7.王霄英讲课的指南文献原文 Eur. Urol. 2016 Weinreb

EUROPEANUROLOGY69(2016)16–40availableatjournalhomepage:PlatinumPriority–ProstateCancerPI-RADSProstateImaging–ReportingandDataSystem:2015,Version2JeffreyC.Weinreba,y,*,JelleO.Barentszb,y,PeterL.Choykec,FrancoisCornudd,MasoomA.Haidere,KatarzynaJ.Macuraf,DanielMargolisg,MitchellD.Schnallh,FainaShterni,ClareM.Tempanyj,HarrietC.Thoenyk,SadnaVermalaYaleSchoolofMedicine,NewHaven,CT,USA;bRadboudumc,Nijmegen,TheNetherlands;cNationalInstitutesofHealth,Bethesda,MD,USA;dRene´DescartesUniversity,Paris,France;eUniversityofToronto,SunnybrookHealthSciencesCentre,Toronto,Canada;fJohnsHopkinsUniversity,Baltimore,MD,USA;gUniversityofCalifornia,LosAngeles,CA,USA;hUniversityofPennsylvania,Philadelphia,USA;iAdMeTechFoundation,Boston,MA,USA;jHarvardUniversity,Boston,MA,USA;kUniversityHospitalofBern,Bern,Switzerland;lUniversityofCincinnati,Cincinnati,OH,USAArticleinfoArticlehistory:AcceptedAugust29,2015AssociateEditor:JamesCattoKeywords:ProstatempMRIProstateMRIMagneticresonanceimagingProstateProstatecancerPleasevisit/europeanurologytoreadandanswerquestionson-line.TheEU-ACMEcreditswillthenbeattributedautomatically.AbstractTheProstateImaging–ReportingandDataSystemVersion2(PI-RADSTMv2)istheproductofaninternationalcollaborationoftheAmericanCollegeofRadiology(ACR),EuropeanSocietyofUroradiology(ESUR),andAdMetechFoundation.Itisdesignedtopromoteglobalstandardizationanddiminishvariationintheacquisition,interpretation,andreportingofprostatemultiparametricmagneticresonanceimaging(mpMRI)ex-amination,anditisbasedonthebestavailableevidenceandexpertconsensusopinion.ItestablishesminimumacceptabletechnicalparametersforprostatempMRI,simplifiesandstandardizesterminologyandcontentofreports,andprovidesassessmentcatego-riesthatsummarizelevelsofsuspicionorriskofclinicallysignificantprostatecancerthatcanbeusedtoassistselectionofpatientsforbiopsiesandmanagement.Itisintendedtobeusedinroutineclinicalpracticeandalsotofacilitatedatacollectionandoutcomemonitoringforresearch.#2015EuropeanAssociationofUrology.PublishedbyElsevierB.V.Allrightsreserved.yTheseauthorsareco-firstauthors.*Correspondingauthor.Tel.+12037855913.E-mailaddress:jeffrey.weinreb@(J.C.Weinreb).1.IntroductionMagneticResonanceImaging(MRI)hasbeenusedfornoninvasiveassessmentoftheprostateglandandsur-roundingstructuressincethe1980s.Initially,prostateMRIwasbasedsolelyonmorphologicassessmentusingT1-weighted(T1W)andT2-weighted(T2W)pulsesequences,anditsrolewasprimarilyforlocoregionalstaginginpatientswithbiopsyprovencancer.However,itprovidedlimitedcapabilitytodistinguishbenignpathologicaltissueandclinicallyinsignificantprostatecancerfromsignificantcancer.Advancesintechnology(bothinsoftwareandhardware)haveledtothedevelopmentofmultiparametricMRI/10.1016/j.eururo.2015.08.0520302-2838/#2015EuropeanAssociationofUrology.PublishedbyElsevierB.V.Allrightsreserved. DownloadedfromClinicalKatPekingUniversityHealthScienceCenteronMarch18,2016.Forpersonaluseonly.Nootheruseswithoutpermission.Copyright©2016.ElsevierInc.Allrightsreserved.17EUROPEANUROLOGY69(2016)16–4017(mpMRI),whichcombinesanatomicT2Wwithfunctionalandphysiologicassessment,includingdiffusion-weightedimaging(DWI)anditsderivativeapparent-diffusioncoeffi-cient(ADC)maps,dynamiccontrast-enhanced(DCE)MRI,andsometimesothertechniquessuchasin-vivoMRprotonspectroscopy.Thesetechnologicadvances,com-binedwithagrowinginterpreterexperiencewithmpMRI,havesubstantiallyimproveddiagnosticcapabilitiesforaddressingthecentralchallengesinprostatecancercare:1)Improvingdetectionofclinicallysignificantcancer,whichiscriticalforreducingmortality;and2)Increasingconfidenceinbenigndiseasesanddormantmalignancies,whicharenotlikelytocauseproblemsinaman’slifetime,inordertoreduceunnecessarybiopsiesandtreatment.Consequently,clinicalapplicationsofprostateMRIhaveexpandedtoinclude,notonlylocoregionalstaging,butalsotumordetection,localization(registrationagainstanana-tomicalreference),characterization,riskstratification,sur-veillance,assessmentofsuspectedrecurrence,andimageguidanceforbiopsy,surgery,focaltherapyandradiationtherapy.In2007,recognizinganimportantevolvingroleforMRIinassessmentofprostatecancer,theAdMeTechFoundationorganizedtheInternationalProstateMRIWorkingGroup,whichbroughttogetherkeyleadersofacademicresearchandindustry.Basedondeliberationsbythisgroup,aresearchstrategywasdevelopedandanumberofcriticalimpedimentstothewidespreadacceptanceanduseofMRIwereidentified.Amongstthesewasexcessivevariationintheperformance,interpretation,andreportingofprostateMRIexams.Agreaterlevelofstandardizationandconsistencywasrecommendedinordertofacilitatemulti-centerclinicalevaluationandimplementation.Inresponse,theEuropeanSocietyofUrogenitalRadiology(ESUR)draftedguidelines,includingascoringsystem,forprostateMRIknownasPI-RADSTMversion1(PI-RADSTMv1).Sinceitwaspublishedin2012,PI-RADSTMv1hasbeenvalidatedincertainclinicalandresearchscenarios.However,experiencehasalsorevealedseverallimita-tions,inpartduetorapidprogressinthefield.InanefforttomakePI-RADSTMstandardizationmoregloballyacceptable,theAmericanCollegeofRadiology(ACR),ESURandtheAdMeTechFoundationestablishedaSteeringCommitteetobuildupon,updateandimproveuponthefoundationofPI-RADSTMv1.ThiseffortresultedinthedevelopmentPI-RADSTMv2.PI-RADSTMv2wasdevelopedbymembersofthePI-RADSSteeringCommittee,severalworkinggroupswithinterna-tionalrepresentation,andadministrativesupportfromtheACRusingthebestavailableevidenceandexpertconsensusopinion.Itisdesignedtopromoteglobalstandardizationanddiminishvariationintheacquisition,interpretation,andreportingofprostatempMRIexaminationsanditisintendedtobea‘‘living’’documentthatwillevolveasclinicalexperienceandscientificdataaccrue.PI-RADSTMv2needstobetestedandvalidatedforspecificresearchandclinicalapplications.PI-RADSTMv2isdesignedtoimprovedetection,locali-zation,characterization,andriskstratificationinpatientswithsuspectedcancerintreatmentnaveprostateglands.Theoverallobjectiveistoimproveoutcomesforpatients.Thespecificaimsareto:.EstablishminimumacceptabletechnicalparametersforprostatempMRI.Simplifyandstandardizetheterminologyandcontentofradiologyreports.FacilitatetheuseofMRIdatafortargetedbiopsy.Developassessmentcategoriesthatsummarizelevelsofsuspicionorriskandcanbeusedtoselectpatientsforbiopsiesandmanagement(e.g.,observationstrategyvs.immediateintervention).Enabledatacollectionandoutcomemonitoring.EducateradiologistsonprostateMRIreportingandreducevariabilityinimaginginterpretations.EnhanceinterdisciplinarycommunicationswithreferringcliniciansPI-RADSTMv2isnotacomprehensiveprostatecancerdiagnosisdocumentandshouldbeusedinconjunctionwithothercurrentresources.Forexample,itdoesnotaddresstheuseofMRIfordetectionofsuspectedrecurrentprostatecancerfollowingtherapy,progressionduringsurveillance,ortheuseofMRIforevaluationofotherpartsofthebody(e.g.skeletalsystem)thatmaybeinvolvedwithprostatecancer.Furthermore,itdoesnotelucidateorprescribeoptimaltechnicalparameters;onlythosethatshouldresultinanacceptablempMRIexamination.ThePI-RADSSteeringCommitteestronglysupportsthecontinueddevelopmentofpromisingMRImethodologiesforassessmentofprostatecancerandlocalstaging(e.g.,nodalmetastases)utilizingnoveland/oradvancedresearchtoolsnotincludedinPI-RADSTMv2,suchasin-vivoMRspectroscopicimaging(MRSI),diffusiontensorimaging(DTI),diffusionalkurtosisimaging(DKI),multipleb-valueassessmentoffractionalADC,intravoxelincoherentmotion(IVIM),bloodoxygenationleveldependent(BOLD)imaging,intravenousultra-smallsuperparamagneticironoxide(USPIO)agents,andMR-PET.ConsiderationwillbegiventoincorporatingthemintofutureversionsofPI-RADSTMasrelevantdataandexperiencebecomeavailable.2.SectionI:ClinicalConsiderationsandTechnicalSpecifications2.1.ClinicalConsiderations2.1.1.TimingofMRIFollowingProstateBiopsyHemorrhage,manifestedashyperintensesignalonT1W,maybepresentintheprostategland,mostcommonlytheperipheralzone(PZ)andseminalvesicles,followingsystem-atictransrectalultrasound-guidedsystematic(TRUS)biopsyandmayconfoundmpMRIassessment.WhenthereisevidenceofhemorrhageinthePZonMRimages,consider-ationmaybegiventopostponingtheMRIexaminationuntilalaterdatewhenhemorrhagehasresolved.However,thismayDownloadedfromClinicalKatPekingUniversityHealthScienceCenteronMarch18,2016.Forpersonaluseonly.Nootheruseswithoutpermission.Copyright©2016.ElsevierInc.Allrightsreserved.18EUROPEANUROLOGY69(2016)16–4018notalwaysbefeasibleornecessary,andclinicalpracticemaybemodifiedasdeterminedbyindividualcircumstancesandavailableresources.Furthermore,iftheMRIexamisperformedfollowinganegativeTRUSbiopsy,thelikelihoodofclinicallysignificantprostatecanceratthesiteofpostbiopsyhemorrhagewithoutacorrespondingsuspiciousfindingonMRIislow.Inthissituation,aclinicallysignificantcancer,ifpresent,islikelytobeinalocationotherthanthatwithbloodproducts.Thus,thedetectionofclinicallysignificantcancerisnotlikelytobesubstantiallycompro-misedbypostbiopsyhemorrhage,andtheremaybenoneedtodelayMRIafterprostatebiopsyiftheprimarypurposeoftheexamistodetectandcharacterizeclinicallysignificantcancerinthegland.However,postbiopsychanges,includinghemorrhageandinflammation,mayadverselyaffecttheinterpretationofprostateMRIforstaginginsomeinstances.Althoughthesechangesmaypersistformanymonths,theytendtodiminishovertime,andanintervalofatleast6weeksorlongerbetweenbiopsyandMRIshouldbeconsideredforstaging.2.1.2.PatientPreparationAtpresent,thereisnoconsensusconcerningallpatientpreparationissues.Toreducemotionartifactfrombowelperistalsis,theuseofanantispasmodicagent(e.g.glucagon,scopolaminebutylbromide,orsublingualhyoscyaminesulfate)maybebeneficialinsomepatients.However,inmanyothersitisnotnecessary,andtheincrementalcostandpotentialforadversedrugreactionsshouldbetakenintoconsideration. Thepresenceofstoolintherectummayinterferewithplacementofanendorectalcoil(ERC).IfanERCisnotused,thepresenceofairand/orstoolintherectummayinduceartifactualdistortionthatcancompromiseDWIquality.Thus,sometypeofminimalpreparationenemaadministeredbythepatientinthehourspriortotheexammaybebeneficial.However,anenemamayalsopromoteperistalsis,resultinginincreasedmotionrelatedartifactsinsomeinstances.Thepatientshouldevacuatetherectum,ifpossible,justpriortotheMRIexam.IfanERCisnotusedandtherectumcontainsairontheinitialMRimages,itmaybebeneficialtoperformthempMRIexamwiththepatientinthepronepositionortodecompresstherectumusingsuctionthroughasmallcatheter.SomerecommendthatpatientsrefrainfromejaculationforthreedayspriortotheMRIexaminordertomaintainmaximumdistentionoftheseminalvesicles.However,abenefitforassessmentoftheprostateandseminalvesiclesforclinicallysignificantcancerhasnotbeenfirmlyestablished.2.1.3.PatientInformationThefollowinginformationshouldbeavailabletotheradiologistatthetimeofMRIexamperformanceandinterpretation:.Recentserumprostate-specificantigen(PSA)levelandPSAhistory.Dateandresultsofprostatebiopsy,includingnumberofcores,locationsandGleasonscoresofpositivebiopsies(withpercentageofcoreinvolvementwhenavailable)..Otherrelevantclinicalhistory,includingdigitalrectalexam(DRE)findings,medications(particularlyinthesettingofhormones/hormoneablation),priorprostateinfections,pelvicsurgery,radiationtherapy,andfamilyhistory.2.2.TechnicalSpecificationsProstateMRIacquisitionprotocolsshouldalwaysbetailoredtospecificpatients,clinicalquestions,managementoptions,andMRIequipment,butT2W,DWI,andDCEshouldbeincludedinallexams.UnlesstheMRIexamismonitoredandnofindingssuspiciousforclinicallysignificantprostatecanceraredetected,atleastonepulsesequenceshoulduseafield-of-view(FOV)thatpermitsevaluationofpelviclymphnodestotheleveloftheaorticbifurcation.Thesupervisingradiologistshouldbecognizantthatsuperflu-ousorinappropriatesequencesunnecessarilyincreaseexamtimeanddiscomfort,andthiscouldnegativelyimpactpatientacceptanceandcompliance.Thetechnologistperformingtheexamand/orsupervis-ingradiologistshouldmonitorthescanforqualitycontrol.Ifimagequalityofapulsesequenceiscompromisedduetopatientmotionorotherreason,measuresshouldbetakentorectifytheproblemandthesequenceshouldberepeated.2.2.1.MagneticFieldStrengthThefundamentaladvantageof3Tcomparedwith1.5Tliesinanincreasedsignal-to-noiseratio(SNR),whichtheoreti-callyincreaseslinearlywiththestaticmagneticfield.Thismaybeexploitedtoincreasespatialresolution,temporalresolution,orboth.Dependingonthepulsesequenceandspecificsofimplementation,powerdeposition,artifactsrelatedtosusceptibility,andsignalheterogeneitycouldincreaseat3T,andtechniquesthatmitigatetheseconcernsmayresultinsomeincreaseinimagingtimeand/ordecreaseinSNR.However,currentstate-of-the-art3TMRIscannerscansuccessfullyaddresstheseissues,andmostmembersofthePI-RADSSteeringCommitteeagreethattheadvantagesof3Tsubstantiallyoutweightheseconcerns.Therearemanyotherfactorsthataffectimagequalitybesidesmagneticfieldstrength,andboth1.5Tand3.0Tcanprovideadequateandreliablediagnosticexamswhenacquisitionparametersareoptimizedandappropriatecontemporarytechnologyisemployed.AlthoughprostateMRIatboth1.5Tand3Thasbeenwellestablished,mostmembersofthePI-RADSSteeringCommitteeprefer,use,andrecommend3TforprostateMRI.1.5TshouldbeconsideredwhenapatienthasanimplanteddevicethathasbeendeterminedtobeMRconditional.1.5TmayalsobepreferredwhenpatientsaresafetoundergoMRIat3T,butthelocationofanimplanteddevicemayresultinartifactthatcouldcompromiseimagequality(e.g.,bilateralmetallichipprosthesis).Therecommendationsinthisdocumentfocusonlyon3Tand1.5TMRIscannerssincetheyhavebeentheonesusedforclinicalvalidationofmpMRI.ProstatempMRIatlowerDownloadedfromClinicalKatPekingUniversityHealthScienceCenteronMarch18,2016.Forpersonaluseonly.Nootheruseswithoutpermission.Copyright©2016.ElsevierInc.Allrightsreserved.19EUROPEANUROLOGY69(2016)16–4019magneticfieldstrengths(<1.5T)isnotrecommendedunlessadequatepeerreviewedclinicalvalidationbecomesavailable.2.2.2.EndorectalCoil(ERC)Whenintegratedwithexternal(surface)phasedarraycoils,endorectalcoils(ERCs)increaseSNRintheprostateatanymagneticfieldstrength.ThismaybeparticularlyvaluableforhighspatialresolutionimagingusedincancerstagingandforinherentlylowerSNRsequences,suchasDWIandhightemporalresolutionDCE.ERCscanalsobeadvantageousforlargerpatientswheretheSNRintheprostatemaybecompromisedusingonlyexternalphasedarrayRFcoils.However,useofanERCmayincreasethecostandtimeoftheexamination,deformthegland,andintroduceartifacts.Inaddition,itmaybeuncomfortableforpatientsandincreasetheirreluctancetoundergoMRI.Withsome1.5TMRIsystems,especiallyolderones,useofanERCisconsideredindispensableforachievingthetypeofhighresolutiondiagnosticqualityimagingneededforstagingprostatecancer.At3TwithoutuseofanERC,imagequalitycanbecomparablewiththatobtainedat1.5TwithanERC,althoughdirectcomparisonofbothstrategiesforcancerdetectionand/orstagingislacking.Importantly,therearemanytechnicalfactorsotherthantheuseofanERCthatinfluenceSNR(e.g.,receiverbandwidth,coildesign,efficiencyoftheRFchain),andsomecontemporary1.5TscannersthatemployarelativelyhighnumberofexternalphasedarraycoilelementsandRFchannels(e.g.,16ormore)maybecapableofachievingadequateSNRinmanypatientswithoutanERC.Crediblesatisfactoryresultshavebeenobtainedatboth1.5Tand3TwithouttheuseofanERC.TakingthesefactorsintoconsiderationaswellasthevariabilityofMRIequipmentavailableinclinicaluse,thePI-RADSSteeringCommitteerecommendsthatsupervisingradiologiststostrivetooptimizeimagingprotocolsinordertoobtainthebestandmostconsistentimagequalitypossiblewiththeMRIscannerused.However,cost,availability,patientpreference,andotherconsiderationscannotbeignored.IfairisusedtoinflatetheERCballoon,itmayintroducelocalmagneticfieldinhomogeneity,resultingindistortiononDWI,especiallyat3T.TheextenttowhichartifactsinterferewithMRIinterpretationwillvarydependingonspecificpulsesequenceimplementations,buttheycanbediminishedusingcorrectpositioningoftheERCanddistentionoftheballoonwithliquids(e.g.liquidperfluoro-carbonorbariumsuspension)thatwillnotresultinsusceptibilityartifacts.Whenliquidisusedforballoondistention,allairshouldbecarefullyremovedfromtheERCballoonpriortoplacement.Solid,rigidreusableERCsthatavoidtheneedforinflatableballoonsanddecreaseglanddistortionhavebeendeveloped.2.2.3.Computer-AidedEvaluation(CAE)TechnologyComputer-aidedevaluation(CAE)technologyusingspecial-izedsoftwareoradedicatedworkstationisnotrequiredforprostatempMRIinterpretation.However,CAEmayimproveworkflow(display,analysis,interpretation,reporting,andcommunication),providequantitativepharmacodynamicdata,andenhancelesiondetectionanddiscriminationperformanceforsomeradiologists,especiallythosewithlessexperienceinterpretingmpMRIexams.CAEcanalsofacilitateintegrationofMRIdatawithsomeformsofMRtargetedbiopsysystems.3.SectionII:NormalAnatomyandBenignFindings3.1.NormalAnatomy(Figure1)Fromsuperiortoinferior,theprostateconsistsofthebase(justbelowtheurinarybladder),themidgland,andtheapex.Itisdividedintofourhistologiczones:(a)theanteriorfibromuscularstroma,containsnoglandulartissue;(b)thetransitionzone(TZ),surroundingtheurethraproximaltotheverumontanum,contains5%oftheglandulartissue;(c)thecentralzone(CZ),surroundingtheejaculatoryducts,containsabout20%oftheglandulartissue;and(d)theouterperipheralzone(PZ),contains70%-80%oftheglandulartissue.Whenbenignprostatichyperplasia(BPH)develops,theTZwillaccountforanincreasingpercentageoftheglandvolume.Approximately70%-75%ofprostatecancersoriginateinthePZand20%-30%intheTZ.CancersoriginatingintheCZareuncommon,andthecancersthatoccurintheCZareusuallysecondarytoinvasionbyPZtumors.BasedonlocationanddifferencesinsignalintensityonT2Wimages,theTZcanoftenbedistinguishedfromtheCZonMRimages.However,insomepatients,age-relatedexpansionoftheTZbyBPHmayresultincompressionanddisplacementoftheCZ.Useoftheterm‘‘centralgland’’torefertothecombinationofTZandCZisdiscouragedasitisnotreflectiveofthezonalanatomyasvisualizedorreportedonpathologicspecimens.Athin,darkrimpartiallysurroundingtheprostateonT2Wisoftenreferredtoasthe‘‘prostatecapsule.’’Itservesasanimportantlandmarkforassessmentofextraprostaticextensionofcancer.Infact,theprostatelacksatruecapsule;ratheritcontainsanouterbandofconcentricfibromusculartissuethatisinseparablefromprostaticstroma.Itisincompleteanteriorlyandapically.Theprostaticpseudocapsule(sometimesreferredtoasthe‘‘surgicalcapsule’’)onT2WMRIisathin,darkrimattheinterfaceoftheTZwiththePZ.Thereisnotruecapsuleinthislocationathistologicalevaluation,andthisappearanceisduetocompressedprostatetissue.Nervesthatsupplythecorporacavernosaareintimatelyassociatedwitharterialbranchesfromtheinferiorvesiclearteryandaccompanyingveinsthatcourseposterolateralat5and7o’clocktotheprostatebilaterally,andtogethertheyconstitutetheneurovascularbundles.Attheapexandbase,smallnervebranchessurroundtheprostateperipheryandpenetratethroughthecapsule,apotentialrouteforextraprostaticextension(EPE)ofcancer.3.2.SectorMap(AppendixII)ThesegmentationmodelusedinPI-RADSTMv2wasadaptedfromaEuropeanConsensusMeetingandtheESURProstateDownloadedfromClinicalKatPekingUniversityHealthScienceCenteronMarch18,2016.Forpersonaluseonly.Nootheruseswithoutpermission.Copyright©2016.ElsevierInc.Allrightsreserved.20EUROPEANUROLOGY69(2016)16–4020Fig.1–AnatomyoftheprostateillustratedonT2-weightedimaging(modifiedfromBonekampD,JacobsMA,El-KhouliR,etal.AdvancementsinMRimagingoftheprostate:fromdiagnosistointerventions.Radiographics2011;31(3):677;withpermission.).MRIGuidelines2012.Itemploysthirty-ninesectors/regions:thirty-sixfortheprostate,twofortheseminalvesicles,andonefortheexternalurethralsphincter.(AppendixII).UseoftheSectorMapwillenableradiologists,urologists,pathologists,andotherstolocalizefindingsdescribedinMRIreports,anditwillbeavaluablevisualaidfordiscussionswithpatientsaboutbiopsyandtreatmentoptions.Divisionoftheprostateandassociatedstructuresintosectorsstandardizesreportingandfacilitatespreciselocali-zationforMR-targetedbiopsyandtherapy,pathologicalDownloadedfromClinicalKatPekingUniversityHealthScienceCenteronMarch18,2016.Forpersonaluseonly.Nootheruseswithoutpermission.Copyright©2016.ElsevierInc.Allrightsreserved.21EUROPEANUROLOGY69(2016)16–4021correlation,andresearch.Sincerelationshipsbetweentumorcontours,glandularsurfaceoftheprostate,andadjacentstructures,suchasneurovascularbundles,externalurethralsphincter,andbladderneck,arevaluableinformationforperiprostatictissuesparingsurgery,theSectorMapmayalsoprovideausefulroadmapforsurgicaldissectionatthetimeofradicalprostatectomy.Eitherhardcopy(onpaper)orelectronic(oncomputer)recordingontheSectorMapisacceptable.ForinformationabouttheuseoftheSectorMap,seeSectionIIIandAppendixII.3.3.BenignFindingsManysignalabnormalitieswithintheprostatearebenign.Themostcommoninclude:3.3.1.Benignprostatichyperplasia(BPH)Benignprostatichyperplasia(BPH)developsinresponsetotestosterone,afteritisconvertedtodi-hydrotestosterone.BPHarisesintheTZ,althoughexophyticandextrudedBPHnodulescanbefoundinthePZ.BPHconsistsofamixtureofstromalandglandularhyperplasiaandmayappearasband-likeareasand/orencapsulatedroundnoduleswithcircum-scribedmargins.PredominantlyglandularBPHnodulesandcysticatrophyexhibitmoderate-markedT2hyperintensityandaredistinguishedfrommalignanttumorsbytheirsignalandcapsule.PredominantlystromalnodulesexhibitT2hypointensity.ManyBPHnodulesdemonstrateamixtureofsignalintensities.BPHnodulesmaybehighlyvascularonDCEandcandemonstratearangeofsignalintensitiesonDWI.AlthoughBPHisabenignentity,itmayhaveimportantclinicalimplicationsforbiopsyapproachandtherapysinceitcanincreaseglandvolume,stretchtheurethra,andimpedetheflowofurine.SinceBPHtissueproducesprostate-specificantigen(PSA),accuratemeasurementofglandvolumebyMRIisanimportantmetrictoallowcorrelationwithanindividual’sPSAlevelandtocalculatethePSAdensity(PSA/prostatevolume).3.3.2.HemorrhageHemorrhageinthePZand/orseminalvesiclesiscommonafterbiopsy.ItappearsasfocalordiffusehyperintensesignalonT1Wandiso-hypointensesignalonT2W.However,chronicbloodproductsmayappearhypointenseonallMRsequences.3.3.3.CystsAvarietyofcystscanoccurintheprostateandadjacentstructures.Aselsewhereinthebody,cystsintheprostatemaycontain‘‘simple’’fluidandappearmarkedlyhyperin-ten