简介:Objective:Noninvasivediffusion-weightedmagneticresonanceimaging(DWI)isawell-studiedMRimagingtechniqueforquantifyingwaterdiffusionespeciallyintumorarea.Thecorrelationbetweenapparentdiffusioncoefficient(ADC)valueandapoptosisorproliferationisnotclearbynow.ThisstudyaimedtoinvestigatewhetherDWI-ADCvaluecouldbeusedasanimagingmarkerrelatedwithpathologicindexesoftumors.Methods:Atotalof30Balb/cmicewithHT29colorectalcarcinomaweresubjectedtoDWIandhistologicanalysis.ThepercentageofADCchangesandtheapoptoticandproliferatingindexeswerecalculatedatpredefinedtimepoints.Kolmogorov-SmirnovdistanceswereconsideredtodeterminewhetherthepercentageofADCchanges,andtheapoptoticandproliferatingindexeswerenormallydistributed.Anindependent-samplest-testwasusedtoanalyzethedifferencebetweenapoptoticandproliferatingindexesinthetwogroups.Results:Therewasastatisticallysignificantdifferenceinproliferatingindexbetweentheradiotherapyandcontrolgroups(meanproliferatingindex:49.27%vs.83.09%),andtherewasastatisticallysignificantdifferenceinapoptoticindexbetweenthetwogroups(meanapoptoticindex:37.7%vs.2.71%).AsignificantpositivecorrelationwasfoundbetweenthepercentageofADCchangesoftheviabletissueandapoptoticindex.Pearson'scorrelationcoefficientwas0.655(P=0.015).AsignificantnegativecorrelationwasfoundbetweenthepercentageofADCchangesoftheviabletissueandki-67proliferationindex.Pearson'scorrelationcoefficientwas0.734(P<0.001).Conclusions:OurresultssuggestthatADCvaluemaybeusedinmeasurementofcellapoptoticandproliferatingindexesincolorectalcarcinoma.
简介:Objective:Toassessifdiffusion-weightedmagneticresonance(MR)imagingwithoutapparentdiffusioncoefficient(ADC)valuesprovidesaddeddiagnosticvalueincombinationwithconventionalMRimaginginthedetectionandcharacterizationofsmallnodulesincirrhoticliver.Methods:Twoobserversretrospectivelyandindependentlyanalyzed86nodules(≤3cm)certifiedpathologicallyin33patientswithlivercirrhosis,including48hepatocellularcarcinoma(HCC)nodules,13high-gradedysplasticnodules(HDN),10low-gradedysplasticnodules(LDNs)and15otherbenignnodules.AllthesefocalnoduleswereevaluatedwithconventionalMRimages(T1-weighted,T2-weightedanddynamicgadolinium-enhancedimages)andbreath-holddiffusion-weightedimages(DWI)(b=500s/mm2).Thenoduleswereclassifiedbyusingascaleof1-3(1,notseen;3,wellseen)onDWIforqualitativeassessment.Thesesmallnoduleswerecharacterizedbytworadiologists.ADCvaluesweren’tmeasured.ThediagnosticperformanceofthecombinedDWI-conventionalimagesandtheconventionalimagesalonewasevaluatedusingreceiveroperatingcharacteristic(ROC)curves.Theareaunderthecurves(Az),sensitivityandspecificityvaluesforcharacterizingdifferentsmallnoduleswerealsocalculated.Results:Among48HCCnodules,33(68.8%)weregradedas3(wellseen),6(12.5%)weregradedas2(partiallyobscured),and9weren’tseenonDWI.Among13HDNs,therewere3(23.1%)and4(30.8%)gradedas3and2respectively.Five(50%)of10benignnoduleswerepartiallyobscuredandslightlyhyperintense.For86nodules,theaveragediagnosticaccuracyofcombinedDWI-conventionalimageswas82.56%,whichwasincreasedsignificantlycomparedwithconventionalMRimageswith76.17%.ForHCCandHDN,thediagnosticaccuracyofcombinedDWI-conventionalimagesincreasedfrom78.69%to86.07%.Conclusions:Diffusion-weightedMRimagingdoesprovideaddeddiagnosticvalueinthedetectionandcharacterizationofHDNandHCC,anditmaynotbehelpfulforLDNandregenerativenodule(RN)incirrhot
简介:自行车,两个大轮子,一前一后,骑上100多斤重的人能行走自如,这是找对了速度中平衡的方法;一架大飞机,庞然大物,能一飞上天,这是从流体力学、空气动力学、平衡运动学中找对了运行与上升的方法。找对一种方法就是成功。画画、艺术创作同理,找对一种方法,造型的、表达的、呈现的、形式的。总之,方法决定着结果。吴带当风、曹衣出水,吴道子,曹不兴是找对了一种线条的表达方法;齐白石从木工雕刻中找到了一种笔墨切块的表达方法;毕加索从吃鱼、玩鸽子中找到了生活化的艺术表达方法。这方法,有时可以是一成不变,有时又可以是每次求变。变与不变,都是在寻找一种方法,变与不变的方法与法度,这方法与法度可以是见山是山,也可以是见山不是山,关键
简介:摘要惯导设备用减振系统(减振器)的性能不光是单纯的减振系统(减振器)的指标考核,需要结合在应用中达到的减振效果和惯导设备的动态精度来分析判断减振系统(减振器)优劣。文中以飞行器的减振器设计要求为例,对结构设计和减振器匹配设计及试验情况进行分析,给出惯导设备用减振器。