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.

Visualizing cortical blood perfusion after photothrombotic stroke in vivo by needle-shaped beam optical coherence tomography angiography

Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods.However,high-resolution imaging in optical microscopy fundamentally requires a tight optical focus,and thus a limited depth of field(DOF).Consequently,large-scale,non-stitched,high-resolution images of curved surfaces,like brains,are difficult to acquire without z-axis scanning.To overcome this limitation,we developed a needle-shaped beam optical coherence tomography angiography(NB-OCTA)system,and for the first time,achieved a volumetric resolution of less than 8μm in a non-stitched volume space of 6.4 mm×4 mm×620μm in vivo.This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam(GB-OCTA).We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo,and quantitatively analyzed the vessel area density(VAD)and the diameters of representative vessels in different regions over 10 days,revealing different spatiotemporal dynamics in the acute,sub-acute and chronic phase of post-ischemic revascularization.Benefiting from our NB-OCTA,we revealed that the recovery process is not only the result of spontaneous reperfusion,but also the formation of new vessels.This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.