Chest CT scan: how is done ?

Chest CT scan in Paris

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What is a chest CT scan?

A Chest CT-Scan, or computed tomography (CT) is an imaging method that uses X-rays to obtain precise cross-sectional images of the thorax and upper abdomen.

Why have a chest CT scan?

The effectiveness of this examination lies in obtaining a precise view of the structures inside the chest. The ct-scan remains one of the best ways toexamine soft tissues such as the heart and lungs. Cela dit, il permet de repérer ou non une anomalie. Si c’est le cas, sa taille et sa localisation. De surcroît, cet examen détecte des anomalies même de très petite taille (inférieure ou égale à 3 millimètres). Dans le cas d’un cancer du poumon, le scanner thoracique permet de repérer si les ganglions lymphatiques à proximité sont anormalement gros.

But what are the most common reasons for undergoing this examination?

There are many reasons why a scanner thoracique, including :

After a chest injury
When a tumor or mass (cluster of cells) is suspected, including a solitary pulmonary nodule seen on a chest X-ray.
To determine the size, shape and position of the organs in the chest and upper abdomen.
To search bleeding or fluid accumulation in the lungs or in other areas.
Pour rechercher une infection ou une inflammation dans la poitrine.
Search for caillots sanguins dans les poumons.
Search for cicatrices dans les poumons.
Significance of abnormal results
Détection de zones anormales connues sous le nom de nodule pulmonaire qui pourraient suggérer un cancer du poumon si elles s’avèrent de grande taille.

On the other hand, the thoracic CT scan can reveal numerous disorders of the heart, lungs, mediastinum or thoracic region, including :

A tear in the wall, an abnormal enlargement or bloating, or a narrowing of the main artery carrying blood away from the heart (aorta).
Other abnormal changes in the main blood vessels in the lungs or chest.
Accumulation of blood or fluid around the heart.
Lung cancer or cancer that has spread to the lungs from another part of the body.
Accumulation de liquide autour des poumons (épanchement pleural).
Damage and enlargement of the large airways of the lungs (bronchiectasis).
enlarged lymph nodes
Lung disorders in which lung tissue becomes inflamed and damaged.
Pneumonia
Esophageal cancer
Lymphoma in the chest
Tumors, nodules or cysts in the chest

Complément sur les techniques et indications du scanner thoracique

Le scanner thoracique est une technique d’imagerie radiologique incontournable pour le diagnostique de nombreuses pathologies touchant le corps humain, en particulier les poumons, les artères et les structures vasculaires du thorax. Réalisé au sein d’un centre hospitalier ou d’un service de radiologie, cet examen radiologique est parfois complété par d’autres examens d’imagerie comme les ultrasons, la scintigraphie, ou le TEP scan, notamment dans les bilans oncologiques (ex. : cancer du sein, biopsies pulmonaires). L’examen peut nécessiter une injection intraveineuse de produit à base d’iode, ce qui justifie parfois d’être à jeun. Le médecin radiologue, assisté d’un manipulateur, s’assure de limiter les doses d’irradiation à leur strict minimum, selon les normes en vigueur. En cas de suspicion de tumeur ou d’infection digestive, osseuse, ou thoracique, un scanner peut aussi être utilisé pour guider une ponction ou une biopsie, renforçant la valeur diagnostique de l’examen.

How do I prepare for a chest CT scan?

A thoracic CT scan without injection of contrast medium does not require the patient to fast. However, for a thoracic CT scan with contrast medium injection (thoracic angioscanner), it is advisable to eat a light meal and fast for at least 3 hours before the examination, as the medium may cause nausea. It is also recommended not to smoke in the hours preceding the scan. Depending on the case, patients may be required to temporarily interrupt a current treatment.

How does a chest CT scan work?

The patient lies on a table, positioned on his or her back, side or stomach, depending on the areas to be examined. Any metal objects (rings, watches, piercings, etc.) must be removed to avoid interference with the X-rays, which could render the images unreadable. Next, the table is slid into the center of a ring containing an X-ray emitting tube. It is essential that the patient remains perfectly still and, at times, stops breathing. The examination takes about 5 minutes.

The patient is alone in the examination room, separated by glass from the radiologist, with whom he or she can communicate via an intercom. This medical imaging examination is non-invasive and totally painless.

Is detecting all these anomalies risk-free?

What are the risks of a chest CT scan?

These CT scans and other X-rays are strictly monitored and controlled to ensure that they use as little radiation as possible. The scanner exposes you to a very small amount of radiation. The dose delivered is limited to the strict minimum and controlled by specialized health professionals.

In order to limit exposure to radiation and possible adverse effects associated with the use of a contrast medium, this examination is prescribed by your doctor for specific indications, at certain stages of diagnosis, treatment or follow-up.

Can a chest CT scan diagnose Covid 19?

The scanner is not a screening tool. It will be used in patients who have difficulty breathing and need to be hospitalized. In such cases, the scanner is a complementary examination to the PCR virological test. The advantage of CT scanning is that it provides an immediate result. The sensitivity of the scan is 90%, i.e. there will be only 10 % of false negatives, hence its irreversible effectiveness.

Thoracic CT in lung exploration

A Chest CT-Scan, or computed tomography can detect anything from the most benign anomaly to a tumor.

Sometimes, CT scans are supplemented or replaced by MRI (magnetic resonance imaging).
These complications of smoking and their quantification (bronchial remodeling, emphysema and chronic inflammation of the respiratory alveoli) are perfectly analyzed on CT.

Screening for lung cancers (in patients at risk of cancer) is performed on CT with the greatest sensitivity.

In the assessment of local extension of bronchopulmonary cancer, CT scans analyze its size, topography and relationship to surrounding structures, so as to optimize treatment planning.

CT is also the examination of choice for exploring infiltrative pathologies of the lung: fibrosis, occupational inhalation diseases or environmental factors, drugs, systemic diseases.

Dernière mise à jour: le 30 mai 2025
Controlled by Dr Antoine Hakime