CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 1 – Foundations of Chest X-Ray Interpretation & Basic Radiological Patterns

1. Introduction to Chest X-Ray (CXR)

A Chest X-ray (CXR) is the most commonly performed radiological investigation worldwide. It is:

Quick
Inexpensive
Widely available
Low radiation exposure
Extremely useful in emergency settings

It is the first-line investigation for:

Respiratory symptoms
Cardiac complaints
Trauma
ICU monitoring
Tuberculosis screening (especially important in countries like Pakistan where TB prevalence is higher)

2. Physics Behind Chest X-Ray

Chest X-ray works on differential absorption of X-rays:

Air → Black (radiolucent)
Fat → Dark grey
Soft tissue → Light grey
Bone → White
Metal → Very white

Understanding densities is essential before recognizing disease patterns.

3. Systematic Approach to Reading Chest X-Ray

To avoid missing findings, always use a structured approach:

A – Airway

B – Breathing (Lungs & Pleura)

C – Cardiac

D – Diaphragm

E – Everything else

Or another common method:

RIPE Assessment:

Rotation
Inspiration
Projection
Exposure

4. Basic Radiological Patterns of Lung Disease

Before discussing diseases, you must understand fundamental patterns seen on chest X-ray:

1. Alveolar Pattern

2. Interstitial Pattern

3. Nodular Pattern

4. Cavitary Pattern

5. Pleural Pattern

6. Atelectatic Pattern

7. Hyperinflation Pattern

These are the building blocks of diagnosis.

5. Alveolar (Airspace) Pattern

Definition:

Filling of alveoli with:

Fluid
Pus
Blood
Cells
Protein

Radiological Features:

Homogeneous opacity
Air bronchogram sign
Silhouette sign
Rapid appearance
Fluffy margins

Common Causes:

Pneumonia
Pulmonary edema
ARDS
Hemorrhage

6. Interstitial Pattern

Definition:

Involvement of lung interstitium.

Radiological Features:

Reticular pattern
Nodular pattern
Reticulonodular pattern
Septal lines
Honeycombing (late stage)

Causes:

Interstitial lung disease
Pulmonary fibrosis
TB (miliary pattern)
Sarcoidosis
Lymphangitic carcinomatosis

7. Nodular Pattern

Types:

Solitary pulmonary nodule
Multiple nodules
Miliary pattern
Cannonball metastases

Causes:

Primary lung tumor
Metastasis
TB
Fungal infections

8. Cavitary Pattern

Definition:

Gas-filled space within lung consolidation or mass.

Causes:

Tuberculosis
Lung abscess
Squamous cell carcinoma
Fungal infection

Upper lobe cavities strongly suggest TB.

9. Pleural Pattern

Includes:

Pleural effusion
Pneumothorax
Hydropneumothorax
Pleural thickening

Key Signs:

Meniscus sign
Blunting of costophrenic angle
Deep sulcus sign (supine pneumothorax)

10. Atelectasis Pattern

Features:

Volume loss
Shift of mediastinum towards lesion
Elevated diaphragm
Crowding of ribs

Causes:

Mucus plug
Tumor
Compression

11. Hyperinflation Pattern

Features:

Flattened diaphragm
Increased lung lucency
Increased retrosternal air space
Barrel chest appearance

Causes:

COPD
Asthma
Emphysema

12. Silhouette Sign (Important Concept)

Loss of border between:

Heart and lung
Diaphragm and lung

Helps localize disease.

Example:

Loss of right heart border → Right middle lobe pneumonia

13. Air Bronchogram Sign

Visible air-filled bronchi due to surrounding alveolar filling.

Seen in:

Pneumonia
Pulmonary edema
ARDS

14. Summary of Part 1

In this part we covered:

Basic CXR interpretation
Systematic reading approach
Fundamental radiological patterns
Core signs like air bronchogram & silhouette sign

These patterns are the foundation for diagnosing:

Infections
TB
Tumors
Pleural disease
Interstitial disease
Cardiac conditions

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 2 – Infectious Lung Diseases (Radiological Patterns)

In this section, we will discuss infection-related radiological patterns seen on chest X-ray. This is extremely important clinically, especially in countries like Pakistan where infectious lung diseases such as tuberculosis remain highly prevalent.

We will cover:

Community Acquired Pneumonia
Lobar vs Bronchopneumonia
Atypical Pneumonia
Tuberculosis (Primary & Post-Primary)
Miliary Tuberculosis
Fungal Infections
Lung Abscess
COVID-19 Pattern
Complications of Infectious Diseases

1. Community Acquired Pneumonia (CAP)

Definition:

Acute infection of lung parenchyma.

Classic Radiological Pattern:

Homogeneous lobar opacity
Air bronchogram sign
Silhouette sign
No volume loss

Lobar Distribution:

Right lower lobe → Most common
Right middle lobe → Loss of right heart border
Left lower lobe → Loss of left diaphragm border

Key Diagnostic Points:

Sharp fissure boundaries
Rapid onset
Clears within weeks after treatment

2. Bronchopneumonia

Pattern:

Patchy bilateral opacities
Ill-defined margins
Multiple lobes involved

Common Causes:

Staphylococcus
Gram-negative bacteria
Hospital-acquired infections

Distinguishing Feature:

Unlike lobar pneumonia, it does NOT respect lobar boundaries.

3. Atypical Pneumonia

Causes:

Mycoplasma
Viral infections
Legionella

Radiological Features:

Interstitial pattern
Reticulonodular shadowing
Minimal consolidation
Sometimes normal early CXR

Clinical symptoms are often worse than X-ray findings.

4. Tuberculosis (TB)

Primary Tuberculosis

Features:

Lower lobe consolidation
Hilar lymphadenopathy
Ghon focus
Pleural effusion (sometimes)

Common in children and immunocompromised patients.

Post-Primary (Reactivation) Tuberculosis

Classic Pattern:

Upper lobe cavitation
Fibrosis
Volume loss
Traction bronchiectasis

Highly infectious stage.

Upper lobe involvement is due to high oxygen tension.

5. Miliary Tuberculosis

Appearance:

Diffuse tiny nodules
1–3 mm size
Uniform distribution

Described as: "Millet seed appearance"

Indicates hematogenous spread.

6. Fungal Infections

Common Types:

Aspergilloma
Histoplasmosis
Coccidioidomycosis

Radiological Signs:

Fungus ball in cavity
Air crescent sign
Nodular lesions
Cavities

Often seen in immunocompromised patients.

7. Lung Abscess

Key Radiological Feature:

Thick-walled cavity
Air-fluid level
Surrounding consolidation

Common Causes:

Aspiration
Anaerobic infection

Distinguish from TB:

Abscess has fluid level
TB cavity usually does not

8. COVID-19 Pattern

Radiological Features:

Bilateral peripheral opacities
Lower lobe predominance
Ground glass appearance
Progressive diffuse involvement

Severe cases resemble ARDS:

White-out lungs
Symmetrical involvement

9. Complications of Infectious Lung Disease

1. Parapneumonic Effusion

Blunting of costophrenic angle

2. Empyema

Loculated pleural opacity

3. Pneumothorax

Especially in TB

4. Bronchiectasis

Chronic infection result

5. Fibrosis

Volume loss

10. Radiological Clues for Exams (MBBS / FCPS / USMLE)

Upper lobe cavity → Think TB
Air-fluid level → Abscess
Bilateral patchy opacities → Bronchopneumonia
Miliary nodules → Hematogenous TB
Peripheral bilateral opacities → COVID
Air crescent sign → Fungal ball

Summary of Part 2

In infectious diseases, chest X-ray patterns can be categorized as:

Alveolar consolidation
Patchy bronchopneumonia
Interstitial infiltrates
Cavitary lesions
Miliary nodules
Pleural involvement

Correct interpretation depends on:

Pattern recognition
Distribution
Clinical history

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 3 – Obstructive Lung Diseases (Radiological Patterns)

Obstructive lung diseases are characterized by airflow limitation, leading to air trapping and hyperinflation. On chest X-ray, the dominant pattern is usually hyperinflation, but each disease has distinguishing features.

We will cover:

Chronic Obstructive Pulmonary Disease (COPD)
Emphysema (Centrilobular & Panlobular)
Chronic Bronchitis
Bronchial Asthma
Bronchiectasis
Small Airway Disease
Acute Exacerbations
Complications (Bullae, Pneumothorax)

1. Chronic Obstructive Pulmonary Disease (COPD)

Definition:

Progressive airflow limitation, commonly due to smoking.

Classic Radiological Features:

Hyperinflated lungs
Flattened diaphragm
Increased intercostal spaces
Increased retrosternal air space (on lateral view)
Narrow elongated cardiac shadow

Important Exam Point:

More than 6 anterior ribs visible = hyperinflation.

2. Emphysema

Emphysema is destruction of alveolar walls.

A. Centrilobular Emphysema

Common in smokers.

B. Panlobular Emphysema

Associated with alpha-1 antitrypsin deficiency.

Radiological Features:

Hyperlucent lungs
Decreased vascular markings
Bullae formation
Flattened diaphragm

Bullae:

Thin-walled air-filled spaces >1 cm.

Large bullae can mimic pneumothorax.

3. Chronic Bronchitis

Defined clinically (productive cough >3 months/year for 2 years).

Radiological Features:

Increased bronchovascular markings
Peribronchial cuffing
“Dirty chest” appearance
Mild hyperinflation

Unlike emphysema:

Less destruction
More airway wall thickening

4. Bronchial Asthma

Key Concept:

Chest X-ray may be NORMAL in mild asthma.

During Acute Attack:

Hyperinflation
Flattened diaphragm
Increased lung lucency

In severe cases:

Pneumothorax
Pneumomediastinum

5. Bronchiectasis

Irreversible dilation of bronchi.

Radiological Signs:

Tram-track appearance
Ring shadows
Thickened bronchial walls
Cystic spaces
Lower lobe predominance

Often secondary to:

Previous infection
TB
Cystic fibrosis

6. Small Airway Disease

Also called bronchiolitis.

Radiological Features:

Hyperinflation
Mosaic attenuation (better on CT)
Air trapping

Often subtle on CXR.

7. Acute Exacerbation Patterns

In COPD or asthma exacerbation:

Marked hyperinflation
Flattened diaphragm
Possible superimposed infection
Increased perihilar markings

Important to rule out:

Pneumonia
Pneumothorax
Pulmonary embolism

8. Complications of Obstructive Lung Disease

1. Giant Bullae

May compress adjacent lung.

2. Secondary Pneumothorax

Features:

Absent peripheral lung markings
Visible pleural line
Mediastinal shift (if tension)

Emergency condition.

9. Differentiating Obstructive Patterns

Feature	Emphysema	Chronic Bronchitis	Asthma
Hyperinflation	Marked	Mild	During attack
Vascular markings	Decreased	Increased	Normal
Bullae	Common	Rare	Rare
CXR normal?	Rare	Rare	Common

10. Key Exam Pearls

Flattened diaphragm → Think COPD
Increased retrosternal space → Emphysema
Tram-track sign → Bronchiectasis
Hyperlucent lung with absent markings → Pneumothorax
Normal CXR does not exclude asthma

Summary of Part 3

Obstructive lung diseases primarily show:

Hyperinflation
Air trapping
Flattened diaphragm
Bullae
Increased or decreased vascular markings depending on pathology

Pattern recognition helps distinguish:

Emphysema
Chronic bronchitis
Asthma
Bronchiectasis

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 4 – Restrictive & Interstitial Lung Diseases

Restrictive lung diseases are characterized by reduced lung expansion and decreased lung volumes. On chest X-ray, the dominant pattern is usually interstitial involvement, fibrosis, or diffuse opacification.

In this section we will cover:

Interstitial Lung Disease (ILD) – General Pattern
Idiopathic Pulmonary Fibrosis (IPF)
Sarcoidosis
Occupational Lung Diseases (Pneumoconiosis)
Acute Respiratory Distress Syndrome (ARDS)
Connective Tissue Disease-Related Lung Disease
Hypersensitivity Pneumonitis
Drug-Induced Lung Disease

1. Interstitial Lung Disease (ILD) – General Pattern

Radiological Features:

Reticular pattern
Reticulonodular opacities
Reduced lung volumes
Basal predominance
Honeycombing (late stage)

Key Concept:

Unlike obstructive disease → lungs are NOT hyperinflated.
Instead → lungs appear smaller with fibrosis.

2. Idiopathic Pulmonary Fibrosis (IPF)

Classic Pattern:

Bilateral basal reticular opacities
Honeycomb appearance
Traction bronchiectasis
Volume loss

Important Exam Clue:

Lower lobe fibrosis + honeycombing → Think IPF.

3. Sarcoidosis

Hallmark Feature:

Bilateral hilar lymphadenopathy (BHL)

Stages (Radiological):

Stage 1 → BHL only
Stage 2 → BHL + interstitial infiltrates
Stage 3 → Interstitial disease only
Stage 4 → Fibrosis

Exam Point:

Young patient + bilateral hilar enlargement → Think sarcoidosis.

4. Occupational Lung Diseases (Pneumoconiosis)

A. Silicosis

Radiological Features:

Upper lobe nodules
Eggshell calcification of lymph nodes
Progressive massive fibrosis

B. Asbestosis

Features:

Lower lobe fibrosis
Pleural plaques
Pleural calcification
Diaphragm involvement

Key difference: Silicosis → Upper lobe
Asbestosis → Lower lobe

5. Acute Respiratory Distress Syndrome (ARDS)

Radiological Features:

Bilateral diffuse opacities
“White-out” lungs
No cardiomegaly
No pleural effusion (usually minimal)

Distinguish from cardiogenic edema: Heart size is normal in ARDS.

6. Connective Tissue Disease (CTD) Lung Involvement

Seen in:

Rheumatoid arthritis
Systemic lupus
Systemic sclerosis

Features:

Interstitial fibrosis
Reticular opacities
Basal predominance
Honeycombing (advanced)

7. Hypersensitivity Pneumonitis

Radiological Pattern:

Diffuse reticulonodular shadowing
Ground-glass appearance
Mid-lung predominance

Associated with:

Bird exposure
Mold exposure

8. Drug-Induced Lung Disease

Common drugs:

Amiodarone
Methotrexate
Bleomycin

Pattern:

Interstitial infiltrates
Fibrosis
Diffuse opacities

Always consider medication history.

9. Differentiating Interstitial Patterns

Feature	IPF	Sarcoidosis	Silicosis	Asbestosis
Lobe Predominance	Lower	Upper/Mid	Upper	Lower
Hilar Nodes	Rare	Common	Common	Rare
Pleural Plaques	No	No	No	Yes
Honeycombing	Yes	Late	Late	Possible

10. Key Exam Pearls

Bilateral hilar lymphadenopathy → Sarcoidosis
Eggshell calcification → Silicosis
Pleural plaques → Asbestosis
White-out lungs with normal heart → ARDS
Basal fibrosis + honeycombing → IPF

Summary of Part 4

Restrictive and interstitial lung diseases typically show:

Reduced lung volumes
Reticular or reticulonodular patterns
Honeycombing
Fibrosis
Bilateral involvement

Recognizing distribution (upper vs lower lobe) is crucial for diagnosis.

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 5 – Pleural Diseases & Mediastinal Pathologies

Pleural and mediastinal abnormalities are very common on chest X-ray and often produce dramatic radiological patterns. Recognition of these patterns is crucial in emergency and clinical practice.

In this section we will cover:

Pleural Effusion
Pneumothorax
Tension Pneumothorax
Hemothorax
Empyema
Pleural Thickening & Plaques
Mediastinal Widening
Mediastinal Masses (Anterior, Middle, Posterior)
Lymphadenopathy
Aortic Pathology

1. Pleural Effusion

Definition:

Accumulation of fluid in pleural space.

Radiological Features:

Blunting of costophrenic angle
Meniscus sign
Homogeneous opacity
Mediastinal shift (if massive)

Types:

Transudative (e.g., heart failure)
Exudative (e.g., infection, malignancy)

Exam Tip:

500 ml fluid needed to blunt CP angle on PA view.

2. Pneumothorax

Definition:

Air in pleural cavity.

Radiological Signs:

Visible pleural line
No lung markings beyond line
Hyperlucent area

Types:

Primary spontaneous
Secondary (COPD, TB)
Traumatic

3. Tension Pneumothorax (Emergency)

Features:

Mediastinal shift away from affected side
Collapsed lung
Depressed diaphragm

Life-threatening emergency.

4. Hemothorax

Cause:

Blood in pleural cavity.

Radiological Pattern:

Similar to pleural effusion.

Clinical context (trauma) is key.

5. Empyema

Features:

Loculated pleural opacity
Lenticular shape
Does not change with position

Distinguish from lung abscess: Empyema forms obtuse angle with chest wall.

6. Pleural Thickening & Plaques

Causes:

Previous infection
TB
Asbestos exposure

Features:

Irregular pleural opacity
Calcified plaques
Reduced lung expansion

7. Mediastinal Widening

Causes:

Aortic dissection
Lymphoma
Thymoma
Massive lymphadenopathy
Trauma

Exam Rule:

Widened mediastinum in trauma → suspect aortic injury.

8. Mediastinal Masses

Anterior Mediastinum (4 T’s):

Thymoma
Teratoma
Thyroid mass
“Terrible” lymphoma

Middle Mediastinum:

Lymphadenopathy
Bronchogenic cyst

Posterior Mediastinum:

Neurogenic tumors

9. Lymphadenopathy

Causes:

Sarcoidosis
TB
Lymphoma
Metastasis

Key Pattern:

Symmetrical bilateral hilar enlargement → Sarcoidosis.

10. Aortic Pathology

Features:

Widened mediastinum
Enlarged aortic knob
Tracheal deviation
Pleural effusion (possible in rupture)

Emergency suspicion → CT confirmation.

Differentiating Pleural & Mediastinal Patterns

Condition	Key Sign	Mediastinal Shift
Massive Effusion	Meniscus	Away
Tension Pneumothorax	Pleural line	Away
Atelectasis	Volume loss	Toward
Empyema	Loculated	Minimal
Fibrosis	Pleural thickening	Toward

Key Exam Pearls

Blunted CP angle → Effusion
Absent lung markings → Pneumothorax
Widened mediastinum in trauma → Aortic injury
Bilateral hilar enlargement → Sarcoidosis
Obtuse angle with chest wall → Empyema

Summary of Part 5

Pleural and mediastinal diseases show:

Fluid patterns
Air patterns
Loculated opacities
Widened mediastinum
Shift of structures

Understanding mediastinal movement (toward vs away) is crucial for diagnosis.

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 6 – Cardiac Causes & Pulmonary Vascular Patterns

Cardiac diseases often produce secondary changes in the lungs and pulmonary vasculature that are clearly visible on chest X-ray. Recognizing these patterns is extremely important for MBBS exams, FCPS, USMLE, and clinical practice.

In this section we will cover:

Cardiomegaly
Congestive Heart Failure (CHF)
Cardiogenic Pulmonary Edema
Pulmonary Hypertension
Congenital Heart Disease Patterns
Pericardial Effusion
Pulmonary Embolism Patterns
Cardiac Valve Disease Effects

1. Cardiomegaly

Definition:

Enlarged cardiac silhouette on chest X-ray.

Diagnostic Rule:

Cardiothoracic ratio > 50% (on PA view).

Causes:

Hypertension
Dilated cardiomyopathy
Valvular disease
Pericardial effusion

Important: AP view can falsely enlarge the heart.

2. Congestive Heart Failure (CHF)

Early Radiological Signs:

Cardiomegaly
Upper lobe venous diversion
Pulmonary vascular redistribution

Interstitial Edema:

Kerley B lines
Peribronchial cuffing
Hazy lung fields

3. Cardiogenic Pulmonary Edema

Classic Pattern:

“Bat-wing” or “Butterfly” pattern.

Features:

Bilateral perihilar opacities
Cardiomegaly
Pleural effusion
Kerley B lines

Distinguish from ARDS: Heart enlarged in cardiogenic edema.

4. Pulmonary Hypertension

Radiological Signs:

Enlarged central pulmonary arteries
Pruning of peripheral vessels
Right ventricular enlargement

Common Causes:

Chronic lung disease
Congenital heart disease
Chronic thromboembolism

5. Congenital Heart Disease Patterns

Certain congenital heart diseases have classic X-ray appearances.

A. Tetralogy of Fallot

Classic Sign:

Boot-shaped heart (“Coeur en sabot”).

B. Transposition of Great Arteries

Classic Appearance:

Egg-on-a-string sign.

C. Atrial Septal Defect (ASD)

Enlarged right atrium
Enlarged pulmonary arteries

6. Pericardial Effusion

Classic Sign:

Water-bottle shaped heart.

Key Points:

Symmetrical enlargement
Rapid enlargement possible
No pulmonary congestion (unless heart failure present)

7. Pulmonary Embolism (Indirect Signs)

Chest X-ray may be normal.

But possible findings:

Signs:

Westermark sign (oligemia)
Hampton hump (wedge infarct)
Elevated hemidiaphragm

CXR mainly used to rule out other causes.

8. Valve Disease Radiological Patterns

Mitral Stenosis:

Left atrial enlargement
Straightened left heart border
Pulmonary venous congestion

Aortic Stenosis:

Left ventricular enlargement

Tricuspid Disease:

Right atrial enlargement

Differentiating Cardiac vs Non-Cardiac Edema

Feature	Cardiogenic Edema	ARDS
Heart Size	Enlarged	Normal
Pleural Effusion	Common	Minimal
Distribution	Perihilar	Diffuse
Kerley B lines	Present	Rare

Key Exam Pearls

Cardiothoracic ratio >50% → Cardiomegaly
Bat-wing pattern + enlarged heart → CHF
Boot-shaped heart → Tetralogy
Water-bottle heart → Pericardial effusion
Enlarged pulmonary arteries + pruning → Pulmonary hypertension

Summary of Part 6

Cardiac diseases on chest X-ray show:

Enlarged cardiac silhouette
Vascular redistribution
Interstitial and alveolar edema
Characteristic congenital shapes
Pulmonary vascular changes

Understanding heart-lung interaction is crucial for diagnosis.

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 7 – Lung Tumors & Neoplastic Patterns

Neoplastic diseases of the chest produce mass lesions, nodules, cavitation, lymphadenopathy, collapse, and pleural involvement on chest X-ray. Pattern recognition is crucial for early diagnosis.

In this section we will cover:

Solitary Pulmonary Nodule (SPN)
Primary Lung Carcinoma
Small Cell vs Non-Small Cell Patterns
Pancoast Tumor
Metastatic Lung Disease
Lymphoma
Carcinoid Tumor
Paraneoplastic Radiological Clues

1. Solitary Pulmonary Nodule (SPN)

Definition:

Single, well-defined opacity <3 cm.

Benign Features:

Smooth margins
Calcification
Stable over 2 years

Malignant Features:

Irregular or spiculated margins
No calcification
Increase in size

Classic term: “Coin lesion”

2. Primary Lung Carcinoma

Radiological Patterns:

Large irregular mass
Hilar enlargement
Cavitation
Lobar collapse
Pleural effusion

May cause:

Obstructive atelectasis
Post-obstructive pneumonia

3. Small Cell vs Non-Small Cell Lung Cancer

Small Cell Carcinoma:

Central/hilar mass
Rapid growth
Lymphadenopathy common

Non-Small Cell Carcinoma:

Often peripheral
Larger solitary mass
May cavitate

4. Pancoast Tumor (Superior Sulcus Tumor)

Location:

Lung apex.

Radiological Clues:

Apical opacity
Rib destruction
Clavicular involvement

Associated with:

Shoulder pain
Horner syndrome

5. Metastatic Lung Disease

Classic Appearance:

“Cannonball metastases”

Primary Sources:

Kidney
Breast
Colon
Thyroid

Pattern: Multiple well-circumscribed nodules.

6. Lymphoma

Radiological Features:

Mediastinal widening
Large anterior mediastinal mass
Hilar lymphadenopathy

Common in young patients.

7. Carcinoid Tumor

Features:

Central endobronchial mass
Recurrent pneumonia
Segmental collapse

Usually slow-growing.

8. Tumor-Related Radiological Complications

1. Atelectasis:

Due to bronchial obstruction.

2. Pleural Effusion:

Malignant effusion.

3. Superior Vena Cava Syndrome:

Mediastinal mass compressing SVC.

9. Differentiating Neoplastic Patterns

Pattern	Likely Diagnosis
Single coin lesion	Primary tumor
Multiple round nodules	Metastasis
Central hilar mass	Small cell carcinoma
Apical mass	Pancoast tumor
Mediastinal widening	Lymphoma

10. Key Exam Pearls

Spiculated mass → Malignancy
Upper lobe cavity + smoker → Squamous cell carcinoma
Cannonball lesions → Metastasis
Apical opacity + shoulder pain → Pancoast
Rapidly enlarging hilar mass → Small cell carcinoma

Summary of Part 7

Neoplastic patterns on chest X-ray include:

Nodules
Masses
Cavitation
Collapse
Lymphadenopathy
Pleural effusion

Distribution (central vs peripheral) helps narrow diagnosis.

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 8 – Trauma & Emergency Radiological Patterns

Chest trauma is a major cause of morbidity and mortality. Chest X-ray is usually the first imaging modality performed in emergency settings.

In this section we will cover:

Rib Fractures
Flail Chest
Pulmonary Contusion
Pneumothorax (Traumatic)
Hemothorax
Pneumomediastinum
Diaphragmatic Rupture
Foreign Bodies
Subcutaneous Emphysema
ICU & Line-Related Complications

1. Rib Fractures

Radiological Features:

Discontinuity of rib cortex
Step deformity
Localized tenderness clinically

Important:

Lower rib fractures → suspect abdominal organ injury.
First rib fracture → high-energy trauma.

2. Flail Chest

Definition:

Multiple adjacent ribs fractured in ≥2 places.

Radiological Clue:

Segmental rib fractures.

Associated with:

Pulmonary contusion
Respiratory failure

3. Pulmonary Contusion

Features:

Patchy, ill-defined opacities
No clear lobar boundaries
Appear within hours after trauma

Distinguish from pneumonia: Contusion appears rapidly after trauma.

4. Traumatic Pneumothorax

Radiological Signs:

Visible pleural line
Absent peripheral lung markings
Hyperlucent hemithorax

Often associated with rib fractures.

5. Hemothorax

Features:

Homogeneous opacity
Blunting of CP angle
Mediastinal shift (if massive)

Clinical context is essential.

6. Pneumomediastinum

Radiological Signs:

Air outlining heart borders
Continuous diaphragm sign
Lucent streaks in mediastinum

Causes:

Trauma
Esophageal rupture
Severe asthma

7. Diaphragmatic Rupture

Features:

Elevated hemidiaphragm
Abdominal organs in chest
Nasogastric tube seen in thorax

More common on left side.

8. Foreign Bodies

Findings:

Radiopaque object
Air trapping (if radiolucent object)
Unilateral hyperinflation

Common in children.

9. Subcutaneous Emphysema

Radiological Appearance:

Streaky lucencies in soft tissue
Air in neck or chest wall

Often associated with pneumothorax.

10. ICU & Line-Related Complications

Common lines:

Endotracheal tube
Central venous catheter
Chest tube

Check for:

Proper tube placement
Pneumothorax
Misplacement into right main bronchus
Perforation

ET tube tip should be 3–5 cm above carina.

Differentiating Trauma Patterns

Finding	Likely Cause
Patchy opacity after trauma	Contusion
Pleural line + hyperlucent area	Pneumothorax
Homogeneous pleural opacity	Hemothorax
Air in mediastinum	Pneumomediastinum
Rib discontinuity	Fracture

Key Exam Pearls

First rib fracture → severe trauma
Left diaphragm rupture → stomach in chest
Continuous diaphragm sign → pneumomediastinum
Subcutaneous air → suspect underlying pneumothorax
Always assess tubes in ICU patients

Summary of Part 8

Trauma patterns on chest X-ray include:

Bone injury
Air leaks
Fluid accumulation
Soft tissue air
Organ displacement
Device-related complications

Rapid recognition is life-saving.

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 9 – Pediatric Chest X-Ray Patterns

Pediatric chest X-rays differ significantly from adult films because of:

Thymic shadow
Smaller thoracic cavity
Higher incidence of congenital anomalies
Different infection patterns

In this section we will cover:

Normal Pediatric Chest & Thymus
Neonatal Respiratory Distress Syndrome (Hyaline Membrane Disease)
Meconium Aspiration Syndrome
Transient Tachypnea of Newborn (TTN)
Pediatric Pneumonia Patterns
Foreign Body Aspiration
Congenital Diaphragmatic Hernia
Congenital Lung Malformations
Pediatric Cardiac Patterns

1. Normal Pediatric Chest & Thymus

Key Features:

Prominent thymus
“Sail sign” appearance
Heart appears relatively large
Ribs more horizontal

Important: Do not mistake thymus for mediastinal mass.

2. Neonatal Respiratory Distress Syndrome (Hyaline Membrane Disease)

Seen in:

Premature infants (surfactant deficiency).

Radiological Features:

Ground-glass appearance
Air bronchograms
Low lung volumes
Diffuse bilateral opacities

3. Meconium Aspiration Syndrome

Seen in:

Term or post-term infants.

Radiological Pattern:

Patchy infiltrates
Hyperinflation
Areas of atelectasis
Possible pneumothorax

4. Transient Tachypnea of Newborn (TTN)

Features:

Prominent vascular markings
Fluid in fissures
Mild hyperinflation

Usually resolves within 48–72 hours.

5. Pediatric Pneumonia Patterns

Common Patterns:

1. Lobar pneumonia

2. Bronchopneumonia

3. Viral pneumonia (interstitial)

4. Round pneumonia (children only)

Round pneumonia appears as circular opacity.

6. Foreign Body Aspiration

Signs:

Unilateral hyperinflation
Mediastinal shift
Air trapping
Visible radiopaque object

Common in toddlers.

7. Congenital Diaphragmatic Hernia (CDH)

Features:

Bowel loops in thorax
Mediastinal shift
Absent abdominal gas

Usually left-sided.

8. Congenital Lung Malformations

A. Congenital Pulmonary Airway Malformation (CPAM)

Features:

Cystic lung lesion
Unilateral opacity

B. Pulmonary Sequestration

Abnormal lung tissue mass
Often lower lobe

9. Pediatric Cardiac Patterns

A. Tetralogy of Fallot

Boot-shaped heart.

B. Ventricular Septal Defect (VSD)

Cardiomegaly
Pulmonary plethora

Differentiating Neonatal Patterns

Condition	Lung Volume	Opacity Pattern
RDS	Low	Diffuse ground glass
Meconium Aspiration	High	Patchy
TTN	Normal/High	Mild interstitial
CDH	Variable	Bowel loops in chest

Key Exam Pearls

Sail sign → Normal thymus
Ground glass + low lung volume → RDS
Patchy + hyperinflation → Meconium aspiration
Round opacity in child → Round pneumonia
Unilateral hyperinflation → Foreign body

Summary of Part 9

Pediatric chest X-ray patterns differ due to:

Developmental anatomy
Neonatal lung physiology
Congenital anomalies
Unique infection patterns

Recognition of neonatal respiratory patterns is critical in emergency settings.

CHEST X-RAY DISEASE RELATED RADIOLOGICAL PATTERNS

Part 10 – Systematic Pattern-Based Diagnostic Approach & High-Yield Review

This section integrates everything from Parts 1–9 into a practical, exam-focused, and clinically applicable diagnostic framework.

We will cover:

Step-by-Step Interpretation Algorithm
Pattern-Based Diagnostic Approach
Opacity-Based Differentiation
Hyperlucency-Based Differentiation
Mediastinal Shift Logic
Emergency Recognition Strategy
High-Yield Exam Tables
Common Pitfalls
Rapid Revision Summary
Final Clinical Integration

1. The Universal 7-Step Chest X-Ray Interpretation Method

Always follow this order:

Step 1: Confirm Patient & View

Name, age
PA vs AP
Erect vs supine

Step 2: RIPE Check

Rotation
Inspiration (≥6 anterior ribs)
Projection
Exposure

Step 3: Airway

Trachea midline?
Carina visible?

Step 4: Breathing (Lungs)

Symmetry
Opacities
Nodules
Cavities

Step 5: Cardiac

Cardiothoracic ratio
Shape abnormality

Step 6: Diaphragm

Costophrenic angles
Elevation

Step 7: Everything Else

Ribs
Soft tissues
Tubes & lines

2. Pattern-Based Diagnostic Approach

Instead of memorizing diseases, recognize patterns first, then think of causes.

A. Alveolar (Airspace) Pattern

Causes:

Pneumonia
Pulmonary edema
ARDS
Hemorrhage

Clue: Air bronchogram present.

B. Interstitial Pattern

Causes:

Fibrosis
Sarcoidosis
TB
Drug toxicity

Clue: Fine reticular or nodular lines.

C. Cavitary Lesion

Think:

TB (upper lobe)
Abscess (fluid level)
Squamous carcinoma

D. Hyperlucent Hemithorax

Causes:

Pneumothorax
Emphysema
Foreign body (child)

E. Pleural Opacity

Clues:

Meniscus → Effusion
Obtuse angle → Empyema
Calcification → Old TB/asbestos

3. Mediastinal Shift Logic

Condition	Shift Direction
Massive effusion	Away
Tension pneumothorax	Away
Atelectasis	Toward
Fibrosis	Toward
Large mass	Away (sometimes)

This is one of the most important exam concepts.

4. Cardiogenic vs Non-Cardiogenic Opacity

Feature	CHF	ARDS
Heart size	Enlarged	Normal
Distribution	Perihilar	Diffuse
Pleural effusion	Common	Rare

Bat-wing pattern + cardiomegaly → CHF.

5. Emergency Recognition Strategy

Immediately identify:

1. Tension Pneumothorax

Pleural line
Shift away
Collapsed lung

2. Massive Hemothorax

White-out hemithorax
Trauma history

3. Aortic Injury

Widened mediastinum

4. ARDS

Diffuse white lungs
Normal heart

5. Diaphragmatic Rupture

Bowel in chest

6. High-Yield Rapid Diagnosis Table

Finding	Most Likely Diagnosis
Upper lobe cavity	TB
Boot-shaped heart	Tetralogy
Water-bottle heart	Pericardial effusion
Cannonball lesions	Metastasis
Egg-on-string	Transposition
Eggshell calcification	Silicosis
Pleural plaques	Asbestosis
Tram-track sign	Bronchiectasis
Kerley B lines	CHF
Round opacity child	Round pneumonia

7. Common Pitfalls

Mistaking thymus for mass (child)
Misinterpreting AP film cardiomegaly
Missing small apical pneumothorax
Ignoring subtle rib fractures
Confusing bulla with pneumothorax
Missing medical devices malposition

8. Integrated Clinical Correlation Strategy

Always correlate:

Age
Smoking history
Trauma
TB exposure
ICU status
Immune status
Occupation

Pattern + Clinical History = Diagnosis

9. Complete Pattern Master Summary

Chest X-ray disease patterns fall into 8 major groups:

Alveolar
Interstitial
Nodular
Cavitary
Pleural
Hyperinflation
Cardiac/Vascular
Traumatic

Every disease discussed in Parts 1–9 fits into one or more of these categories.

10. Final Takeaway

Mastering chest X-ray interpretation requires:

Systematic approach
Pattern recognition
Understanding mediastinal shift
Recognizing emergency signs
Clinical correlation

If you can:

Identify pattern
Determine distribution
Assess heart size
Evaluate shift

You can diagnose most chest conditions confidently.

ADVANCED CHEST X-RAY DISEASE PATTERN EXPANSION

Section 11 – Deep Pattern Analysis & Advanced Interpretation

1️⃣ Advanced Alveolar Pattern Analysis

A. Segmental vs Lobar Consolidation

Lobar consolidation

Respects fissures
Dense homogeneous opacity
Clear anatomical boundaries

Segmental consolidation

Irregular
Does not respect fissures
Often bronchopneumonia

B. Air Bronchogram – Deeper Understanding

Air bronchogram occurs when:

Bronchi are air-filled
Alveoli are fluid-filled

Seen in:

Pneumonia
Pulmonary edema
ARDS
Pulmonary hemorrhage

Absent in:

Atelectasis (bronchus blocked)

This distinction is high-yield for exams.

C. Rapid vs Slow Opacity Development

Rapid (hours–days)	Slow (weeks–months)
Edema	Tumor
Hemorrhage	Fibrosis
Pneumonia	TB (chronic)

Time course matters.

2️⃣ Mixed Alveolar + Interstitial Pattern

Seen in:

ARDS
Severe COVID
Acute interstitial pneumonia
Drug toxicity

Clue: Diffuse bilateral opacities + ground-glass + possible air bronchograms.

3️⃣ Advanced Cavitary Lesion Differentiation

Wall Thickness Rule:

Wall Thickness	Suggestion
Thin (<4 mm)	Benign
Thick (>15 mm)	Malignant
Irregular wall	Carcinoma
Smooth inner wall	Abscess

Air Crescent Sign

Seen in:

Aspergilloma
Recovering invasive fungal infection

Appears as: Air surrounding fungal ball inside cavity.

4️⃣ Advanced Pleural Pattern Differentiation

Subpulmonic Effusion

Fluid collects under lung.

Clue:

Elevated hemidiaphragm
Lateral displacement

Hydropneumothorax

Air + fluid level in pleural cavity.

Key: Straight horizontal air-fluid level (not meniscus).

5️⃣ Advanced Mediastinal Compartment Approach

Divide mediastinum into 3 compartments:

Compartment	Common Mass
Anterior	4 T’s
Middle	Lymph nodes
Posterior	Neurogenic tumor

Exam trick: Anterior mass often displaces trachea posteriorly.

6️⃣ Pulmonary Vascular Pattern Advanced Review

Cephalization

Upper lobe vessels become prominent.

Means: Pulmonary venous hypertension.

Seen in: Left heart failure.

Pruning

Large central arteries + small peripheral vessels.

Seen in: Pulmonary hypertension.

7️⃣ Volume Loss Signs (Critical Concept)

Signs of collapse:

Mediastinal shift toward lesion
Rib crowding
Fissure displacement
Elevated diaphragm

Very exam-important.

8️⃣ Radiological-Pathological Correlation

Understanding pathology improves radiology interpretation.

Pathology	Radiological Appearance
Fluid in alveoli	Consolidation
Fibrosis	Reticular lines
Necrosis	Cavity
Tumor growth	Mass
Air leak	Pneumothorax

Think pathology first.

9️⃣ ICU Chest X-Ray Advanced Reading

Always check:

Tube placement
New opacities
Barotrauma
Pneumothorax
Line tip position

Common ICU mistake: Right main bronchus intubation.

🔟 Rare but High-Yield Signs

Sign	Meaning
Golden S sign	Central tumor with collapse
Luftsichel sign	Left upper lobe collapse
Deep sulcus sign	Supine pneumothorax
Continuous diaphragm sign	Pneumomediastinum
Silhouette sign	Localizes lesion

Advanced Differential Diagnosis Algorithm

When you see opacity:

Is heart enlarged?
→ Yes → CHF
→ No → ARDS / Pneumonia
Is there shift?
→ Toward → Collapse
→ Away → Effusion / Tension
Is there air bronchogram?
→ Yes → Alveolar disease
→ No → Obstruction

ADVANCED CHEST X-RAY INTERPRETATION

Section 12 – Lobar Collapse & Advanced Volume Loss Patterns

Lobar collapse (atelectasis) is one of the most commonly tested and clinically missed findings.

1️⃣ Right Upper Lobe (RUL) Collapse

Radiological Signs:

Elevated minor fissure
Triangular opacity in upper zone
Right hilum elevation
Mediastinal shift toward lesion

Golden S Sign

Central mass causing collapse → S-shaped minor fissure.

Highly suggestive of bronchogenic carcinoma.

2️⃣ Left Upper Lobe (LUL) Collapse

Key Signs:

Veil-like opacity over left lung
Left hilum elevation
Luftsichel sign (air crescent around aortic arch)
Shift toward lesion

Luftsichel sign is a classic exam favorite.

3️⃣ Right Middle Lobe (RML) Collapse

Radiological Clue:

Loss of right heart border (silhouette sign).

Often subtle — easily missed.

4️⃣ Lower Lobe Collapse (Right & Left)

Signs:

Retrocardiac opacity (especially left)
Diaphragm elevation
Posterior triangular opacity
Mediastinal shift toward lesion

5️⃣ Differentiating Collapse vs Effusion vs Consolidation

Feature	Collapse	Effusion	Consolidation
Volume	Decreased	Increased	Normal
Shift	Toward	Away	None
Air bronchogram	Rare	No	Yes
CP angle	Sharp	Blunted	Sharp

This table is extremely high-yield.

Section 13 – Advanced Mediastinal Interpretation

1️⃣ Anterior Mediastinal Mass (4 T’s)

Clue: Seen best on lateral film.

Displaces trachea posteriorly.

2️⃣ Middle Mediastinal Enlargement

Common causes:

Lymphadenopathy
Bronchogenic cyst

Symmetrical hilar enlargement → Think sarcoidosis.

3️⃣ Posterior Mediastinal Mass

Often: Neurogenic tumors.

May erode vertebrae.

Section 14 – Complex Combined Patterns

Some diseases show overlapping features.

1️⃣ TB with Collapse + Effusion

Pattern:

Upper lobe cavity
Fibrosis
Volume loss
Possible effusion

2️⃣ Lung Cancer with Post-Obstructive Pneumonia

Findings:

Central mass
Distal consolidation
Lobar collapse

3️⃣ COPD with Superimposed Infection

Clue: Hyperinflation + focal opacity.

Section 15 – Post-Surgical & Post-Treatment Patterns

1️⃣ Post Lobectomy

Findings:

Surgical clips
Mediastinal shift toward operated side
Volume loss

2️⃣ Post Pneumonectomy

Entire lung removed.

Findings:

Complete opacification
Shift toward side
Rib crowding

Section 16 – Subtle Radiological Traps

1. Skin Fold Mimicking Pneumothorax

Linear shadow outside lung markings.

2. Nipple Shadow Mimicking Nodule

Symmetrical round opacity.

3. Rotated Film Mimicking Mediastinal Shift

4. Underexposed Film Hiding Pneumonia

Section 17 – Expert-Level Diagnostic Strategy

When you see any abnormality, ask:

Is there volume change?
Is there air bronchogram?
Is there cavitation?
Is mediastinum shifted?
Is heart enlarged?
Is pattern focal or diffuse?
Acute or chronic?

ADVANCED CHEST RADIOLOGY EXPANSION

Section 18 – Chest X-Ray to CT Correlation (Pattern Upgrade)

Chest X-ray is a 2D projection. CT provides 3D cross-sectional detail. Understanding how CXR patterns correlate with CT findings dramatically improves diagnostic accuracy.

1️⃣ Alveolar Consolidation → CT Correlation

On Chest X-Ray:

Dense opacity
Air bronchogram

On CT:

Ground-glass opacities
Consolidation with visible bronchi
Segmental/lobar distribution

CT Advantage:

Detects early disease before CXR changes
Differentiates fluid vs tumor

2️⃣ Interstitial Pattern → CT Correlation

On CXR:

Reticular shadows
Reduced lung volume

On CT:

Honeycombing
Septal thickening
Subpleural fibrosis
Traction bronchiectasis

CT is gold standard for ILD classification.

3️⃣ Cavitary Lesion → CT Correlation

CT Helps Determine:

Wall thickness
Internal mass (fungus ball)
Necrotic tumor vs abscess
Surrounding lymph nodes

4️⃣ Pulmonary Embolism (CXR vs CT)

CXR:

Often normal.

CT Pulmonary Angiography:

Direct visualization of clot
Vascular cutoff
Pulmonary infarction

Section 19 – Rare but Exam-Important Syndromes

1️⃣ Kartagener Syndrome

Triad:

Situs inversus
Bronchiectasis
Chronic sinusitis

CXR clue: Heart on right side (dextrocardia).

2️⃣ Lymphangitic Carcinomatosis

Features:

Diffuse reticulonodular pattern
Septal thickening
Known malignancy history

3️⃣ Goodpasture Syndrome

Pattern: Diffuse alveolar hemorrhage.

Rapid progression.

4️⃣ Pulmonary Alveolar Proteinosis

CXR: Bilateral perihilar opacities.

CT: “Crazy paving” pattern.

Section 20 – Advanced Pulmonary Vascular Disorders

1️⃣ Chronic Thromboembolic Pulmonary Hypertension

CXR:

Enlarged pulmonary artery
Pruning

CT: Chronic thrombus.

2️⃣ Eisenmenger Syndrome

Findings:

Enlarged pulmonary arteries
Right ventricular enlargement

Section 21 – Diffuse Lung Disease Fine Differentiation

Pattern	Suggestion
Upper lobe nodules	Silicosis
Lower lobe fibrosis	IPF
Bilateral hilar nodes	Sarcoidosis
Random tiny nodules	Miliary TB
Perihilar opacity	CHF

Distribution is diagnostic key.

Section 22 – Diagnostic Paradoxes & Mimics

1. Massive Effusion vs White-Out Lung

White-out lung causes:

Effusion
Collapse
Pneumonectomy

Clue: Look for shift direction.

2. Bulla vs Pneumothorax

Bulla: Thin internal wall.

Pneumothorax: Pleural line + no lung markings beyond.

3. Consolidation vs Mass

Mass: Well-defined, convex borders.

Consolidation: Ill-defined, air bronchogram.

Section 23 – Case-Based Expert Reasoning Example

Case: 55-year-old smoker
CXR shows:

Upper lobe cavity
Thick irregular wall
No air-fluid level

Most likely: Cavitating squamous cell carcinoma.

Reason: Smoker + thick irregular wall + upper lobe.

FINAL MASTER CONSOLIDATION

At super-specialist level, interpretation requires:

✔ Understanding pathophysiology
✔ Recognizing pattern distribution
✔ Identifying volume changes
✔ Correlating CT findings
✔ Considering rare syndromes
✔ Avoiding mimics