What is the difference between a CT scan and an MRI for cancer?

According to the U.S. National Cancer Institute (NCI), both a CT scan and an MRI make a series of detailed pictures of areas inside the body, but they use different technology. NCI defines a CT scan as a procedure that uses a computer linked to an x-ray machine to make detailed pictures taken from different angles, used to create 3-dimensional views of tissues and organs. An MRI, by contrast, is a procedure that uses radio waves, a powerful magnet, and a computer to make its detailed pictures — it does not use x-rays. NCI notes that for either scan, a dye or contrast agent (such as gadolinium for MRI) may be given to help tissues and organs show up more clearly, and that both may be used to help diagnose disease, plan treatment, or find out how well treatment is working. NCI adds that MRI is especially useful for imaging soft tissues such as the brain and spinal cord. This is general information, not personal medical advice.

Last updated: 2026-07-12

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