Evaluation of virtual ureteroscopy for flexible ureteroscopy lithotripsy

Objective To establish computer assisted virtual ureteroscopy (VU) through data from computerized tomography urography(CTU) of patients with renal stones and make validation of effectiveness. Methods From June of 2015 to January of 2016, 23 cases of renal stones cases was selected by 5 experts in 3 different centers. There were 21 unbilateral cases and 2 bilateral cases.The age ranged from 31 to 79(54.7±12.5). Mean stone burden was(19.0±6.2)mm. Stone number ranged from 1 to 5(2.7±1.2). VU generation was accomplished by specialized software (Crusher) with incorporating CTU data. After patient-specific VUs were presented to the experts, and the FURS surgeries were all finished successfully, face and content validations about VU using modified Likert questionnaire ordinal 10-point rating scales were made. 20 trainee were selected to do the flexible ureteroscopy lithotripsy with assistance of VU. After observation of CTU and VU, the numbers of renal calyces and stones found by the experts and trainees were recorded. The statistical analysis were made before and after observation of VU between the experts and trainees. Result Face and content validation of VU: overall usefulness 7.6±0.5, graphics 7.6±0.5, intrarenal collecting system 8.4±0.5, stone details 8.4±0.5, usefulness in surgical planning and training 8.0±0.7. Significant improvement was found when the trainees doing the surgery with the help of VU. Compared with using CTU only, VU could help the trainees had better understanding of intrarenal structure and stone information [the number of calyces (16.7±3.7)vs.(24.6±1.8), P<0.001; the number of stones (4.9±1.4)vs. (8.2±1.3), P<0.001]. Before observation of VU, trainees found much fewer calyces and stones compared with experts (P=0.004 and P<0.001 respectively). However, this gap disappeared after VU observation (P=0.327 and 0.292 respectively). Conclusions Establishing computer assisted VU through CTU data from renal stone patients is feasible and rapid. VU can significantly improve trainee′s view of intrarenal collecting system and stone information before practicing FURS. Key words: Virtual ureteroscopy; Computer assisted; Flexible ureteroscopy lithotripsy; Validation; Effectiveness