Precise needle puncture of the renal collecting system is an essential step for successful percutaneous nephrolithotomy (PCNL). Puncture is technically challenging and has many pitfalls. We describe the use of a real time image guidance system, the SabreSource™, in combination with a novel mechanical apparatus “the locator” to potentially assist accurate percutaneous needle placement and compare this with conventional manual techniques.
The SabreSourceTM system (Minrad International Inc.; New York, USA) is a real time image guidance system. The system platform is mounted on a C-Arm fluoroscope. It employs targeting cross hairs on the fluoroscopic image that can be easily positioned to target the desired renal calyx. The system directs a visible laser beam onto the patient which is precisely aligned with the cross hairs on the fluoroscopic image. This provides the correct “bull's-eye” angle of approach to the calyx, even after the x-ray source is turned off. The locator then stabilises the needle in the bull’s eye position so that only screening for depth is required.
Objective assessment was obtained by in vitro testing using simulated PCNL puncture of a kidney phantom with and without using the SabreSource. Fluoroscopy screening time (FST) and amount of radiation (mGy) used to achieve successful puncture was assessed.
Seven urologic trainees were recruited to test the SabreSource. Simulated PCNL puncture was quicker and with reduced radiation exposure when the apparatus was used. The mean FST for traditional “bull’s eye” vs SabreSource puncture was 17 vs. 5 seconds (p = 0.01), and the mean radiation exposure to puncture was 0.7 vs 0.2 mGy (p = 0.03).
The SabreSource is a novel assistant to achieving successful PCNL puncture. In combination with “the locator” the preliminary in vitro testing suggests that the device reduces fluoroscopic exposure and is quicker. The device warrants further evaluation in the clinical setting.