Collecting system percutaneous access using real-time tracking sensors: first pig model in vivo experience

PURPOSE: Precise needle puncture of the renal collecting system is a challenging and essential step for successful percutaneous nephrolithotomy (PCNL). This works aims to evaluate the efficiency of a new real-time electromagnetic tracking (EMT) system for in vivo kidney puncture. MATERIALS AND METHODS: Six anesthetized female pigs underwent ureterorenoscopies in order to place a catheter with an EMT sensor into the desired puncture site and to ascertain the success of puncture. Subsequently, a tracked needle with a similar EMT sensor was navigated into the sensor inside the catheter. Four punctures were performed by two surgeons in each pig: one in the kidney and one in the middle ureter, on both right and left pig sides. Number of attempts and time needed to evaluate the virtual trajectory and to perform the percutaneous puncture were outcomes measurements. RESULTS: Overall 24 punctures were easily performed without any complications. Surgeons required more time to evaluate the trajectory during ureteral puncture than kidney (median 15 versus 13 seconds, range 14 to 18 and 11 to 16 seconds, respectively; p= 0.1). The median renal and ureteral puncture time were 19 and 51 seconds respectively (range 14 to 45 and 45 to 67; p=0.003). Two attempts were needed to achieve a successful ureteral puncture. The presented technique demands presence of renal stone for testing. CONCLUSIONS: The proposed EMT solution for renal collecting system puncture proved to be highly accurate, simple and quicker. This method might represent a paradigm shift in percutaneous kidney access techniques