乌鸦传媒

Upfront use of biparametric magnetic resonance imaging (bpMRI), a more rapid and lower-cost version of multiparametric MRI, rules out almost all significant disease in men with suspected prostate cancer and thus would spare many from invasive biopsy, a new study indicated.

Among 1,020 men who underwent both bpMRI and standardized transrectal (TRUS) biopsy, low-suspicion bpMRI had a negative predictive value of 97% in ruling out significant prostate cancer (95% CI 95%-99%), reported Lars Boesen, MD, PhD, of Herlev Gentofte University Hospital in Denmark, and colleagues.

"The results suggest that bpMRI may be used as a triage test to exclude the presence of aggressive disease and avoid unnecessary biopsies with its inherent complications," the investigators explained in .

Boesen's group also found that restricting combined biopsies just to those with suspicious bpMRI findings meant 30% of men could avoid a TRUS biopsy. "Most of these men had low-risk disease qualifying for surveillance," the authors noted.

Use of bpMRI also improved diagnoses of significant prostate cancer by 11% while insignificant prostate cancer diagnoses were reduced by 40% (P<0.001 for both endpoints). And this was done using fewer biopsy cores compared with standard TRUS biopsy alone. "If combined biopsies were restricted solely to patients with suspicious bpMRIs, only 8 men with significant prostate cancer would have been missed and significantly fewer men ... with insignificant prostate cancer would have been diagnosed," the authors observed.

The 715 men with suspicious bpMRI lesions underwent a targeted biopsy, and prostate cancer was detected in 67%, with clinically significant cancer found in 47% of the biopsied group. Standard TRUS biopsy detected prostate cancer in 63% of the men, and in 34% of them the cancer was significant.

, Timothy Wilt, MD, MPH, and Philipp Dahm, MD, both of the University of Minnesota School of Medicine in Minneapolis, said that while the authors emphasized the sensitivity (98%) and negative predictive value (97%) of bpMRI, specificity (48%) and positive predictive values (56%) were less impressive.

They also point out that the rate of prostate cancer in the study seemed to be "extraordinarily high," with a 40% rate of clinically significant disease. A more typical scenario in a standard U.S. practice would likely peg that risk at roughly 9% based on a standardized risk calculator, they said.

"For MRI-based triaging strategies to be cost-effective, patients and physicians must be willing to change management based on MRI findings," Wilt and Dahm wrote. "The use of MRI will result in low-value rather than high-value care if patients with negative MRI findings ... still undergo a biopsy or active surveillance imaging and if all men with MRI-defined clinically significant disease undergo radical interventions."

The BIDOC (Biparametric MRI for Detection of Prostate Cancer) study required a clinical suspicion of prostate cancer in all participants as evidenced by either a prostatic-specific antigen (PSA) of 4.0 ng/mL or greater or an abnormal digital rectal exam that necessitated a diagnostic prostate biopsy. The median PSA level of the cohort was 8.0 ng/mL.

Clinically significant prostate cancer was defined as any high-grade prostate cancer (Gleason score 4+3 or maximum cancerous core length greater than 50% for Gleason 3+4). Prior to undergoing standard TRUS biopsy, men underwent bpMRI using a 3-T MRI magnet with a pelvic-phase-array coil positioned over the pelvis. All bpMRI images were reviewed by the same experienced radiologist, who was blinded to the clinical findings.

Patients also underwent standard 10-core extended sextant biopsies, and then any suspicious lesion detected by TRUS was sampled by a standard biopsy scheme. This was followed by targeted biopsies of any bpMRI suspicious lesions. Overall, 64% of the men had prostate cancer and 40% of them had significant prostate cancer.

Limitations of the study include the fact that it was carried out at a single center with a single dedicated radiologist reading the bpMRIs and two TRUS operators performing the biopsies.