Chest Magnetic Resonance Imaging - Uses, Procedure, and Contraindications

Introduction

Chest magnetic resonance imaging (MRI) is a noninvasive diagnostic tool that uses magnetic fields and radio waves to detect the structures and abnormalities of the chest region. Chest MRI is an effective alternative imaging to angiography (an imaging tool used to visualize the blood vessels). Chest MRI possesses the advantage of morphological and functional assessment of the structures in a single image. The major advantage of chest magnetic resonance imaging is that it does not use ionizing radiation for scanning, which is a drawback of most imaging techniques. Ionizing radiation is more harmful to children and pregnant women.

What Are the Uses of Chest Magnetic Resonance Imaging?

Chest MRI is used to detect:

• Tumors.

• Cysts.

• Evaluate the blood flow in the chest region.

• Detect the metastasis of cancer in the chest region.

• Visualize the blood vessels and lymph nodes.

• Abnormal growth in the chest region.

• An additional imaging tool to confirm the diagnosis made by chest X-ray or CT (computed tomography) scan.

When Is Chest Magnetic Resonance Imaging Performed?

Chest magnetic resonance imaging (MRI) is commonly indicated in the diagnosis of the following conditions:

• Lung cancer.

• Tumors of the heart.

• Thymus tumor.

• Pleural effusion (abnormal collection of fluid in the pleural space).

• Esophageal (food pipe) cancer.

• Congenital heart defects such as arterial septal defect and patent ductus arteriosus (a congenital heart condition characterized by failure in the closure of the fetal ductus arteriosus).

• Bronchiectasis (a lung condition that damages the airways and results in coughing up mucus).

• Aortic aneurysm (a balloon-like enlargement of the main blood vessels of the body).

• Lymph node enlargement.

• Endocarditis (infection of the lining of the heart valve and heart chambers).

• Tumors or cysts (fluid-filled sacs) in the chest region.

• Used to assess the abnormalities of the chest bone and soft tissues.

• Diseases of the pericardium (a membrane that covers the heart).

• Myocardial infarction (a heart disease caused by decreased blood flow to the heart muscles).

• Determine the location, size, and extent of the tumors in the chest region.

• Cardiomyopathy (a condition that affects the muscles of the heart and makes it difficult to pump blood).

How Do Patients Prepare for a Chest Magnetic Resonance Imaging?

• Patients can eat, drink and take their regular medications prior to the scan.

• Patients should inform the health provider about their medical conditions and their regular medications.

• Patients are asked to remove metal jewelry or accessories prior to the scan, as magnets are used in this procedure. If they have any of the metal inside their body, such as pacemakers, intrauterine devices, or cochlear implants, they cannot undergo this procedure.

• Patients should tell their doctor if they had allergic reactions to contrast material from their previous scan.

• Patients should inform the radiologist if they are afraid of closed spaces (claustrophobic). They might be given medicine to make them feel comfortable and reduce their anxiety.

• Patients should inform their doctor if they are pregnant.

How Is Chest Magnetic Resonance Imaging Performed?

During chest magnetic resonance imaging, patients may be asked to lie on the table that will be moved into the scanner. Sometimes, patients may require contrast material that is given through the blood vessels to visualize the target site more accurately. Gadolinium is the choice of contrast material used in MRI scans. For the patients' comfort, the healthcare professional may keep a pillow or some blankets. In some cases, patients may be given earbuds to help them block out the loud noise made by the scanner while they undergo imaging. Using an intercom, the technician will converse with patients from a separate room.

When the patient is prepared, the MRI machine generates a powerful magnetic field around them, and radio waves are directed to the target location to produce the necessary images of the area. Throughout the procedure, patients are advised to remain still because moving could degrade the image quality. Sometimes, they may be asked to hold their breath for a few seconds to get better images. The final images will appear on the computer screen. The contrast material commonly used in this procedure is gadolinium. It rarely causes allergic reactions. This procedure usually takes about 90 minutes.

What Are the Post-scan Instructions Given to the Patients?

• After the test, patients can continue their regular activities and take their regular medications.

• Patients may be asked to drink plenty of water to flush out the contrast material from the body used in this procedure.

What Are the Contraindications of Chest Magnetic Resonance Imaging?

• Carrying items such as eyeglasses, pens, watches, hairpins, jewelry, or zippers.

• Metallic foreign bodies such as bullets in the body.

• Magnetic surgical clips or staplers.

• In pregnant women it is not advised to inject contrast material during the first trimester of pregnancy. At 3.0 tesla (T) or less, it is regarded as safe during the second and third trimesters.

• Intracranial aneurysm clips (surgical treatment for brain aneurysm [enlargement of an artery caused by weakness in the arterial wall] by placing the metal clip).

• Kidney disorder, patients with kidney disease may experience a significant adverse reaction to the contrast medium.

• Any implant that is electrically or magnetically activated, such as a cochlear implant, cardiac pacemaker, insulin pump bio stimulator, neurostimulator, or hearing aid.

What Are the Disadvantages of Chest MRI?

• Chest MRI requires more time to complete the imaging process, which is about an hour or longer.

• Larger people cannot fit into an MRI machine.

• During chest MRI, patients can hear a loud noise from the scanner.

• Nausea (urge to vomit), vomiting, headache, and skin rashes may occur as side effects of the procedure due to the contrast material used.

• Chest MRI is costly when compared to chest X-rays and CT scans.

Conclusion

Chest magnetic resonance imaging is an effective imaging tool used as a substitute for computed tomography (CT) in patients allergic to iodinated contrast agents. Chest MRI has limited signal intensity due to low proton density, artifacts created by air and tissues, and physiological movements from respiration and pulsation. However, recent advances such as ultrafast turbo-spin-echo acquisitions, breath-hold imaging, and very short echo times improve the potential for diagnosing chest abnormalities.