MRI Scan

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What is an MRI scan?

MRI is used to analyse the body using radio waves and strong magnetic fields. The scanning procedure is done in a large tube. It detects the problems of the heart, prostate gland, blood vessels, brain, spinal cord, bones, joints, breasts and womb. 

Raymond Vahan Damadian, an American physician, was the first person to discover the magnetic resonance imaging machine in 1977. The first MRI scanner was used in Scotland. His research on sodium and potassium in cells paved the way for his experiment with the magnetic resonance technique.

What does an MRI show?

An MRI scan is effective in a detailed examination of the body parts with – the scanning is used for detecting cysts, tumours, certain heart problems, screening of breast cancer, problems relating to the spinal cord and brain, injuries & dysfunction of the joints, uterine abnormalities in women, diseases of the kidney & liver, and pain in the pelvic area.

How is an MRI done?

Initial preparations involve the removal of all types of accessories from the patient’s body before the screening. People with a pacemaker in their body are not eligible for this scanning. Intravenous(lV) contrast liquid is injected in the body to enhance the visibility of the image. 

Then the patient lies down on the scanning table comfortably. Usually, headphones are provided to the patient to ease the anxiety and to block all the noises. This is more beneficial in the case of children as they tend to panic in limited space. When the patient is slid under the scanner, communication through the intercom is established. It is normal for loud noises to occur during the procedure. Scanning can be stopped in between if the patient experiences discomfort. The patient is free to go home after the procedure if the results are satisfactory and all other required tests are done. 

What is MRI contrast?

Contrast agents are compounds or pigments which enhance the visibility of the internal body parts on MRI screening. Usually, Gadolinium-based compounds are used for contrast enhancement. These contrast agents are classified under magnetic properties, nature of metal atoms, chemical composition, administration and effects of the images. Contrast agents are applicable as blood pool agents, extracellular fluid agents, Ph sensitive agents, cell labelling agents, responsive agents and organ-specific agents.

Gadolinium (lll) is a contrast agent which is used for detecting brain tumours in association with degrading blood-brain barrier. It is also used in MRI angiography for enhancing the visibility of blood vessels. Its administration varies depending on the size of blood vessels – for large blood vessels the quantity of gadolinium required is low. This contrast agent circulates throughout the body for some time before scattering in the intestinal space and eventually being filtered out by kidneys.

The images of the gastrointestinal tract can be enhanced using an oral contrast agent. These oral contrast agents are manganese chelates, iron salts and gadolinium. For T1 signal contrast enhancement, products rich in manganese like green tea, dark chocolate, spinach, brown bread and bran cereals can be used.

What is the difference between a CT scan and an MRI?

MRI and CT scan are both used to obtain images of the body. Their suitability differs depending on the condition of the patient. The major difference is that scanning in an MRI is done with the help of radio waves whereas X-rays are used in a CT scan. However, they have various risks and benefits.

Risks of an MRI- claustrophobia, rise in the body temperature, problems of hearing, and reactions to metal caused by magnets. Prior consultation with a doctor is necessary if implants such as artificial joints, IUD, pacemaker and eye implants have been placed.

The patients who have had an aneurysm – collapse in the blood vessels in the brain should not go through MRI – it can lead to a future episode of an aneurysm leading to coma or death. No metal objects should be placed near the machine while performing an MRI as it creates a magnetic field. Patients with a cardiac pacemaker or any metal device in the body should be more careful as the magnetic field generated by an MRI can damage these battery-operated devices or it can remove them from their place.

Benefits of an MRI- MRI provides a more clear image of the tissues than that of a CT scan – it detects cancer easily and provides a blueprint for further treatment, it can generate hundreds of images easily from all directions and orientation. Procedures like mammography and ultrasound detect a small portion of the body at a time but magnetic resonance imaging detects a large portion of the body. Allergies are rare due to MRI. The biggest benefit of MRI is that it is painless – although, you may experience slight discomfort.

CT scan stands for computed tomography – it creates crisscross images of the body by the rotating action of the x-ray machine. It can show different parts of the body like bone, blood vessels and tissues. In CT scan patients lie in a tunnel shape machine and the inner part of the machine rotates and captures the x-ray images at different angles. Then the images are sent to a computer where it creates a 3d image of the body.

Risks of CT scan- potential risks include harm from radiation, harmful reactions due to the use of dye and potential harm to unborn babies. The chances of developing cancer are moreover present though it is a very rare case. 

The risk of cancer is high if the person has to go through the scan multiple time. The exposure of radiation is more in CT scan than an x-ray. It can cause an allergic reaction due to contrast material – iodine is mainly used as a contrast material. So, if you have any allergy caused by iodine consult your doctor before you go for a scan.

Benefits of CT scan- It is faster than MRI. It is cheaper as compared to an MRI scan. 

Which is a better option – MRI or CT scan?

MRI is better than CT scan because it shows better results and minute details of the body. It generates a clear image that easily detects cancer in heart, liver and other body parts. MRI lessens the need for other tests. 

Although, choosing between an MRI or CT Scan is not at your convenience – the procedure most suitable for your condition, doctor’s expertise, and cost factors will be selected.

FAQs

What is the cost of an MRI scan?

MRI scanning is an expensive procedure. It can cost between $400 and $800 per test. Your insurance can cover some of the cost but without insurance, it has a hefty price. 

How to prepare for an MRI scan?

Before MRI screening, the patient should remove all the metals objects they are carrying and additional accessories – so that it will not create any interference during the process.

How long does it take to finish an MRI scan?

The scanning usually takes between 15 to 90 minutes depending upon the medical condition of the patient. MRI scanning does not require any admission to the hospital after the procedure and one can go home immediately. 

Is an MRI scan painful?

MRI screening is not at all painful. Discomfort, anxiety and panic may occur but you can stop the scanning any time you feel like. MRI is not recommended during pregnancy.

Which diseases are detected with the help of an MRI scan?

MRI scanning can detect all the soft tissue problems and problems of joints such as wrist, ankle, knee and elbow. Heart, liver and kidney disorders can also be detected by MRI.