V08-04: Magnetic resonance / Ultrasound fusion-guided cryoablation of the prostate
Given its accessibility, familiarity amongst urologists, and long-term experience, the use of prostate cryoablation as a focal therapy modality is growing. Focal cryoablation has been predominantly performed with "visual registration" and estimation of treatment margins. This is challenging as it requires cognitive fusion planning in 3 dimensions, taking into consideration multiple cryoprobes with differing isotherm treatment volumes. MR/Ultrasound fusion-guided prostate cryoablation is novel technique that allows for accurate treatment planning with visualization and guidance of cryoablation of a pre-segmented target lesion.
MR/US fusion-guided focal cryoablation technique in a 74 year old male with PSA of 9.5 and Gleason 4+3=7 prostate cancer and tertiary pattern 5 prostate cancer confined to an MRI region of interest is demonstrated. Treatment planning was performed with Dyncad for segmentation of the MR-visible lesion at 10mm treatment margin. A novel electromagnetic transperineal fusion biopsy platform (UroNav, Invivo, Gainesville, FL) was used for MR/US fusion guidance. Cryoablation was performed with the Galil Medical Visual Ice Cryoablation system.
Successful fusion-guided focal cryoablation was performed with 2 freeze thaw cycles with confirmation of the iceball extending 5mm beyond the segmented treatment margin. The patient was discharged home with a catheter for 3 days and experienced no postoperative complications within 90 days. Postoperative prostate MRI at 2 weeks and 6 months confirmed complete tumor ablation. Repeat prostate biopsy at 6 months post-treatment demonstrated no evidence of disease. Patient's PSA declined to 1.6ng/mL and remains low at 1 year. His International Prostate Symptom Score (I-PSS) as well as his Sexual Health Inventory for Men (SHIM) returned to baseline at 6 months.
Fusion-guided focal cryoablation for localized prostate cancer is feasible and safe, with satisfactory short-term outcomes. It allows for accurate targeting of both the lesion and a margin of ablation while minimizing treatment of non-target tissue. Long-term follow-up regarding this technique is needed to further evaluate functional and oncologic outcomes.