[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Radiology](https://durgical.com/en/radiology/) › [Chest](https://durgical.com/en/radiology/areas/chest/) › Reading a chest CT step by step

# Reading a chest CT step by step

- Reading

A chest CT is a stack of slices; reading it in the same order every time, in three windows, keeps you from missing what is outside the obvious.

Updated Nov 13, 2026

## Key points

- Same order every time; three windows (soft tissue, lung, bone).
- Check contrast and phase first: they decide what you can exclude.
- Classic misses: lung apices, behind the heart, bones and the upper abdomen.
- Vessels branch and continue; nodules start and stop.

## What it is

A chest CT is read by scrolling through the slices, organ system by organ system, in a fixed order and in more than one window: the soft-tissue (mediastinal) window for the heart, vessels, lymph nodes and pleura; the lung window for the airways and lung tissue; and the bone window for the skeleton. Before looking for disease, the reader checks whether contrast was given and in which phase, because that decides what can be judged: emboli need a pulmonary arterial phase, and a scan without contrast can still show nodules, emphysema and fibrosis. The mediastinum is read with its anatomy in mind (thyroid and great vessels at the top, the aortic arch, the pulmonary trunk and its branches, the heart and pericardium, the oesophagus behind). Comparison with earlier studies, the lung apices, the area behind the heart and the upper abdomen are the places where findings are most often missed.

## What to check

- Patient, date, indication and any prior CT or X-ray for comparison.
- Contrast or not, and the phase (pulmonary arterial, systemic arterial, venous).
- Three windows: soft tissue (mediastinum), lung and bone; coronal and sagittal reformats help.
- Thin-slice images, or a maximum intensity projection, help separate small nodules from vessels.

## Reading it step by step (and why)

- Check patient, date, indication and prior studies — change over time is often the real finding.
- Note contrast and phase — a non-contrast scan cannot exclude embolism; an arterial phase can.
- Soft-tissue window, top down: thyroid, great vessels, aorta, pulmonary arteries — find dissection, aneurysm or emboli.
- Heart and pericardium: size, effusion, coronary calcium — pericardial fluid and calcification are easy to overlook.
- Lymph nodes in the mediastinum, hila and axillae — a short axis over about 1 cm is usually enlarged.
- Trachea and bronchi down to the segments — find obstruction, mucus plugging or bronchiectasis.
- Lung window, both lungs side by side, apex to base — compare for nodules, consolidation, ground glass and emphysema.
- Pleura and chest wall: effusion, thickening, plaques, pneumothorax — look in both soft-tissue and lung windows.
- Bone window: spine, ribs, sternum, shoulders — lytic or sclerotic lesions and fractures hide in the soft-tissue window.
- Upper abdomen in the field (liver, adrenals, spleen, kidneys), then answer the clinical question in the summary.

## Common mistakes

- Satisfaction of search: stopping after the first finding and missing a second one (a nodule beside the pneumonia).
- Reading only the lung window and missing nodes, effusions or bone metastases.
- Calling a vessel a nodule: vessels branch and continue on the next slice; a nodule appears and disappears.
- Mistaking poor contrast mixing or flow artefact in a pulmonary artery for an embolus.
- Not comparing with prior studies, so a stable nodule is worked up again or a growing one is missed.

## Next step

- Large pulmonary embolism, aortic dissection, tension pneumothorax or airway compromise: tell the senior and treating team at once.
- Incidental lung nodule: follow the accepted nodule guidelines (for example the Fleischner Society recommendations) based on size and risk.
- Incidental adrenal, liver or thyroid lesion: report it and arrange the dedicated follow-up the radiologist suggests.
- Finding unclear or the wrong phase for your question: ask the radiologist whether another series or study is needed.
- Ask for prior images from other hospitals when available; comparison avoids repeat imaging and radiation.

## Test yourself

Think of the answer, then tap the question to see it.

## Which three windows should be reviewed on every chest CT?

The soft-tissue (mediastinal) window, the lung window and the bone window.

## Why must the contrast phase be checked before excluding pulmonary embolism?

Only a scan timed to the pulmonary arteries opacifies them well enough; a non-contrast or late venous scan cannot rule out emboli.

## How do you tell a small lung nodule from a vessel when scrolling?

A vessel branches and continues across slices; a nodule appears, grows and then disappears within a few slices.

## What is satisfaction of search?

Stopping the search after the first abnormality and missing another, such as a nodule or bone lesion next to an obvious pneumonia.

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## Connections

## Related 6

- [CT: windows, Hounsfield units and contrast phases](https://durgical.com/en/radiology/ct-windows-hounsfield-units-and-contrast-phases/)
- [Reading a chest X-ray step by step](https://durgical.com/en/radiology/reading-a-chest-x-ray-step-by-step/)
- [High-resolution CT patterns: ground glass, crazy paving, tree-in-bud](https://durgical.com/en/radiology/high-resolution-ct-patterns-ground-glass-crazy-paving-tree-in-bud/)
- [CT pulmonary angiography for pulmonary embolism](https://durgical.com/en/radiology/ct-pulmonary-angiography-for-pulmonary-embolism/)
- [The widened mediastinum and the hila](https://durgical.com/en/radiology/the-widened-mediastinum-and-the-hila/)
- [A nodule or a mass on the chest X-ray](https://durgical.com/en/radiology/a-nodule-or-a-mass-on-the-chest-x-ray/)

## Related conditions 3

- [Solitary pulmonary nodule](https://durgical.com/en/conditions/solitary-pulmonary-nodule/)
- [Lung cancer](https://durgical.com/en/conditions/lung-cancer/)
- [Pulmonary embolism](https://durgical.com/en/conditions/pulmonary-embolism/)

[← All of radiology](https://durgical.com/en/radiology/)

Educational content; it does not replace a radiologist's report and is not a clinical instruction. Each study is ordered on the patient's assessment and your institution's protocols.

Sources: [Chest and Mediastinal Imaging](https://www.ncbi.nlm.nih.gov/books/NBK559145/) (StatPearls (NCBI Bookshelf), 2026); [Anatomy, Thorax, Mediastinum](https://www.ncbi.nlm.nih.gov/books/NBK539819/) (StatPearls (NCBI Bookshelf), 2023).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/radiology/reading-a-chest-ct-step-by-step/