Recent research shows that new MRI-TRUS fusion biopsy can more effectively detect high-grade prostate cancers than conventional TRUS biopsy.
Traditional methods for detecting and grading prostate cancers, typically transrectal ultrasound (TRUS) biopsy, have not always been effective at differentiating between aggressive, high-grade cancers and slow-growing, low-grade cancers. However, magnetic resonance imaging (MRI) is proving useful in prostate cancer diagnosis and grading. Researchers investigating a relatively new prostate cancer diagnosis procedure combining MRI and TRUS, called TRUS-MRI fusion biopsy, have determined that it can more effectively detect high-grade prostate cancers with fewer biopsies.
What is MRI-TRUS fusion biopsy?
During TRUS biopsy, ultrasound is used to visualize the prostate gland, about the size of a walnut, while around 12 biopsy needles are injected through the rectum to remove tissue for sampling. Ultrasound can see the outlines of the prostate gland well, but cannot produce detailed images of tissue within the prostate gland and biopsy needles are shot blindly into the prostate gland. This is inefficient because there is potential to:
- Miss cancers completely
- Capture low-grade samples while missing high-grade samples
- Create the need for repeat biopsies, increasing risk to infection and bleeding.
In TRUS-MRI fusion biopsy, a special type of MRI called a multiparametric MRI is performed prior to biopsy. MRI can produce images of internal prostate in much more detail than ultrasound, showing the exact location of suspicious areas. Multiparametric MRI images are then fused with real-time ultrasound using advanced computer software and biopsy needles are guided precisely to targeted areas.
TRUS-MRI in high-grade prostate cancer diagnosis
To see how TRUS-MRI fusion biopsy compared to TRUS biopsy in the detection of high-grade prostate cancers, researchers analyzed exams performed on 105 men who underwent conventional TRUS biopsy, three rounds of multiparametric MRI from 2012-2013 and. Mean age of patients was 65.8 years and a mean prostate specific antigen (PSA) level of 9.5 ng/ml, which is considered high. Results were published in the June 2014 issue of Journal of Urology.
Researchers determined that conventional TRUS biopsy completely missed prostate cancers in nearly 15 percent of cases. Of those cancers, more than 85 percent were considered clinically significant on TRUS-MRI fusion biopsy. Additionally, nearly one-quarter of cancers considered clinically insignificant after TRUS biopsy were upgraded to clinically significant after TRUS-MRI fusion biopsy.
These results provide further evidence that TRUS-MRI fusion biopsy can result in fewer biopsy needles reducing the need for repeat biopsies and to more effectively detect high-grade cancers, which can help to inform men and their physicians about appropriate treatment choices.
“Results of the phase III clinical trial show that a target fusion biopsy detects more clinically significant prostate cancer,” said Art Rastinehad, D.O., principal investigator for the study and director of interventional urologic oncology at the North Shore-Long Island Jewish Health System Arthur Smith Institute for Urology. “This is the type of cancer that patients may benefit from treatment to other patients with low-grade and low-volume prostate cancer.”
Multiparametric MRI and MRI-TRUS fusion biopsy have the potential to improve patient care by improving prostate cancer diagnosis. Future research may reveal even more applications for these cutting-edge technologies in the detection, monitoring and treatment of prostate cancers.