Magnetic Resonance Imaging (MRI) is a medical test that is used to make pictures of organs and structures inside the body using a magnetic field and pulses of radio wave energy.
MRI gives different information about body structures that can be seen with an X-ray, ultrasound, or CT scan (computed tomography). MRI will also show problems that cannot be seen with other imaging methods.
Process of MRI Test:
The area of the patient body is placed inside a MRI machine that contains a strong magnet. Pictures obtained from an MRI scan are the digital images that can be saved and stored on a computer or any storage device for more study.
The digital images obtained also can be reviewed remotely by a doctor. In few cases the contrast material may be used during the MRI scan to show certain structures more clearly.
Why a MRI scan is done?
Magnetic Resonance Imaging (MRI) is done for many reasons as prescribed by the consulting doctor. It is mainly used to find problems such as tumours, bleeding, injury, blood vessel diseases or any infection. MRI sometimes will be done to get more information about the health problem which is seen on an X-ray, ultrasound scan or CT scan.
Types of MRI scan:
1. Head MRI / Brain MRI:
A Head MRI or Brain MRI can look at the brain to diagnose any tumours, an aneurysm, bleeding in the brain, nerve injury and other problems such as stroke damages. A head MRI can also find abnormalities of the eyes and optic nerves, and the ears and auditory nerves.
2. Chest MRI / Heart MRI:
A Chest MRI / Heart MRI can look at the heart, the heart valves and coronary blood vessels. It can show the damages in the heart or lungs. An MRI of the chest will also be used to detect breast or lung cancers. These may be prescribed after a mammogram test has been given to see areas of the breast tissue in more detail.
3. Bone MRI / Joints MRI:
Bone and Joint MRIs can diagnose problems such as arthritis, problems with the temporomandibular joint, bone marrow problems, bone tumors, cartilage problems, torn ligaments or tendons or any infection. These MRI scans will also detect if any bone is broken even if X-ray results are not clear. MRI scans are done more commonly to check for bone and joint problems.
Bone MRI / Joints MRI includes Knee MRI, Shoulder MRI.
4. Spine MRI:
A Spine MRI will diagnose the problems with the discs and nerves of the spine for conditions such as spinal stenosis, disc bulges, and spinal tumours.
5. Abdomen and Pelvis MRI scan:
Abdomen and Pelvis MRI scans can find problems in the liver, gallbladder, pancreas, kidneys, and bladder. They can be used to find tumours, bleeding, infection and blockage if any. In women, MRI scans can look at the uterus and ovaries. In men, they can look at the prostate.
6. Magnetic Resonance Angiography (MRA):
MRA is a type of MRI scan. Generally a Magnetic Resonance Angiography (MRA) is a MRI scan which is used to observe the blood vessels and the flow of blood through the blood vessels. MRA scans can diagnose the problems of the arteries and veins, such as an aneurysm, a blocked blood vessel or dissection (the torn lining of a blood vessel). Contrast material may be used to see the blood vessels more clearly.
Preparing for MRI Scan:
It’s good to inform your MRI technician / doctor:
- If you are allergic to any of the medicines. The contrast material will not contain iodine. If you know that you are allergic to the contrast material, tell your doctor before having the test.
- If you have a health issue such as BP, diabetes, sickle cell anaemia, or kidney problems.
- If you are a pregnant.
- If you have any metal implanted in your body. This helps doctor to know if the test is safe or not. Inform if you have coronary artery stent, pacemaker, ICD (Implantable Cardioverter Defibrillator) or a metal heart valve.
- Metal pins, clips or metal parts in your body including artificial limbs and dental braces.
- Any other implanted medical device such as a medicine infusion pump or a cochlear implant.
- Cosmetic metal implants such as in your ears or tattooed eyeliner.
- If you have underwent any recent surgery on a blood vessel. In some cases, you may not be able to have the MRI test.
- Have an intrauterine device (IUD) in place. An IUD may prevent you from having the MRI test done.
How a MRI scan is done:
A MRI test is usually done by an MRI technician. The digital pictures are usually interpreted by a radiologist. But some other types of doctors can also interpret the MRI scan reports.
You should remove all the metal objects (hearing aids, jewellery, watches and hairpins etc.) from your body because these objects may be attracted to the powerful magnet used for the MRI test.
During the test you should lie on your back on a MRI table that is part of the MRI scanner machine. Your head, chest and arms may be held with straps to help you remain still. The table will slide into the space that contains the magnet. A coil may be placed or wrapped around the area to be scanned. A special strap may be used to sense your breathing or heartbeat. This triggers the machine to take the scan at the right time.
When you are inside the MRI scanner you will hear a fan sound and feel air moving. You may also hear tapping or snapping noises when the MRI scans were taken. You may also be given earplugs or headphones with music to reduce the noise. It is very important to hold completely still while the MRI scan is being done. You may be requested to hold your breath for short periods of time if required.
During the MRI test, you will be alone in the MRI scanner room. But the MRI technician will watch you through a connected window. You will be able to talk with the technician through a two-way intercom.
If contrast material is needed, the MRI technician will put an intravenous line in your arm. The material may be given over 1 to 2 minutes. Then more MRI scans are done.
An MRI test generally takes around 30 to 60 minutes, but sometimes can take as long as 2 hours.