MRI & CT Scans
Need a Medical Imaging Scan?
If your doctor has recommended that you get an MRI or CT scan, you may be wondering what to expect. Imaging tests provide important insight into your body and support doctors and specialists in making a diagnosis and identifying a treatment plan that is right for you.
MRI
What is MRI?
Magnetic Resonance Imaging, also known as MRI, is an imaging exam that can create high-definition images of internal organs and tissues using a magnetic field. Unlike CT and x-ray, an MRI scan does not use radiation. However, it is always important to make the MRI staff aware of your health history and conditions at the time of the test. During the test, the MRI scanner uses the magnetic field to capture signals from molecules in your body, generating high resolution images. The images provided by MRI can show differences between soft tissues in the body and can help distinguish the structures in the area of interest.
MRI
How Do You Prepare for an MRI Exam?
You will be given a health & safety questionnaire prior to your MRI exam to ensure you are safe around the strong magnet. Inform the MRI technologist of your health history and if you have surgical implants, such as a pacemaker. You will be asked to change into hospital clothing and remove all the metal on your body, such as earrings.
MRI
What Happens In An MRI Exam?
The test is performed on a machine with a ring shape called an MRI scanner. The radiologist, a doctor that reviews medical imaging exams, may recommend a contrast agent to highlight certain parts of your body to make it easier to see. The exam could take up to 45 minutes and you will lie very still as you listen to instructions from the MRI technologist. If you feel a bit anxious, you can press a button to speak to them.
MRI
Understanding What To Expect In An MRI
This brochure will help to answer any questions you have going into an MRI scan.
CT
What Is CT?
Computed Tomography, also known as CT, is a test that uses x-rays to generate images of slices of the body, which allows the structures and organs to be seen from a different perspective. This allows the radiologist, a doctor who reads the images, to see the many organs and bones in your body.
CT
How Do You Prepare for a CT Exam?
Prior to the CT exam you may be asked screening questions. It is important to report your health history such as allergies, pregnancy status, or history of kidney disease.
The test is performed on a machine with a ring shape called a CT scanner. You will lie down and receive instructions from the CT technologist throughout the exam. The bed you lie on will move in and out of the CT scanner. You may be injected with a contrast agent which highlights organs, tissues and blood vessels for the radiologist. The scan can last from anywhere between 5 and 30 minutes.
Contrast Media
What Is a Contrast Agent?
The radiologist will decide if you need a contrast agent, depending on what information they are looking for in the scan. A contrast agent is a special substance used to enhance the appearance of certain structures or tissues and blood vessels in the body. Contrast agents are injected into a vein and they help to differentiate one tissue from another by increasing their “contrast”. This makes it easier for the radiologist to see any potential abnormalities and provide clear answers to the questions your doctor may have.
How Do Contrast Agents Work in MRI?
The contrast agents used in MRI contain gadolinium. They allow the radiologist to better see different structures, thus helping to differentiate what is healthy from what is not. Not all MRI exams need a contrast agent. It will depend on what the radiologist is looking for.
How Do Contrast Agents Work in CT?
The contrast agents used in CT contain iodine and they allow the radiologist to see different structures such as blood vessels and organs like the brain, liver and heart better. Contrast agents help the radiologist see the differences between tissues next to each other. Not all CT tests will require the use of a contrast agent.
Are Contrast Agents Harmful?
Contrast agents are used every day and are safe. Side effects, such as nausea, may occur in a small percentage of people and are usually mild and go away on their own without treatment. Some patients may experience an allergic reaction, such as hives, but radiology staff are trained to respond to reactions.
After the exam, the contrast agent exits through your urine or bowel movements. Tiny traces of certain contrast agents may stay in different organs afterwards but there are no known negative effects from this. Talk to the technologist or healthcare professional if you have any concerns.
Let's Talk About Scans
Help kids prepare for an MRI or CT scan with this playful video that entertains them as it explains the procedure.
PP-PF-RAD-CA-1023-1 June 2026