Factors affecting fluoroscopy time during percutaneous nephrolithotomy: Impact of stone volume distribution in renal collecting system

ABSTRACT Purpose: To identify the factors increased fluoroscopy time during percutaneous nephrolithotomy and investigate the relationship between the 3D segmentation volume ratio of stone to renal collecting system and fluoroscopy time. Materials and Methods: Data from 102 patients who underwent percutaneous nephrolithotomy were analyzed retrospectively. Volume segmentation of both the renal collecting system and stones were obtained from 3D segmentation software with the images on CT data. Analyzed stone volume (ASV), renal collecting system volume (RCSV) measured and the ASV-to-RCSV ratio was calculated. Several parameters were evaluated for their predictive ability with regard to fluoroscopy time. Results: The stone-free rate was 55.9% after the percutaneous nephrolithotomy. Complications occurred in 31(30.4%) patients. The mean fluoroscopy time was 199.4±151.1 seconds. The fluoroscopy time was significantly associated with the ASV-to-RCSV ratio (p<0.001, r=0.614). The single tract was used in 77 (75.5%) cases while multiple tracts were used in 25 (24.5%) cases. Fluoroscopy time was significantly associated with multiple access (p<0.001, r=0.689). On univariate linear regression analysis, longer fluoroscopy time was related with increased stone size, increased stone volume, increased number of access, increased calyx number with stone, increased ASV-to-RCSV, increased operative time and decreased stone essence. On multivariate linear regression analysis, the number of access and the ASV-to-RCSV were independent predictors of fluoroscopy time during percutaneous nephrolithotomy. Conclusions: The distribution of the stone burden volume in the pelvicalyceal system is a significant predictor for prolonged fluoroscopy time during percutaneous nephrolithotomy. Measures to decrease FT could be beneficial in patients with a high ASV-to-RCSV ratio for precise preoperative planning.

摘要 目的：明确经皮肾镜碎石取石术（percutaneous nephrolithotomy）术中透视时间延长的相关影响因素，并探究结石与肾集合系统的三维分割体积比与透视时间之间的关联。材料与方法：回顾性分析102例行经皮肾镜碎石取石术患者的临床资料。基于CT影像数据，通过三维分割软件获取肾集合系统与结石的体积分割结果，测量分析结石体积（analyzed stone volume, ASV）、肾集合系统体积（renal collecting system volume, RCSV），并计算ASV与RCSV的比值。对多项参数的透视时间预测能力进行评估。结果：经皮肾镜碎石取石术后结石清除率为55.9%。31例（30.4%）患者出现并发症。平均透视时间为199.4±151.1秒。透视时间与ASV-to-RCSV比值显著相关（p<0.001，r=0.614）。77例（75.5%）患者采用单通道手术，25例（24.5%）采用多通道手术。透视时间与多通道穿刺显著相关（p<0.001，r=0.689）。单因素线性回归分析显示，透视时间延长与结石直径增大、结石体积增加、穿刺通道数量增多、合并结石的肾盏数目增加、ASV-to-RCSV比值升高、手术时间延长及结石质地降低相关。多因素线性回归分析显示，穿刺通道数量与ASV-to-RCSV比值是经皮肾镜碎石取石术术中透视时间的独立预测因子。结论：结石负荷体积在肾盂肾盏系统中的分布情况是经皮肾镜碎石取石术术中透视时间延长的重要预测因子。对于ASV-to-RCSV比值较高的患者，采取针对性措施缩短透视时间有助于开展精准术前规划。