Magnetic resonance imaging (MRI) is a type of imaging, or way to take pictures of the inside of the body. It creates images with a magnetic field and computer-generated radio waves. The MRI machine is a large tube-shaped structure that you lie inside. For prostate cancer imaging, the machine will take pictures of your pelvis (lower abdomen), including your prostate gland.

Why would I get a prostate MRI?

There are several reasons why your doctor may order an MRI to help them with staging and planning treatment for your prostate cancer.

When Considering Prostate Biopsy After an Elevated PSA

If your PSA blood test (a screening test for prostate cancer) is elevated or high, your urologist may order a prostate MRI before considering a prostate biopsy (to see if you have prostate cancer). There are several large clinical studies that show that men who have an elevated PSA and receive an MRI before getting a biopsy benefit in at least two ways.

First, some men may have such a good result from their MRI that a biopsy is not needed right away. However, a “normal” MRI does not guarantee there is no prostate cancer. So, you should still talk with your urologist about whether or not you need a prostate biopsy.

Second, the MRI provides a “map of the prostate” to guide a urologist to perform targeted biopsies of those areas most likely to have prostate cancer. As a result, these studies have shown that clinically significant prostate cancer (that which requires treatment) is more likely to be found in men who have an MRI before biopsy.

During Active Surveillance for Low-Grade/Low Volume Prostate Cancer

There are many protocols that doctors may follow when patients are on active surveillance. However, nearly all modern protocols use prostate MRI at some point in the active surveillance journey. Patients that are being considered for active surveillance most often have an MRI soon after their first biopsy. This is done to see if there are areas in the prostate that should be targeted at the time of the second, or confirmation, biopsy. For men that have been on active surveillance, most doctors will perform an MRI every one to two years to make sure there are no changes in how the prostate looks on MRI.

Local Staging for High-Risk Prostate Cancer

Prior to local therapy (i.e., surgery or radiotherapy) for high-risk prostate cancer, your doctor may order an MRI to get a better look at the anatomy of the prostate. The MRI will also help your doctor see the areas around the prostate, such as any enlarged lymph nodes (which is a common location for prostate cancer to spread).

Specifically, for patients who will have surgery, a prostate MRI may allow your urologist to see if prostate cancer is close to the prostate capsule (the wall of the prostate gland). This information can help your urologist to plan how much nerve-sparing can or should be done for each side of the prostate gland during the operation. Your urologist can be better prepared to do the cancer operation and provide you with the best chance to return to your normal life as much as possible.

What does a prostate MRI involve?

During an MRI, you will lie on the narrow bed of the MRI machine while it moves in and out of the MRI tube. This process takes about 30 minutes. In most cases, you will receive contrast dye through an I.V. during the scan.

Some men are claustrophobic (afraid of small spaces) and may find being in the MRI “tube” hard to tolerate.  If you are claustrophobic, you should mention this to your doctor. They may prescribe a light sedative or a medication (i.e., Valium) to help ease the anxiety of the MRI.

Before the MRI you must remove any clothing with snaps or zippers. You likely will be asked to wear a hospital gown in the MRI scanner. Additionally, you should take off any jewelry or metal, including hearing aids.

There are several absolute contraindications (i.e., reasons why you should NOT have an MRI) to receiving an MRI. These include having a cardiac implantable electronic device (CIED) such as a pacemaker, an implantable cardioverter defibrillator (ICDs), and cardiac resynchronization therapy (CRT) device. Patients who have one of these devices are at risk of device malfunction (not working right), device heating/movement, and possible irregular heartbeat (arrhythmia) during an MRI.

If you have an elevated or high PSA test, an MRI may help your urologist to check to see if and where cancer may be in your prostate. The results of the MRI will help your urologist plan the next steps of your prostate cancer journey, and guide you and your loved ones in shared decision-making.

Zachary Klaassen, MD, MSc
Urologic Oncologist, Georgia Cancer Center, Augusta University, Augusta, GA, USA