PI-RADS Score of MRI of the Prostate and What It Means

By: Omatseye Edema MD

PI-RADS MRI Report. Explaining the various grades to colleagues.PI-RADS MRI of the Prostate Report.

PI-RADS is a grading system used to interpret an MRI of the prostate to determine if you have prostate cancer or not.

There are grades 1 to 5, often reported as PI-RADS 1 to 5.

  • PI-RADS 1 almost certainly indicates the absence of prostate cancer (very low likelihood)
  • PI-RADS 2 image characteristics supports a low likelihood of cancer
  • PI-RADS 3 MRI image suggests a 50/50 chance, of the presence of prostate cancer
  • PI-RADS 4 MRI image of the prostate makes the presence of cancer very likely and
  • PI-RADS 5 MRI refers to an image where the presence of prostate cancer is highly likely to be present.

Developed by the European Society of Urogenital Radiology, PI-RADS is the short for Prostate Imaging Reporting and Data System.

With the availability of very high resolution MRIs referred to as 3-Tesla (3T) multiparametric MRIs, a number of things are looked for in an MRI image.

These include:

  • The presence of nodules or shadows on the image (also referred to as T2 or T3 weighted morphology) which helps to locate where exactly on the prostate gland a tumour is
  • How dense the nodule or shadow seen is (referred to on your MRI report as DWI or diffusion-weighted imaging) and how well does water molecule move in and out of the suspected area in the prostate gland. The rate of diffusion is different in an healthy prostate tissue compared to an area of the prostate with a collection of cancer cells or nodule
  • How well does it take up contrast dye (referred to as DCE or dynamic contrast enhanced images) during imaging which could help indicate normal or abnormal blood flow pattern within the gland. Blood flow in tumour cells tends to be more than normal gland cells
  • How much are other secretions or metabolites being produced by the area of the prostate gland under examination or that is suspected to be abnormal, compare to normal prostate tissue (referred to as MRI spectroscopy).

With a combination of these parameters, a PI-RADS score is then developed, which would help your doctor determine if you have a high likelihood of prostate cancer or not. 

So, a 3T multiparametric MRI is able to take a look at the prostate gland in a 360 degree fashion, pick up abnormal cell types in the prostate and determine if this is cancer or not by comparing the characteristics of an abnormal area with normal prostate tissues.

How Sensitive or Reliable is MRI of the Prostate?

Comparing MRI of the prostate with TRUS biopsy.Comparing MRI of the prostate with TRUS biopsy.

Because an 3Tesla multiparametric MRI of the prostate does not just look at a shadow in the prostate gland alone, but also look at other parameters and behaviours of the abnormal area as discussed above, it has a very high sensitivity and specificity.

A TRUS biopsy is only reliable about 50 % of the time (TRUS biopsy is Trans Rectal Ultrasound guided biopsy of the prostate).

In comparison, an MRI of the prostate has over 90% reliability in the detection of prostate cancer. The combination of a positive PSA test (above expected range for your age), a high PSA velocity ( the rate of rise of your PSA over time) and a PI-RADs of 4 or more makes the presence of prostate cancer more likely in a patient. Even a Prostate Imaging Reporting and Data System score of 3 should trigger the possibility of an increased probability of prostate cancer, warranting periodic follow up and screening. 

PI-RADS 4 or More: What To Do?

Discuss with your doctor, your options for further tests and treatment.Discuss with your doctor, your options for further tests and treatment.

The general consensus among top urologists worldwide now is that a PI-RADS 4 or 5 is increasingly associated with the presence of an intermediate and high-grade prostate cancer.

The Gleason classification of prostate cancer assumes that a Gleason score of 6 or more suggests the presence of prostate cancer. A PI-RADS 4 or 5 is equivalent to a Gleason 7 or more.

A PI-RADS score of 4 or more is also now a trigger for definitive treatment for prostate cancer.

It means that if you have a Prostate Imaging – Reporting and Data System score of 4 or more, you are more likely to develop a metastatic cancer. Have you just had an MRI report showing a PI-RADS 4 or more, and have a positive PSA as well, the best approach would be to be seen by a urologist or interventional radiologist with experience in real-time MRI guided biopsy of the prostate. 

This is different from the usual prostate biopsy that is done blindly and tumour cells or nodules are often missed. A biopsy if important to help get suspected abnormal cells and confirm the diagnosis by taking a look at the cells directly under the microscope.

Once this is done, the aggressiveness of the tumour or not could be established and the most appropriate treatment option adopted. Treatment for prostate cancer is increasingly getting better.

More options that ensure the preservation of the nerves around the organ and ensuring you retain erection and control of your urine are now available.

Do not think that having a PI-RADS 4 or more prostate MRI result automatically confines you to a life of impotence and leaking bladder. Speak with your doctor for a urologist consult immediately.

New! Comments

Have your say about what you just read! Leave me a comment in the box below.