Prostate MRI and Targeted Biopsy

Michael D. Orsi, MD, and Daniel R. Saltzstein, MD
Monday, May 15, 2017

According to SEER Cancer Statistics Review 1975–2007 (Bethesda Maryland NCI 2010), the mortality rate from prostate cancer has dropped 39 percent in the age of the PSA screening.

Michael D. Orsi, MD, Body Imaging and Diagnostic Radiology at South Texas Radiology Group

Despite that fact, there is still controversy over screening guidelines.

Many urologists have concerns about the potential for over-diagnosing and over-treating prostate cancer. For that reason, physicians have been searching for new tools to help make important testing and treatment decisions. With prostate MRI and targeted biopsies, urologists now have more information than ever to help guide those decisions.

For the past 30 years, the prostate biopsy technique hasn’t changed much. Routine random needle biopsies are still the norm. This is not the case for other cancers. For example, to diagnose breast cancer, physicians use high-quality imaging to guide biopsies. This allows precise targeting of suspicious areas. The same is now true with high-quality imaging of the prostate. With a prostate MRI, urologists can target and sample suspicious lesions.

Urology San Antonio, in collaboration with the radiologists at South Texas Radiology Imaging Centers (STRIC), are now employing multiparametric MRI (mpMRI) to aid in this process. This new technology has the backing of the National Comprehensive Cancer Network and the European Association of Urology and has been shown in numerous randomized clinical trials to be better than standard systematic 12-core biopsies in detecting clinically significant cancers.

Daniel R. Saltzstein, MD, Medical Director of Research, Medical Director of the Advanced Therapeutic Clinic and Member of the Prostate Cancer Committee at Urology San Antonio

The technology utilizes a high-field strength 3 Tesla magnet with a specialized imaging protocol for assessing the prostate including high-resolution T2 weighted imaging, diffusion-weighted imaging and dynamic contrast enhancement to help detect cancer and differentiate low grade from high grade cancers. These three parameters constitute the mpMRI exam. Abnormalities on the mpMRI can suggest the presence of aggressive, high-risk prostate cancer. The radiologist reads the exam and reports it, much in the same way that the likelihood for breast cancer on mammography is reported, with a grading and reporting system assessing the likelihood of there being clinically significant prostate cancer.

This exam is performed with a coil placed over the pelvis, exterior to the patient. The technology has advanced to the point that the endorectal coils are no longer needed for high-quality imaging. The exam can be limited by artifact in some patients, particularly if they have implanted metal such as with hip prostheses.

The concept of targeted biopsy is facilitated by fusion software packages that fuse MRI images that have been interpreted and lesions marked by the radiologist with real-time ultrasound images the urologist uses when performing the biopsy. The technique, known as targeted fusion biopsy, makes the detection and diagnosis of prostate cancer more accurate than ever.

In a study of 1,003 men published in JAMA in 2015, targeted fusion biopsy successfully diagnosed 30 percent more aggressive prostate cancers than were diagnosed with random biopsy. When compared to random biopsy, targeted fusion biopsy found 17 percent fewer low-risk prostate cancers, as smaller and less aggressive prostate cancers are often not seen on mpMRI. Other studies have reported mpMRI negative predictive values of 82–90 percent for all cancers, and even higher for clinically significant cancers. False negatives are usually from small volume cancers and benign prostatic hypertrophy masking prostate cancer.

Currently, mpMRI is being utilized for the patients who have had a prior negative biopsy but PSA continues to rise. The 2016 Joint Consensus Statement from the American Urological Association and the Society of Abdominal Radiology states that following an initial negative biopsy, if repeat biopsy is recommended, prostate MRI and subsequent MRI-targeted core biopsies appear to facilitate the detection of clinically significant disease over standardized repeat biopsy. When high-quality prostate MRI is available, it should be strongly considered for any patient with a prior negative biopsy who has persistent clinical suspicion for prostate cancer and who is undergoing a repeat biopsy.

mpMRI is also used for patients on active surveillance who are trying to determine if they have a clinically significant prostate cancer. If the mpMRI shows a suspicious lesion, targeted fusion biopsy can be used to confirm clinically significant disease and facilitate definitive treatment.

For additional information, contact Tamara Oranday, PR and Communications Specialist, at South Texas Radiology Imaging Centers, by calling (office) 210-575-6614 or (cell) 210-687-0346.