MRI or CT Scan

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

Dr. Roach says: A CT (computerized tomography) scan uses X-rays to create an image that looks like a slice through the body, head or a limb. The quality of the picture is excellent, but it has much more radiation than a regular X-ray. An MRI uses powerful magnetic waves to create an image that also looks like a slice. It uses no radiation. CT scans are cheaper and faster, in general. One isn’t necessarily “better” than the other. MRI tends to be better for looking at soft tissues, like the brain, and CT usually is better for looking at bones. Your doctor, or the consulting radiologist, can tell you which is more likely to be better in your individual situation.

I read your response to T.M. about his PSA level. Rather than a biopsy, would a PCA3 urine test be as good?

Dr. Roach says: The prostate cancer antigen 3 gene (PCA3) has been proposed both as a screening test by itself, and as a confirmatory test after an abnormal PSA test. It was a bit better than PSA as a screening test, and shows promise as a test to reduce unnecessary biopsies for men with abnormal PSA levels. However, the most recent study from Brown University in 2013 concluded that there isn’t yet enough evidence to start using this test on a routine basis.

By Keith Roach, M.D.

(c) 2014 North America Synd., Inc.; All Rights Reserved