MicroUS an Effective Alternative to MRI for Prostate Cancer Diagnosis

Microultrasonography (microUS)-guided biopsy is a noninferior alternative to multiparametric (mp) MRI with conventional US fusion-guided biopsy for clinically significant prostate cancer (csPCa) detection. It can provide faster and more affordable care, according to data from the OPTIMUM trial, the largest clinical trial of the technology to date.

"Clinicians should consider microUS-guided biopsy, with mpMRI where possible, as the highest sensitivity test available for prostate cancer," said co-author Sangeet Ghai, MD, director of research and professor of the Joint Department of Medical Imaging at the University of Toronto. "MicroUS imaging is a useful tool for both risk stratification and biopsy in cases where mpMRI is logistically challenging, or where patient factors make avoiding the extra procedure preferrable."

“Clinicians should consider microUS-guided biopsy, with mpMRI where possible, as the highest sensitivity test available for prostate cancer. MicroUS imaging is a useful tool for both risk stratification and biopsy in cases where mpMRI is logistically challenging, or where patient-factors make avoiding the extra procedure preferable.”

Sangeet Ghai, MD

According to Dr. Ghai, microUS technology, operating at 29 MHz for 70-micron resolution, produces real-time images that are much sharper and more detailed than conventional US. It offers about three times greater resolution than conventional US and allows visualization of changes in the prostate’s cellular and ductal architecture associated with cancer. “There are currently more than 300 microUS systems in use in the U.S., Canada, Europe and Asia, and more than 150,000 microUS procedures have been performed,” Dr. Ghai said.

OPTIMUM Trial: Design and Findings

The OPTIMUM Trial, an open-label, randomized noninferiority trial, enrolled 678 biopsy-naïve men aged 59 to 71, across 20 centers in eight countries. All participants were indicated for prostate biopsy due to elevated prostate-specific antigen (PSA) and/or an abnormal digital rectal exam finding. They had no history of genitourinary cancer, including prostate cancer.

Patients were randomized into three groups: those receiving microUS-guided biopsy alone, those receiving microUS plus mpMRI-guided biopsy using microUS, and those receiving mpMRI/conventional US fusion-guided biopsy. Each group underwent targeted biopsies guided by their assigned imaging modality, followed by synchronous systematic biopsies using transrectal or transperineal techniques.

MicroUS-guided prostate biopsy was found to be noninferior to mpMRI/conventional US fusion-guided biopsy in detecting Gleason Grade Group 2 or higher prostate cancer. The difference in detection between the two methods was 3.5%, with a 95% confidence interval ranging from -4% to 10.9% and a noninferiority p value of 0.0026.

“This has great implications because microUS is faster and less expensive,” Dr. Ghai said. “And the conclusion was robust across variations in csPCa definition, biopsy approach and biopsy route.”

“The group receiving microUS-guided biopsy actually had an insignificantly higher csPCa detection rate than the group receiving mpMRI fusion with conventional ultrasound, by about 3.5%,” Dr. Ghai added. “This didn't meet the statistical cutoff for superiority but was surprising given that guidance on recognizing anterior cancers on microUS was only released partway through the study. We expected microUS to be slightly below mpMRI-fusion but that was not observed.”

Dr. Ghai said microUS should be considered when ordering mpMRI would introduce a delay in diagnosis or if there are concerns about image quality due to implanted devices, claustrophobia or kidney function.

“MicroUS has the potential to streamline care. Providing a diagnosis and treatment plan sooner reduces anxiety for the patient and provides more certainty for the provider,” he noted. “The fact that the MicroUS can be used in conjunction with mpMRI through the elastic fusion feature built into the platform, and may improve sampling of mpMRI targets, is an additional benefit.”

Access the session, “Microultrasonography-Guided Vs. MRI-Guided Biopsy for Prostate Cancer Diagnosis – The OPTIMUM Randomized Clinical Trial,” (S1-SSGU01-5) on demand at RSNA.org/MeetingCentral.