Visual registration in combination with image fusion may offer the highest detection rate of clinically significantly prostate cancer (PCa) and thus could aid in risk stratification, according to a new study published in European Urology.
Studies have shown that multiparametric magnetic resonance imaging (mpMRI)-targeted prostate biopsies can improve detection of clinically significant PCa while decreasing the risk of overdetection of insignificant cancers. Still, controversy remains regarding whether visual-registration targeting (mentally translating mpMRI targets onto real-time ultrasound images) is sufficient or whether augmentation of this approach with image-fusion software may be optimal, according to a team led by Hashim U. Ahmed, MD, PhD, of Imperial College London, UK.
Dr Ahmed and colleagues examined the concordance between both methods in a randomized, prospective, within-person study that included 129 men who had undergone a prior transrectal ultrasound biopsy and had a discrete lesion on mpMRI (score 3–5) requiring targeted transperineal biopsy.
The mpMRI-directed or targeted biopsies included in-bore targeted biopsies, visual-registration and software-based MRI/ultrasound image-fusion systems overlaying MRI targets onto real-time ultrasound images.
None of these methods previously has been studied for superiority in a clinical setting. The current study, which is called the Smart-Target Biopsy trial (ClinicalTrials.gov NCT02341677), found that both strategies detected 80/93 of University College London (UCL) definition 2 clinically significant disease (Gleason pattern 3+4=7 or higher and cancer core length of 4 mm or greater in any core), with an overall detection rate of 80/129 (62%). Each method identified 13 cancers that the other missed. The combination of the methods resulted in a significant 14% improvement in the detection of clinically significant PCa.
Study strengths included a design that helped to minimize potential incorporation of bias. Investigators randomized the order of the biopsy strategies for each patient and reset equipment to a default setting prior to each biopsy strategy. In addition, biopsies were conducted by 14 urologists who were considered highly experienced, suggesting that the visual registration strategy was as optimized as possible.
A key limitation of the study was the capping of biopsy sample number to just 3 per strategy, thus reducing detection rates for both visual registration and image fusion. Further, the study did not examine costs, which the authors acknowledged could be an issue.
The study did not reveal any unexpected safety issues. Both biopsy strategies were consistent with the safety profile associated with either strategy performed alone, according to the authors.
“I think this is a good study that further adds to our growing knowledge base about the optimal role of imaging in the prostate biopsy procedure,” said Tomasz M. Beer, MD, Deputy Director of the Knight Cancer Institute and Professor of Medicine at Oregon Health and Sciences University in Portland. “This study alone does not establish care standards, but taken together with other studies, there is a growing body of evidence that supports the use of MRI imaging prior to biopsy, and this study speaks to how the images might be best utilized.”
Obtaining an MRI can add to costs upfront, but if used as intended it can lead to a reduction in unproductive biopsies, Dr Beer added.
William J. Catalona, MD, Professor of Urology at the Northwestern University Feinberg School of Medicine in Chicago, said cost could be a significant barrier for a number of patients. “Cost is a big issue in the US, where MRI scans are far more expensive, and many insurance companies do not cover them unless the patient has had a prior negative biopsy but still has a rising PSA,” Dr Catalona told Renal & Urology News.
Daniel Oberlin, MD, a urologic oncologist at Golden Gate Urology in San Francisco, said visual registration may offer an advantage over MRI-ultrasound fusion techniques in terms of time and cost. “This study confirms for me that visual registration will miss tumors that MRI-ultrasound fusion detects, and, therefore, the majority of men with lesions on MRI should consider fusion technologies,” Dr Oberlin said. “I do believe, however, that exceptions to this rule exist, and for those men with large lesions … visual techniques may be able to equally detect these cancers.”
Hamid S, Donaldson IA, Hu Y, et al. The Smarttarget Biopsy trial: A prospective, within-person randomised, blinded trial comparing the accuracy of visual-registration and magnetic resonance imaging/ultrasound image-fusion targeted biopsies for prostate cancer risk stratification. Eur Urol. 2018; published online ahead of print.