Predictive Value Of CT Value Of Renal Calculi During Flexible Ureteroscopy With Holmium Laser Lithotripsy

Purpose:To assess the utility of renal calculus CT value as predictors of surgical outcome in flexible ureteroscopy(URS)with holmium laser lithotripsy.A large number of studies have proved that CT value can be used to predict the operation efficacy of extracorporeal shock wave lithotripsy(ESWL)and percutaneous nephrolithotomy(PCNL).However,there are rare studies that evaluated the CT value as the predictor on the efficacy of flexible ureteroscopic with holmium laser lithotripsy.Methods:The clinical data of patients with renal stones who were treated by flexible URS with holmium laser lithotripsy between January 1,2015 to December 31,2017 in our hospital were retrospectively evaluated.This is a single medical center study.The data used in this study were access to case history and related data.CT scans were used to obtain relevant data,including stone length,width,height,and calculus CT values,and urinary tract tablets(KUB)to obtain the maximum diameter of the stones.All of these patients underwent flexible ureteroscopy with holmium laser.The operators were all experienced Department of Urology doctors and had experience of more than 50 cases in flexible ureteroscopy with holmium laser.The determination of stone clearance depends on the results of reexamination of kidneys-ureters-bladder(KUB)radiography or urinary system CT at postoperative month 3.The interpretation of imaging data by an experienced radiographer.The patients enrolled in the study were divided into stone clearance group and stone residue group,and the univariate and multivariate logistic regression were used to analyze the association between the possible predictive factors and the Stone status at 3 months after the operation to assess which factors can be used as independent risk factors affecting the stone residue,and whether the CT value as an independent risk factor for stone residue.The effect of CT value on operative efficiency was further studied,and the CT value of kidney stones in patients with stone removal group was divided into the low CT value group and the high CT value group with the median as the cut-off point.The diameter of the stone was 20 mm as the boundary point.The Mann-Whitney U test was used to compare the difference in lithotripsy efficiency、time from starting fragmentation and overall operative time between the CT value groups.Results:In this study,a total of 300 cases of patients with renal stone were collected.Through the inclusion and exclusion criteria,120 cases of data were excluded,and 180 cases of data meet the conditions of this study.Three months after ureteroscopic soft tissue laser lithotripsy,the results of reexamination of KUB plain film or urinary tract CT showed 153 patients in the stone removal group and 27 patients in the residual stone group.The stone-free rate was 85%(153/180).Between stone removal group and residual stone group,the number of stones(P<0.001),stone position(P=0.003),stone diameter(P<0.001),stone volume(P<0.001),overall operative time(P<0.001),time from starting fragmentation(P<0.001),The amount of laser use(P<0.001)had statistically significant differences,and CT values(p=0.251)were not statistically different.To further study the effect of CT value on postoperative stone status,The logistic regression were used to analyze,we found that in the univariate analysis,the variables related to the residual state of stones were the number of stones(P=0.001)and the diameter of stones(P<0.001),stone location(P<0.001),CT value(P=0.131);A P value of 0.15 was used as the criterion for determining variable entry and removal from the multivariate analysis.Stone diameter(P<0.001),stone location(without/ with lower pole calculi)(P=0.031),which still have statistically significant.It was proved that the diameter of stones and the position of stones were independent risk factors that affected the residual stones.However,CT value(P=0.075)could not significantly predict the postoperative stone status and was not an independent risk factor that affected residual stone.As for the effect of CT value on the surgical efficiency,the non-calculus residual group was further divided into high CT value group and low CT value group.The lithotripsy efficiency between the two CT value groups was statistically significant(p=0.001).The low CT value group is superior to the high CT value group.When the stone diameter was less than 20 mm,the overall operative time(P = 0.001)and the time from starting fragmentation(P = 0.002),There was significant statistical difference.The overall operative time and time from starting fragmentation were significantly longer in the high CT value group than in the low CT value group;however,when the stone diameter was more than 20 mm,The overall operative time(P=0.683)and time from starting fragmentation(P=0.701)between the high CT value group and the low CT value group were not statistically significant.This research is a retrospective study design,it has its inherent limitations,and the data taken from a single medical center,which is also the limitations of this study.Conclusions:In this study,we found that CT values could not independently predict the postoperative calculi status and were not independent risk factors affecting calculus residuals.However,the CT value of stone had significant correlation with the efficiency of holmium laser lithotripsy.The low CT value group is superior to the high CT value group.That is,the lower the CT value is,the higher the lithotripsy efficiency is.In addition,this study also showed that when the stone diameter is less than 20 mm,the CT value has a significant predictive effect on the time from starting fragmentation and the overall operative time.The higher the CT value,the longer the time from starting fragmentation and the overall operative time.When the stone diameter was more than20 mm,there was no significant statistical difference in the time from starting fragmentation and the overall operative time between the high CT value group and the low CT value group,and the predictive value was low.