Application Of Three-dimensional Nephrometry Score In The Evaluation Of Tumor Anatomical Features

Background and objectivePatients diagnosed with renal tumors ? 4 cm(T1a)were suggested to undergo partial nephrectomy(PN)surgery by both EAU and AUA guidelines.Many classical nephrometry scoring systems have been developed by urologists about 5-10 years ago to measure renal tumors' anatomical features.These popular nephrometry scoring systems including R.E.N.A.L.score,PADUA score and C-index score have greatly improved the prediction of renal tumors' anatomical complexity.However,more and more recent studies pointed that existing scoring systems also had various limitations.With the rapid development of three-dimensional(3D)imaging technique,we have proposed a 3D scoring system which can greatly improve the clinical experience during our daily work.Methods135 patients having undergone PN for renal tumors in Qilu Hospital of Shandong University from November 2016 and January 2018 were retrospectively reviewed in our study.All PNs were performed through extra-peritoneal and laparoscopic approach by one experienced surgeons.All patients took contrast-enhanced CT scans before PN.Original imaging data including arterial,venous and excretory phases were then input into advanced rendering tools(CSA,Hisense).Tumor areas and endophytic tumor proportions could be efficiently rendered by advanced post-processing software.The software could also efficiently build up visualized 3D models.On the basis of 3D models,software could efficiently work out the tumor volume,endophytic proportions and longitudinal distance from tumor to equatorial plane(LDTE).The whole anatomical structures could be demonstrated from different angles.All cases met our study inclusion criteria of a single tumor excision,a contralateral symmetrical kidney,not allergies to enhanced contrast agent,available preoperative enhanced CT images and postoperative pathological findings of renal clear cell carcinoma.Based on the 3D model and clinical needs,the scoring system analyzed renal tumors' anatomical features from the following points:tumor volume;renal vascular variation;endophytic tumor proportion;tumor's relationships with renal sinus or urinary collecting system(UCS);LDTE.Five sub-scores add up to get the total 3D score.The correlations between warm ischemic time(WIT)and different nephrometry scores including R.E.N.A.L.score,PADUA score,C-index score and 3D score were further explored and compared during our analysis.ResultsOn the basis of preoperative enhanced CT data,all 3D images were reconstructed successfully.The average tumor diameter measured 2.53(IQR:1.70-3.00)cm,the average tumor volume measured 31.25(IQR:6.07-28.59)ml;the average LDTE measured 1.41(IQR:0.00-2.12)cm.The endophytic tumor volume was<50%in 42 cases,>50%in 79 cases and 100%in 14 cases.30 patients(22.2%)were identified with renal vascular variation.The average WIT was 28 minutes.The average 3D score measured 8.3(IQR:7-10),the average PADUA score measured 8.19(IQR:7-9),the average R.E.N.A.L.score measured 7.01(IQR:6-8)and the average C-index score measured 3.12(IQR:1.97-3.73).WIT was identified to have a significant relationship with volume score(p=0.005),endophytic proportions score(p=0.018),score for relationship with renal sinus or UCS(p=0.032),LDTE score(p=0.006)and vascular variation score(p=0.007).During the Spearman correlation analysis,WIT had the most significant correlation with 3D scoring system(rs=0.64,p<0.001).WIT also showed significant correlation with R.E.N.A.L.score(rs=0.216,p=0.012),C-index score(rs=-0.20,p=0.019)and PADUA score(rs=0.20,p=0.025).Receiver operating characteristic(ROC)curve analysis revealed the area under ROC curve(AUC)of 3D score,R.E.N.A.L.score,PADUA sore and C-index score as 0.91,0.67,0.67 and 0.68 respectively(p<0.05).Conclusion3D nephrometry score can greatly improve the evaluation for anatomical complexity of renal tumors.It has great value in the guidance of PN performance compared to previous classical nephrometry score systems.