Application Of Dual-energy Spectral Computed Tomography In Diagnosing Impacted Ureteral Stones With Ureteral Lesions

ObjectiveThe aim of the study was to determine the possible predictive value of spectral CT on the ureteral lesions caused by impacted stones,and to explore the relationship between different types of ureteral lesions and the risk of ureteral stricture.Methods93 adult patients who underwent ureteroscopic laser lithotripsy(URSL)for impacted ureteral stones were included in this prospective study from January 2018 to October 2019 in the first affiliated hospital of Soochow university.All of them underwent the abdominal ct scan on a spectral CT(GE Revolution,USA)with spectral mode.The polychromatic images and a set of monochromatic images were obtained and spectrum parameters were analyzed on the AW4.6 workstation.The Calcium concentration of ureteral lesions were measured on the calcium-based material images.The Water concentration of the lesions were measured in water-based material images.Slope of Spectral HU curve(AHU)and effective atomic number(Effective-Z)were also measured and calculated.The stone size,location of stones,hydronephrosis and ureteral thickness were measured in the PACS system.During surgery operator used ureteroscopy to identify the ureteral lesions,which is classified into four categories as edma,polyps,pallor and hardening.Three months later,90 patients reviewed the urinary system B-ultrasound to obtain the extent of relief of hydronephrosis.To analyze the predictive value of ureteral lesions by spectral CT parameters and clinical parameters and the influence of different ureteral lesions on the relief of hydronephrosis.ResultsThe endoscopic observations of 38 patients were ureteral edma,of 20 patients were ureteral polyps,of 13 patients were ureteral pallor,of 20 patients were ureteral hardening.There was no significant difference in age,gender,site of impaction,ureteral wall thickness(UWT),Effective-Z and Water concentration among the four ureteral types(P>0.05).Meanwhile,hydronephrosis,the period of impaction,the calcium concentration and slope of spectral HU curve were significantly different among the 4 groups,with P value of.001,0.037,0.001 and 0.038,respectively.After that,we assessed factors associated with ureteral hardening using multiple logistic regression analysis and found that calcium concentration(OR,0.0.595;P=0.014)and hydronephrosis(OR,1.063;P=0.001)remained independent predictors of ureteral hardening.ROC analysis showed that calcium concentration of 5.27mg/cm3 was the optimal cut-off value predictive of ureteral hardening,with an area under the curve(AUC)of 0.84(95%confidence interval[CI],0.72-0.96).This cut-off had a sensitivity of 81.8%and a specificity of 87.3%in predicting ureteral hardening.A total of 90 patients were followed-up by B-ultrasonography for 2-12mouths after operation,with a mean of 7 months。80 patients had complete remission of hydronephrosis,with a complete remission rate of 61.9%(13/21)in the hardening group and 97.1%(67/69)in the non-hardening group,P=0.000.And there were 8 cases of hydronephrosis slightly relieved,including 7 cases of hardening type and 1 case of polyp type.Furthermore,There were only two patients with aggravated hydronephrosis.one is the hardening group and the other is the pallor group.ConclusionCalcium concentration and hydronephrosis were independent predictors of ureteral hardening.And calcium concentration value of 5.27mg/cm3 was the optimal cutoff value.The hydronephrosis after holmium laser lithotripsy in patients with ureteral hardening was worse than that of non-hardening ureteral stricture.When the value of calcium concentration is less than 5.27mg/cm3,the possible ureteral hardening should be actively treated while the ureteral stone was removed,so as to reduce the risk of postoperative ureteral stricture and maximize the protection of renal function.