may obscure subtle

pathologies.

Inadequate lung detail.

In underpenetrated radiograph you will not able to see thoracic

vertebrae through the heart shadow.

Lung tissue behind the heart cannot be assessed.

Hemidiaphragm is obscured.

Inspiratory versus Expiratory film

Inspiratory film (Fig. 12.9) Expiratory film (Fig. 12.10)

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Fig. 12.9: Inspiratory film. Fig. 12.10: Expiratory film.

Should be able to count 9–10 posterior ribs.

Heart shadow should not be hidden by the

diaphragm.

Poor inspiration can crowd lung markings producing pseudo-airspace

disease.

Expiration reduces lung volume, making a small pneumothorax easier to

see.

Rotation

Fig. 12.11: Normal rotation.

Normal rotation (Fig. 12.11): Medial ends of bilateral clavicles are equidistant from the midline or

vertebral bodies.

Left-rotated film (Fig. 12.12) Right-rotated film (Fig. 12.13)

Fig. 12.12: Left-rotated film. Fig. 12.13: Right-rotated film.

If spinous process appears closer to the right clavicle (red arrow),

the patient is rotated toward their own left side.

If spinous process appears closer to the left clavicle (red arrow),

patient is rotated toward their own right side.

Angulation

Fig. 12.14: Normal angulation.

Normal angulation (Fig. 12.14): Clavicle should lie over the 3rd rib (posterior end). With proper

angulation the apex of lungs are clearly visualized.

Soft tissues and Bony Structures

Soft Tissues (Fig. 12.15)

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Fig. 12.15: Soft tissues.

Soft Tissues

Breast shadows

Supraclavicular areas

Axillae

Tissues along the side of breasts

Bony structures (Fig. 12.16)

Fig. 12.16: Bony structures.

Bony Structures

Ribs

Sternum

Spine

Shoulder girdle

Clavicles

Trachea (Figs. 12.17A and B)

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Fig. 12.17A: Trachea (PA view). Fig. 12.17B: Trachea (lateral view).

Hilum/mediastinum (Fig. 12.18)

Fig. 12.18: Hilum.

Hilum is the wedge-shaped area on the central portion of each lung where the following structures leave the lung.

Bronchi

Pulmonary—arteries, veins and nerves.

Important point:

Left hilar point is usually higher than right.

Diaphragm (Fig. 12.19)

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Fig. 12.19: Diaphragm.

Diaphragm

Dome-shaped

Position:

Right hemidiaphragm is located at 9th–10th rib posteriorly or 6th rib anteriorly

Right hemidiaphragm is higher than the left by 2 cm because the cardia keeps the left hemidiaphragm down

Costophrenic angles

Cardiophrenic angles

Normally the costophrenic and cardiophrenic angles are clear, they are obliterated due to fluid, fat or fibrosis

Height—normally 2.5 cm

When do you say diaphragm is flattened (Figs. 12.20A and B)?

Fig. 12.20A: Normal height of diaphragm. Fig. 12.20B: Flattening of diaphragm.

Draw a line from cardiophrenic angle to costophrenic angle. Now draw a perpendicular onto the line from the highest point of

dome of diaphragm. Measure the height of the perpendicular (red line). If the height is <2.5 cm it suggest flattened diaphragm.

Lung Fields

Lung fields and hilum

Hilum

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Pulmonary arteries

Pulmonary veins

Lungs

Linear and fine nodular shadows of pulmonary vessels

Blood vessels

40% obscured by other tissue

Segments of the Lung

Right lung Left lung

Superior lobe: Apical, posterior, and anterior

Middle lobe: Lateral and medial

Inferior lobe: Superior (apical), medial basal, anterior basal, lateral

basal, and posterior basal

Total: 10 segments on right.

Superior lobe: Apicoposterior, anterior, superior lingular,

and inferior lingular

Inferior lobe: Superior (apical), anterior basal, lateral

basal, and posterior basal

Total: 8 segments on left side.

Zones of Lung (Fig. 12.21)

Fig. 12.21: Two lines are drawn one connecting the anteroinferior end of 2nd rib on both sides and 2nd

connecting the anteroinferior ends of the 4th rib on both sides.

Note: Zones do not correspond to lobes.

Silhouette sign (Fig. 12.22)

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Fig. 12.22: Silhouette sign.

Silhouette sign: It actually denotes the loss of a silhouette; thus, it is sometimes also known as loss of silhouette sign or loss of

outline sign.

Felson defined it as “An intrathoracic lesion touching a border of the heart, aorta, or diaphragm will obliterate that border on

the roentgenogram. An intrathoracic lesion not anatomically contiguous with a border of one of these structures will not obliterate

that border”.

Loss of the anatomic border is described as a positive silhouette sign.

Recognition of this sign is useful in localizing areas of consolidation, atelectasis or mass within the lung, with the loss of these

normal silhouettes on a PA chest X-ray.

Right paratracheal stripe: Right upper lobe

Right heart border: Right middle lobe or medial right lower lobe

Right hemidiaphragm: Right lower lobe

Aortic knuckle: Left upper lobe

Left heart border: Lingular segments of the left upper lobe

Left hemidiaphragm or descending aorta: Left lower lobe.

Cardia (Fig. 12.23)

Fig. 12.23: Cardia. 1: Edge of superior vena

cava; 2: Right atrium; 3: Aortic arch; 4: Edge

of main pulmonary artery; 5: Left atrial

appendage; 6: Left ventricle.

Cardiomegaly (Fig. 12.24)

Fig. 12.24: Cardiomegaly.

The cardiothoracic ratio (CTR) is obtained by dividing the transverse cardiac

diameter [sum of the horizontal distances from the right and left lateral-most margins of the heart to the midline (spinous processes of the vertebral bodies)] by

the maximum internal thoracic diameter.

Cardiomegaly (Fig. 12.24):

Adults: >0.50

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Neonates and elderly: >0.60

Chicken heart: Cardiothoracic ratio less than 25%. Small sized heart.

Causes are:

Bilateral emphysema

Anorexia nervosa

Addison’s disease

Differential diagnosis for gross cardiomegaly (wall-to-wall heart)

Pericardial effusion

Multivalvular heart disease

Severe aortic regurgitation (cor bovinum)

Ebstein’s anomaly

Dilated cardiomyopathy

Chamber/vessel

enlargement

Condition seen

Left atrial

enlargement

Enlarged left atrial appendage causes filling up of normal concavity between pulmonary artery

shadow and the left ventricle.

Double atrial shadow: Border of enlarged left atrium together with right atrial border gives an

appearance like atrium within an atrium.

Straightening of left heart border: Mitralization of heart.

Pushing of left main bronchus upwards causing wide carinal angle (splaying of carina).

Pushing esophagus backwards visible in lateral view of chest X-ray.

Left shift of aorta (Bedford sign).

walking man sign in lateral xray.

Pulmonary

venous/capillary

hypertension

Grade 1: Cephalization (prominence of veins of upper lobe of lung) of pulmonary vasculature

(pulmonary venous pressure ≤20 mm Hg) (reverse moustache sign or Stag’s antler sign).

Grade 2: Kerley’s lines (A, B, C) (pulmonary venous pressure 20–25 mm Hg), peribronchial,

perivascular cuffing.

Kerley A line: Linear opacities extending from the periphery to hilum; they are caused by

distension of anastomotic channels between periphery and central lymphatic’s.

Kerley B line: Short horizontal lines situated perpendicularly to the pleural surface at the lung

base; they represent edema of interlobar septa.

Kerley c line: Reticular opacities at lung base, representing Kerley’s B line.

Grade 3: Batwing opacities (pulmonary venous pressure >25 mm Hg).

Pulmonary arterial

hypertension

Prominent pulmonary outflow tract: enlarged pulmonary arteries (diameter of right descending

pulmonary artery >14 mm in women and >16 mm in men) + pruning of peripheral pulmonary vessels.

Right ventricle Apex forms an acute angle with diaphragm

Right ventricular hypertrophy: In presence of cardiomegaly, acute angle is observed between apex

of enlarged heart and diaphragm.

Sternal contact sign: Earliest and most sensitive sign in the lateral X-ray is obliteration of

Holtzneck’s space, i.e. retrosternal space.

Right atrial

enlargement

Right border >5.5 cm from midline or 3.5 cm from sternal border.

2½ intercostal space in its vertical extent.

>50% vertical height compared with mediastinal height.

Left ventricular

enlargement

Left ventricular enlargement results in cardiomegaly with obtuse left cardiophrenic angle.

Differential diagnosis of consolidation

Based on the chronicity

Acute Chronic

Pneumonia

Aspiration

Edema

Organizing pneumonia

Malignancy

Alveolar proteinosis

Sarcoidosis

Eosinophilic pneumonia

Based on the content

Water filled Pus filled Blood filled

Heart failure

ARDS

Renal failure

Pneumonia Trauma

Vasculitis (good pasture disease, HSP, SLE)

Based on the pattern of involvement

Diffuse disease Pulmonary edema

ARDS

Bronchopneumonia

Diffuse alveolar hemorrhage

Malignancy

Organizing pneumonia

Hypersensitive pneumonitis

Lobar disease Lobar pneumonia

Infarction

Contusion/hemorrhage

Lymphomas

Multiple ill defined Bronchopneumonia

Septic emboli

Metastasis

Lymphomas

Wegener’s granulomatosis

Bat wing appearance Pulmonary edema

Pneumocystis carinii pneumonia

Reverse bat wing appearance Bronchoalveolar carcinoma

Radiation induced

BOOP

Eosinophilic pneumonia

Differential diagnosis of atelectasis

Resorption atelectasis Relaxation atelectasis

Mucus plug

Tumor block

Foreign body obstruction

Pleural effusion

Pneumothorax

Differential diagnosis of Nodule-Mass

Solitary Multiple

Nodule <3 cm Mass >3 cm

Granulomas

Lung carcinoma

Lung carcinoma

Metastatic lesions

Infections (TB/septic emboli/histoplasmosis)

Metastasis

Metastatic lesions

Hamartomas

Hamartomas Sarcoidosis Wegener’s granulomatosis

Rheumatoid nodules

Differential diagnosis of interstitial disease

Based on the pattern

Reticular Nodular

Smooth septal Irregular septal Honeycombing Perilymphatic Centrilobular Random

Pulmonary edema

Lymphangitis

carcinomatosis

Fibrosis

Lymphangitis

carcinomatosis

UIP

Hypersensitive

pneumonitis

Sarcoidosis

Sarcoidosis

Silicosis

Pneumoconiosis

Lymphangitis

carcinomatosis

Endobronchial infection

Pulmonary edema

Tuberculosis and MAC

infections

Miliary TB

Metastases

Fungal

infection

Based on the attenuation

Low attenuation High attenuation (ground glass appearance)

Emphysema Cystic disease Acute Chronic

Centrilobular

Paraseptal

Panlobular

Langerhans cell histiocytosis

Pneumatoceles

Lymphangioleiomyomatosis (LAM)

Lymphocytic interstitial pneumonia (LIP)

Pulmonary edema

Pulmonary hemorrhage

Pneumocystis pneumonia

Fibrosis

Alveolar proteinosis

Differential diagnosis of pleural Opacities

Solitary Multiple

Loculated pleural effusion

Loculated empyema

Malignancy

Pleural plaques (asbestosis)

Loculated pockets of effusions

Sarcoidosis

Silicosis

Metastasis

Differential diagnosis of cavitary lesions (Flowchart 12.1)

Flowchart 12.1: Diagnosis of cavity lesions.

Differential diagnosis of mediastinal masses (Fig. 12.25)

Fig. 12.25: differential diagnosis of mediastinal masses.

Differential diagnosis of hilar mass

Unilateral Bilateral

Infections

Tumors

Vascular aneurysm

Sarcoidosis

Silicosis

Lymphomas

Pulmonary artery hypertension

Hidden areas of lung (Fig. 12.26)

Fig. 12.26: Hidden areas of lung.

Discussion of Common X-rays (Figs. 12.27 to 12.59)

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Fig. 12.27: Chest X-ray PA view showing homogeneous

opacity on the right hemithorax with trachea shifted to same

side suggestive of right-sided collapse/pneumonectomy.

Fig. 12.28: Chest X-ray PA view showing homogeneous

opacity on the left hemithorax with trachea shifted to opposite

side suggestive of left-sided massive pleural effusion

(arrow).

Causes of hemithorax white homogeneous opacity/white-out lung: With no mediastinal shift

Consolidation

Mesothelioma

Fibrothorax With mediastinal shift to opposite side

Pleural effusion (moderate to large)

Diaphragmatic hernia With mediastinal shift to same side

Collapse

Postpneumonectomy

Fig. 12.29: Chest X-ray PA view showing trachea

central, cardiophrenic and costophrenic angles are

normal, homogeneous opacity in right upper zone with

air bronchogram suggestive of right upper lobe

pneumonia.

Fig. 12.30: Chest X-ray PA view showing trachea central,

cardiophrenic and costophrenic angles are normal, homogeneous

opacity in right mid and lower zone with air bronchogram, right heart

border is not clear (silhouette sign) suggestive of right middle lobe

pneumonia.

Fig. 12.31: Chest X-ray PA view showing trachea central,

cardiophrenic and costophrenic angles are normal, nonhomogeneous opacity in bilateral mid and lower zones with air

bronchogram suggestive of bilateral/atypical pneumonia.

Fig. 12.32: Chest X-ray PA view showing trachea central,

cardiophrenic and costophrenic angles are normal, nonhomogeneous opacity in right upper zone with air

bronchogram and bulging horizontal fissure suggestive of

right upper lobe pneumonia due to Klebsiella.

Fig. 12.33: Chest X-ray PA view showing trachea central,

cardiophrenic and costophrenic angles are normal,

nonhomogeneous opacity in left upper zone with cavity with air

crescent sign suggestive of aspergilloma—crescent sign of

Monad.

Fig. 12.34: Chest X-ray PA view showing trachea central,

cardiophrenic and costophrenic angles are normal, thick

walled cavity with air fluid level suggestive of lung

abscess.

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