Study On The Renal Vessels With Ureteropelvic Junction Obstruction In Children By Using CTA And Three-dimensional Image Fusion Technique

Objective:The purpose of this study was to find out the anatomical relationship between UPJ and ureteropelvic junction obstruction(UPJO)in renal vessels with the CT three-dimensional image fusion technique in three-dimensional images of pelvis and renal vessels,which provided the significant evidence for the surgical anatomy.Methods:38 unilateral UPJO-induced hydronephrosis were reviewed retrospectively,including 29 males and 9 females,aged from 3 months to11 years,with an average of 5.7 years.In total,30 left kidneys and 8 right kidneys were included,26 severe hydronephrosis,11 moderate hydronephrosis and 1 mild hydronephrosis.The contralateral normal kidney was used as a control group.Fusion of three-dimensional renal pelvis images and three-dimensional blood vessel images.Evaluation of image quality.Statistics of vascular variation.Measurement of the distance between the ureteropelvic junction and the renal blood vessels in fused images.Results:1.Display of renal artery: At arterial phase,all 76(76/76)renal arteries and their secondary branches were clearly seen.Display of renal vein:At arterial phase,54(54/76)renal veins and their secondary branches were clearly seen.There were 22(22/76)renal veins and secondary branches in the arterial phase were not shown.Of these,20(20/22)renal veins and their secondary branches can be seen in the venous phase.There were 2(2/22)cases of severe hydronephrosis with poor perfusion,and no renal veins were observed at all.All 76(76/76)sides of the pelvis and calyx have clear boundary and uniform density.2.There was no significant difference in the incidence of renal vascular variability between the uninjured and the affected side of UPJO(p > 0.05).3.Renal vascular variation in the affected side: one accessory renal artery,one accessory renal vein,7 prehilar branch of renal artery,one late convergence of renal vein.In the healthy side,there were 3 accessory renal arteries,8 prehilar branch of renal artery,and no late confluence of renal veins and accessory renal veins.4.On the healthy side,the display rate of UPJ "conical" structure was38/38,and in the affected side the display rate of UPJ "conical" structure was 25/38.Of the 13 cases without UPJ "conical" structure,all had severe hydronephrosis,accounting for 13/26 of the severe hydronephrosis.Retrograde pyelography(RP)was performed in 8 cases(8/13),and 4 cases(4/8)showed high position of UPJ(Fig.10-Fig.11).In 2 cases(2/13),compression of crossing vessels were seen at UPJ,Consistent with intraoperative findings.5.On the affected side,the distance between the UPJ and the renal vessels in front of it was larger than that of the healthy side(t = 10.148,P =0.000,P < 0.05).The distance between UPJ and its posterior renal vessels was larger than that of the healthy side(t = 10.963,P = 0.000,P < 0.05).6.The distance between UPJ and anterior renal vessels in severe hydronephrosis was larger than that in mild and moderate hydronephrosis(t= 2.756,P = 0.011,P < 0.05).The distance between UPJ and posterior renal vessels in severe hydronephrosis was larger than that in mild and moderate hydronephrosis(t = 2.920,P = 0.008,P < 0.05).7.On the contralateral side,the distance between UPJ and the posterior renal vessels is larger than that in front(t=6.945,P=0.000,P < 0.05).8.In mild and moderate hydronephrosis,there was no significant difference in the distance between UPJ and in posterior vs in front of renal vessels(t = 1.540,P = 0.152,P > 0.05).In severe hydronephrosis,there was no significant difference in the distance between UPJ and in posterior vs in front of renal vessels(t = 1.166,P = 0.266,P > 0.05).9.There were 2 cases of UPJ with crossing vessels were seen at UPJ,consistent with intraoperative findings,one case of late convergence of renal vein,and one case of accessory renal arteries.Conclusion:1.The three-dimensional image fusion technique of CTA and pelvis can satisfactorily demonstrate the anatomical relationship between renal vessels and renal pelvis.2.In severe hydronephrosis,especially with high UPJ or ectopic vascular compression,the UPJ "conical" structure may not be displayed.3.Renal vascular abnormalities can occur in both the healthy side and the affected side.4.In the absence of renal vascular variability,UPJO-induced hydronephrosis makes UPJ away from renal vessels,which is significant with the aggravation of hydronephrosis and loses the distribution of renal vessels on the contralateral side.5.It may compress UPJ when there are vascular variations(such as polar accessory renal artery,inferior vagal vein and so on).Therefore,preoperative CTA and three-dimensional image fusion of renal pelvis can be an intuitive and an accurate measurement to study the relationship between renal pelvis and renal vessels,and to provide anatomical basis for urological surgeries.