Micro-ultrasound–guided biopsies were found for the first time to be “noninferior” to MRI-guided procedures, according to new research presented at the 2025 annual congress of the European Association of Urology.
The OPTIMUM study found 4.5% more clinically significant cancers among men who underwent micro-ultrasound–guided biopsies of the prostate than in those scanned using MRI.
“The take-home message is that men being worked up for an elevated PSA [prostate-specific antigen] or an abnormal digital rectal examination who are at increased risk of prostate cancer may safely undergo a micro-ultrasound–guided biopsy rather than an MRI-guided biopsy,” said Adam Kinnaird, MD, PhD, the Frank and Carla Sojonky Chair in Prostate Cancer Research at the University of Alberta, Edmonton, Alberta, Canada, and principal investigator of the study.
Micro-ultrasound can image to as small as 70 μm, ie, the width of a human hair.
OPTIMUM was an international, open-label, randomized, noninferiority trial in 20 centers in eight countries of men with clinical suspicion of prostate cancer, elevated PSAs, abnormal digital rectal exams, or a combination of these risk factors. None of the men previously had undergone biopsies.
The study had three arms to which men were assigned randomly: Micro-ultrasound–guided biopsy (n = 121); biopsies guided by micro-ultrasound and fusion MRI (n = 226), and MRI plus conventional ultrasound–guided biopsy (n = 331).
Subjects had a median age of 65 years and a median PSA level of 6.9 ng/mL; 83% self-identified as White individuals.
“Micro-ultrasound was found to be no worse than MRI at the detection of clinically significant prostate cancer. We don’t show it is equivalent. We don’t show it better. We show it is not worse,” Kinnaird said.
The study, funded by Exact Imaging, which makes the ExactVu micro-ultrasound platform, appeared simultaneously in JAMA.
Laurence Klotz, MD, the Sunnybrook Chair of Prostate Cancer Research at the University of Toronto Sunnybrook Health Sciences Centre, and senior researcher on the OPTIMUM trial, said as the incidence of prostate cancer rises globally, micro-ultrasound may be of particular value in low-income and middle-income countries where MRI is not widely available.
“It’s extremely appealing in places that can’t offer MRI to everyone, but I think it also will have a role going forward in regions where there is no problem about getting access to MRI,” Klotz told Medscape Medical News.
This group is next studying the financial aspects of the technology, he added.
Gerald Andriole, MD, then urology chief at Washington University in St. Louis, St. Louis, Missouri, designed the original studies of the ExactVu system, which the US Food and Drug Administration approved in 2017.
Andriole, now chief medical officer of Prostatype Genomics, said MRIs are costly, subjective, and uncomfortable for many patients, due to claustrophobia and obesity, requiring complicated co-registration procedures to perform an accurate targeted biopsy into the most worrisome regions of the prostate. “Proceeding directly to a micro-ultrasound study avoids these impediments to discovering whether the patient has clinically significant cancer,” he said.
Micro-ultrasound testing involves a single visit to a urologist whereas MRI requires two trips for the patient — one to the urologist and the other to a radiologist, Klotz said. “It’s one-stop shopping,” he said. “So, the patient has his micro-ultrasound. If there’s a target found, he then does the targeted biopsy.”
Klotz said micro-ultrasound helps patients avoid the expense and health risks of gadolinium in contrast with MRIs.
“I don’t think micro-ultrasound is going to replace MRIs,” he said. “I think they’re somewhat complementary. You get cases where they’re visible on MRI and not visible on micro-ultrasound and vice versa.”
The researchers received a grant from Exact Imaging.
Howard Wolinsky is a Chicago-based freelance writer.