V2155: Intra-operative ultrasonography using miniature drop-type ultrasound probe manipulated by surgeon during robot-assisted radical prostatectomy

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Introduction and Objectives
Image navigation beyond the endoscopic view potentially improves oncological and functional outcomes. We evaluate the utility of drop-type miniature ultrasound (US) probe (Hitachi Aloka Medical Ltd. CT, USA) for real-time navigation during robot-assisted radical prostatectomy (RARP).

Methods
Seventeen patients with age (64 years), clinical stage T1c/T2a/T2b=6/6/5, PSA (7.5 ng/ml), and biopsy Gleason score of 3+3 (n=7) 3+4 (n=3), 4+3 (n=3), 4+4 (n=3) were enrolled. 41% (6/17) had high risk cancer with Gleason 4+3 or higher in biopsy. Mini probe was designed as ?gdrop-type?h to be manipulated by robotic arm with a flexible cord through the laparoscopic port. The size was 9?~16?~6 mm in diameter, and multi-frequency from 5 to 13 MHz was available, to allow various penetration of US to visualize any tissues with various distances from the probe. Intra-operative US data was transferred to the da Vinci console to provide the real-time US image shown directly to surgeon in parallel to the surgical view in the Tile-pro display.

Results
The median time to use intra-operative US was only 3 minutes in total. Based on the surgeon?fs rating for the utility of the probe, its utilities were excellent regarding 3 aspects as following: (a) visualization of bladder neck to facilitate preservation of bladder neck as small as possible, (b) intra-operative localization of biopsy-proven hypo-echoic lesion (HEL), and (c) identification of releasing line of the neuro-vascular bundle (NVB) adjacent to the posterior-lateral surface of the prostate. Combined consideration of (b) and (c) helped intra-operative decision making to perform wider dissection for partial or complete nerve sparing in order to achieve negative surgical margin. Prostatectomy specimens revealed Gleason score 6/3+4/4+3/8/9 cancer in N=3/8/1/3/2, respectively, and pathological stage pT2a/pT2c/pT3a/pT3b in N=4/7/2/4, respectively. Although over 40% men of this series had high risk and/or extra-prostatic disease, negative surgical margins were achieved in 94% (16/17). Intraoperative complication was none.

Conclusions
Intra-operative navigation using novel mini US probe is feasible and safe. To visualize the critical anatomy beyond the endoscopic view such as cancer location and proximity of NVB in console display provided a new opportunity for surgical navigation controlled by robotic surgeon.

Funding: none