脊柱变异

NormalVariantsandFrequentMarrowAlterationsthatSimulateBoneMarrowLesionsatMRImagingBrunoC.VandeBergBC,etal.RadiolClinNAm43(2005)761–770Outline•Normalappearance•Normalvariants•FocalvertebralalterationsthatmaysimulatemetastasisSiegelMJ,MRIofbonemarrow,169-17973YAfterradiation26Y14M,normalbonemarrow56Y,MMNormalappearance•MRimagingappearanceofthevertebralmarrowmerelydependsontherelativeproportionofhematopoieticcellsandadipocyteswithinthemedullarycavityofthevertebralbodies•MostlesionsandnormalvariantsinterferewiththismedullarywaterfatbalanceandarebestdepictedonT1-weightedspinecho(SE)MRimages•Asarule,signalintensityofnormallumbarvertebralbodiesonT1-weightedSEimagesmustbehigherthanthatofadjacentintervertebraldiskinanadultpatient•Afterintravenousinjectionofgadolinium-containingcontrastmaterial,enhancementofmarrowsignalintensityisbarelyvisibleatvisualinspectiononT1-weightedSEimages13Y45YNormalappearance•Redmarrowisgenerallydistributedinahomogeneouspatternwithinthevertebralbody.•Occasionally,redmarrowismorecellularnearthevertebralendplate,whichisametaphysealequivalent,anareawherethevasculatureisgenerallymoredeveloped.•Redmarrowcanalsobemorecellularintheanterioraspectsofthevertebralbodies.•Finally,fattymarrowcanbecomeprominentaroundthevertebralbasilarveins.•Asarule,thesevariationsinvertebralmarrowMRimagingappearanceshouldinvolveallvertebralbodiesofthesamesubjectinasimilarmanner(noorminorintervertebralvariations)•ItisimportanttokeepinmindthatevenanormallookingT1-weightedSEimageofthespinedoesnotenableonetoexcludemarrowinfiltrationbyabnormalplasmocytesorlymphocytes,probablyinsituationsinwhichthewater-fatbalanceisnotsufficientlyalteredtobecomedetectable•Normalvariants–Islandsoffattymarrow–Islandsofredmarrow•Islandsoffattymarrow–Fociofyellowmarrowappearinthevertebralbodies.–Theirfrequencyincreaseswithage,buttheirnumberandsizeremainunalteredatshort-termfollow-upMRimagingstudy.–HighsignalintensityonT1-weightedSEimagesandlowsignalintensityonfat-saturatedimages.Onnon–fat-saturatedintermediateorT2-weightedfastSEimages,theseareasshowhighsignalintensiy.•Islandsofredmarrow–Cellularityofhematopoieticmarrowcanshowspatialvariationswiththepresenceofislandsofhighlycellularhematopoieticmarrow.–ThesevariationsleadtotheappearanceofareasofmorepronounceddecreaseinsignalintensitythanadjacentmarrowonT1-weightedSEMRimages.•Focalvertebralalterationsthatmaysimulatemetastasis–Vertebralhemangioma–Vertebralenostosis:compactboneisland–Focalnodularhyperplasiaofredmarrow•Vertebralhemangioma–Vertebralhemangiomaisacommonvertebrallesionwithafrequencyof12%inwomenand9%inmen.–Hemangiomasaremultipleinaboutonethirdofcasescorrespondtocavernoushemangiomasandcontaindilated,blood-filled,vascularspaceslinedbyflatendothelialcells,setinastromacontaininglargeamountsofadiposetissueandnohematopoieticcells•OnT1-weightedSEimages,signalintensityofasymptomaticvertebralhemangiomaishighertothatofadjacentmarrow,althoughitcanalsobeequivalentandnotvisibleonT1-weightedimages.•OnT2-weightedSEimages,itssignalisconsistentlyhigh.PresenceoffatcellsanddilatedvesselswithinterstitialedemamostlikelyaccountsforitshighsignalintensityonT1-andT2-weightedimages,respectively•Signalenhancementofhemangiomaaftergadoliniuminjectionisvariable,dependingonitsappearanceonT1-weightedimagesandthetypeofsequencethatisobtainedaftercontrastinjection.•Enhancementpatterncanbehomogeneousorperipheral.•Occasionally,asymptomaticvertebralhemangiomashowslowsignalintensityonT1-weightedimages,withmarkedenhancementonpostcontrastT1-weightedSEimages.Thesehemangiomascanbeconfusedwithsignificantmarrowlesions.•CTimagesgenerallyshowaratherspecifictrabecularP10011173,75Y,bladderca•Vertebralenostosis:compactboneisland–Acompactboneislandconsistsoflamellarcorticalboneembeddedwithinthetrabecularnetworkofthemedullarycavity–Frequentlyinvolvetheperipheryofthevertebralbodiesandsparethecentralarea.–Theirsignalintensityisverylowonallsequencesandadjacentmarrowgenerallyhasanormalappearance•Focalnodularhyperplasiaofredmarrow–Mostextremepatternoffocalhypertrophyoftheredmarrowcomponent.–ItcausesthepresenceofoneormultiplenodulesofdecreasedsignalonT1-weightedimages.–Itoccursrelativelyrarelyinnormalindividualsbutitisfrequentinpatientswithregeneratinghematopoieticmarrowaftermarrowaplasiaorinresponsetotheadministrationofhematopoieticgrowthfactors.•Mostfrequently,thenodulesignalintensityissimilarorslightlylowerthanthatoftheadjacentintervertebraldisk.•CTimagesandbonescanimagesshouldbenormal.FNHofredmarrow•Diffusehematopoieticmarrowhyperplasia–Presenceofhypercellularhematopoieticmarrowintheaxialskeletonandbyexpansionofhematopoieticmarrowintheappendicularskeleton(marrowreconversion)–Itoccursinresponsetonumerousstimulithattriggerproductionofredmarrowcells.–Administrationofhematopoieticgrowthfactorsduringchemotherapytypicallycausestransientincreaseinmarrowcellularity•Severalchronicdisordersthatareassociatedwithanemiaincludinghereditaryhemoglobinopathiesandchronicinfectionalsocauseredmarrowexpansion.•Diffuseredmarrowhyperplasiaisalsoobservedinmiddle-ag