Percutaneous Kidney Puncture with Three-dimensional Mixed-reality Hologram Guidance: From Preoperative Planning to Intraoperative Navigation

Despite technical and technological innovations, percutaneous puncture still represents the most challenging step when performing percutaneous nephrolithotomy. This maneuver is characterized by the steepest learning curve and a risk of injuring surrounding organs and kidney damage.To evaluate the feasibility of three-dimensional mixed reality (3D MR) holograms in establishing the access point and guiding the needle during percutaneous kidney puncture.This prospective study included ten patients who underwent 3D MR endoscopic combined intrarenal surgery (ECIRS) for kidney stones from July 2019 to January 2020. A retrospective series of patients who underwent a standard procedure were selected for matched pair analysis.For patients who underwent 3D MR ECIRS, holograms were overlapped on the real anatomy to guide the surgeon during percutaneous puncture. In the standard group, the procedures were only guided by ultrasound and fluoroscopy.Differences in preoperative and postoperative patient characteristics between the groups were tested using a χ2 test and a Kruskal-Wallis test for categorical and continuous variables, respectively. Results are reported as the median and interquartile range for continuous variables and as the frequency and percentage for categorical variables.Ten patients underwent 3D MR ECIRS. In all cases, the inferior calyx was punctured correctly, as planned using the overlapping hologram. The median puncture and radiation exposure times were 27 min and 120 s, respectively. No intraoperative or major postoperative complications occurred. Matched pair analysis with the standard ECIRS group revealed a significantly shorter radiation exposure time for the 3D MR group (p < 0.001) even though the puncture time was longer in comparison to the standard group (p < 0.001). Finally, use of 3D MR led to a higher success rate for renal puncture at the first attempt (100% vs 50%; p = 0.032). The main limitations of the study are the small sample size and manual overlapping of the rigid hologram models.Our experience demonstrates that 3D MR guidance for renal puncture is feasible and safe. The procedure proved to be effective, with the inferior calyx correctly punctured in all cases, and was associated with a low intraoperative radiation exposure time because of the MR guidance.Three-dimensional virtual models visualized as holograms and intraoperatively overlapped on the patient's real anatomy seem to be a valid new tool for guiding puncture of the kidney through the skin for minimally invasive treatment.