There are two types of MRI/MRA scans, one with contrast medium (dye) and one without.
The contrast medium is a dye injected into the patient’s bloodstream before taking the images to enhance (highlights) certain parts of the patient’s anatomy. It is particularly helpful in the following conditions:
- Tumours
- Inflammation
- Certain organs’ blood supply
- Blood vessels
- Distinguishing between scar tissue and normal organ tissue
The dye is injected via a small plastic cannula inserted into a blood vessel in your arm. The injection takes a few seconds and then you are ready to be scanned. The dye is a clear liquid solution called Gadolinium-Based Contrast Agents (GBCA) and is excreted by your kidneys next time you go to the toilet.
How long does the dye stay in the body?
In patients with normal kidney function, most of the dye is removed from the body within 24 hours. Studies have shown small amounts of Gadolinium based dye are retained in different parts of our bodies, including the brain, and take longer to be removed from the body.
There’s no evidence of adverse effects meaning Gadolinium is not linked to any patient symptoms or illnesses.
Do you have asthma or allergies?
Being treated for asthma or suffering with other allergies are not contraindicated for MRI dye injection, meaning there’s no link between certain allergies or conditions and Gadolinium allergy.
However, it is always important to tell your doctor or staff member performing the scan of your known health issues.
If you do have a known allergy to Gadolinium, it might still be possible to have your scan with dye. You might need medication and your scan time might be longer if you need to stay for observation afterwards to make sure you’re safe to go home.
Do you have poor kidney function?
This might disqualify you from having a contrast (dye) enhanced MRI scan. Individual assessment is necessary and your doctor might refer you for blood tests before your scan. Most MRI scans are done without dye.