Investigation Of Contrast-Enhanced Ultrasonography In Renal Cortex Of Kidney Graft Dysfunction

Part 1 The Evaluation of Normal Transplanted Kidney Cortical Microcirculatory Perfusion with Contrast-enhanced UltrasonographyObjective: To evaluate the characteristics of normal transplanted kidney cortical microcirculatory perfusion between subcapsular cortex and juxtamedullary cortex by contrast-enhanced ultrasonography.Methods: A total of 32 patients underwent CEUS(Sono Vue bolus injection) after 6 months to 1 year of kidney transplantation, normal renal function tests for three consecutive months(SCr≤104 μmol/L, urea nitrogen tendency 3.2~7.1 mmol/L), urine(1000~2000 ml), negative body examination result(graft area without swelling and tenderness), conventional ultrasound examination without exception(no hematoma, no water, RI<0.7), estimated glomerular filtration rate(e GFR)≥90 ml/min·1.73m2. Except for the following cases: a. urinary tract obstruction, perirenal hematoma, infection of surgical area and other cases; b. patients who do not use of Sono Vue. The dynamic images of CEUS were analyzed off-line with the quantitative software. Two elongated regions of interest(ROI), which minor axis about 3 mm and major axis about 20 mm, were drawn both in the same two positions: subcapsular cortex and juxtamedullary cortex. Then the time-intensity curve(TIC) and some quantitative parameters, which including arrival time(AT), rise time(RT), absolutely time to peak(ATTP) and mean transit time(MTT) were obtained. Quantitative analysis was performed about the normal transplanted kidney cortical microcirculatory perfusion between different ROIs.Results: The CEUS perfusion characteristics of normal renal allograft cortex: “Wash in phase”, the micro-bubbles first arrived at the juxtamedullary cortex, then got to the outer cortex. After the arrival of micro-bubbles in the field of view, the subcapsular cortex got to “peak enhancement”, followed by the juxtamedullary cortex. “Wash out phase”, the outer cortex and the juxtamedullary cortex washed out layer by layer. The TIC’s AT, RT, ATTP and MTT of subcapsular cortex and juxtamedullary cortex increased progressively.Conclusion: There were significant difference about the microcirculation perfusion of subcapsular cortex and the juxtamedullary cortex with normal renal allograft. Compared with detected the entire cortex, it can observed the characteristic of microcirculation perfusion in renal cortex obviously by analyzing the subcapsular cortex and juxramedullary cortex, and should be used in the clinical diagnosis.Part 2 Analysis of the Characteristics of Microcirculatory Perfusion Changes between Subcapsular Cortex and Juxtamedullary Cortex of Renal dysfunction with Contrast-Enhanced UltrasonographyObjective: To investigate the value of diagnose early kidney graft dysfunction by CEUS to detect subcapsular cortical microcirculation perfusion.Methods: A total of 74 patients underwent CEUS(Sono Vue bolus injection) after 6 months to 1 year of kidney transplantation, which were divided into normal group(e GFR≥90 ml/min·1.73m2), mild reduction group(60≤e GFR<90 ml/min·1.73m2) and moderate reduction group(30≤e GFR<60 ml/min·1.73m2). The standard for normal group were set as follows: renal post-transplantation within 6 months to 1 year, normal renal function tests for three consecutive months(SCr≤104 μmol/L, urea nitrogen tendency 3.2~7.1 mmol/L), urine(1000~2000 ml), negative body examination result(graft area without swelling and tenderness), conventional ultrasound examination without exception(no hematoma, no water, RI<0.7); And for mild reduction group: renal post-transplantation more than 6 months, abnormal renal function tests for three consecutive months(SCr>104 μmol/L), urine(normal or abnormal), negative body examination result, conventional ultrasound examination without exception(RI<0.7). Except for the following cases: a. renal cortical thickness less than 6mm; b. urinary tract obstruction, perirenal hematoma, infection of surgical area and other cases; c. renal function occurred acute unstable situation such as SCr increased rise within 3 months before the test; d. severe cardiopulmonary disease, iliac artery and transplant renal artery stenosis, renal artery and(or) venous thrombosis and other affected kidney graft perfusion and external factors; e. patients who do not use of Sono Vue. The patients were asked if an informed consent was taken or not before CEUS. The dynamic images of CEUS were analyzed off-line with the quantitative software. Two elongated regions of interest(ROI), which minor axis about 3 mm and major axis about 20 mm, were drawn both in the same two positions: subcapsular cortex and juxtamedullary cortex. The other ROI was drawn in the middle of the entire renal cortical, which minor axis about 6mm and major axis about 20 mm. Then the time-intensity curve(TIC) and some quantitative parameters were obtained, which including AT, RT, ATTP and MTT. Comparison of the microcirculation perfusion differences of three ROIs in different groups.Results: Comparison of renal function in mild reduction group with that in normal group, there was significant difference of RT and ATTP in the subcapsular cortex, but no significant difference of all parameters in both juxtamedullary cortex and entire cortex. Comparison of renal function in moderate group with that in normal group, there was significant difference of all parameters among the subcapsular cortex, juxtamedullary cortex and entire cortex. ROC curve displayed that RT longer than 6.49 s could be used to diagnose renal allograft dysfunction, the sensitivity, specificity, accuracy, PPV, NPV and AUC were 63.16%, 77.78%, 70.27%, 75.00%, 66.67% and 0.744, while for TTP longer than 10.22 s were 73.68%, 77.78%, 75.68%, 77.78%,73.68% and 0.792.Conclusion: While we detected the microcirculation perfusion characteristic of renal cortex, only the quantitative parameters of the subcapsular cortex changed obviously, when the function reduced mild. Moreover, there were changed obviously between the subcapsuar cortex and the juxtamedullary cortex, when the renal function reduced moderately. Comparison of analysis the subcapsular cortex and the juxtamedullary cortex with that the entire cortex can detection of the microcirculation perfusion abnormalities of renal dysfunction earlier.