The Application Of Virtual Touch Tissue Imaging Quantification In Diagnosis Of Chronic Allograft Nephropathy

ObjectiveTo investigate the value of Virtual Touch Tissue Imaging Quantification(VTIQ)in the diagnosis of chronic allograft nephropathy(CAN),and to analyze the influencing factors of the transplanted renal cortex shear wave velocity(SWV).MethodsExclusion criteria based on this study,98 patients who underwent postoperative reexamination in ultrasound department of Qianfoshan Hospital of Shandong province from November 2017 to May 2018 were included.They were divided into two groups: 40 with normal renal function and 58 with CAN.Firstly,the body mass index(BMI)was calculated by measuring the height and weight of patients,and the biochemical data of patients were obtained.Secondly,the routine ultrasonography was performed on patients to gain the size,shape and blood flow of the transplanted kidneys.Thirdly,the region of interest was selected in the cortex of the transplanted kidney to measure the distance from the surface of the transplanted kidney to the body surface,as the subcutaneous depth of the transplanted kidney,and the shear wave velocity(SWV)of the cortex of the transplanted kidney was measured by VTIQ at the same time.The data of two groups were statistically analyzed.The Receiver operator characteristic curve(ROC)was used to gain the cut-off value for diagnosing chronic allograft nephropathy by VTIQ.Univariate and multivariate analysis were used to examine the correlation between the influencing factors and the SWV of transplanted renal cortex.Finally,the effects of subcutaneous depth of transplanted kidney and body mass index on the accuracy of VTIQ results in normal group were analyzed retrospectively.ResultsIn this study,the parameters of 98 patients were analyzed by statistics: The mean SWV of the transplanted kidney cortex was 2.36 ± 0.24m/s in the group with CAN,whereas it was 1.90 ± 0.21m/s in the group with normal function,the difference was statistically significant(P<0.05).According to the ROC curve,the cut-off value for diagnosing chronic allograft nephropathy by VTIQ was 2.09m/s.At this point,the sensitivity was 82.8% and the specificity was 87.5%.The univariate analysis showed that the SWV of transplanted renal cortex was positively correlated with Cr,and negatively correlated with anastomotic resistance index(RI),e GFR,BMI and subcutaneous depth of transplanted kidney(P < 0.05),while other parameters such as anastomotic width and peak flow velocity of the stoma were not correlated with SWV.In multivariate analysis,the SWV was only related to subcutaneous depth,Cr and anastomotic RI(P < 0.05).Retrospective analysis of the data of the normal group showed that the greater the BMI and subcutaneous depth of transplanted kidney are,the lower the accuracy of the measured VTIQ results.And the BMI of patient has a higher accuracy in the evalution of VTIQ results.VTIQ results with diagnostic value could not be obtained when the BMI of patient was more than 23.99 kg/m~2.Conclusions1.The hardness of transplanted renal cortex in patients with CAN was significantly higher than that in the patients with normal renal function.2.When SWV value of transplanted renal cortex measured by VTIQ is more than2.09m/s,the diagnosis of CAN can be considered.3.The SWV value measured by VTIQ was positively correlated with Cr,negatively correlated with anastomotic RI and subcutaneous depth of transplanted kidney.The higher the Cr,the higher the SWV value,and the greater the anastomotic RI and subcutaneous depth of transplanted kidney,the lower the SWV value.4.Compared with the subcutaneous depth of transplanted kidney,the BMI of patient has a higher accuracy in the evalution of VTIQ results.When the BMI of patient was more than 23.99 kg/m~2,the VTIQ results were not of diagnostic value.Virtual Touch Tissue Imaging Quantification(VTIQ)is a new ultrasonic imaging technique with a promising prospect on clinical applications.It can be used to analyze and evaluate the function of renal allograft quantitatively and non-invasivly,thus providing a guarantee for clinicians to provide early diagnosis and accurate treatment timely.