Feasibility of MRI-guided transurethral ultrasound for lesion-targeted ablation of prostate cancer

Abstract

Background: MRI-guided transurethral ultrasound ablation (TULSA) has been evaluated for organ-confined prostate cancer (PCa). The purpose of this study was to assess the safety and toxicity, accuracy and short-term evolution of cell-death after lesion-targeted TULSA. Methods: This prospective, registered, Phase-I treat-and-3-week-resect-study enrolled six patients with MRI-visible-biopsy-concordant PCa. Lesions were targeted using TULSA with radical intent, except near neurovascular bundles (NVB). Robot-assisted-laparoscopic-prostatectomy (RALP) was performed at 3 weeks. Post-TULSA assessments included MRI (1 and 3 weeks), adverse events and quality-of-life (QoL) to 3 weeks, followed by RALP and whole-mount-histology. Treatment accuracy and demarcation of thermal injury were assessed using MRI and histology. Results: Six patients (median age ¼ 70 years, prostate volume ¼ 60 ml, PSA ¼ 8.9 ng/ml) with eight biopsy-confirmed MRI-lesions (PIRADS 3) were TULSA-treated without complications (median sonication and MRI-times of 17 and 117 min). Foley-catheter removal was uneventful at 2-3 days. Compared to baseline, no differences in QoL were noted at 3 weeks. During follow-up, MRI-derived non-perfused-volume covered ablated targets and increased 36% by 3 weeks, correlating with necrosis-area on histology. Mean histological demarcation between complete necrosis and outer-limit-ofthermal-injury was 1.7 ± 0.4 mm. Coagulation necrosis extended to capsule except near NVB, where 3 mm safety-margins were applied. RALPs were uncomplicated and histopathology showed no viable cancer within the ablated tumor-containing target. Conclusions: Lesion-targeted TULSA demonstrates accurate and safe ablation of PCa. A significant increase of post-TULSA non-perfused-volume was observed during 3 weeks follow-up concordant with necrosis on histology. TULSA achieved coagulation necrosis of all targeted tissues. A limitation of this treat-and-resect-study-design was conservative treatment near NVB in patients scheduled for RALP.

Palliative MRI-guided transurethral ultrasound ablation for symptomatic locally advanced prostate cancer

“…The relief of anatomical obstruction after TULSA is slower compared to TURP because tissue ablated by TULSA gradually disappears by sloughing of necrotic tissue into the urinary tract and eradication of ablated necrotic tissue via the hematogenic route. Recent studies have reported that, despite an initial increase in prostate volume as a result of thermal injury derived inflammation, at 3 weeks the prostate volume starts to decrease [11]. This suggests that anatomical obstruction relief is obtained gradually, which should be considered when defining the duration of post-TULSA catheterization.…”

“…Treatment was delivered using TULSA (TULSA-PRO, Profound Medical Inc., Mississauga, Canada). A detailed description of the intervention is described in our previous study assessing TULSA for lesion-targeted ablation of localized PCa [11]. Due to the heterogeneity of the study participants, the treatment approach was dependent on the individual disease characteristics.…”

“…Combining MRI treatment planning and real-time temperature monitoring, TULSA generates conformal ultrasound ablation in the prostate via a transurethral ultrasound catheter. Previous TULSA studies have demonstrated oncological efficacy among men with localized PCa with a favorable safety profile and low impact on QoL [11][12][13].…”

Salvage Magnetic Resonance Imaging–guided Transurethral Ultrasound Ablation for Localized Radiorecurrent Prostate Cancer: 12-Month Functional and Oncological Results

“…Treatment was delivered using TULSA (TULSA-PRO, Profound Medical Inc., Mississauga, Canada). A detailed description of the technology is provided in our earlier paper [20] . The TULSA technique and study intervention are described in detail in the Supplementary material.…”

“…MRI-guided transurethral ultrasound ablation (TULSA) is a new treatment alternative that has been used for both whole-gland (WG) [18] , [19] and lesion-targeted [20] , [21] ablation of primary localized PCa. During TULSA the ablation is monitored and automatically controlled in real time under MRI thermometry for highly conformal ablation, while still allowing users the necessary control to intervene at their discretion to ensure that critical surrounding structures are spared.…”