NIH Chest X-ray Reference Library

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.

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.

Consolidation

This is one of the represented labels in the current NIH-derived reference subset.

Edema

This is one of the represented labels in the current NIH-derived reference subset.

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.

Emphysema

This is one of the represented labels in the current NIH-derived reference subset.

Fibrosis

This is one of the represented labels in the current NIH-derived reference subset.

Hernia

This is one of the represented labels in the current NIH-derived reference subset.

Infiltration

Infiltration is a broad chest X-ray term for hazy or patchy opacity in the lung. It can be seen with infection, inflammation, fluid, or other air-space processes, so it is not very specific by itself.

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.

No Finding

No Finding means the source dataset did not assign one of its target abnormality labels to that image. It does not guarantee a perfect or universally normal chest X-ray in every clinical sense.

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.

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. Read the deep dive

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. Read the deep dive