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Magnetic Resonance Imaging (MRI)

MRI stands for Magnetic Resonance Imaging, which is a noninvasive medical test that helps physicians diagnose and treat medical conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, bone and virtually all other internal body structures. The images can then be examined on a computer monitor, transmitted electronically, printed or copied to a CD. MRI does not use ionizing radiation (i.e., x-rays).

Detailed magnetic resonance images allow physicians to better evaluate various parts of the body and determine the presence of certain diseases that may not be assessed adequately with other imaging methods
such as x-rayor ultrasound.

What does the equipment look like?
The traditional MRI unit is a large cylinder-shaped tube surrounded by a circular magnet. You will lie on a moveable examination table that slides into the center of the magnet. The computer workstation that processes the imaging information is located in a room adjacent to the scanner.
  • Tumors
  • Abnormality of spine
  • Abnormality of bones, joints and muscles
  • Certain types of heart problems
  • Blockages or enlargements of blood vessels
  • Diseases of the liver, such as cirrhosis, and that of other abdominal organs, including the bile ducts, gallbladder, and pancreatic ducts
  • Cysts and solid tumors in the kidneys and other parts of the urinary tract
  • Causes of pelvic pain in women, such as fibroids, endometriosis and adenomyosis
  • Breast tumors
  • MRI is non-invasive and does not use radiation.
  • MRI gives clear, detailed images of neurologic structures such as brain, neck and spine that other imaging techniques cannot achieve.
  • MRI can show liver diseases better than other imaging techniques.
  • MRI has proven value in diagnosing a broad range of conditions, including cancer, heart and vascular disease, and muscular and bone abnormalities.
  • MRI allows assessing blood vessel noninvasively.
  • MRI contrasting agent is less likely to produce an allergic reaction that may occur when iodine-based substances are used for x-rays and computed tomography (CT) scan.
  • A special MRI technique called magnetic resonance (MR) spectroscopy can provide additional information on the chemicals present in the body's cells
You are required to complete an MRI safety questionnaire before scanning. You may be asked to wear a gown during the exam or you may be allowed to wear your own clothing if it is loose-fitting and has no metal fasteners. You can eat and drink normally on the day of the scan except for some specific procedures that you may be asked not to eat or drink for a period of time before scanning.

For some MRI scans, you will be given an injection of a special dye, known as a contrast agent. Some conditions, such as severe kidney disease, hypertension or diabetes may prevent you from being given a contrast agent. It may be necessary to perform a blood test to determine whether the kidneys are functioning adequately. However, the contrast material used for an MRI exam, called gadolinium, does not contain iodine and is less likely to cause side effects or an allergic reaction. Women should always inform their physician or staff if there is any possibility that they are pregnant. To date, there are no reports of any ill effects on pregnant women or their babies from MRI. However, because the baby will be in a strong magnetic field, pregnant women should not have this exam unless the potential benefit from the MRI is assumed to outweigh the potential risks. If you have claustrophobia or anxiety, you may ask your physician or MRI staff for a prescription for a mild sedative prior to the scheduled examination.

Due to the strong magnetic fields that are used by the MRI scanner, it is important to remove any metal objects from your body, including:
  1. Watches, jewelry, credit cards and hearing aids, all of which can be damaged
  2. Piercings, such as ear, nipple and nose rings
  3. Dentures (false teeth)
  4. Wigs (as some wigs contain traces of metal)

In most cases, an MRI exam is safe for patients with metal implants, except for a few types of the following:
  1. Artificial heart valves
  2. Implanted electronic device, including a cardiac pacemaker
  3. Electronic inner ear implants (bionic ears)
  4. Implanted nerve stimulators

If you have any of these, experienced MRI staff will have to discuss the exact implant or metal with you to decide if it is safe to perform the scan. Deciding which implants cannot be scanned takes special knowledge and experience. Please do not try to guess, and do not just rely on your doctor to determine if we can scan you. Some people with tattoos have reported a burning sensation during an MRI scan. This is because some tattoo ink contains traces of metal. If, during the scan, you experience any pain related to your tattoo, tell the technologists immediately.
The Technologist will guide you on to our MRI scan table. Straps and bolsters may be used to help you stay still and maintain the correct position during imaging. A small receiving device is placed behind or around the part of your body being scanned. You are moved into the scanning tube. You will usually be alone in the exam room during the MRI procedure. But a friend or family member may be allowed to stay in the room with you. It is normal for the area of your body being imaged to feel slightly warm, but if it bothers you, notify the technologist. It is important that you remain perfectly still while the images are being recorded, which is typically only 2-5 minutes at a time. You will know when images are being recorded because you will hear tapping or thumping sounds. You will be able to relax between imaging sequences. For some types of exams, you may be asked to hold your breath.

During your MRI examination, the magnetic resonance system operator will be able to speak to you, hear you, and observe you at all times. Consult the scanner operator if you have any questions or feel anything unusual.

You may be given earplugs or headphones to wear to reduce the noise of the MRI scanner. For some MRI scans, you will be given an injection of a special dye, known as a contrast agent. A nurse will insert an intravenous (IV) line into a vein in your hand or arm before scan. A contrast agent will be injected into the intravenous line (IV) after 30-45 minutes. It is very important to keep still during the injection.
There is no special care required after an MRI scan. If contrast dye is used for the procedure, it is important to drink plenty of water (about 1-2 liters) after the examination. For the woman who is breastfeeding, it is advised to wait for 48 hours after receiving a contrast injection before breastfeeding again.

Risks and complications

  • Claustrophobic patients may find it difficult to stay still in the MRI scanner. Usually, a mild sedative is given to relieve the symptoms. The risk of over sedation for claustrophobia is tackled by close monitoring of vital signs during the procedure.
  • Undetected metal implants in the body may produce unsatisfactory consequences since they are affected by a strong MRI magnet.
  • Since MRI is very sensitive to motion, image blurring is common. This can occur if you cannot hold your breath well. Blurred images may reduce the ability of your physicians to give an accurate impression of your diseases. There is a very small chance that you could develop an allergic reaction to the MRI contrast agent, or that a skin infection could develop at the site of injection.
  • We do not routinely perform MRI with contrast agent in patients with poor kidney function. In these patients, there is an increased risk of developing a rare but potentially lethal disease called nephrogenic systemic fibrosis (NSF) if they received an MRI contrast agent.

Recommendations for Travel Before and After the Procedure

There are no limitations for travel before or after the procedure.

Accuracy of MRI

An MRI scan is about 80-95% accurate when comparing with other imaging studies. However, accuracy depends on the type of test, the disease, and patient factors like age and health. Please talk to your doctor if you have any questions.

What if the procedure is not performed?

None.

Alternative Procedure

  • Computed tomography (CT) scan
  • Ultrasound

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