Abnormal Chest X-ray & Advanced Imaging Interpretation

Objective 1.5.1 — Recognize characteristic chest X-ray findings for common pulmonary and cardiac pathologies; correlate radiographic terminology with clinical patient assessment findings; and describe the indications, principles, and limitations of advanced thoracic imaging modalities including CT, MRI, ultrasound, V/Q scanning, and PET.

Abnormal Findings on Chest X-ray

The following section pairs each condition with clinical assessment findings (what the respiratory therapist observes at the bedside) and radiographic terminology (what is seen on the chest X-ray). Mastery of both sides is essential for clinical correlation.

Chronic Obstructive Pulmonary Disease (COPD)

Patient Assessment

General appearance: Barrel chest (increased A-P diameter), clubbing, cyanosis
Respiratory pattern: Dyspnea, accessory muscle use, pursed-lip breathing
Breath sounds: Diminished aeration with bilateral expiratory wheeze
Diagnostic chest percussion: Tympanic or hyperresonant
Cough: Congested, productive of thick sputum

Radiographic Terminology

Term	Description
Hyperlucent	Lung fields appear abnormally dark due to air trapping and destruction of lung parenchyma
Hyperinflated	Lungs are overexpanded beyond normal volume
Diaphragms lowered and flattened	Chronic hyperinflation pushes the diaphragms downward, blunting their normal dome shape
Increased space between the ribs	Intercostal spaces widen as the thorax remains in a chronic inspiratory position
Increased retrosternal airspace	On the lateral view, the space behind the sternum appears enlarged

Pneumonia

Patient Assessment

General appearance: Diaphoretic, cyanotic
Respiratory pattern: Tachypnea
Breath sounds: Crackles, bronchial breathing, whispered pectoriloquy
Diagnostic chest percussion: Flat or dull note over the affected area
Cough: Productive of yellow/green sputum; may also be rust-colored
Vital signs: Febrile, tachycardia, hypertension

Radiographic Terminology

Term	Description
Consolidation	Replacement of air in the alveoli with fluid, pus, or blood — appears as a radiopaque (white) area
Air bronchogram	Air-filled bronchi become visible as dark branching lines against the opaque, consolidated lung parenchyma

Air bronchogram sign in lobar pneumonia

Atelectasis

Radiographic Terminology

Term	Description
Increased radiopacity	The collapsed segment appears whiter than surrounding aerated lung
Increased air bronchograms	Crowded bronchial markings may be visible within the atelectatic region
Displacement of fissures toward the collapsed lung	As the lobe loses volume, the fissures shift toward the side of collapse — a key sign differentiating atelectasis from consolidation

Left lower lobe atelectasis

Pleural Effusion

Radiographic Terminology

Term	Description
Blunting of costophrenic angles	Fluid accumulates in the most dependent pleural region, obliterating the sharp angle normally formed by the diaphragm and chest wall
Fluid accumulates in the most dependent pleural region	On an upright film, fluid layers at the base; on a lateral decubitus film, fluid layers along the dependent lateral chest wall
Left lateral or Right lateral	Decubitus views confirm the presence of free-flowing pleural fluid

Pleural effusion blunting the right costophrenic angle

Pneumothorax

Patient Assessment

General appearance: Possible diaphoresis, cyanosis, tracheal and/or mediastinal shift away from the affected side, bruising over the affected area
Respiratory pattern: Tachypnea, reduced movement on the affected side
Breath sounds: Diminished or absent on the affected side
Diagnostic chest percussion: Hyperresonant / tympanic note over the affected side
Vital signs: Tachycardia, pulsus paradoxus, hypertension
Heart sounds: May be displaced

Radiographic Terminology

Term	Description
Visceral pleural line	The thin white line of the visceral pleura is visible separated from the chest wall
Vascular markings — absent	No lung markings are visible peripheral to the pleural line
Increased lucency in the hemi-thorax	The affected side appears abnormally dark due to free air in the pleural space

Tension Pneumothorax

Same terminology as simple pneumothorax, but with additional features indicating life-threatening pressure:

Tracheal deviation away from the affected side
Mediastinal shift to the contralateral side
Flattening or inversion of the diaphragm on the affected side
Cardiovascular compromise due to reduced venous return

Right-sided tension pneumothorax with mediastinal shift

Hemothorax

Patient Assessment

Most associated with some kind of trauma
Presents similarly to pleural effusion but with blood in the pleural space
May cause hypovolemic shock depending on the volume of blood loss

Radiographic Terminology

Same findings as pleural effusion (opacification, blunted costophrenic angle)
The opacity may appear homogeneous and can layer or completely opacify the hemithorax depending on the volume of blood

Left Heart Failure / Pulmonary Edema

Patient Assessment

General appearance: Peripheral/pedal edema, diaphoresis, cyanosis
Respiratory pattern: Tachypnea, orthopnea, paroxysmal nocturnal dyspnea (PND)
Breath sounds: Crackles, wheezing
Cough: Pink, frothy secretions
Diagnostic chest percussion: Flat or dull percussion note
Other chest assessment findings: Increased tactile and vocal fremitus

Radiographic Terminology

Severity	Findings
Mild	Increased vascular markings — engorged pulmonary vessels, particularly in the upper lobes (cephalization)
Moderate	Butterfly / batwing infiltrates — bilateral perihilar opacities that spare the lung periphery
Severe	Kerley B lines — thin, horizontal lines at the lung bases representing engorged interlobular septa; diffuse alveolar opacification

Pulmonary edema with batwing distribution

Pulmonary Embolism (PE)

Patient Assessment

General appearance: Anxious, diaphoretic, cyanotic, cool or clammy skin
Respiratory pattern: Sudden-onset shortness of breath, tachypnea
Breath sounds: Wheezing, crackles, pleural friction rub
Cough: Possible hemoptysis
History: Sudden onset of signs and symptoms

Hard to see on chest X-ray — a normal or near-normal CXR does not rule out PE. Obtain a V/Q scan or CT pulmonary angiography.

Radiographic Terminology

Term	Description
Wedge-shaped infiltrate	A triangular opacity with the base against the pleura, representing a pulmonary infarction (Hampton hump)
Plate-like or discoid atelectasis	Linear areas of atelectasis that may accompany PE due to surfactant loss

Acute Respiratory Distress Syndrome (ARDS)

Patient Assessment

General appearance: Cyanotic
Respiratory pattern: Tachypnea, substernal or intercostal retractions
Breath sounds: Bronchial breath sounds, crackles
Diagnostic chest percussion: Flat / dull note
Vital signs: Tachycardia, hypertension

Radiographic Terminology

Term	Description
Bilateral diffuse infiltrates	Opacities present in all lung zones on both sides
Poorly defined opacities	No clear borders — the infiltrates blend into surrounding lung tissue
Fluffy / patchy appearance	Irregular, cloud-like densities scattered throughout the lungs
Ground glass appearance	Hazy increased opacity that does not obscure underlying bronchovascular markings

ARDS with bilateral diffuse ground glass opacities

Epiglottitis

Patient Assessment

Past medical history: Sudden onset within 6 – 8 hours
General appearance: Pale or cyanotic, lifeless, drooling, hoarseness, inspiratory stridor, difficulty swallowing (dysphagia), tongue thrusts forward during inspiration, voice and cry muffled, jaw jutted forward
Respiratory pattern: Tachypnea
Breath sounds: Diminished, inspiratory stridor

Radiographic Terminology

Term	Description
Thumb sign	On a lateral neck radiograph, the epiglottis appears swollen and rounded — resembling a thumb — instead of its normal thin, pointed shape

Epiglottitis — Thumb sign

Laryngotracheobronchitis / Croup

Patient Assessment

Past medical history: Recent cold that developed gradually into a barking cough over 2 – 3 days; more common in fall and winter
General appearance: Alert with some accessory muscle usage, cyanosis, barking cough, hoarse voice
Respiratory pattern: Tachypnea
Breath sounds: Diminished, inspiratory stridor

Radiographic Terminology

Term	Description
Steeple sign	On a lateral neck radiograph, subglottic narrowing of the trachea produces a tapered, steeple-like appearance

Croup — Steeple sign

Foreign Body Aspiration

Patient Assessment

Cough, wheeze, stridor, dyspnea, cyanosis

General Considerations

Children between 1 – 3 years are most at risk
Twice as common in males as females
Until age 15, the right and left main bronchi arise at about the same angle from the trachea — objects may be aspirated into either side
The most frequently aspirated foreign bodies are food (especially nuts), teeth, and dental devices

Imaging Findings

Normal chest radiograph does not exclude an aspirated foreign body
Indirect signs: air trapping on the affected side (expiratory film), atelectasis, or hyperinflation
Treatment: Bronchoscopic removal

Flail Chest

Patient Assessment

General appearance: Anxious, cyanosis, bruising over the area involved
Respiratory pattern: Shallow, rapid respirations; paradoxical chest movement (the flail segment moves inward during inspiration and outward during expiration)
Breath sounds: Diminished over the affected area
Diagnostic chest percussion: May have signs and symptoms of pneumothorax (hyperresonant / tympanic note)

Radiographic Terminology

Multiple rib fractures (two or more fractures in two or more contiguous ribs)
The flail segment may appear displaced
Often associated with pulmonary contusion (underlying opacification)

🔗 Radiology Masterclass Galleries — Extensive collection of normal and abnormal chest X-rays for additional review.

Additional Imaging Overview

Beyond plain chest radiography, several advanced imaging modalities provide complementary diagnostic information. The following section outlines their basic principles and clinical indications relevant to the respiratory therapist.

Computed Tomography (CT)

Principles

CT uses X-rays taken from multiple angles around the body to produce cross-sectional (axial) images of the thorax. The images provide far greater anatomical detail than plain radiography.

Key Respiratory Therapy Diagnoses

Diagnosis	CT Finding
Bronchiectasis	Dilated, thick-walled bronchi that fail to taper — the "tram track" or "signet ring" sign
Pneumonia	Better characterization of extent, cavitation, and necrotizing features
Pulmonary nodules	High-resolution detection, characterization, and sizing of solitary or multiple nodules
Pulmonary embolism	CT pulmonary angiography (CTPA) is the gold standard — directly visualizes filling defects in pulmonary arteries
Interstitial pulmonary fibrosis	Reticular opacities, honeycombing, and traction bronchiectasis

CT scan showing a spiculated lung nodule

Magnetic Resonance Imaging (MRI)

Principles

MRI uses strong magnetic fields and radio waves (not ionizing radiation) to generate two- and three-dimensional views of organs and structures.

Key Respiratory Therapy Diagnoses

Thoracic aneurysms
Congenital anomalies of the aorta and major thoracic vessels
Determining the precise position of tumors, soft tissue abnormalities, and involvement of surrounding structures

Important Considerations for Respiratory Therapists

Claustrophobic patients may not tolerate the procedure
Very obese patients may not fit into the narrow confines of the machine
Ventilator considerations:
- Fluidic (non-electric, gas-powered) ventilators are used because magnetic fields would disrupt electronic devices
- All tubing should be secured so airway and lines are not dislocated when the examination table moves
Manual resuscitation equipment should have:
- Additional tubing length to allow for patient movement into the MRI unit
- Detachable non-rebreathing valves made of non-ferrous (non-metallic) materials
- Aluminum gas cylinders used in the MRI room instead of steel cylinders

Ultrasound

Principles

Ultrasound uses high-frequency sound waves passed into the body and detects the waves that bounce back (similar to radar / sonar).

Limitations for Pulmonary Imaging

Negative: The ability of ultrasound waves to pass through air-filled lungs is poor — image quality for lung parenchyma is limited compared to CT or X-ray

Applications Relevant to Respiratory Therapy

Positive: Rapid assessment of heart function and volume status in the emergency and ICU setting
Procedure guidance: Used to guide placement of central venous catheters and arterial lines — accomplishes the procedure safely and easily
Pleural ultrasound: Can detect pleural effusions and guide thoracentesis

Pulmonary Ventilation / Perfusion Scan (V/Q Scan)

Indications

Pulmonary embolism (especially when CT angiography is contraindicated — e.g., renal failure, contrast allergy)
Chronic or severe COPD (pre-operative evaluation for lung volume reduction surgery)

Procedure

Component	Description
Ventilation scan	A radioisotope (xenon gas) is inhaled, and a camera records its distribution throughout the lungs. Any obstruction to airflow prevents gas from filling that area — producing a photographic pattern of ventilation distribution
Perfusion scan	Albumin tagged with radioactive iodine is injected into a peripheral vein. It passes into the pulmonary circulation and lodges in the capillaries. A scanning device passes over the chest, producing a pattern of radiation indicating the distribution and volume of perfusion

Interpretation

Normal ventilation scan + Abnormal perfusion scan = Indicates pulmonary embolism

A mismatched segmental or larger perfusion defect with normal ventilation is the hallmark of acute PE.

Positron Emission Tomography (PET Scan / PET Imaging)

Principles

PET is a nuclear medicine imaging technique that uses a radioactive tracer to observe metabolic processes in the body. The patient is injected with the tracer, which is given time to distribute throughout the body, then imaging detects areas of increased metabolic activity.

Indications

Cancer: Detects and diagnoses malignant disease earlier than MRI or CT; can also monitor response to treatment
Brain disorders
Heart disease

Note

Tumors and masses "light up" or "glow" on PET imaging because they consume more glucose (metabolically active) than surrounding normal tissue
Often combined with CT (PET/CT) for precise anatomical localization

Quick Reference Summary

Abnormal Chest X-ray Findings at a Glance

Condition	Key Radiographic Sign
COPD	Hyperlucent, hyperinflated, flattened diaphragms, increased retrosternal airspace
Pneumonia	Consolidation with air bronchogram
Atelectasis	Fissure displacement toward the collapsed lobe
Pleural Effusion	Blunted costophrenic angle, fluid layering on decubitus
Pneumothorax	Visceral pleural line, absent vascular markings peripherally
Tension Pneumothorax	Same as pneumothorax + tracheal/mediastinal shift away
Hemothorax	Opacification similar to effusion, history of trauma
Left Heart Failure	Cephalization, batwing/butterfly infiltrates, Kerley B lines
Pulmonary Embolism	Wedge-shaped infiltrate (Hampton hump); CXR often normal — V/Q or CTPA needed
ARDS	Bilateral diffuse ground glass / fluffy opacities
Epiglottitis	Thumb sign on lateral neck radiograph
Croup	Steeple sign on lateral neck radiograph
Foreign Body Aspiration	May be normal; air trapping or atelectasis; bronchoscopy for treatment
Flail Chest	Multiple rib fractures, paradoxical chest wall movement

Advanced Imaging Modalities

Modality	Principle	Best For	Key RT Consideration
CT	Cross-sectional X-rays	Detailed lung anatomy, PE, nodules, bronchiectasis	Higher radiation dose than X-ray
MRI	Magnetic fields + radio waves	Vascular anomalies, thoracic tumors	Non-ferrous equipment required; gas-powered ventilators
Ultrasound	Sound wave reflections	Heart function, pleural effusion, line guidance	Limited for air-filled lung
V/Q Scan	Ventilation + perfusion isotopes	Pulmonary embolism	Normal V + abnormal Q = PE
PET	Radioactive glucose tracer	Cancer metabolism	Often combined with CT (PET/CT)