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Magnetic Resonance Imaging (MRI)

Published on Feb 04, 2021 and last reviewed on Sep 01, 2022   -  6 min read


MRI is an advanced diagnostic tool that is highly beneficial. Read this article to know more.

What Is an MRI Scan?

MRI refers to the Magnetic Resonance Imaging procedure. It serves as a diagnostic tool for visualizing and imaging the different organs and tissues of the body. This method uses a high energy magnetic field and radio waves that are created with the help of a computer. The specialty of MRI is the ability to produce three-dimensional images. These three-dimensional images can be visualized from various angles. It is a harmless procedure, and most doctors will recommend a magnetic resonance imaging scan over a computed tomography scan. The average time taken for an MRI procedure to complete is about 20 to 60 minutes. If there is any disruption in the images, the patient will be called again for the repetition of the procedure.

How Does MRI Work?

Magnetic resonance imaging systems take help from radio waves and magnetic waves. The computer is of additional support to develop a cross-sectional and detailed image of internal structures and organs. The working of magnetic resonance imaging is discussed below.

The functioning of the magnetic resonance imaging scanner requires two magnets that are highly powerful. These magnets are inevitable components of the equipment. Our body contains a large number of water molecules. These water molecules are made up of both hydrogen and oxygen. A smaller particle called proton is present in both the hydrogen and oxygen molecules. These protons serve as a magnetic system that is highly responsive to the magnetic field created by the scanner. The randomly arranged water molecules of the body change in a particular direction after it gets exposed to the first magnet. The second magnet changes the alignment of the hydrogen molecules. The patient would not feel any of the changes happening in the body during the scan.

What Are the Uses of MRI Scans?

MRI scan helps in the examination of tumors, cysts, or any other pathological condition in the human tissues. These might include the following:

What Are the Types of MRI Scans?

There are two types of MRI scans. They are:

  1. Open MRI: In open MRI, all four sides of the patient are open, and this might make them feel less enclosed. It is suitable for patients with claustrophobia. The time consumption is relatively higher. But, this procedure is more friendly for children.

  2. Closed MRI: An MRI scan that is performed in a specific space is known as closed MRI. Closed MRI can produce a high-quality image when compared to the open MRI. The imaging procedure can be completed faster. But, since it is performed in a closed environment, the patient's level of anxiety increases. This method is also associated with an increased level of noise.

Are All Patients Eligible for an MRI Scan?

All the patients are not eligible for an MRI scan. There are several contraindications associated with magnetic resonance imaging. If you come under any of the following categories, then it is essential to get an opinion from your doctor before going for an MRI scan.

  • Pregnancy: As much as possible, MRI should be avoided in pregnant women during the first trimester, but it is not contraindicated. Doctors do recommend MRI scans in the later part of the second and the third trimester. Special care should be given to these patients.

  • Pacemaker: A pacemaker is a tool that is placed on the abdomen or the chest to regulate the rhythms of the heart. It is made up of metal, and such materials are not advisable for an MRI procedure. It is also not possible to remove the pacemaker just for the sake of diagnosis with an MRI. In such cases, it is better to go for alternative diagnostic methods.

  • History of Kidney Problems: One of the life-threatening complications of magnetic resonance imaging is nephrogenic systemic fibrosis. Therefore, patients who are having problems associated with kidneys have refrained from MRI.

  • Claustrophobia: Claustrophobia is a condition in which the patient feels anxious about closed and non-ventilated environments. Since the MRI scan is carried out in an enclosed room, these patients should be exposed to such diagnostic procedures without the prior intake of anti-anxiety medications.

  • Dental Implants: Dental implants are prosthesis that compensates for the tooth that is lost. It is also a metal piece that might interfere with the results of the MRI scan. For this purpose, the patients who have dental implants are not advised to go for this procedure.

  • Allergy to Iodine or Gadolinium: Certain MRI procedures might require the usage of contrast dyes like iodine or gadolinium. All the patients would not have compatibility with these dyes. People who are allergic to them are limited from getting exposed to MRI.

In addition to these, people with the following criteria are also restricted from MRI procedures.

  • Artificial heart valves.

  • Cochlear implants.

  • Vascular stent or stent-graft.

  • Bullet wounds.

  • History as a metal worker.

  • Dorsal column stimulators.

  • History of diabetes.

  • Other health conditions.

  • Neurostimulators (TENS-unit).

  • Skin tattoos.

  • Aneurysm clips.

How to Prepare a Patient Before an MRI?

The patient is asked to remove all the rings, earrings, belts, watches, and other metallic gadgets outside the scanning room. The patient will be asked to remove their clothing and change into the hospital gown. The patients should consume regular medications before the scan. The patient can eat well before the procedure and does not require any fasting condition.

In some conditions, the patient will be given contrast material in the form of a liquid to get more precise visibility of the tissues. The patient will be made to lie down on a scanning table. In addition to this, headphones or earplugs will be provided to avoid the scanner's unnecessary sounds. Children are made to listen to soft music in headphones to ease their anxiety.

During the scanning procedure, the patient will be asked to stay still without any movements. If the patient changes their position during the scan, then there would be a distortion of the images. At a certain point in time, the patient is also asked to hold their breath.

What Are the Side Effects of an MRI Scan?

The common side effects associated with MRI scan are:

  • Allergic reactions to the contrast dyes.

  • Headache.

  • Pain at the injection site.

  • Nervousness.

  • Dizziness.

What Is the Advantage of an MRI Scan Over a CT Scan?

When soft tissues are concerned, both MRI and CT scans are helpful. But, magnetic resonance imaging is beneficial in providing more precise and detailed images of the soft tissues. The risk associated with MRI is relatively low compared to CT scan. MRI can also produce clear pictures of bony structures also. CT scan requires the use of X-rays and might not be suitable for some patients. This problem is overcome by magnetic resonance imaging.

What Are the Disadvantages of an MRI Scan?

The disadvantage associated with an MRI scan are:

  • The cost of an MRI scan is very high.

  • A minor movement might produce a blurry image.

  • Harmful for patients with metallic devices.

  • The presence of foreign matter in the body can cause artifacts.

  • The imaging time is longer.

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Last reviewed at:
01 Sep 2022  -  6 min read




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