Other than skin cancer, prostate cancer is the most common cancer in American men. The American Cancer Society estimates that 180,890 new cases of prostate cancer will be diagnosed in 2016 in the U.S. If a man’s annual physical reveals an elevated PSA (prostate specific antigen) blood test, he’s usually referred for a biopsy. A high-tech prostate screening method is improving the way physicians locate, assess, target and track suspicious areas in the prostate by fusing advanced MRI images with live ultrasound images taken during biopsy.
To learn more about this powerful screening method called UroNav MRI-TRUS fusion biopsy, we spoke with a radiologist and a urologist who have been using it. UTHealth Radiologist Varaha S. Tammisetti, M.D., is affiliated with Memorial Hermann-Texas Medical Center. Urologist Ramesh Krishnan, M.D., is affiliated with Memorial Hermann Katy Hospital and Memorial Hermann Memorial City Medical Center.
What has been the traditional biopsy method for prostate cancer?
Dr. Tammisetti: “Transrectal ultrasonography (TRUS) was used to perform most prostate biopsies, but only the back of the prostate where majority (but not all) of the cancers are located could be sampled randomly. Two-thirds of the front of the prostate gland is not sampled. On average, it samples 12 separate sites of the prostate gland.”
Why do so many cancers go undetected using TRUS screening alone?
Dr. Tammisetti: “TRUS is in fact a ‘hit and miss’ approach because you are essentially sampling only 1 percent of the prostate gland before making a treatment decision. Imagine doing this for breast cancer in women without doing any prior imaging. Approximately 30 to 40 percent of clinically significant cancers are missed using TRUS biopsy alone. It also detects low-grade/low-risk prostate cancers.”
How does the UroNav system improve biopsy accuracy?
Dr. Tammisetti: “The UroNav MRI-TRUS fusion biopsy gives us the ability to fuse together the advanced MRI images taken before biopsy with the ultrasound used during the biopsy to improve the odds of detecting cancer. This enables us to evaluate 100 percent of the prostate, improving biopsy accuracy rates and helping ensure that more prostate cancers don’t go undetected or untreated. In essence, UroNav guided fusion biopsy helps detect a higher number of clinically significant (intermediate/high-risk) prostate cancers and fewer low-grade/low-risk prostate cancers.”
How does the advanced MRI used with UroNav provide a more complete picture of the prostate?
Dr. Tammisetti: “Multiparametric prostate MRI (mpMRI) combines several advanced imaging techniques of MRI, including 2-D and 3-D anatomic imaging of the prostate. This diffusion-weighted imaging technique highlights the ‘clinically significant’ tumors while the dynamic contrast enhancement (DCE) technique allows us to measure increased blood flow to prostate tissues, which can indicate a tumor is present.”
What is a “clinically significant” cancer?
Dr. Tammisetti: “According to the American College of Radiology (ACR) PI-RADS v2 document, clinically significant cancers, (intermediate and high-grade/high-risk cancers) are defined based on pathology/histology as Gleason Score > 7 (including 3+4 with prominent but not predominant Gleason 4 component), and/or volume > 0.5cc, and/or extraprostatic extension (EPE).”
What are PI-RADS categories and how are they assigned based on the MRI data?
Dr. Tammisetti: “PI-RADS v2 is designed for detection and localization of ‘clinically significant cancer’ using a 5 point likelihood (probability) scale. An experienced sub specialized abdominal radiologist assigns each abnormality found on the prostate MRI a PI-RADS category from 1-5. Lesions with PI-RADS categories of 3, 4 and 5 are selected for biopsy with post-processing done on a dedicated DynaCAD workstation that is linked to the MRI. Images can be transferred directly from the MRI to DynaCad for quick processing and customized 3-D views of the prostate. The largest and most aggressive lesion will be identified as Index lesion.”
How is prostate MRI used to see if the cancer has spread?
Dr. Tammisetti: “Prostate MRI is also used for local staging to see if the cancer has spread locally outside the prostate. In addition, we also perform imaging of the whole pelvis and not just the prostate, which allows us to see if the tumor has spread into the pelvic bones or lymph nodes.”
How is this new system helping you improve care for your patients?
Dr. Tammisetti: “We have been using UroNav for the last 2 years at the Memorial Hermann –Texas Medical Center Campus. Here, UroNav biopsies are performed by urologists Kevin Slawin, M.D., Steven Canfield, M.D., and Tung Shu, M.D., and lesion selection is done in close collaboration with the radiologist. From a patient point of view, a prostate MRI and subsequent MRI-US fusion UroNav guided biopsy increases the confidence in the selection of the right treatment for the right grade of prostate cancer in the list of clinical scenarios mentioned above. This helps to detect more intermediate/high-risk prostate cancers and decrease detection of low-risk/low-grade prostate cancers.”
Dr. Krishnan: “I’ve been using UroNav for diagnosis and treatment for over a year for my urology patients. My experience has been excellent. The procedure is very easy to do, sensitive and accurate, and much more comfortable for the patient than TRUS biopsies. UroNav provides a much higher level of confidence in the results than TRUS, which translates to earlier detection and earlier treatment when needed. Accurate biopsies help improve the prostate cancer cure rate.”
Currently, UroNav MRI-TRUS fusion biopsy is available at these campuses:
- Memorial Hermann-Texas Medical Center
- Memorial Hermann Memorial City Medical Center
- Memorial Hermann Katy Hospital
To learn more about UroNav and other innovations in prostate cancer detection and treatment, visit http://www.memorialhermann.org/cancer/prostate-cancer/