Dynamic changes of renal cortical blood perfusion before and after percutaneous transluminal renal artery stenting in patients with severe atherosclerotic renal artery stenosis

Background:This study aims to observe the dynamic changes of renal artery(RA)disease and cortical blood perfusion(CBP)evaluated by contrast-enhanced ultrasound(CEUS)after percutaneous transluminal renal artery stenting(PTRAS)in patients with severe atherosclerotic renal artery stenosis(ARAS)and to analyze the relationship between CBP and prognosis.Methods:This was a single-center retrospective cohort study.A total of 98 patients with unilateral severe ARAS after successful PTRAS in Beijing Hospital from September 2017 to September 2020 were included.According to renal glomerular filtration rate(GFR)detected by radionuclide imaging at 12 months after PTRAS,all patients were divided into the poor prognosis group(n=21,GFR decreased by≥20%compared with baseline)and the control group(n=77,GFR decreased by<20%or improved compared with baseline).Renal artery stenosis was diagnosed by digital subtraction angiography,and renal CBP was evaluated by CEUS using TomTec Imaging Systems(Germany)before PTRAS,at 6 months and 12 months after discharge.The receiver operating characteristic(ROC)curve with area under the curve(AUC)was used to analyze the predictive value of CBP parameters,including area under ascending curve(AUC1),area under the descending curve(AUC2),rising time(RT),time to peak intensity(TTP),maximum intensity(IMAX),and mean transit time(MTT)for poor prognosis.Results:Among the 98 patients,there were 52 males(53.1%),aged 55–74 years old,with an average age of 62.1±8.7 years,and an average artery stenosis of 82.3±12.9%.The poor prognosis group was associated with significantly increased incidence of diabetes(76.2%vs.41.6%),and lower levels of GFR of the stenotic kidney(21.8 mL/min vs.25.0 mL/min)and total GFR(57.6 mL/min vs.63.7 mL/min)(all P<0.05),compared with the control group(P<0.05).In addition,the rate of RA restenosis was significantly higher in the poor prognosis group than in the control group(9.5%vs.0,χ^(2)=9.462,P=0.002).Compared with the control group,the poor prognosis group was associated with significantly decreased baseline AUC1 and AUC2,and extended duration of TTP and MTT(P<0.05).At 6 months and 12 months of follow-up,patients in the control group were associated with markedly increased AUC1,AUC2,and IMAX,and shorter duration of RT and MTT(P<0.05).The ROC curve showed that the predictive values of AUC1,AUC2,RT,TTP,IMAX,and MTT for poor prognosis were 0.812(95%CI:0.698–0.945),0.752(95%CI:0.591–0.957),0.724(95%CI:0.569–0.961),0.720(95%CI:0.522–0.993),0.693(95%CI:0.507–0.947),and 0.786(95%CI:0.631–0.979),respectively.Conclusions:Preoperative renal CBP in severe ARAS patients with poor prognosis is significantly reduced,and does not show significant improvement after stent treatment over the first year of follow-up.The parameter AUC1 may be a good predictor for renal dysfunction after PTRAS in severe ARAS patients.Trial Registration:ChiCTR.org.cn,ChiCTR1800016252.

Differentiation of Renal Oncocytoma and Renal Clear Cell Carcinoma Using Relative CT Enhancement Ratio

Background：The difference between renal oncocytomas （RO） and renal clear cell carcinomas （RCCs） presents the greatest diagnostic challenge.The aim of this study was to retrospectively determine ifRO and RCCs could be differentiated on computed tomography （CT） images on the basis of their enhancement patterns with a new enhancement correcting method.Methods：Forty-six patients with a solitary renal mass who underwent total or partial nephrectomy were included in this study.Fourteen of those were RO and 32 were RCCs.All patients were examined with contrast-enhanced CT.The pattern and degree of enhancement were evaluated.We selected the area that demonstrated the greatest degree of enhancement of the renal lesion in the corticomedullary nephrographic and excretory phase images.Regions of interest （ROI） were also placed in adjacent normal renal cortex for normalization.We used the values of the normal renal cortex that were measured at the same time as divisors.The ratios of lesion-to-renal cortex enhancement were calculated for all three phases.The Student＆#39;s t-test and Pearson＆#39;s Chi-square test were used for statistical analyses.Results：All RCCs masses showed contrast that appeared to be better enhanced than RO on all contrast-enhanced phases of CT imaging,but there was no significant difference in absolute attenuation values between these two diseases （P 〉 0.05）.The ratio of lesion-to-cortex attenuation in the corticomedullary phase showed significantly different values between RO and RCCs.The degree of contrast enhancement in RCCs was equal to or greater than that of the normal renal cortex,but it was less than that of the normal cortex in RO in the corticomedullary phase.The ratio of lesion-to-cortex attenuation in the corticomedullary phase was higher than the cut off value of 1.0 in most RCCs （84%,27/32） and lower than 1.0 in most RO （93%,13/14） （P 〈 0.05）.In the nephrographic phase,the ratio of lesion-to-cortex attenuation was higher than that in the corticomedullary phase in most RO （71%,10/14）,showing a prolonged enhancement pattern; and was lower than that in most RCCs （97%,31/32）,showing an early washout pattern （P 〈 0.05）.In the differentiation of RO from RCCs,the sensitivity was 93%,specificity 84%,positive predictive value 72%,negative predictive value 84%,and accuracy for RO was 87,if the ratio of lesion-to-cortex attenuation in a cortex phase was lower than the cutoff value of 1.0.The sensitivity was 71%,specificity was 97%,positive predictive value was 91%,negative predictive value was 91%,and accuracy for RO was 89%,if the ratio of lesion-to-cortex attenuation in nephrographic phase was higher than that in the corticomedullary phase.Conclusions：The ratios of renal lesion-to-cortex attenuation ratios may be helpful in differentiating RO from RCCs.