What is a Magnetic Resonance Imaging (MRI)?
This procedure provides detailed images of soft tissues, bones, fats, muscles and the internal organs of your body. The MRI machine uses a very strong magnetic field and radio waves to examine a specific area of your body. A series of images are taken through sections of your body, in any direction desired. This technique does not use x-rays and is considered safe and painless.
The examination is performed by an MRI technologist (a technologist trained in medical imaging) and interpreted by a Radiologist (a doctor who specializes in medical imaging).
Must read: Frequently Asked Questions on MRI.
Pre-Procedure Guidelines & Instructions – Things You Need To Know
- You will typically receive a gown to wear during your MRI examination.
- Before entering the MR system room, you and any accompanying friend or relative will be asked questions (i.e., using a screening form) regarding the presence of implants or devices and will be instructed to remove all metallic objects from pockets and hair, as well as metallic jewelry.
- You will be asked to fill out a screening form asking about anything that might create a health risk or interfere with imaging (like prior medications, if any). Items that may create a health hazard or other problem during an MRI exam include:
- Certain cardiac pacemakers or implantable cardioverter defibrillators (ICDs)
- Ferromagnetic metallic vascular clips placed to prevent bleeding from intracranial aneurysms
- Implanted or external medication pumps (such as those used to deliver insulin, pain-relieving drugs, or chemotherapy)
- Certain cochlear (inner ear) implants
- Certain neurostimulation systems
- Catheters that have metallic components
- A bullet, shrapnel or other types of metallic fragment. Even IUD’s
- A metallic foreign body within or near the eye (such an object generally can be seen on an x-ray; metal workers are most likely to have this problem).
- Additionally, any accompanying individual will need to fill out a screening form to ensure that he or she may safely enter the MR system room. If you have questions or concerns, please discuss them with the MRI technologist or radiologist prior to the MRI examination.
- Some items, including certain cardiac pacemakers, neurostimulation systems, and medication pumps are acceptable for MRI. However, the MRI technologist and radiologist must know the exact type that you have in order to follow special procedures to ensure your safety.
- Everyday objects like:
- Purse, wallet, money clip, credit cards, cards with magnetic strips
- Electronic devices such as beepers or cell phones
- Hearing aids
- Metal jewelry, watches
- Pens, paper clips, keys, coins
- Hair barrettes, hairpins
- Shoes, belt buckles, safety pins
- Any article of clothing that has metallic fibers or threads, metallic zippers, buttons, snaps, hooks, or underwire.
- Objects that may interfere with image quality if close to the area being scanned include:
- Metallic spinal rod
- Plates, pins, screws, or metal mesh used to repair a bone or joint
- Joint replacement or prosthesis
- Metallic jewelry including those used for body piercing or body modification
- Tattoos/tattooed eyeliner (these alter MR images, and there is a chance of skin irritation or swelling; black and blue pigments are the most troublesome)
- Makeup, nail polish or other cosmetics that contains metal
- Dental fillings (while usually unaffected by the magnetic field, these may distort images of the facial area or brain; the same is true for orthodontic braces and retainers).
- Prior to the test, you will also undergo a Dye sensitivity.
- In general, in preparation for the MRI examination, you will be required to wear earplugs or headphones to protect your hearing because, when certain scanners operate, they may produce loud noises. These loud noises are normal and should not worry you.
- For some MRI studies, a contrast agent called gadolinium may be injected into a vein to help obtain a clearer picture of the area being examined. Investigations like PT/INR, RFT/Sr. Serum creat levels are mandatory before the test. Any history of allergies, asthma, heart conditions which might interfere with dye administration.
- At some point during the examination, a nurse or MRI technologist will slide the table out of the scanner in order to inject the contrast agent. This is typically done through a small needle connected to an intravenous line that is placed in an arm or hand vein.
- A saline solution will drip through the intravenous line to prevent clotting until the contrast material is injected at some point during the exam.
- The most important thing for the patient to do is to lie still and relax. Most MRI exams take between 15 to 45 minutes to complete depending on the body part image and how many images are needed, although some may take as long as 60 minutes or longer. You will be told ahead of time how long your scan is expected to take.
- You will be asked to remain perfectly still during the time the imaging takes place, but between sequences, some minor movement may be allowed. The MRI technologist will advise you, accordingly.
- When the MRI procedure begins, you may breathe normally. However, for certain examinations, it may be necessary for you to hold your breath for a short period of time.
- During your MRI examination, the MR 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.
- If you are pregnant or suspect you are pregnant, you should inform the MRI technologist and/or radiologist during the screening procedure that is conducted before the MRI examination.
- In general, there is no known risk of using MRI in pregnant patients. However, MRI is reserved for use in pregnant patients only to address very important problems or suspected abnormalities.
- You should inform your radiologist if you are breastfeeding at the time of a scheduled MRI study if you may need to receive an MRI contrast agent. One option under this circumstance is to pump breast milk before the study, to be used until injected contrast material has cleared from the body, which typically takes about 24 hours. The radiologist will provide additional information to you regarding this matter.
- In case of excessive anxiety or high BP, you may be given a mild sedative before the examination.
- You might experience claustrophobia (fear of closed spaces) during the exam. Please inform the radiology staff.
- Report for any allergic reaction to dye (itching/breathlessness) posts the examination.
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