3D MR+US fusion may be best of both worlds for prostate biopsy

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A new technique of targeted biopsy using MR-ultrasound fusion technology can accurately target prostate lesions and potentially improve diagnosis, according to a study published in the January issue of Journal of Urology.

Researchers from the University of California-Los Angeles (UCLA) said the technique, which is performed using local anesthesia in an office setting, could aid in selecting which patients are suitable for active surveillance and which need focal therapy.

“The technology exists to biopsy prostate tumors under [MRI] guidance and this has been shown to improve prostate cancer diagnosis,” first author Geoffrey Sonn, MD, said in a press release. “But such procedures are time-consuming, costly, and impractical in most settings. Magnetic resonance ultrasound (MR-US) systems that fuse stored MR images with real-time ultrasound combine the resolution of MRI with the ease and practicality of ultrasound, offering a savings in time and cost, while potentially retaining the accuracy of MR-guided biopsy.”

To test prostate cancer detection rates, the authors evaluated findings in a group of 171 consecutive men undergoing MR-US fusion prostate biopsy. Sixty-five of the men had an increased prostate specific antigen (PSA) level but previously negative biopsies, and the remaining 106 were undergoing biopsy for surveillance. Together the men had a median PSA of 4.9 ng/ml and a median prostate size of 48 cc.

Prior to biopsy, the authors explained that each participant underwent multiparametric 3T MRI, with identified lesions outlined in 3D and assigned a cancer suspicion level. These images were then fused with real-time ultrasound to make a 3D model, which was used for a transrectal biopsy of target lesions. Twelve systematic biopsies were also performed. The procedure was conducted with the patient under local anesthesia in a clinic.

Results showed a targeted biopsy was three times more likely to identify cancer than a systematic biopsy, with rates of 21 percent and 7 percent, respectively. Prostate cancer was found in 53 percent of the participants, 38 percent of whom had a Gleason 7 or greater cancer. Of the participants with a Gleason grade 7 or greater cancer, 38 percent had disease detected only on targeted biopsies, according to Sonn and colleagues. Of the 16 men with the highest level of suspicion on MRI, 15 had prostate cancer.

In addition to improving patient selection, the MR-US technique also could identify tumors missed on transrectal ultrasound (TRUS) biopsies, according to the authors.

In a comment on the study, Bradford Hood, MD, and colleagues at the National Cancer Institute in Bethesda, Md., wrote, “MR-US fusion guided biopsy unblinds the ‘blind’ biopsy and has great potential to supplement or replace ‘blind’ TRUS prostate biopsies. However, significant hurdles remain to broad adoption and the best approach is yet to be determined.”