What happens during the test?
You will lie on your back on a narrow, movable table with your head toward the entrance of the tunnel. A small device that sends and receives radio waves may be placed around your head. The technician will slide the table into the large tunnel of the MRI scanner using an automatic control. You will be alone in the exam room during the scan; however, the technician will be able to see you through a window from an adjacent room and hear and speak with you through a two-way intercom.
An MRI scanner.
Inside the scanner you will hear loud humming or thumping noises as the machine takes each picture. Ear plugs are usually provided. You may also experience a slightly warm feeling in the area of your body that is being scanned. This is normal, but if it feels uncomfortable, tell the technician.
It is very important that you lie completely still and hold your breath if instructed while each scan is being done because movement can blur the image. You can relax between each set of images, but try not to move too much. If you have a serious problem with being in narrow or closed spaces and cannot hold still, you may be given a sedative to help you relax.
If you are having a scan that requires contrast dye, the dye will be injected through an IV in your hand or arm, usually after taking an initial set of images. You may experience coolness and a flushed sensation for a minute. After the dye injection, more images are taken.
The test usually takes about 45 minutes to an hour, but in some cases it can take up to 2 hours.
What happens after the test?
After the scan is completed you may be asked to wait while the technician reviews the images and makes sure no more scans are needed. If you are a hospitalized stroke patient, you will be taken back to your room after the test. If you are a former stroke patient having a follow-up MRI, you will be discharged into the care of the person who brought you.
If you have not had a stroke or TIA but are having an MRI to screen for narrowing or aneurysms in your blood vessels, you may go back to your regular activities immediately after the exam. If you have received a medication to help you relax you will need to rest until the effect wears off and should avoid driving. Nursing mothers who have MRI or MRA with contrast dye should wait 36 to 48 hours before breastfeeding.
The images will be reviewed by a radiologist, who will send the results to your doctor. Your doctor will discuss the results with you.
What do the results mean?
If you have MRI tests done in the first few hours after a stroke and they show severe narrowing of the blood vessels or clots but no bleeding, you may be eligible for treatment with tPA or, alternatively, with carotid endarterectomy or stent placement. These scans can also show which of the affected areas may be saved by restoring blood flow to that area.
MRA can evaluate the condition of the blood vessel and see if it is healthy or diseased. If the MRA detects a bulge in your blood vessels, you may have an aneurysm. Your doctor will discuss with you if the aneurysm is at risk of bursting and causing a bleeding stroke and should be sealed off with either surgical clipping or endovascular coiling.