MRI Scan (Magnetic Resonance Imaging)
Magnetic resonance imaging (MRI) is a diagnostic tool that uses radio frequencies, magnetic fields, and computers to produce cross-sectional images of the soft tissues in the body. These images can be used to aid in the diagnosis of medical conditions. MRI does not use ionizing radiation to produce these images.
MRI exams use electromagnetic fields to produce images, so the presence of items such as surgical implants, metal fragments, and metal piercings could be a safety concern.
Before your MRI exam, an MRI technologist will help determine if these items are magnetic; for example, surgical implants typically have identification numbers that can be used to check their compatibility for MRI tests.
It is important that you inform the clinic if you have any surgical implants or embedded metal fragments when you book your MRI appointment. Note that any piercings will need to be removed before your MRI exam.
What to Expect During an MRI Exam
Before the MRI exam, an MRI technologist will review a safety questionnaire with you to determine whether it is safe to proceed. This will include asking about your surgical history and any injuries involving metal, such as having metal fragments removed from your eyes.
Following the safety questionnaire, you will be provided with a gown or scrubs to change into before your MRI exam. You will also be given a locker in which to secure your belongings.
The MRI machine produces loud noises as a normal part of its operation. Because of this, you will be given ear protection when you enter the MRI room to dampen the noise produced by the machine during the MRI exam.
You will be positioned on the MRI table. At this point, an additional piece of equipment – called a “coil” – is placed around, over, or under the region of interest in order to produce the image.
Then the table is moved into the MRI tube to position the body region being examined in the middle of the MRI machine. The technologist will monitor you at all times during the MRI exam. You will also be provided with an emergency button so you can communicate with the technologist at any time during the MRI procedure.
Generally, MRI procedures last from 30 to 60 minutes, depending on the body part being examined. It is important that you do not move during the MRI exam - movement will result in blurry images.
In some cases, an intravenous injection of a contrast agent is administered to aid in the MRI diagnosis. The need for contrast is determined by the radiologist. This contrast is injected intravenously in the arm and may cause a cooling sensation.
After the MRI exam is complete, the images are analyzed by one of our radiologists, and a report is sent to your doctor as soon as possible.
Important MRI Notes
- You must provide your complete surgical history, and information on any injuries involving metal, when booking an MRI appointment.
- If you are claustrophobic, please consult with your doctor to see if they would recommend taking anti-anxiety medication before your examination.
- Note that MRI exams performed outside of the hospital are a private service and the cost is not reimbursed by Alberta Health Services.
- Recent studies have shown that some clothing items may contain trace elements that heat up when exposed to magnetic resonance. These items can include underwear with sweat wicking material (silver nitrate) or socks with odour absorbing material (copper). To prevent burns, we may ask you to remove your underwear or socks during the exam. Please note that you will still be provided with scrubs or a gown so you are fully covered.
Frequent MRI Exam Questions
MRIs apply powerful magnets that produce a strong magnetic field. This magnetic field forces the protons in the body to align with that field. A subsequent radiofrequency current is then pulsed through the patient and the protons are stimulated. When the radiofrequency is disabled, the protons realign with the magnetic field and the MRI sensors detect the energy released. Based on the time it takes the protons to realign and the energy released, doctors are able to decipher the various types of tissues in the body.
The noise created by an MRI machine originates from the magnetic field being cycled on and off. An MRI machine contains metal coils known as gradient coils. When these receive electrical pulses, they generate a magnetic field. The sound you hear during an MRI is the pulse of electricity moving through the gradient coils causing them to vibrate.
Although MRI scans are completely painless, there can be discomfort due to being required to lie still for the length of the MRI procedure, and anxiety caused by potential claustrophobia, intravenous injection of a contrast agent, or by the loud noises caused by the MRI machine. Our MRI technologist will review a safety questionnaire with you prior to the exam to ensure the MRI procedure is as safe and comfortable as possible.
Depending on the type of MRI and the part of the body that is being scanned, an MRI exam can take anywhere from 30 to 60 minutes.
Before your MRI exam, our technologists will review a safety questionnaire with you to ensure your safety. If you have any injuries involving metal, have pacemaker or aneurysm clips, or any piercings, inform your MRI technologist. Furthermore, although you will be provided with a gown or scrubs, some clothing material, especially undergarments with sweat or odour absorbing materials, can heat up and cause burns. Please inform your MRI technician if you have any underwear or socks containing these substances before your MRI exam.
An MRI scan is still a safe procedure even if you are pregnant. There have been no proven risks to unborn babies or pregnant women during or after an MRI exam. In fact, thousands of women have received MRI scans while pregnant with no known harmful effects.
If your MRI technician or radiologist deems it necessary to inject a contrast agent to aid in the MRI diagnosis, it will be administered intravenously in the arm. There have been side effects associated with the contrast agent and if you are concerned about mitigating the discomfort, speak with your technician prior to the MRI exam.
Before coming to your MRI exam, talk to your doctor about obtaining a mild sedative or anti-anxiety medication if you suffer from claustrophobia. If you do use a sedative, ensure you have a driver present after your MRI exam.
After your MRI exam is completed, the images will be analyzed by one of our radiologists. Upon completion of the analysis, a report will be sent to your doctor as soon as possible.