| ObjectiveTo evaluate contrast-enhanced ultrasound (CEUS) and quantitative analysis in assessing renal blood perfusion characteristics in UUO rat models, to provide a theoretical basis for clinical noninvasive quantitative evaluation of obstructive nephropathy blood flow perfusion.Subjects and MethodsTen SD rats from Tianjin medical university animal center were used in the study. CEUS were preformed prior to and7days after the UUO operation.CEUS examination were performed prior to and7days after UUO. The rats were anesthesed under continuesly inhaled sevoflurane,using the Type IU22ultrasonic diagnostic instrument (Philips, Netherlands), L9-3linear array probe with3～9MHz frequency, modulated the instrument to the harmonic state,15～20fps, mechanical index was set to0.06, the image depth was about4.0cm, time gain compensation (TGC) curve all set to the neutral position, focal point was set to the region of interest(ROI), the aultrasound probe was placed along the long axis of the left kidney.0.2ml suspension liquid of Sonovue (Bracco Switzerland) was injected and followed by1ml saline flash via tail vein. Image acquisition was initialed at the same time of injection to observe the left kidney blood flow perfusion and dynamic process, the acquisition was lasting for6mins.15mins later, the progress was repeated for the right kidney. After CEUS examination, The rats were executed immediately and both kidney specimens were taken.After using1%formalin fixed, sections were paraffin embeded and stained by conventional HE.QLAB software analyzing were performed on the related region of interest (ROI) after CEUS.ROI was placed in the section of kidney cortex and renal medulla perpendicular to the sound beam. The QLAB software automatically generated renal cortical perfusion time-intensity curve (TIC), and a series of related parameters were derived by TIC:slope rate of ascending curve, A; peak intensity, PI; time to peak, TTP; area under curve, AUC. SPSS16.0statistical software were used to process the data, all measured values were presented with mean±standard deviation(x±s). Two independent samples test were used, and P<0.05was considered as the statistically significant difference.Results1. CEUS results During the experiment, one rat died in the preoperative anesthesia and the other rats succeed in UUO model. Preoperative and postoperative rats’renal CEUS under anesthesia completed successfully, developing the same order of ultrasound contrast agents, renal artery-renal cortex-renal medulla; the washout order was just in the opposite order.7days after UUO, kidneys ultrasound contrast blood flow perfusion showed that the hydronephrosis kidney cortex perfusion slowed down significantly compared with the preoperative kidney, intensities were decreased, the contrast agent washout time prolonged; Renal medulla perfusion also slowed down compared with the preoperative perfusion, the contrast agent washout time prolonged, however, the intensities didn’t change significantly; The infusion speed and intensity of the contralateral renal cortex did not change compared with the preoperative kidneys, however, the washout time prolonged significantly; All the perfusion parameters in renal medulla of the contralateral kidneys had no significant difference compared with the preoperative kidneys.2. Quantitative analysis The hydronephrosis renal cortex compared with the preoperative blood perfusion slowed down significantly, TTP(21.27±4.08s preoperatively, postoperatively to27.42±6.17s)(P<0.05) were increased, A(1.81±0.45dB/s preoperatively, postoperatively to0.88±0.79dB/s)(P<0.05) and Pl(16.50±1.36dB preoperatively, postoperatively to13.60±2.64dB)(P<0.05) compared with the preoperative were decreased obviously, AUC (1309.40±306.93dB.s preoperatively, postoperatively to1508.43±481.56dB.s)(P<0.05) compared with the preoperative kidney were increased significantly; The hydronephrosis renal medulla compared with the preoperative blood perfusion slowed down significantly,TTP (25.59±3.92s preoperatively, postoperatively to28.48±4.67s) (P<0.05) compared with the preoperative were increased significantly, hower, A, PI and AUC had no significant difference compared with the preoperative kidneys (P>0.05); The contralateral renal cortex perfusion curve similar to the preoperative in30s,30s later the curve slowed down significantly, AUC(1209.94±298.41dB.s preoperatively and postoperatively to1311.50±406.14dB.s)(P<0.05) compared with the preoperative kidneys were increased obviously, however, A, PI, and TTP had no significant difference compared with the preoperative kidneys (P>0.05); The contralateral renal medulla did not change significantly compared with the preoperative perfusion curve,all the perfusion parameters in renal medulla of the contralateral kidneys had no significant difference compared with the preoperative kidneys (P>0.05).3. The histopathological findingsAfter CEUS examination the rats were executed immediately and took both kidney specimens7days after UUO. After using1%formalin fixed, sections were Paraffin embeded and stained by conventional HE. All hydronephrosis side kidney volume increased obviously and the hydronephrosis side kidney the color changed, the renal papilla showed flattened manner and disappeared, the boundary between cortex and medulla became obscure; Microscopically, the proximal convoluted tubules and distal convoluted tubules of the hydronephrosis kidney appeared slightly to moderately dilatation, mononuclear macrophage and lymphocyte infiltration were observed, renal interstitial volumes increased accompanied by interstitial edema, among of9cases,2cases showed renal tubules atrophied (22.2%). The gross and microscopic appearance of the contralateral kidney showed no abnormalities.ConclusionCEUS and quantitative analysis techniques could reflect the change of kidney perfusion seven days after UUO in rat model, it provides the theoretical basis for clinical noninvasive quantitative evaluation of obstructive nephropathnephropathy. |
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