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ObjectiveVolumetriccontrast-enhancedultrasound(VCEUS)imaginghasthepotentialtomonitorchangesinrenalperfusionfollowingvascularinjury.容積超聲造影顯像可以作為一種監測血管損傷后腎臟灌注變化的潛在手段。CurrentmethodsforquantifyingAKIaresearchingforbio-markersindicativeofkidneyinjurysuchaspositivefluctuationsinserumcreatinine.However,serumcreatininelevelslackthesensitivityandspecificitynecessaryforearlydetection.DuetothenephrotoxicnatureofbothCTandMRcontrastagents,otherstandardperfusionimagingmodalitiesarenotsuitablefordiagnosisandmonitoringofAKI.目前確診AKI的方法主要通過尋找血液中腎臟損害的生物標志物，例如血肌酐水平升高。但是血肌酐缺乏早期診斷的敏感性及特異性。由于CT及MR造影本身存在腎毒性，而其他標準灌注顯像模式不適合診斷及監測AKI。VCEUScouldprovideamoredetailedideaoftheactualpercentageofischemictissueresultingfromthisrenalcomplicationbyidentifyingregionsofischemictissue.通過鑒別缺血組織區域，腎臟造影能夠對由于腎臟并發癥造成的缺血組織的實際百分比提供更加細致的理念。ThefocusofthispaperistoinvestigatetherepeatabilityandrobustnessofVCEUSimagingfortrackingperfusionchangesinthehealthyandinjuredkidney.這篇文章主要致力于觀察超聲造影顯像追蹤正常及受損腎臟灌注變化的可重復性及穩定性。二MethodVCEUSutilizesaseriesofplanarimageacquisitions,capturingthenon-linearsecondharmonicsignalfrommicrobubble(MB)contrastagentsflowinginthevasculature.Tissueperfusionparameters(peakintensity,IPK;time-to-peakintensity,TPK;wash-inrate,WIR;areaundercurve,AUC)werederivedfromtime-intensitycurvedatacollectedduringinvitroflowphantomstudiesandinvivoanimalstudiesofhealthyandinjuredkidney.容積超聲造影通過一系列的二維圖像采集，捕捉流入脈管系統的微氣泡造影劑形成的非線性二次諧波信號。在體外流速模型及體內正常/受損腎臟的動物研究中，收集來自時間-強度曲線的組織灌注參數（峰強度、達峰值強度時間、內洗率、曲線下面積）。Fortheflowphantomstudies,eithertheconcentrationofMBcontrastagentwasheldconstant(10μL/L)withvaryingvolumetricflowrates(10,20,and30mL/min)ortheflowratewasheldconstant(30mL/min)andthecontrastagentconcentrationwasvaried(5,10,and20μL/L).在體外流速模型研究中，保證微氣泡濃度穩定（10μL/L），改變容積流速率（10,20,and30mL/min），或者保證流速穩定（30mL/min），改變微氣泡濃度(5,10,and20μL/L)。Animalstudieswereperformedusingeitherhealthyratsorthosethatunderwentrenalischemia-reperfusioninjury.Aseriesofrenalstudieswereperformedusinghealthyrats(N=4)whiletheangleofthetransducerwasvariedforeachVCEUSimageacquisition(referenceor0°,45°,and90°)toassessifrepeatedrenalperfusionmeasureswereisotropicandindependentoftransducerposition.Bloodserumbiomarkersandimmunohistologywereusedtoconfirmacutekidneyinjury.動物研究應用健康小鼠及遭受缺血再灌注的小鼠來完成。用正常小鼠完成一系列腎臟研究，每次超聲造影圖像采集的傳感器角度是多變的（參考角度為0°、45°、90°），以便評估重復的腎臟灌注方法是等向性的，其獨立于傳感器方位。血漿生物標記物及免疫組織學用來確診急性腎損害。三Results1.FlowphantomresultsrevealedalinearrelationshipbetweenMBconcentrationsinjectedintotheflowsystemandtheIPK,WIR,andAUCperfusionmeasures(R2>0.56,P<0.005).Further,therewasalinearrelationshipbetweenchangesinvolumeflowrateandtheTPK,WIR,andAUCmetrics(R2>0.77,P<0.005).1.血流模型結果提示注射入流速系統的微泡濃度與峰強度、內洗率及曲線下面積呈線性相關（R2>0.56，P<0.005）。另外，容積流率變化值與時間流速峰值、內洗率、曲線下面積度量值呈線性相關(R2>0.77,P<0.005)。圖1a顯示固定容積流速，改變微泡造影劑濃度所形成的時間-強度曲線。三條時間強度曲線均在同一時間達到了峰強度。Figure1ashowstime-intensitycurvesforthreedifferentMBconcentrationsforafixedvolumetricflowrate.Allthreetime-intensitycurvesreachtheirpeakintensityatthesametimepoint。Thederivedperfusionparametersfromtime-intensitycurvedata(i.e.,IPK,TPK,WIR,andAUC)aredescribedinFigure1a.從時間強度曲線中可以得出IPK/TPK/WRI/AUC等灌注參數。IPKrevealedalinearrelationshipwiththeconcentrationofcontrastagentused(Figure2e,R2=0.56,P<0.001),asdidWIR(Figure2g,R2=0.75,P<0.005)andAUC(Figure2h,R2=0.93,P<0.001).TPK(Figure2b,R2=0.93,P<0.001),WIR(Figure2c,R2=0.92,P<0.001),andAUC(Figure2d,R2=0.77,P<0.005)hadlinearrelationshipswithchangesinflowrate.therewasalsonosignificantchangeinTPKwithrespecttocontrastconcentration(Figure2f,P>0.85)aswellasIPKwithrespecttoflowspeed(Figure2a,P>0.06).2.Nosignificantdifferencewasfoundbetweenthetransducerangleduringdataacquisitionandanyofthederivedrenalperfusionmeasures(P>0.60).2.數據獲取期間傳感器角度與所有腎臟灌注參數之間無顯著性相關性(P>0.60)。Figure3illustratesthetimeintensitycurvesobtainedatdifferenttransducerorientations:0°(origin),45°,and90°.Importantly,astrongcorrelationwasfoundbetweentimeintensitycurvesacquiredatthevarioustransducerscanningangles(ρ>0.98,P<0.001).圖3為傳感器在0°、45°及90°三個不同角度所獲得的時間強度曲線。從圖中可以看出不同傳感器角度獲得的時間強度曲線存在顯著相關性。Figure4describestheperfusionparametersversuschangesinimageacquisitionangle.Therewasnostatisticaldifferencebetweenallthreeanglesinanyofthefourparametersinvestigated(P>0.48).圖4提示灌注參數與接收器角度變化之間的關系。從圖中可以看出四個灌注參數與與傳感器角度無統計學差異(P>0.48)。3.Afterinductionofrenalischemia-reperfusioninjuryinaratanimalmodel(N=4),VCEUSimagingoftheinjuredkidneyrevealedaninitialreductioninrenalperfusionwhencomparedtocontrolanimalsfollowedbyaprogressiverecoveryofvascularfunction.3.建立老鼠腎臟缺血再灌注損害動物模型后，與持續血管功能恢復的對照組動物模型組相比，受損腎臟的容積超聲造影圖像顯示腎臟灌注顯著降低。Figure5depictstherelativedifferencebetweenthepercentchangeofthemeanvaluesforeachoftheperfusionmeasurementobtainedincontrolkidneysandthosesubjectedtoacuteischemicconditions.EarlyUSmeasurementsindicatethatperfusionwasconsiderablylowerintheinjuredkidneys.圖5描述對照組腎臟及缺血再灌注腎臟組兩組間每個灌注值的均數值變化的相對偏差。早期提示灌注的超聲參數，腎損傷組較對照組明顯下降。Specifically,theIPKparametricmeasurementwasthemostdisparateatthe5-hrtimepointandmostsimilaratthe48-hrtimepoint.Thisdatasuggeststhatpostsurgerytheinjurygroupwaslessperfusedthanthecontrolgroup,andbythe48-hrtimepointlimitedreperfusionhadoccurred.SimilarresultswerefoundforTPK,WIR,andAUCdemonstratingapeakdifferenceateitherthe5-hror24-hrtimepointwithanincreaseinsimilaritytocontrolmeasuresbythe48-hrtimepoint.尤其是灌注參數IPK，在第5小時是最不同的，在48小時是最相似的。這組數據說明，與對照組相比，術后腎損害組存在低灌注，在48小時時出現有限的再灌注。其它灌注參數也有相似結果，與對照組相比，TPK、WIR及AUC在5小時或24小時時達到峰值差異，在48小時時逐步增加到對照組參數相似值。Thiswasalsosupportedbyserumcreatininelevels,asshowninFigure6,wheretherewasapeakinthedifferencebetweenmeanserumcreatininevaluesfromcontrolratsandratssubjectedtoischemicinjuryatthe24-hrtimepointandthenhadpartiallyrecoveredby48hr.圖6中血漿肌酐水平能支持上述結果，在24小時時，對照組小鼠及缺血再灌注小鼠肌酐水平均數差值達到最大，在48小時時有部分恢復。四DiscussionEnhancingmethodsfordetectingseverityofAKIhasthepotentialofimprovingpatientoutcomebyincreasingtheinformation,knowledgeandunderstandingofhowtotreatthedisease.ThestrategiesinvestigatedhereareintendedtosupplementcurrentmethodstogainamoreinformativedescriptionofAKIwhereportionsofthetissuebecomeis-chemic.通過優化提高探知AKI嚴重性的方法，增加對怎樣治療AKI的信息、知識和理解，為提高患者預后提供可能性。本文目的是為目前的方法提供補充，以便對由缺血造成的AKI提供更加詳盡的描述。五ConclusionAcutekidneyinjury