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CT Scan of the Chest: An Overview

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Contrast is used to highlight the chest image with a CT scan. Read the article below to learn about the chest CT scan with contrast.

Written by

Dr. Saberitha

Medically reviewed by

Dr. Kaushal Bhavsar

Published At November 7, 2022
Reviewed AtNovember 7, 2022


CT (computed tomography) scan is an imaging method used for the diagnosis. It is a combination of X-rays and computer technology. It is used to record pictures of the internal organs. The disease or injuries of the organs and structures inside the chest can be diagnosed using a CT scan. The use of computer technology gives a more detailed image of the chest cavity than X-rays. Though the images are two-dimensional, they can be modified into three-dimensional images using computer technology.

What Are the Uses of a Chest CT Scan Using Contrast?

Computed tomography is used to identify the abnormalities in the chest.

  • Block: The contrast dye highlights the blood vessels in the chest. Any block produced by the embolus formation in the blood vessels is observed using computed tomography.

  • Injuries: The trauma to the hard structures like ribs is observed on the monitor after scanning.

  • Bleeding: The injuries to the components in the intrathoracic cavity, like aortic injury and damage to the cardiac tissue, cause profuse bleeding. This intrathoracic bleeding is visualized with the computed tomography scan.

  • Infections: Respiratory infections cause an accumulation of unwanted fluid in the chest cavity. The presence of fluid is indicated in the CT scan.

  • Tumor: The abnormal tissue proliferation over the internal organs causes a lung tumor or thoracic tumor. This is diagnosed with the scan images. The size and the spread of the cancer tissue can be diagnosed.

  • Biopsy: A part of the cancer tissue is removed from the lungs for biopsy. A surgeon uses the scan pictures to guide the tool while removing the tissue. A sample is collected from the chest cavity to know about the cause of the fluid. One end of the needle is pierced inside the chest with a CT scan examination.

What Is the Role of Contrast in Computed Tomography?

  • Before scanning, the contrast dye is given to the patient. This dye is used to enhance the quality of the image.

  • Computed tomography with contrast is used by radiologists to interpret internal organs.

  • The contrast is injected into the body through the intravenous route. Along with that, the patient is asked to drink the contrast. It is ingested into the body through the oral route. This method is called a double contrast study.

  • The higher the contrast, the higher the quality of the scanned image. So the radiologist can easily visualize the abnormality using high contrast media.

What Are the Instructions to Follow While Scanning the Chest?

There are a few necessary measures to be taken before proceeding with the computed tomography scan. They are as follows;

  • The patient should remove their dress and must wear the hospital gown. The body piercings and metallic or gold jewelry must be removed before scanning.

  • A consent form explaining the uses and risks of the contrast in the chest computed tomography scan should be signed by the patient before the scan.

  • Necessary medications are provided for patients who previously had anaphylactic reactions to the contrast.

  • Do not consume food for three hours before the scan. The patient can drink water or clear fluids.

  • The diabetic patient should avoid medication for up to 48 hours before the scan. The medication can be continued only if the contrast is eliminated from the body.

  • After the procedure, the patient is kept under observation to monitor the rashes, skin reactions in the IV (intravenous) site, and breathing. If there is no trouble, the patient is discharged and sent home. Even a mild allergy in the past must be informed to the medical professional priorly.

  • A device revolves around the body and produces X-ray beams. The images are developed as slices or sections of the lungs and chest. It is then processed in a computer, and the images are displayed on the monitor.

  • Since the contrast dye is injected through an IV (intravenous route), it causes sensitivity and adverse side effects in some patients. Contact the physician if the IV site is tender and red. Swelling in the site indicates signs of infection.

  • After the procedure, the patient can take the usual diet and carry on regular physical activities.

What Are the Risks of Computed Tomography Scan And Contrast?

  • Radiation: Ask the operator about the amount of radiation exposure. Do not take risks if there have been multiple exposures in the past. It is better to have a time interval between two exposures. Maintain a record of radiation exposure during the treatment to avoid risks.

  • Pregnancy: The physician must be informed if the patient is planning for pregnancy or is pregnant presently because there is a potential risk for the baby in organ formation due to the radiation. Breastfeeding mothers should consult the physician about feeding after the procedure.

  • Allergic to Contrast: Some patients are allergic to the dye ingested during the computed tomography scan.

  • Kidney Problems: If the patient has kidney problems, the waste products from the dye cannot be eliminated during excretion. So do not use contrast dye for patients with kidney problems. Also, there is a chance of kidney failure after the use of contrast. The risk rate is higher for patients with severe dehydration.

  • Diabetes: The diabetic patient intakes Metformin medication during treatment. Ingestion of contrast interacts with the Metformin drug in the blood and causes metabolic acidosis. This change in the blood pH level is a life-threatening condition.

  • Heart Disease: The presence of a pacemaker gives less accuracy to the CT scan. As they are more prone to cardiac infection, contrast dye should not be ingested.

  • Stomach Problems: If the contrast is given through the oral route, the patient has diarrhea or constipation.

  • Excretion: Iodine-based contrast cannot be ingested for patients with excretory problems. In that case, the physician must perform a computed tomography scan procedure without contrast.


Computed tomography is advised by the medical professional when the final diagnosis cannot be made using X-rays because the density of the organs observed in computed tomography is intense. Also, there is high radiation compared to X-rays. So computed tomography scans are advised only if there is a critical condition. Research says one in 2000 patients who are exposed to computed tomography are prone to malignancy. The radiation dosage produced during computed tomography is 10 to 20 mSv. Any exposure greater than 20 mSv causes potential effects and induces cancer. The U.S government has set an average limit of 3 mSv for CT scans.

Frequently Asked Questions


Can Heart Problems Be Shown in the CT Scan?

A heart CT (computed tomography) scan is an imaging technique that can easily help create detailed images of the heart and blood vessels. The heart CT scan helps diagnose congenital heart diseases and heart valve problems.


Before a CT Scan What Should Not Be Done?

Some of the things that cannot be done before a CT scan includes:
 - Avoid eating or drinking a few hours before getting the test done.
 - Do not wear any metal objects like earrings, nose pins, belts, eyewear, and chains before entering the CT scan chamber.
 - If any medication is ongoing, it should be informed to the healthcare provider and if told, avoid taking the medication before the examination.


Is a CT Scan Done Due To Something Severe?

Many a time, a CT scan is advised to rule out any underlying condition. It is usually ordered if there is a blood clot or a tumor present in a certain part of the body but should be done as early as possible to treat the condition.


After a Lungs CT Scan How Long Does It Take for the Results To Come?

In most cases, the results of the lung CT scan come back within the same day or take two to four days.


What Are the Indications of an Abnormal Chest CT Scan?

Some of the indications of an abnormal chest CT scan include the following:
 - Heart failure.
 - Lung cancer.
 - Infections.
 - Tuberculosis.
 - Embolism (a blocked artery).
 - Emphysema (lung condition that causes breathing issues)


What Is the Duration of a Contrast Chest CT Scan?

The total duration of a contrast chest CT scan is 40 minutes, of which 20 minutes for preparation and 20 minutes for the test to get a clear, detailed image of the arteries.


Is Lung Inflammation Visible in a CT Scan?

A lung CT scan shows complications and inflammation of pneumonia and enlarged lymph nodes. The lung CT scan shows findings of noninfectious inflammatory lung diseases.


Are Blocked Arteries Visible in the CT Scan?

From a CT coronary angiogram, narrowed and blocked arteries are easily available. A dye is injected into the vein to get dense and clear images of the blocked arteries. The blockage is scanned when the dye reaches the fatty build-up or clot of the blocked arteries.


What Finding Can Be Missed Out in a CT Scan?

In most cases, a CT scan is not able to detect soft tissue injuries and other disorders. However, a CT scan detects many conditions but is not able to detect tumors like prostate cancer very clearly.


Is It Needed To Remove Clothes To Get a CT Scan Done?

A healthcare expert will advise wearing loose-fitted clothes. A gown can also be provided before the scan. Hospital gowns are recommended as they are loose, accessible, and do not have any metal microfibers attached to them, which can cause skin burns.


What Types of Lungs Disorders Can Be Detected Through a CT Scan?

A CT scan of the lungs detects pulmonary nodules (clumps of cells in the lungs) and abnormal tissues. It also detects blood clots, excess fluid deposition around the lungs, lung scarring, and pulmonary embolism.


Is It Possible To Detect if a Lung Nodule Is Cancerous Through a CT Scan?

Lung nodules, in many cases, are not cancerous, but a CT scan does not clearly specify it. The size, site, and shape of the nodules through a CT scan can give a clue, but to confirm if it is cancerous, a biopsy is advised along with the scan.


What Is the Next Step Once the CT Scan Is Completed?

If a contrast dye is used for the scan, a healthcare expert will monitor the patient for some time for any reactions like itching or swelling. Other than this, the expert will advise to drink plenty of fluids after the scan and can carry on with everyday routine.


Is It Ok To Eat Before Going for a CT Scan?

No, the doctor asks not to eat at least two to three hours before the test. Clear liquids like water, juice (non-sugary), and black tea can be taken. It is advised so because if a contrast dye is used, it interacts with the food particles inside the body, which can lead to nausea and vomiting.


Is an Individual Sedated Before a Contrast CT Scan?

A healthcare professional can give sedatives to children who do not stay still or are scared. It helps in completing the scan efficiently. Other than this, there is no need to give sedatives for a contrast CT scan.
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Dr. Kaushal Bhavsar
Dr. Kaushal Bhavsar

Pulmonology (Asthma Doctors)


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