Thoracic computed tomography (CT) scan with iodine contrast injection

This is an automatically translated article.

The article was professionally consulted by Specialist Doctor I Vo Cong Hien - Radiologist - Radiology Department - Vinmec Nha Trang International General Hospital. BSCK I Vo Cong Hien has many years of experience in the field of imaging, especially in thoracic computed tomography with iodine contrast injection.
Computed tomography of the chest with iodine contrast injection helps to diagnose lung, mediastinal, and chest wall pathologies and clarify lesions related to blood vessels. This is a fast and highly accurate imaging method, thereby helping to accurately diagnose and limit missed lesions.

1. Purpose of thoracic computed tomography with iodine contrast injection

Computed tomography of the chest with iodinated contrast is a method of using X-rays to project the chest in slices and process images by computer before and after contrast injection to evaluate the pathological status of the pleura, ribs, heart, lung parenchyma, bronchi, mediastinum... to clarify the damage related to blood vessels.
Chest computed tomography can reveal abnormalities that are difficult or impossible to detect on routine chest radiographs.
Contrast that is introduced into the body will cause some structures to show up differently on the images than they did in the absence of contrast. This improves the visualization of organs, blood vessels or tissues to help doctors diagnose a patient's medical condition. After imaging studies with contrast material, the body will absorb or excrete this substance through the urinary tract or gastrointestinal tract depending on the type of contrast agent.
There are different types of contrast medium, but iodine-containing contrast is the most commonly used contrast agent today.

2. Indications and contraindications

Indications:
Occurrence of manifestations such as: Pain in the chest area or the entire skeleton in the chest. When diagnosing lung cancer, liver cancer or gastrointestinal cancer, it is necessary to examine the thorax to assess tumor status, invasion and metastasis to help identify the disease. Detect abnormal diseases in the chest wall, lungs, mediastinum... Contraindications:
Relative contraindications: Pregnant women must use a lead coat to cover the abdomen if taking pictures. Absolutely contraindicated in cases with contraindications to iodinated contrast agents such as: Patients with renal failure, liver failure, severe heart failure, history of contrast agent allergy, chronic diabetes mellitus diabetes, bronchial asthma, untreated hyperthyroidism, sickle cell anemia...

3. Procedure for thoracic computed tomography with iodine contrast injection

3.1 Preparation

Performer: Team of doctors and technicians specializing in diagnostic imaging.
Means used to take computed tomography include:
Computerized tomography machine, specialized electric injection pump. Film, photo printer and image storage system. Water soluble iodine contrast agent. Medical supplies include: Syringes (type 10ml, 20ml, 50ml), threaded needles (18-20G), syringes for electric injection pumps, antiseptic solution, physiological saline, gloves, mask, tray set, cotton gauze, bean tray, surgical forceps. Anti-shock box, drugs and necessary tools to manage complications in case of abnormality when the patient injects contrast agent.

Patients:
Patients are clearly explained how to take pictures and some possible complications when taking pictures to coordinate with the photographer. Remove items that can cause image noise and affect image quality such as earrings, necklaces, hairpins... (if any). Need to fast and drink 4-6 hours before the scan. You can drink water but not more than 50ml. Patients who are overstimulated, anxious and fearful are not coordinated when taking the scan: Give a sedative as prescribed by the treating doctor before taking the scan.

3.2 Steps to take

Patient position: Lie on your back, raise your arms above your head, instruct the patient to inhale and hold the breath several times with the same level to get the right consecutive cuts. Place an infusion line, ensure that the vein is large enough to withstand the high pressure and rapid injection rate, and insert the contrast pump. Take consecutive, spiral cuts before injecting contrast from the top of the lung to the end of the costophrenic angle, the thickness of the cut depends on the size of the lesion, from 3-10mm. Conduct contrast injection by electric syringe, with dose of 1.5-2ml/kg body weight, injection rate 3-5ml/s. Repeated sequential tomography of the entire lung field after contrast injection started at 30 seconds after contrast injection. Late-tense cuts can be performed after 3-10 minutes depending on the individual case. In the case of bronchopulmonary tumor, it is necessary to cut all the way to the adrenal gland to find metastases. After taking and determining the standard image, print the image or transfer the image to the doctor's work station for the doctor to read the film.

3.3 Evaluation of results

The film meets the criteria when: The layers are symmetrical, the image is clear, distinguishes the lung parenchyma, the components of the mediastinum, shows abnormal changes in density, lung morphology, mediastinum and mediastinum. chest wall. The doctor reads the lesion, describes it on a computer, and prints the results.

4. Complications of thoracic computed tomography with iodine contrast injection

Complications that may occur due to contrast agents:
Anaphylaxis: Symptoms such as nausea, vomiting, abdominal pain, skin rash, changes in blood pressure, severe disturbances in consciousness, difficulty breathing appear. .. Contrast-induced renal failure Thyroid storm: Symptoms of increased temperature, tachycardia, emotional disturbances, if not detected, the signs will be worse, pulmonary edema, heart failure, coma. ..if not treated can be life-threatening. Pregnant women need to consider carefully before taking pictures.

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