An Update on the Current Role for Prostate Multiparametric MRI

A prominent urologist wrote an articulate article on how the U.S. Preventive Services Task Force made a recommendation against broad PSA screening based on an oversimplification of a complex issue. He made an eloquent declaration on several ways in which urologists are “embracing strategies to preserve, or even further decrease, prostate cancer mortality while minimizing the unnecessary morbidity and costs associated with the prior standard of care.”[i]

The author is the Chair of his academic institution’s Urology Department. He notes that the PSA blood test has limitations, but that one of the methods by which he overcomes them is his adoption of multiparametric MRI (mpMRI), noting that it is helpful to rule the need for a biopsy in or out. This is, indeed, an important service provided by mpMRI, especially since the USPSTF recommendation partly grew out of the unnecessary number of biopsies inflicted on men whose PSA signaled a non-life-threatening condition, not prostate cancer.

I was motivated by the article to summarize the number of ways in which mpMRI currently plays a key role in overcoming prostate cancer through detection, diagnosis and treatment of this disease. Since the Sperling Prostate Center has a powerful 3 Tesla (3T) magnet, and we don’t use an endorectal coil, my comments are based on our imaging protocol using what are called “functional parameters” to detect differences between healthy and unhealthy tissue:

1. In addition to basic prostate anatomy and surrounding structures, mpMRI highlights prostate cancer’s characteristics that differ from normal tissue. These are differences such as tissue density, tumor blood flow, and the restriction of water molecules in tissue that raise suspicion of a tumor.
2. Traditional systematic ultrasound guided biopsies are basically blind and random, so they miss about 30% of tumors, and often underestimate the true aggressiveness of the cancer. They tend to miss cancers in the region called the anterior. mpMRI identifies the size, shape and location of tumors within the gland, and can also reveal tumor growth that has penetrated the prostate capsule or invaded the nerves.
3. Based on the images, the need for a biopsy (or not) can be determined. If a biopsy is necessary, mpMRI makes the sampling process both efficient and highly accurate, because under MRI guidance, needles can be directed precisely into the areas of suspicion. mpMRI thus makes the biopsy much more accurate.
4. mpMRI can give important clues as to the aggressiveness of the tumor, especially when the images are interpreted by an experienced reader. This can help identify which patients are truly candidates for Active Surveillance (insignificant prostate cancer) and which need immediate intervention (significant prostate cancer.)
5. For a patient on Active Surveillance, mpMRI can be used in conjunction with blood tests (PSA, free PSA and PSA density) to monitor for any cancer progression. This saves patients from repeat biopsies unless something unusual is detected by biomarkers and imaging.
6. mpMRI can help determine if a patient is a candidate for radical prostatectomy by ruling out extracapsular disease or seminal vesicle invasion.
7. After any prostate cancer treatment, if recurrence is suspected due to a rising PSA, mpMRI is essential to detect if and where the new growth is located, and the extent of it.
8. In all of the above roles, mpMRI aids in informed decision-making.
9. If, based on mpMRI and other appropriate tests, the patient is a candidate for a focal treatment that targets just the tumor and a margin of safety, a focal treatment such as our MRI-guided focal laser ablation (FLA) is a safe, simple outpatient procedure that destroys the tumor without damaging urinary or sexual function. In fact, the accuracy and effectiveness of the procedure can be evaluated during and immediately after based on mpMRI.

In addition to mpMRI, new molecular biomarkers round out the resources available to help doctor and patient know which steps to take. Perhaps one of the greatest roles for mpMRI is the one it is playing to help usher in a new, more accurate era of conquering localized prostate cancer and detecting advanced prostate cancer when the greatest number of treatment options are still open.

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[i] Herbert Lepor, MD. “Managing Prostate Cancer: Screen, Detect and Test Smarter.” The Huffington Post/Huffpost Healthy Living, February 5, 2016. http://www.huffingtonpost.com/herbert-lepor-md/managing-prostate-cancer-screen-detect-and-treat-smarter_b_9134812.html