胆囊的MRI成像.docx

胆囊的MRI成像.docx

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胆囊的MRI成像

MRImagingoftheGallbladder:

APictorialEssay1

1.OnofrioA.Catalano,MD,2,

2.DushyantV.Sahani,MD,

3.SanjeevaP.Kalva,MD,

4.MatthewS.Cushing,MD,

5.PeterF.Hahn,MD,PhD,

6.JeffreyJ.Brown,MDand

7.RobertR.Edelman,MD

+AuthorAffiliations

1.1FromtheDepartmentofRadiology,DivisionofGastrointestinalRadiology,MassachusettsGeneralHospital,WHT270,55FruitSt,Boston,MA02114（O.A.C.,D.V.S.,S.P.K.,M.S.C.,P.F.H.）;MallinckrodtInstituteofRadiology,WashingtonUniversitySchoolofMedicine,StLouis,Mo（J.J.B.）;andtheDepartmentofRadiology,NorthwesternUniversitySchoolofMedicine,Evanston,Ill（R.R.E.）.Presentedasaneducationexhibitatthe2004RSNAAnnualMeeting.ReceivedOctober23,2006;revisionrequestedJanuary23,2007;finalrevisionreceivedJune7;acceptedJune11.Theauthorsdiscussaninvestigationalorunlabeleduseofacommercialproduct,device,orpharmaceuticalthathasnotbeenapprovedforsuchpurposebytheFDA.D.V.S.isaresearcherforGEHealthcareandaconsultantwithBraccoDiagnostics;S.P.K.receivedresearchgrantsfromJohnson&Johnson（Cordis）andCookandiswiththespeakers’bureauofJohnson&Johnson;J.J.B.isaconsultantwithTycoHealthcare（Mallinckrodt）,BayerHealthcare,andGEHealthcareandiswiththespeakers’bureauofBraccoDiagnostics;andR.R.E.receivedresearchsupportfromGEHealthcareandSchering（Berlex）;allremainingauthorshavenofinancialrelationshipstodisclose.

1.Addresscorrespondenceto

D.V.S.（e-mail:

dsahani@partners.org）.

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Abstract

Thegallbladderservesastherepositoryforbileproducedintheliver.However,bilewithinthegallbladdermaybecomesupersaturatedwithcholesterol,leadingtocrystalprecipitationandsubsequentgallstoneformation.Themostcommondisordersofthegallbladderarerelatedtogallstonesandincludesymptomaticcholelithiasis,acuteandchroniccholecystitis,andcarcinomaofthegallbladder.Otherconditionsthatcanaffectthegallbladderincludebiliarydyskinesia（functional）,adenomyomatosis（hyperplastic）,andpostoperativechangesorcomplications（iatrogenic）.Ultrasonography（US）hasbeenthetraditionalmodalityforevaluatinggallbladderdisease,primarilyowingtoitshighsensitivityandspecificityforbothstonediseaseandgallbladderinflammation.USperformedbeforeandafteringestionofafattymealmayalsobeusefulforfunctionalevaluationofthegallbladder.However,USislimitedbypatientbodyhabitus,withdegradationofimagequalityandanatomicdetailinobeseindividuals.Withtheadventoffasterandmoreefficientimagingtechniques,magneticresonance（MR）imaginghasassumedanincreasingroleasanadjunctmodalityforgallbladderimaging,primarilyinpatientswhoareincompletelyassessedwithUS.MRimagingallowssimultaneousanatomicandphysiologicassessmentofthegallbladderandbiliarytractinbothinitialevaluationofdiseaseandexaminationofthepostoperativepatient.ThisassessmentisaccomplishedchieflythroughtheuseofMRimagingcontrastagentsexcretedpreferentiallyviathebiliarysystem.

©RSNA,2008

∙BOPTA=benzyloxypropionictetraacetate

∙CHD=commonhepaticduct

∙HIDA=hydroxyiminodiaceticacid

∙MnDPDP=mangafodipirtrisodium

∙SE=spin-echo

∙XGC=xanthogranulomatouscholecystitis

∙3D=three-dimensional

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LEARNINGOBJECTIVESFORTEST3

Afterreadingthisarticleandtakingthetest,thereaderwillbeableto:

∙Discussthestate-of-the-artMRandMRcholangiographicimagingtechniquesforthediagnosisofgallbladderdisease.

∙DescribethenormalMRimagingfeaturesofthegallbladder.

∙IdentifytheMRimagingappearancesofgallbladderdisease.

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Introduction

Thegallbladderisapear-shapedhollowviscuslocatedintherightupperquadrant,lodgedonthevisceralsurfaceoftheliverbetweensegmentsIVandV,andconnectedtothehepaticductthroughthecysticducttoformthecommonbileduct.Thegallbladderiscomposedofthefundus,whichusuallyprojectsbeyondtheinferiorborderoftheliver;thebody;andtheneck.Itisusually7–10cmlongand2.5cmwide,andthewallmeasureslessthan3mminthickness

（1）.Thegallbladderservesastherepositoryforbileproducedintheliver,withanaveragevolumeof30–50mL

（2）.Bilewithinthegallbladdermaybecomesupersaturatedwithcholesterol,leadingtocrystalprecipitationandsubsequentgallstoneformation.

Imagingofthegallbladderistypicallyrequestedforevaluationofrightupperquadrantpaininpatientswithorwithoutfeverandjaundice.Ultrasonography（US）istypicallytheinitialimagingmodality.However,technologicadvancesinmagneticresonance（MR）imagingsoftware,hardware,andcontrastmedia（eg,phased-arraysurfacecoils,breath-holdimaging,single-shotimagingtechniques,hepatobiliarycontrastagents）allowMRimagingtobeusedastheinitialimagingmodalityfortheevaluationofpain,jaundice,ormassesorasaproblem-solvingtoolforgallbladderdisease.Moreover,MRimagingallowsfunctionalassessmentofthegallbladderthroughtheuseofcontrastagentsexcretedpreferentiallyviathebiliarysystem.

Inthisarticle,wereviewMRimagingtechniquesfortheevaluationofthegallbladderandthenormalMRimagingappearanceofthisstructure.Inaddition,wediscussandillustratecongenitalabnormalitiesofthegallbladderandavarietyofpathologicconditionsaffectingthegallbladder（cholelithiasis,acuteandchroniccholecystitis,Mirizzisyndrome,xanthogranulomatouscholecystitis[XGC],adenomyomatosis,carcinoma,lymphoma,endometrialimplants）.Wealsodiscussfunctionalevaluationofthegallbladderintheacutesetting,postoperativefunctionalevaluationofthegallbladderandbiliarytree,andtheassessmentofangiogenesisasapossiblefutureapplication.

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ImagingTechniques

MRimagingsequencesshouldbetailoredtotheclinicalquestion.T2-weightedsequences（usuallyfastspin-echo[SE]sequenceswithrespiratorygating）areoptimalforevaluatingsoft-tissueabnormalitiesinvolvingthewallofthegallbladder,thebiliarysystem,andadjacentsoft-tissuestructures.Thesectionthicknessshouldbelessthan5mm,witha1–2-mmgapbetweensections.UsefuladditionalT2-weightedsequencesaresimilartothoseusedtoevaluatethebiliarytree（MRcholangiopancreatography）（Figs1,2）:

acquisitiontechniquessuchashalf-Fourierrapidacquisitionwithrelaxationenhancementandsingle-shotfastSEimaging.AlthoughT1-weightedMRimagingofthegallbladdercanbeperformedwitheitherSEorbreath-holdspoiledgradient-echotechniques,thelatteraresuperiorbecausetheydecreaserespiratoryartifacts.

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Figure1a.  Two-dimensionalversusthree-dimensional（3D）MRcholangiopancreatography.（a）Duringtwo-dimensionalacquisition,athickslabisimagedinanobliqueplane.Two-dimensionalheavilyT2-weightedMRcholangiopancreatogramshowsfluid-filledstructures,whichmayoverlapbecausetheimagingisperformedinonlyoneplane.Thebiliaryandpancreaticductsarewellvisualized.（b）Three-dimensionalthin-sectionmaximum-intensity-projectionreformattedheavilyT2-weightedMRcholangiopancreatogramshowshowitispossibletorotateandseparatethestructureswitha3Dsequence.

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Figure1b.  Two-dimensionalversusthree-dimensional（3D）MRcholangiopancreatography.（a）Duringtwo-dimensionalacquisition,athickslabisimagedinanobliqueplane.Two-dimensionalheavilyT2-weightedMRcholangiopancreatogramshowsfluid-filledstructures,whichmayoverlapbecausetheimagingisperformedinonlyoneplane.Thebiliaryandpancreaticductsarewellvisualized.（b）Three-dimensionalthin-sectionmaximum-intensity-projectionreformattedheavilyT2-weightedMRcholangiopancreatogramshowshowitispossibletorotateandseparatethestructureswitha3Dsequence.

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Figure2.  Three-dimensionalMRcholangiopancreatogramshowsthenormalgallbladder.Thecysticductappearsasacurvilinearbrightlineconnectingthegallbladderwiththecommonhepaticduct（CHD）.Pancreasdivisumisincidentallynoted.

Dynamiccontrastmaterial–enhancedfat-suppressedT1-weightedMRimagingsequencesimprovethedelineationofthegallbladderwall,bileducts,andassociatedentitiessuchasinflammationandneoplasmsandallowassessmentoftheliverparenchymafortumorinvasionandmetastaticdisease（Table1）.

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Table1.MRImagingProtocol

Twoagents,MnDPDPandgadoliniumBOPTA—thelatternotyethavingbeenapprovedintheUnitedStatesforevaluationofthegallbladderandbiliarytree—areexcretedintothebile.Afterbeinginjectedintravenously,theseagentsarespecificallytakenupbythehepatocytesandsubsequentlyexcretedintothebile,resultinginsignificantT1shorteningofthebile,whichappearshyperintenseonT1-weightedMRimages.Thisphenomenonpermitsevaluationofthephysiologiccharacteristicsofthegallbladderandbiliarytree.ThisbranchofMRcholangiographyisknownasfunctionalMRcholangiography（2–4）.

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NormalAppearanceoftheGallbladder

Thegallbladdershouldbeimagedafterthepatienthasfastedfor8–12hours,whichpromotesphysiologicdistentionofthegallbladder.OnT2-weightedimages,thegallbladderwallhaslowsignalintensityandstandsoutagainstthebrightvisceralfat.Th