Comparative Study Of Color Doppler Ultrasound And Contrast-enhanced Ultrasound In The Diagnosis Of Diabetic Nephropathy

Objective: The purpose of this study was to explore the clinical value of Color Doppler Flow Images(CDFI) and Contrast-enhanced Ultrasound(CEUS) in the assessment of the renal functional impairment in diabetic nephropathy, by comparing the changes between CDFI and CEUS of renal artery at different period of diabetic nephropathy(DN) patients.Methods: From 2013 July to 2014 December, 45 patients were diagnosed as type 2 diabetic mellius(with the exclusion of other possibility that may lead to renal function damage and organic disease) by the Endocrinology Department of the Affiliated Hospital of Luzhou Medical College. Of the 45 cases, 23 males and 22 females aged from 40-65(average 50.44±6.79 years old) have suffered the illness for 0.5-15 years(average 6.55±3.45). On the premise of being informed, voluntary and having signed an informed consent, they accepted the inspections. Taking 24-hour micro-scale urinary albumin excretion rate(UAE) as the grouping criterion, the 45 patients were grouped as Group I with UAE< 30mg/24 h, Group II with 30mg/24h≤UAE≤300mg/24 h and Group III with UAE≥300mg/24 h. Group I had 15 cases(7 males, 8 females). Group II had 15 cases(8 males, 7 females). Group III had 15 cases(8 males, 7 females). At first, in the routine ultrasound examination, the three dimensions(long, wide, thick) of the kidney in the patient were measured through the two-dimensional gray ultrasound so as to work out the volume of the kidney(volume = π/6×length×width×thickness). Then by displaying the color flow signal of the vascular bed in the kidney so as to obtain clear Pulsed Wave Doppler(PW) of the main renal artery(MRA), the segment renal artery(SRA) and the interlobar renal artery(IRA) in both left and right kidneys. We then recorded the peak systolic velocity(PSV),end diastolic velocity(EDV),time average peak velocity(TAPV),pulsatility index(PI) and resistance index(RI)of the three levels of renal artery, at the same time stored all the images. At last, in the harmonic condition, by applying contrast-enhanced ultrasound and quantitative ultrasound analysis software(Wash in/Wash out), we observed the variation of echo contrast agent in the kidney and analysed the echo time intensity curve(TIC) of different patients of the renal cortex. The observed parameters include the gradient from start frame to peak frame(Grad), time to peak(TTP), derived peak intensity(DPI) and area under the curve(AUC). We assessed the diagnostic value of CDFI and CEUS for the renal function change in diabetes nephropathy by comparing the change of the parameters of CDFI and TIC curve between different groups.The parameters of different groups of CDFI and TIC curve were undertaking ANOVA analysis(P<0.05 was regarded as statistically significance); The relationship of the parameters between two groups of two were analyzed by LSD analysis further(P<0.05 was regarded as statistically significance).Results: The routine two-dimensional ultrasound examination showed that the patients in the three groups had regular renal morphology, complete capsule and uniform homogeneous echo. Except that there are 3 patients in the three groups who had the renal parenchyma echo enhancement, the other patients had no visible obvious abnormality on the kidney appearance. The kidney volumes in each group were respectively 158.43±8.93cm3 for Group I, 170.17±9.01cm3 for Group II and 148.94±24.14cm3 for Group III. The differences between Group I & Group II and Group II & Group III had statistically significance(P < 0.05),while the differences between Group I & Group III had no statistically significance(P > 0.05).(2) CDFI can clearly display "dendritic" distribution of blood vessels in the kidney of every patient and obtain the standard spectrum of renal artery at three levels. But CDFI can not clearly display the arcuate artery and the blood flow perfusion under. The parameters of CDFI were as follow: ①Group I:The main renal artery parameters were as PSV 64.15±10.06(cm/s), EDV 21.81±3.20(cm/s),TAPV 29.89±5.02(cm/s),PI 1.41±0.14,RI 0.67±0.02; The segmental artery parameters were as PSV 41.97±7.49(cm/s),EDV 16.50±3.07(cm/s),TAPV 18.58±3.54(cm/s),PI 1.36±0.17,RI 0.66±0.02;The interlobar artery parameters were as PSV 26.47±5.52(cm/s),EDV 11.21±2.31(cm/s),TAPV 11.08±3.37(cm/s),PI 1.37±0.10,RI 0.65±0.03;②Group II:The main renal artery parameters were as PSV 61.66±9.67(cm/s),EDV 19.85 ±3.07(cm/s),TAPV 28.15±5.58(cm/s),PI 1.45±0.18,RI 0.68±0.04;The segmental artery parameters were as PSV 42.01±6.69(cm/s),EDV 14.66±2.64(cm/s),TAPV 20.09±2.68(cm/s),PI 1.35±0.16,RI 0.66±0.04;The interlobar artery parameters were as PSV 25.83±6.67(cm/s),EDV 10.25±2.43(cm/s),TAPV 11.73±3.42(cm/s),PI 1.31±0.21,RI 0.65±0.04;③Group III:The main renal artery parameters were as PSV 54.83±8.30(cm/s),EDV 10.89±3.91(cm/s),TAPV 24.41±3.17(cm/s),PI 1.80±0.17,RI 0.72±0.05;The segmental artery parameters were as PSV 38.31± 6.38(cm/s),EDV 8.86±2.78(cm/s),TAPV 18.60±3.06(cm/s),PI 1.58±0.12, RI 0.72±0.04;The interlobar artery parameters were as PSV 23.29±4.90(cm/s),EDV 4.83±1.83(cm/s),TAPV 10.78±2.29(cm/s),PI 1.62±0.19,RI 0.73±0.05.The comparison results of CDFI blood flow parameters among the groups were as follows: For three levels of renal artery,the differences of EDV,PI and RI between Group I & Group III and Group II & Group III had statistically significance(P< 0.05), but the differences of EDV,PI and RI between Group I & Group II had no statistically significance(P< 0.05).For main renal artery,the differences of PSV and TAPV between Group I & Group III and Group II & Group III had statistically significance(P< 0.05).(3) Results of gray scale CEUS: after fast bolus injection of contrast agent via the ulnar vein 8-16 s, the contrast agent was strengthened in the sequence of segmental renal artery, interlobar artery, arcuate artery, cortex renis, medulla nephrica and sinus renalis. For about 26-45 s, the entire kidney was enhanced as a “fire ball”. Then gradually, the contrast agent was fading away in the sequence as before. By the naked-eye observation, the time of contrast agent strengthening and fading in Group III was comparatively longer than that in both Group I and Group II.(4) For the TIC curve, it showed rapidly rising to peak and then slowing down for group I,while the curve of group II showed rising a bit slow and slowing down after reach peak.The speed of rising of group III was the slowest,and the falling was slow also.The comparison among the three groups showed that: As the urine protein increase,Grad was gradually increased; TTP was gradually extended; DPI was gradually reduced;AUC presented a trend of increasing first and decreasing later.The differences of AUC、TTP and DPI among the groups had statistically significance,the differences of Grad between Group I & Group III and Group II & Group III had statistically significance(P< 0.05). Conclusions:(1) As a method which can quantitatively reflect the status of renal vascular perfusion,contrast enhanced ultrasound might able to check out the renal damage more early or sensitive than CDFI of the patients with diabetes nephropathy.(2)The operation of CDFI is comparatively simple and applicable, which is a suitable methods for us to apply in the primary hospital which has incomplete medical conditions to monitor the renal damage of diabetes nephropathy,under the present situation that CEUS has not yet been to popularize and apply in diabetes nephropathy patients.(3)In clinical work, it is suggested to choose the suitable ultrasonography methods in accordance with the actual situation of the patient and medical conditions, using strong points to close the gap. If it can be combined with the existing diagnostic criteria for diabetic nephropathy, hopefully, this study may provide new ideas in clinical diagnosis and treatment of diabetic nephropathy, thus to improve the accuracy in the diagnosis of diabetic nephropathy renal damages.