title: Denonvilliers' space expansion by transperineal injection of hydrogel: implications for focal therapy of prostate cancer.
abstract: We developed and assessed a technique of: (i) expanding Denonvilliers' space by hydrogel (polyethylene glycol) during focal cryoabation; and (ii) temperature mapping to ensure protection of the rectal wall. In a fresh cadaver, 20 cc of hydrogel was injected transperineally into Denonvilliers' space under transrectal ultrasound guidance. Successful expansion of Denonvilliers' space was achieved with a range of 9-11 mm thickness covering the entire posterior prostate surface. Two freeze-thaw cycles were used to expand the iceball reaching the rectal wall as an end-point. Intraoperative transrectal ultrasound monitoring and temperature mapping in Denonvilliers' space by multiple thermocouples documented real-time iceball expansion up to 10 mm beyond the prostate, and safety in protecting the rectal wall from thermal injury. The lowest temperatures of the thermocouples with a distance of 0 mm, 5 mm and 10 mm from the prostate were: -35°C, -18°C and 0°C (P < 0.001), respectively. In gross and microscopic examination, the hydrogel mass measured 11 × 40 × 34 mm, which was identical to the intraoperative transrectal ultrasound measurements, there was no infiltration of the hydrogel into the rectal wall or prostate and no injury to the pelvic organs. In conclusion, the expansion of Denonvilliers' space by transperineal injection of hydrogel is feasible and a promising technique to facilitate energy-based focal therapy of prostate cancer.
authors.affiliation: USC Institute of Urology, Center for Prostate Cancer Focal Therapy, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Andre Luis
authors.initials: AL
authors.lastname: de Castro Abreu
authors.forename: Yanling
authors.initials: Y
authors.lastname: Ma
authors.forename: Sunao
authors.initials: S
authors.lastname: Shoji
authors.forename: Arnaud
authors.initials: A
authors.lastname: Marien
authors.forename: Scott
authors.initials: S
authors.lastname: Leslie
authors.forename: Inderbir
authors.initials: I
authors.lastname: Gill
authors.forename: Osamu
authors.initials: O
authors.lastname: Ukimura
mesh_terms: D000368:Aged; D002102:Cadaver; D003452:Cryosurgery / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology*; D007267:Injections; D008297:Male; D010502:Perineum / Q000000981:diagnostic imaging / Q000601:surgery*; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D012007:Rectum / Q000000981:diagnostic imaging / Q000601:surgery*; D013696:Temperature; D014463:Ultrasonography
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate
keywords: Denonvilliers' space; cryoablation; focal therapy; prostate cancer; rectum separation; spacer