Computed tomography characteristics of equine paranasal sinus cysts—a case series

• COMPUTEDTOMOGRAPHYCHARACTERISTICSOFEQUINEPARANASALSINUSCYSTS-ACASESERIESJ.Ostrowska,T.T´oth,L.Lindstr¨om,K.Hansson,M.Uhlhorn,C.J.Ley.FromtheUniversityAnimalHospital(Ostrowska,T´oth,Uhlhorn),DepartmentofClinicalSciences(Hansson,Ley),andDepartmentofBiomedicalSciencesandVeterinaryPublicHealth,SwedishUni-versityofAgriculturalSciences,UppsalaSE-75007,Sweden(Lindstr¨om).Introduction/Purpose:Differentiatingparanasalsinuscysts(PSC)fromotherparanasalsinusdiseasesinhorsesbasedondiagnosticimagingischallenging.TheaimofthisstudywastoidentifythepatternofCTfeatures,typicalforPSC,byretrospectivecomparisontootherdiseasesoftheequineparanasalsinuses. Methods:NineCTscansofeighthorses(diseasereoccurredafter1yearinonehorse)withtypicalsurgicalappearanceofPSC(sevenconfimedwithhistopathology)wereretrospectivelyre-viewed(group-1).Imagingfndingswerecomparedtoagroupof11horseswithparanasalsinusdiseaseofotherorigin(twoneoplasia,sevenchronicsinusits/granuloma,twopro-gressiveethmoidhematoma),withallhorsesinthisgrouphavingsurgery/necropsyandculture/histopathologyconfimationofthediagnosis(group-2).Thirteenofthehorsesre-ceivedcontrast;IVIohexol300mgI/ml,20ml/s,400ml/horse,scannedapproximately2and7minpostcontrast.MeanHounsfielUnits(HU)valuesofthesofttissue/fluidensitylesionswereobtainedforthreeregionsofinterestinthreedifferentslices.Studentt-testforindependentsamples,P<0.05consideredsignificantwasusedtocomparemeandensityofthecysticcontentwithfreesinusfluiingroup-1andsofttissue/fluidensitylesionsingroup-2.Results:Insixhorsesthepresumedwallofthecystwasatleastpartiallymineralized.Subtlepost-contrastenhancementofthecysticwallwasseenintwohorsesinwhichthemineralizedwallwasabsent.Presenceoffocalorspicule-like,peripheralmineralizationswereseenintwogroup-1horsesandinonegroup-2horsewithaparanasalsinusgranuloma.Allcystswerefillewithsofttissue/fluidensity(mean±SD,25±11HU),exceptonethatcontainedonlyair.Nosignificandifferencewasfoundbetweenthemeandensityofthecysticcontentandthesofttissue/fluidensitylesionsingroup-2(mean±SD,25±11vs.42±23HU,P=0.06),orbetweenthefreesinusfluisurroundingthecysts(mean±SD,25±11HUvs.34±17HU,P=0.2).Corticaldestructionwasdetectedinfourgroup-1andtwogroup-2horses.Sevenhorsesineachgrouphadcancellousbonethinning/destruction,whichalwaysinvolvedatleasttheinfraorbitalcanal.Bonedistortionwasmostfrequent/severeingroup-1horsesandboneproductionwasmostcommoningroup-2horseswithsinusitis.Discussion/Conclusions:ParanasalsinuscystsoftenhavemineralizationinthecystwallandthisfeaturemaybeusefultodifferentiatePSCfromotherparanasalsinusesdiseasesinCTimages.DespitethebenigncharacterofPSCcorticaldestructioniscommoninhorseswithPSC.ThereisconsiderableoverlapbetweenHUvaluesofthecontentsofPSCandthefluid/tissupresentinotherparanasalsinusdiseases.

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LANTBRUKSVETENSKAPER  -- Veterinärmedicin -- Klinisk vetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Veterinary Science -- Clinical Science (hsv//eng)

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