Performance of a New Blunt-Tip Needle for the Displacement of Critical Structure in Thermal Ablation.

Purpose: To ascertain the performance of a new blunt-tip needle (HydroGuard), which allows injection of fluids during needle advancement in order to safely approach, displace and insulate nearby critical structures during thermal ablation (TA).

Materials And Methods: This study included 27 consecutive patients treated by TA [cryoablation (CA), radiofrequency (RFA), and microwave MWA)] between April 2018 and January 2019. During TA, hydro- or gas dissection was performed with HydroGuard needle to displace and protect critical structures close to the tumor (< 10 mm). Technical and clinical success, distance between critical structure and tumor before and after hydro/gas dissection and complications were recorded.

Results: Eighteen patients were treated by CA (66.7%), 7 by MWA (25.9%) and 2 by RFA (7.4%). Majority of patients were treated with a curative intent (24/27; 88.8%). Adjacent critical structures include vessels (n = 3), nerves (n = 10), ureter/renal pelvis (n = 3), bowel/rectum (n = 10), stomach: (n = 3), diaphragm (n = 2), and pleura (n = 1). Technical success was 100%. Clinical success was 88% (24/27). Median minimum distance to adjacent critical structures before hydro/gas dissection was 1 mm (range 0-9 mm; IQR: 0-3 mm) versus 10.5 mm (range 4-47 mm; IQR: 9.7-18 mm) after displacement. Of the 27 patients treated, four developed complications (14.8%; 95% CI: 1.4-28.2): 1 major (3.7%; 95% CI: 0-10.8) and 3 minors (11.1%; 95% CI: 0-23). Only one minor complication was related to inadequate hydro-dissection, resulting in close proximity of the critical structure to the ablation zone.

Conclusion: HydroGuard is a safe and effective needle when used to approach, displace and insulate nearby critical structures during TA.