What Is the Dye in an MRI With Contrast?

This page is for people who have an MRI scheduled, or whose order or report mentions contrast. It explains what the dye is and what to tell the staff first.

An MRI uses a strong magnet and radio waves to take pictures of your body in slices. NCI says the slices are put together to make detailed images that can show places where there may be tumors.

Sometimes a special dye is injected into a vein before or during the MRI. This dye is called a contrast agent. NCI says it can make tumors show up brighter in the pictures.

NIBIB says contrast agents for MRI often contain an element called gadolinium. NCI's dictionary gives the same example and says the agent may be injected into a vein to help tissues and organs show up more clearly. It is given through a vein, before or during the scan.

Orders and reports may say "with contrast," "without contrast," or "with and without contrast." If you are not sure what yours means, ask your care team or the imaging center whether dye will be used and when.

NIBIB lists several things to raise before an MRI.

• Kidney problems. People with severe kidney failure who need dialysis may risk a rare but serious illness called nephrogenic systemic fibrosis. It may be linked to certain gadolinium-containing agents. NIBIB says a causal link has not been established. It says current US guidelines recommend that dialysis patients get gadolinium only when essential.
• Pregnancy. NIBIB says no effects on the baby have been shown. It still recommends avoiding MRI as a precaution, especially in the first three months, and says contrast agents could enter the baby's bloodstream.
• Implants and devices. NIBIB says to tell your doctors about any medical device or implant before the scan. Some implants can be affected by the strong magnet, and whether a device is safe depends on that exact device and the conditions its maker sets. The MRI team checks this before the scan, so tell them about every implant, including any you are not sure about. Do not assume a device is safe or unsafe on your own. The FDA also has an overview of MRI.

NIBIB also says MRI machines are loud and that people who are uncomfortable in small spaces may find long scans hard. Tell the staff beforehand. They can talk with you about ways to make the scan easier.

Reports sometimes say a spot "enhances" or shows "contrast enhancement." That is a description of how the area looked on the pictures. It is not a diagnosis by itself. These pages explain the wording: what contrast enhancement means and what an enhancing lesion means on MRI.

For a plain comparison of the two scan types, see MRI versus CT scan. The CT scan has its own dye. See CT with and without contrast.

Contrast is a normal part of many scans. Before the scan, tell the staff about kidney disease, dialysis, pregnancy, and any implant or device. If you feel unwell after a scan, call your care team right away. If you think you are having an emergency, call 911.

• Does my MRI need contrast, and why?
• Is contrast safe for me, given my kidneys, pregnancy status or devices?
• What does the wording on my order mean, and will dye be used?
• If the report says an area took up contrast, what does that mean for me?

• National Cancer Institute: How Cancer Is Diagnosed
• National Cancer Institute: Dictionary of Cancer Terms, "magnetic resonance imaging" and "contrast material"
• National Institute of Biomedical Imaging and Bioengineering: Magnetic Resonance Imaging (MRI)