Emerging research suggests that micro-ultrasound focal laser ablation (FLA) with magnetic resonance imaging (MRI)-guidance may facilitate targeted treatment and improved outcomes for localized prostate cancer.
For the randomized prospective study, recently published in Radiology, researchers assessed MRI-guided micro-ultrasound multifiber and single-fiber FLA based on data from 55 patients (median age of 70) who had a total of 58 PI-RADS 3 or higher lesions. The study authors noted that 74 percent of the treated lesions had a Gleason score of 3+4 and 17 percent had a Gleason score of 3+3.
The researchers found that micro-ultrasound improved localization for 91 percent (53/58) of prostate cancer (PCa) lesions shown on MRI.
“The high tumor detection rate may be due to the high resolution of 29 MHz, which provides a real-time spatial resolution of 70 μm, resulting in a threefold increase in resolution compared with conventional 9–12-MHz transrectal (ultrasound) probes. However, MRI scan fusion proved valuable during the planning phase of the FLA, allowing for precise needle position adjustment for optimal target volume coverage,” wrote lead study author Francois Cornud, M.D., who is affiliated with the Department of Radiology at Clinique de l’Alma in Paris, France, and colleagues.
(Editor's note: For additional content on prostate cancer imaging, click here.)
Examining 12-month follow-up data for 35 of the treated prostate cancer lesions, the study authors noted a 44 percent reduction of participant prostate-specific antigen (PSA) level after a single-fiber FLA (from 6 ng/mL to 3.4 ng/mL). However, they also noted that FLA had a 49 percent PCa recurrence rate with single-fiber FLA accounting for 77 percent (10 of 13) in-field recurrences.
After transitioning to multifiber FLA treatments, the researchers noted a 65 percent reduction of PSA levels (from 8 ng/mL to 2.8 ng/mL) and an 18 percent recurrence rate for PCa.
“Our study confirmed that micro-US can help to effectively localize PCa tumor foci before focal therapy and guide transperineal interventional prostate procedures,” maintained Cornud and colleagues.
Three Key Takeaways
1. Improved localization with micro-ultrasound. Micro-ultrasound with 29 MHz resolution successfully localized 91 percent of prostate cancer lesions, offering a threefold increase in resolution compared to conventional ultrasound.
2. Efficacy of multifiber FLA. Multifiber focal laser ablation (FLA) reduced prostate-specific antigen (PSA) levels by 65 percent and had a lower in-field recurrence rate (18 percent) compared to single-fiber FLA (56 percent).
3. Safety and complications. The procedure had no significant impact upon quality of life and urinary function but researchers noted a slightly lower median International Index of Erectile Function score. They also noted a retroprostatic fistula complication, highlighting the need for hydrodissection to reduce this risk.
The study authors noted no significant impact upon the median International Prostatic Symptom Score or quality of life. They did acknowledge a slightly lower median International Index of Erectile Function score (19 vs. 21 at baseline).
The researchers also noted one severe complication of a retroprostatic fistula, which occurred after treatment of a bilateral peripheral zone tumor. Pointing out the challenges of simultaneous temperature monitoring at multiple sites of treatment with micro-ultrasound multifiber FLA, they suggested that rectoprostatic hydrodissection can reduce the risk of this complication.
(Editor’s note: For related content, see “FDA Clears AI ‘Contouring Assistant’ in MRI-Guided Ultrasound Ablation Procedures,” “A Closer Look at MRI-Guided Transurethral Ultrasound Ablation for Intermediate Risk Prostate Cancer” and “Top Five Prostate Imaging Content of 2024.”)
Beyond the inherent limitations of a single-center study, the authors acknowledged the small cohort size and a lack of long-term outcome assessment beyond 12 months. They also noted the lack of thermosensors during laser treatment limited comparison to MRI thermometry for in-bore MRI-guide focal laser ablation.
