An MRI is considered the most accurate imaging test for visualizing the tissue in your prostate. Doctors use MRIs to see if you might need a biopsy or to see the size and location of your tumor.

The American Cancer Society estimates close to 300,000 new prostate cancer cases in 2023.

Prostate cancer requires a positive biopsy for diagnosis. A biopsy is when doctors take a small amount of tissue from your prostate for examination in a laboratory. Doctors use imaging to help see if a biopsy is necessary and to see how far the cancer has spread.

Ultrasound and MRI scans are the primary imaging techniques used for initial prostate detection and diagnosis. The use of MRI has become increasingly important since it has much better soft tissue resolution than ultrasound and CT scans.

Read on to learn more about the role MRI plays in helping diagnose and monitor prostate cancer.

MRI is the best imaging technique for estimating prostate cancer volume and for the initial detection of prostate cancer. Doctors often use a contrast MRI to detect prostate cancer.

A contrast MRI is when the substance gadolinium is injected into a vein in your arm through an IV to allow doctors to better visualize your prostate.

Doctors use MRIs:

  • to see if you should get a biopsy
  • to help locate the cancer before a biopsy
  • during a biopsy to guide the needle into your prostate
  • to see if your cancer has spread to seminal vesicles or other structures in your pelvis after a positive biopsy.

The results of an MRI alone aren’t considered sufficient to diagnose prostate cancer because a negative MRI can miss about 1 in 4 high grade prostate cancers.

Doctors sometimes combine MRI scans with PET scans. A PET scan involves injecting a radioactive substance into your body to better visualize certain tissues.

In research from 2021, doctors found combined use of MRI and PET scans was more accurate than either test alone for the initial detection of prostate cancer. The researchers found that using both MRI and PET scans together may be helpful for:

  • diagnosing prostate cancer
  • helping with biopsy targeting
  • predicting or monitoring tumor aggressiveness, especially during active surveillance
  • detecting recurrent prostate cancer early
  • guiding targeted therapies

A multiparametric MRI is considered the best type of imaging for visualizing prostate cancer. It can help identify where in your prostate the cancer is growing and give doctors an idea of how fast the cancer will grow.

Doctors can also use a multiparametric MRI to show if the cancer has spread outside of the prostate.

A multiparametric MRI combines multiple MRI techniques to create an image of your prostate. It provides a more detailed image than a standard MRI scan does.

CT scans aren’t generally used for diagnosing prostate cancer because they don’t visualize the prostate as well as MRIs. Doctors use CT scans for other purposes, such as seeing if the cancer has spread to lymph nodes or other structures in your pelvis.

Some insurance companies don’t cover MRIs for people who haven’t had a biopsy. A 2019 study found that 88.9% of insurance companies didn’t cover an MRI unless preceded by a biopsy.

Some insurance companies may not cover a CT scan for people who haven’t already been diagnosed with prostate cancer. If you have insurance, review your plan for details.

Prostate MRIs generally take about 45 minutes. MRIs that don’t use contrast tend to be quicker and cheaper. You can generally eat and drink normally before your exam, but you may be asked to avoid drinks that cause bloating or gas 24 hours before the scan.

You may also be asked to empty your bladder and bowel immediately before your scan to help make your images clearer. Some healthcare professionals will ask that you avoid drinking caffeine for up to 24 hours before your test because caffeine can constrict your blood vessels.

In addition, you may be asked to refrain from ejaculating for up to 3 days before your MRI.

When interpreting the results of a multiparametric MRI for the initial diagnosis of prostate cancer, doctors often use the Likert scale. The results are classified 1–5 based on your risk of having prostate cancer.

Likert scoreRisk of cancer
1 or 2low risk of cancer
3medium risk
4 or 5high risk of cancer

Your doctor will likely recommend that you get a biopsy if your score is 4 or 5. In addition, they may recommend a biopsy if you have a score of 3, a family history, or a high prostate specific antigen score.

MRIs are considered the best imaging technique for visualizing the prostate. Doctors often use them to see if you need a biopsy or to see how far the cancer has spread. A biopsy is needed for a definitive prostate cancer diagnosis.

The most accurate type of MRI for prostate cancer is called a multiparametric MRI. This special MRI scan combines multiple techniques to visualize your prostate.