Route Does Not Impact Diagnostic Accuracy of Micro-Ultrasound Targeted Prostate Biopsies, Study Finds

The report suggests that high-resolution micro-ultrasound could help identify clinically significant lesions that would be missed with conventional MRI.

High-resolution micro-ultrasound (micro-US) appears to be effective at identifying prostate cancer lesions regardless of access route and may outperform conventional MRI ultrasound fusion biopsies when it comes to diagnosing patients, a new report shows.

Findings of the study, published in PLoS One, suggest that multiparametric MRI (mpMRI) using micro-US might help identify clinically significant disease that would otherwise be missed using conventional MRI.

The study authors said current guidelines call for the use of mpMRI prior to prostate biopsy, since the method tends to be a more productive diagnostic strategy than biopsies performed without prior imaging.

Still, the investigators said current MRI ultrasound fusion strategies have significant limitations.

“Indeed, conventional transrectal ultrasound technology is unable to characterize prostatic tissue and to differentiate between benign and nonbenign areas,” they wrote. “This may lead to incorrect sampling due to needle deviation, fusion error, and/or lack of operator experience.”

High-resolution micro-US is a new imaging modality that operates at 29 MHz and improves spatial resolution by 300%. The authors said the device can be used to perform transrectal (TR-B) or transperineal (TP-B) prostate biopsies.

“TP-B has been gaining popularity due to its higher cancer detection rate in the antero-apical zones, lower sepsis rate, and lower risk of rectal bleeding,” the authors said. However, they added no study has yet to look at whether the route used affects the diagnostic accuracy of biopsies using micro-US mpMRI fusion devices.

The investigators used propensity score matching on 56 TR-B and 266 TP-B procedures in which physicians used the ExactVu micro-US system with mpMRI image fusion. Their goal was to see if the transrectal or transperineal route outperformed the other. Their results were based on 47 men who underwent TR-B and 88 men who underwent TP-B. The participants were matched by age, prostate-specific antigen levels, and other clinical factors.

Overall, the route used for the procedure did not significantly affect the likelihood of finding cancer, the investigators found. Among the TR-B group, the rate of clinically significant prostate cancer was 45% compared with 42% in the TP-B group. In addition, the odds of finding any prostate cancer were 57% in the TR-B and 59% in the TP-B group.

“This study shows that there is no difference between TR-B and TR-P in terms of detection rate of clinically significant and insignificant prostate cancer using micro-US mpMRI fusion-targeted biopsy,” they wrote.

Detection rates were also similar between random and targeted biopsies stratified by access route.

However, the data suggested that the newer device made a difference. In 33 patients, micro-US targeted biopsy identified 36 lesions that were invisible on MRI. Nineteen percent of those were positive for clinically significant disease, the study authors reported.

“In our series, this amounts to a 2% upgrading to clinically significant disease based on micro-US targeted biopsy,” they wrote.

The investigators noted some limitations to their study, including its retrospective nature and relatively small sample size. They added that patients with anterior lesions were systematically given TP-B, and thus it was not possible to compare the 2 approaches in those patients.

Still, they said their findings appear to bolster the case that micro-US targeted biopsy can provide added value as a diagnostic tool.

“Whether micro-US can be a replacement for or an add-on test to standard of care is being further explored in ongoing studies,” they said.


Rakauskas A, Peters M, Martel P, et al. Do cancer detection rates differ between transperineal and transrectal micro-ultrasound mpMRI-fusion-targeted prostate biopsies? a propensity score-matched study. PLoS One. Published online January 18, 2023. doi:10.1371/journal.pone.0280262

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