Frequently Asked Questions Regarding MRI
What is an MRI?
MRI is short for Magnetic Resonance Imaging. (If your doctor has sent you for an MRA [Magnetic Resonance Angiography], this is also a kind of MRI looking specifically at blood vessels.) MRI is an advanced technology that lets your doctor see internal organs, blood vessels, muscles, joints, tumors, areas of infection, and more – without the use of x-rays or surgery. MRI is very safe and painless. In fact, it makes use of natural forces and has no known harmful effects. It's important to know that MRI will not expose you to any harmful radiation.
How does the MRI machine work?
The MRI machine creates a magnetic field, sends radiofrequency waves through your body, and then measures the response with a computer. This creates an image or picture of the inside of your body that is much clearer than can be obtained with most other methods.
Why an MRI?
MRI can provide very early detection of many conditions, so treatment can be more effective, accurate and rapid. MRI images may also provide useful information for pre-surgical planning if surgery is required. If there is an abnormality, MRI can show exactly where it is, its size and what tissues are involved.
How should I get ready for the exam?
In most cases, you can just stick with your normal, everyday routine - no special preparation is needed. You can eat and drink your usual diet, work, or play sports (unless you have an injury!) - and take any prescription medications you need. However, there may be some circumstances in which you'll be given specific instructions to follow before the exam. These will be given to you by your doctor, or by the MRI booking clerk at the time the MRI is arranged.
Are there any restrictions with the exam?
Yes. Because the MRI machine uses a strong magnetic field, which will move objects made with iron or steel, let your doctor know if you have:
- A pacemaker
- Aneurysm clips
- Cochlear implants
- A neuro-stimulator (Tens-unit)
- Metal implants
- Steel surgical staples or clips
- An implanted drug infusion device
- Any implant made partially or wholly of iron or steel
Also, if you're pregnant, let the doctor know.
Even metal objects not made of iron or steel can interfere with the exam – so don't bring any of the following into the examination room (a secure place to store your valuables will be provided):
- Dentures or partial plates
- Hearing aids
- Cell phone
Magnetic waves can also erase the code on bank cards and credit cards, so don't bring your credit or bank cards into the MRI examination room. They should be stored in the locked change room we provide to you.
Last of all, you will be asked to change into a gown that we will provide for your comfort and convenience during the examination.
May I bring someone to the exam with me?
Yes, although they will likely have to wait in a waiting room while the scan is being done. While you're having your scan, you can communicate with the technologist at any time through an intercom system.
What's the exam actually like?
There are many varieties of MRI exams. Depending upon the area being scanned, the set up of the room, and your position may be different. To begin the exam, you will lie down on the scan table. When the machine starts to work, you'll hear some loud knocking sounds. These sounds occur whenever the MRI pictures are being taken. Think of them as the clicks a VERY large camera would make when taking pictures! You will be provided with headphones that stream music if you choose to have music. The headphones help block out the knocking sounds.
In any case, although it's noisy, an MRI exam is completely painless. The only thing you must do is HOLD STILL. When you take a picture with a camera, your subject must keep still or the picture will come out blurry. It's the same with an MRI machine. If you move, the scans will be out of focus - and you may have to repeat the exam.
If necessary, you may be injected with a solution called a contrast agent or “dye”. This allows the radiologist to see the image more clearly. MRI contrast agents typically have few or no side effects, and the injection likely will just feel like a slight pinch. You may be asked to give your consent to this injection, at which time a more detailed explanation about the contrast agent will be given to you by our MRI technologist.
How long does the scan take?
The exam can last from 30 minutes to about an hour.
What is the difference between an MRI and a CT scan?
A CT scan uses ionizing radiation to obtain the information, whereas MRI uses magnetic fields and radiofrequency waves. For certain types of organs and diseases MRI is preferred because it provides superior images with better definition than CT scanning.
What happens if I can’t lay still or want to get off the table?
You will be able to communicate with the technologist with a call-bell and over an intercom throughout the exam. It is very important that you hold still during the entire time a set of pictures is being taken so the images turn out clearly. We take every measure to ensure that you are comfortable throughout the exam. Very occasionally, patients may feel claustrophobic in the MRI scanner. Some of these people may require a light sedative during the examination which your ordering provider will prescribe for you before your exam. In this case, you will not be able to operate your motor vehicle after the exam and will require a ride home.
Why do you want to know about metal implants in my head if I’m having my back scanned?
Certain items that are implanted into the body are not safe to come into the scan room, therefore, we need to know your full medical history to ensure your safety. All parts of your body are exposed to the magnetic field, not just the body part being scanned.