胆囊

CToftheGallbladder:SpectrumofDiseaseIntroductionCThasplayedasignificantroleintheevaluationofgallbladderdisease.AdvancementsinCTscannertechnologyhaveimprovedtheabilitytodiagnosethegallbladderandarangeofconditionsincludinggallstones,cholecystitis,andcancer.ThispictorialessayreviewsthecurrentroleofCTintheevaluationofgallbladderdiseaseFig.1.—Healthy40-year-oldwoman.Contrast-enhancedCTscansrevealnormalappearanceofgallbladderincoronal(A)andaxial(B)planes1B1ACholecystitis:AcuteandChronicTheclinicalsignsandsymptomsofacutecholecystitisarenonspecific.ThediagnosisofacutecholecystitisviaabdominalCTrequiresattentiontoaconstellationoffindings.Ninety-fivepercentofpatientswithacutecholecystitishavegallstones,butthesensitivityofCTfordetectionofthesestonesisonlyapproximately75%.Calcium-containingstonestendtobewellseen;however,cholesterolstonesmaybeisoattenuatingorhypoattenuatingcomparedwiththeattenuationofbile,makingtheirdetectiondifficultFig.2.—UnenhancedCTscanobtainedin62-year-oldwomanwithrightupperquadrantpainrevealscalcifiedstonesingallbladderFig.3.—Contrast-enhancedCTscanobtainedin45-year-oldmanshowslow-densitygallstonesTheCTfeaturesofacutecholecystitisincludegallstones,thickeningofthegallbladderwall,pericholecysticfluid,strandingofthepericholecysticfat,high-attenuationbile,andblurringoftheinterfacebetweenthegallbladderandtheliver.Inaddition,transientincreasesinattenuationoftheportionoftheliveradjacenttothegallbladderinpatientswithacutecholecystitishavebeenreported.Thisfindinghasbeenattributedtohepaticarterialhyperemia.Chroniccholecystitisisadifficultdiagnosistomakeonimaging,regardlessofthetechniqueused.Findingsincludegallstonesandthickeningofthegallbladderwall;however,correlationwiththeclinicalfindingsiscriticalFig.4.—OnCTscanobtainedin50-year-oldmanwithacutecholecystitis,gallstonesareseenindependentportionofgallbladder.ThickeningofgallbladderwallandstrandingofpericholecysticfatareevidentFig.5A.—45-year-oldmanwithacutecholecystitis.CTscanshowsthickeningofgallbladderwallwithextensivepericholecysticinflammationandfluidFig.5B.—CTscanshowsinflammationextendingtoandinvolvinghepaticflexureofcolon5A5BFig.6.—57-year-oldmanwithacutecholecystitis.Contrast-enhancedCTscanshowsincreasedliverenhancementadjacenttoinflamedgallbladder.CalcifiedgallstoneisalsovisibleFig.7.—Contrast-enhancedCTscanobtainedin65-year-oldwomanwithrightupperquadrantpainrevealsgallstoneandminimalthickeningofgallbladderwallwithoutpericholecysticinflammation,findingsthatarecompatiblewithchroniccholecystitisComplicationsofcholecystitisincludegangrenouscholecystitis,gallbladderrupture,andformationofabscessesandfistulas.Gangrenous,oremphysematous,cholecystitisoccursmostcommonlyindiabeticpatientsviagas-formingorganisms.CTisthemostspecificimagingtechniqueforestablishingthediagnosisofemphysematouscholecystitis.Findingsincludeairinthegallbladderwallorlumen,anair–liquidlevelwithinthegallbladderlumen,andpericholecysticabscessEmphysematouscholecystitisFig.8.—Contrast-enhancedCTscanobtainedin65-year-oldmanwithdiabetesandwhopresentedwithrightupperquadrantpainshowsairinwallofgallbladderaswellaswallthickeningandpericholecysticinflammation,characteristicofemphysematouscholecystitisFig.9.—Contrast-enhancedCTscanobtainedin72-year-oldmanwithemphysematouscholecystitisrevealsairingallbladderlumenandthickeningofwallMirizzi'ssyndrome,whichistheobstructionoftheextrahepaticbileductbyastoneimpactedwithinthecysticductandsubsequentextrinsiccompressionorinflammation.ThissyndromemaybesuggestedonCTbyidentificationofastonewithinthecysticductwithconcurrentbiliaryductaldilatationFig.10.—65-year-oldmanwithrightupperquadrantpain.TheCTscanrevealsintrahepaticductaldilatation,gallbladderisalsodistended,calcifiedstoneisidentifiedincysticduct，characteristicofMirizzi‘ssyndromeApproximately6,500newcasesofgallbladdercarcinomaarereportedannuallyintheUnitedStates,witha4:1female-to-maleratioandthepeakincidenceoccurringinthesixthandseventhdecadesoflife.Clinicalandradiologicfeaturesofgallbladdercarcinomaoverlapwiththoseseenincholelithiasisandcholecystitis,whichoftencausesadelayindiagnosisuntilthediseaseisinthelatestageGallbladderCarcinomaThemostcommonCTfindingingallbladdercarcinomaisamassthatfillsmostofanenlargedanddeformedgallbladder.Thesemassesaretypicallylowinattenuationwithvariableenhancement.Polypoidmassesarethesecondmostcommonpresentation;differentiationfrombenignpolypsisbasedonsize,withthepolypoidmassestypicallylargerthan1cm.Finally,gallbladdercarcinomacanpresentasasymmetricoranasymmetricgallbladderwallthickeningthatmaybedifficulttodistinguishfromthegallbladderwallseeninchroniccholecystitis.Afocalmasshasbeenreportedtobeareliableindicatorofcarcinomaratherthancholecystitis.Othersignsaretheresultofdiseaseprogressionincludingbiliaryobstructionandliverinvolvement,featuresthatarecommonlyconfusedwithcarcinomaofthepancreasorevenliverFig.11.—67-year-oldwomanwithgallbladdercarcinoma.ArterialphaseCTscanrevealslargemassoriginatingfrominferioraspectofgallbladderandinfiltratingadjacentliverFig.12.—Contrast-enhancedC