Diagnostic Value Of Contrast-enhanced Ultrasound In Combination With Serum Cystatin C For Early Detection Of Renal Function In Lupus Nephritis

bjective: To investigate the diagnostic value of quantitative analysis of contrast-enhanced ultrasound imaging in combination with Serum cystatin C for early detection of renal function in Lupus Nephritis.Methods : With the consent of the hospital Ethics Committee,Twenty-five patients with Systemic Lupus Erythematosus(SLE)admitted in the department of Rheumatoid immunology and Nephrology in Southwest medical university affiliated hospital from April 2015 to October 2017 were enrolled in this study.The inclusion criteria:All patients are clinically diagnosed with SLE,meanwhile The levels of serum creatinine(SCr)is located in the normal range.Clinical data was well documented.According to the urinalysis,Patients were divided into groups L(average age :31.1±12.2 years,2 males,11 females)with impairment of renal function and groups S(average age years:33.0±9.6 years,2 males,10 females)without renal impairment.The healthy controls without history of kidney disease,Diabetic Kidney Disease,hypertension and Rheumatoid immunology disease as groups N(average age yeas:31.7±9.3years,2 males,8 females).The average age was 32.0±10.2 years,The youngest was19 years old and the oldest was 66 years old,There were no statistically significant differences between the three groups gender and weight.Blood samples were drawn for evaluation of renal function including serum creatinine(SCr)and serum cystatin C(SCys-C),and urine samples were assayed for quantity of urinary protein(PRO)and urinary albumin/uric creatinine ratio(Up/Ugcr).Patients in this study should have rest for at least 15 minutes.Let the patient take the supine position with ordinarily breathe.Check the Bilateral renal morphology,size,and substance echo by routine gray-scale ultrasound examination.Then,contrast-enhanced ultrasound(CEUS)was performed to observe the real-time renal perfusion.The parameter settings were as follows:Mechanical index(MI):0.10,Focus position setting behind the observed the kidney 3-4 cm,Double SCreen to observe 1.6ml SonoVue contrast-enhanced ultrasound agent SonoVue was injected in bolus through left median cubital vein,followed by 5ml saline flush.The video recording was started as well as the changes of echo intensity in the kidney were observed within 250 seconds after the injection was finished.The ACQ quantitative analysis software provided by SIMENS was used to analyze the TIC curve of the region of interest(ROI).Then,identified the time-intensity curve(TIC)parameters and the serum cystatin C(SCys-C)levels that could differentiate participants among the 3 groups,tested the time-intensity curve(TIC)parameters and the serum cystatin C(SCys-C)levels' s relationship as well as their correlations with quantity of urinary and urinary albumin/uric creatinine ratio.Results: 1.Contrast-Enhanced Ultrasound(CEUS)enables dynamic assessment of Renal micro-vascular infusion not only successively but also clearly.2.The differences between the three groups of Peak Intensity(PI)and area under the descending curve(AUC)were statistically significant,but Time to peak(TP)and Average transit time(MTT)showed no significant differences.Compared to the group N and group S,group L had significantly higher AUC(P=0.001),There was no significant difference between group N and group S.Also,Compared to the group N,group L had lower PI(P=0.023),The statistical differences between group L and group S,group L and group N were not observed.PI was Negatively correlated with The quantity of urinary protein(r =-0.314)and urinary albumin/uric creatinine ratio(r =-0.288),The quantity of urinary protein was positively correlated with AUC(r =0.443).3.Cystatin C was positively correlated with the quantity of urinary protein(r =0.512)and urinary albumin/uric creatinine ratio(r =0.237).The difference of serum cystatin C(SCys-C)in the three groups was statistically significant.Group L and group B were higher than that in group N(P<0.01).The high proportion of SCys-C in the three groups was statistically significant,Furthermore,group L was higher than that in group S and group N,There was no significant difference between group N and group S.the differences between each two groups were statistically significant(P<0.01).Cystatin C was positively correlated with AUC(r=0.410)and Negatively correlated with PI(r=-0.367),but showed no significant difference with TP and MTT.Conclusion:1.CEUS could be early and sensitive reflect the renal microvascular hyperperfusion in LN with early renal injury,AUC is remarkable.2.Serum SCys-C is a sensitive and promising marker to estimate early renal impairment in LN.3.It is suggest thatcombined with SCys-C and CEUS can sensitively and effectively indicate the early renal failure of lupus nephropathy.