Reference library

Chest X-ray reference topics and example images

Browse educational finding pages, common interpretation terms, and reference chest X-ray examples from a curated NIH-derived subset.

How to use this library: Start with a topic page if you want an explanation, or browse the example set if you want to inspect visual patterns. This library is educational and not a diagnostic tool.

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AC joint osteoarthritis

Acromioclavicular osteoarthritis is degenerative wear of the AC joint that can appear on X-ray as joint narrowing, sclerosis, and spurring.

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AC joint separation

AC joint separation means the acromioclavicular joint alignment is disrupted, usually after trauma to the shoulder.

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Air Bronchogram

An air bronchogram is an imaging sign where dark air-filled bronchi are visible within denser surrounding lung tissue.

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Aortic atherosclerosis

Aortic atherosclerosis means chronic plaque and calcific change along the aorta, sometimes visible on chest X-ray as curvilinear calcification.

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Apical pleural capping

Apical pleural capping means there is pleural-based opacity or thickening at the lung apex, often from chronic scarring.

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Atelectasis

Atelectasis means part of the lung is not fully expanded. It can happen from shallow breathing, mucus blockage, or pressure around the lung and is not the same thing as an infection by itself.

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Blunted Costophrenic Angle

Blunting of the costophrenic angle often suggests pleural fluid or another process affecting the lower pleural recess.

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Bronchial wall thickening

Bronchial wall thickening means the airways appear more visible or thick-walled than expected, which can suggest airway inflammation or chronic bronchitic change.

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Bronchiectasis

Bronchiectasis is chronic widening and distortion of the airways that can predispose to mucus retention and recurrent infection.

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Calcific rotator cuff tendinopathy

Calcific rotator cuff tendinopathy means calcium has deposited near a rotator cuff tendon, often causing shoulder pain and limited motion.

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Calcified granuloma

A calcified granuloma is a calcified nodule that often reflects prior healed infection or old inflammatory change.

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Calcified pleural plaque

Calcified pleural plaques are dense pleural calcifications that often reflect old pleural scarring, especially from prior asbestos-related exposure.

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Cardiomegaly

Cardiomegaly means the heart appears enlarged on the chest X-ray. It is a descriptive imaging finding that can be related to heart strain, chronic pressure or volume changes, or even projection effects.

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Central line position

Chest X-ray is commonly used to assess the course and tip position of a central venous catheter after placement.

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Clavicle fracture

A clavicle fracture may appear on X-ray as a cortical break, step-off, displacement, or angulation involving the collarbone.

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Consolidation

Consolidation refers to air-space filling that makes part of the lung appear denser on imaging.

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COPD / Emphysema

COPD and emphysema are chronic lung diseases that can change chest X-ray appearance but are not diagnosed by X-ray alone.

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Degenerative spine change

Degenerative spine change refers to common age-related wear findings such as disc-space narrowing, osteophytes, and facet or endplate degeneration.

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Elevated Hemidiaphragm

An elevated hemidiaphragm means one side of the diaphragm appears higher than expected on chest X-ray.

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Emphysema

Emphysema is a chronic lung condition that may appear on chest X-ray through hyperinflation, flattened diaphragms, increased lucency, and reduced vascular markings.

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Endotracheal tube position

Chest X-ray is commonly used to confirm that an endotracheal tube sits at an appropriate depth above the carina after intubation.

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Enlarged Heart on X-ray

An enlarged heart on X-ray usually refers to an enlarged cardiac silhouette, but projection, positioning, and other factors can affect how large it looks.

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Eventration of the diaphragm

Diaphragm eventration means part or all of the diaphragm sits abnormally high because of thinning or weakness, often as a chronic finding.

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Fibrosis

Fibrosis refers to scarring within lung tissue and may appear on chest X-ray as coarse linear opacity, reticulation, distortion, or volume loss.

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Flail chest

Flail chest is a severe chest wall injury caused by multiple adjacent rib fractures that create an unstable chest segment.

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Fracture

Fracture is a break or structural disruption in bone that may be obvious or subtle on X-ray.

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Free subdiaphragmatic air

Free subdiaphragmatic air means extraluminal gas is visible beneath the diaphragm, a finding that can indicate perforated abdominal viscera and may require urgent evaluation.

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Glenohumeral arthritis

Glenohumeral arthritis is degenerative wear of the main shoulder joint and can appear on X-ray as joint-space narrowing, osteophytes, and chronic remodeling.

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Healed rib fracture

A healed rib fracture may appear on X-ray as callus formation, cortical remodeling, or chronic rib deformity from an older injury.

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Heart Failure

Heart failure can produce chest X-ray findings such as cardiomegaly, vascular congestion, pulmonary edema, and pleural effusions, especially when fluid overload is present.

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Hemothorax

Hemothorax means blood has collected in the pleural space, often after trauma, surgery, or thoracic injury.

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Hiatal hernia

A hiatal hernia means part of the stomach has moved through the diaphragm into the chest, sometimes creating a retrocardiac air-fluid level on imaging.

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Hilar Enlargement

Hilar enlargement means one or both hila look more prominent than expected on chest X-ray.

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Hydropneumothorax

Hydropneumothorax means both air and fluid are present in the pleural space, often producing a visible air-fluid level on imaging.

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Hyperinflation

Hyperinflation means the lungs appear more expanded than usual on chest X-ray.

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Infiltrate

Infiltrate is a broad chest imaging term often used for abnormal lung density, but it is not a precise diagnosis by itself.

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Interstitial Opacities

Interstitial opacities are increased lung markings or diffuse reticular densities seen on chest X-ray.

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Kyphosis

Kyphosis means an exaggerated forward curvature of the thoracic spine, which can be seen on radiographs and may reflect posture, degeneration, fracture, or structural spine disease.

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Lucency

Lucency means an area looks darker or less dense than expected on an X-ray, but the meaning depends heavily on where it appears and the imaging context.

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Lung Mass

A lung mass is a larger focal lung opacity seen on imaging that often needs further evaluation.

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Lung Opacity

Lung opacity is a broad imaging term for an area of increased density in the lung.

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Mass

A mass is a larger focal opacity or lesion seen on the image. It is a descriptive finding that can have several causes and usually needs more imaging or clinical context to characterize.

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Mediastinal Shift

Mediastinal shift means the central chest structures are displaced from their usual position on the X-ray.

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Nasogastric tube position

X-ray is commonly used to confirm that a nasogastric or enteric tube follows the esophagus and reaches the stomach.

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Nodule

A nodule is a small rounded opacity in the lung or chest field. It is a descriptive imaging finding that can be benign or more concerning depending on size, appearance, and context.

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Normal vs Abnormal Chest X-ray

A normal chest X-ray usually shows relatively clear lungs, sharp pleural angles, and no major new dense abnormality, while an abnormal X-ray can show opacity, fluid, collapse, enlargement, or device-related findings.

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Old granulomatous disease

Old granulomatous disease refers to chronic calcified nodules, lung scars, or hilar nodes that often reflect prior healed infection.

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Osteopenia

Osteopenia means reduced bone density and may make bones appear relatively more lucent or less robust on X-ray.

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Pacemaker lead position

Chest X-ray can show the presence and general course of pacemaker leads and help assess whether they follow expected positions.

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PICC line position

Chest X-ray helps confirm the course and general tip location of a PICC line after placement.

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Pleural Effusion

Pleural effusion means extra fluid has collected around the lung in the pleural space. It can happen with heart problems, infection, inflammation, or other underlying conditions.

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Pleural thickening

Pleural thickening means the pleural lining appears abnormally thickened, scarred, or irregular on imaging.

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Pneumomediastinum

Pneumomediastinum means free air is present in the mediastinum and may appear as linear lucency outlining the heart, great vessels, or central airways on X-ray.

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Pneumonia

Pneumonia is an infection of the lung tissue, often caused by bacteria, viruses, or less commonly fungi. On chest X-ray it can appear as focal or patchy air-space opacity, though imaging alone does not always prove the cause.

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Pneumoperitoneum

Pneumoperitoneum means free air in the peritoneal cavity and can be an urgent clue to perforated bowel or another abdominal emergency.

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Pneumothorax

Pneumothorax means air is present outside the lung in the pleural space, which can allow part of the lung to collapse. It is an important imaging finding because the size and clinical impact can vary widely.

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Port catheter position

Chest X-ray can show the reservoir and catheter course of an implanted venous access port and help assess tip position.

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Postoperative free air

Postoperative free air means air is visible after a recent operation or procedure, and whether it is expected depends on timing and symptoms.

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Prosthetic aortic valve

A prosthetic aortic valve is a postoperative cardiac device finding seen after aortic valve replacement.

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Prosthetic mitral valve

A prosthetic mitral valve is a postoperative cardiac device finding seen after mitral valve replacement.

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Pulmonary bullae

Pulmonary bullae are large air-filled spaces within the lung, often related to emphysema or focal lung destruction.

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Pulmonary Edema

Pulmonary edema is fluid inside the lungs that often appears on chest X-ray as bilateral or central opacities, sometimes with vascular congestion or pleural effusions.

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Pulmonary Nodule

A pulmonary nodule is a small rounded opacity in the lung seen on chest imaging.

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Pulmonary vascular cephalization

Pulmonary vascular cephalization means upper-lung vessels look disproportionately prominent, often suggesting elevated left-sided cardiac filling pressure.

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Pulmonary vascular congestion

Pulmonary vascular congestion means the lung vessels look more prominent than expected and can suggest elevated cardiac filling pressures or fluid overload.

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Rib Fracture

A rib fracture may appear as a visible cortical break or irregularity on X-ray, but nondisplaced fractures can be subtle or not clearly seen.

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Scoliosis

Scoliosis means the spine curves abnormally to the side, often with some vertebral rotation, and can be visible on chest or spine X-rays.

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Shoulder dislocation

A shoulder dislocation means the humeral head is no longer in its normal alignment with the glenoid, most often after trauma.

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Shoulder osteoarthritis

Shoulder osteoarthritis is degenerative joint wear that may appear on X-ray as joint-space narrowing, bone spurs, and irregular articular surfaces.

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Sternotomy wires

Sternotomy wires are metallic closure wires seen after median sternotomy, most commonly following cardiac surgery.

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Subacromial spur

A subacromial spur is a bony projection under the acromion that can narrow the subacromial space and contribute to shoulder impingement symptoms.

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Subcutaneous emphysema

Subcutaneous emphysema means air is present in soft tissues outside the lung and may appear as streaky or bubbly lucency over the chest wall, neck, or shoulders.

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Support Devices

Support devices on chest X-ray include lines, tubes, and implanted hardware whose position may affect safety and management.

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Thoracic aortic ectasia

Thoracic aortic ectasia means mild diffuse enlargement of the thoracic aorta, larger than expected but not necessarily aneurysmal.

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Tortuous aorta

A tortuous aorta means the thoracic aorta appears elongated, unfolded, or more winding than usual on chest X-ray.

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Tracheostomy tube position

Chest X-ray can help show the course and general position of a tracheostomy tube within the airway.

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Tuberculosis

Tuberculosis is an infectious disease that can affect the lungs and create chest imaging abnormalities, but imaging alone cannot confirm it.

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Vertebral compression fracture

A vertebral compression fracture means part of a vertebral body has collapsed or lost height, often due to osteoporosis, trauma, or underlying bone disease.

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Vertebral height loss

Vertebral height loss means one or more vertebral bodies appear shortened, which can reflect compression fracture, chronic deformity, or structural bone change.

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