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Thyroid ultrasound

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sonography of thyroid by Dr. Raham Bacha Lecturer UIRSMIT UOL
www.uol.edu.pk

Published in: Health & Medicine
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Thyroid ultrasound

  1. 1. قالو سُبحانك ل ا ع لام لنا ال اما عا لمتنا انك انت العليمُ الحكيم Surah Al Baqarahverse 32
  2. 2. اسلام علیکم Welcome to THYROID
  3. 3. By: Dr. Raham Bacha MD KMU MSc SonologyGold Medalist (UOL) The university of Lahore
  4. 4. OBJECTIVE •INDICATION OF THYROID SCANNING •THYROID ANATOMY •SCANNING TECHNIQUES •SONOGRAPHIC ANATOMY •THYROID PATHOLOGIES •CHARACTERIZATION OF THYRIOD NODULES •DIFFUSE THYROID DISEASES
  5. 5. 1.Toconfirmpresenceofathyroidnodulewhenphysicalexaminationisequivocal. 2.Tocharacterizeathyroidnodule(s),i.e.tomeasurethedimensionsaccuratelyandtoidentifyinternalstructureandvascularization. 3.Todifferentiatebetweenbenignandmalignantthyroidmasses,basedontheirsonographicappearance. 4.Todifferentiatebetweenthyroidnodulesandothercervicalmasseslikelymphadenopathy, thyroglossalcystandcystichygroma. INDICATIONS
  6. 6. INDICATIONS 5.Toevaluatediffusechangesinthyroidparenchyma. 6.Todetectpost-operativeresidualorrecurrenttumorinthyroidbedormetastasestonecklymphnodes. 7.Toscreenhighriskpatientsforthyroidmalignancylikepatientswithhistoryoffamilialthyroidcancer,multipleendocrineneoplasia(MEN)andirradiatedneckinchildhood. 8.Toguidediagnostic(FNAcytology/biopsy)andtherapeuticinterventionalprocedures.
  7. 7. ANATOMY
  8. 8. ANATOMY
  9. 9. ANATOMY
  10. 10. Ultrasound Examination Technique Allpatientsareexaminedinsupinepositionwithhyperextendedneck,usingahighfrequencylineararraytransducer(7-15MHz)thatprovidesadequatepenetrationandhighresolutionimage. Scanningisdonebothintransverseandlongitudinalplanes.Realtimeimagingofthyroidlesionsisperformedusingbothgray-scaleandcolorDopplertechniques.Theimagingcharacteristicsofamass(viz.location,size,shape,margins, echogenicity,contentsandvascularpattern)shouldbeidentified.
  11. 11. Normal Anatomy Thenormalthyroidglandconsistsoftwolobesandabridgingisthmus.Thyroidsize, shapeandvolumevarieswithageandsex. Normalthyroidlobedimensionsare:18-20mmlongitudinal,10-12mmantero-posterior(AP)diameterand8-9mminwidth,innewborn;25mmlongitudinaland12-15mmAPdiameteratoneyearage;and40-60mmlongitudinal,20-30mminAPdiameterand13-18mmwidthinadultpopulation.
  12. 12. Thelimitsofnormalthyroidvolume(excludingisthmus,unlessitsthicknessis>30mm)are10-15mlforfemalesand12-18mlformales. Therelationshipswithsurroundingstructuresare:sterno-cleido-mastoidandstrapmusclesanteriorly;trachea/esophagusandlonguscollimusclesposteriorly;andcommoncarotidarteriesandjugularveinsbilaterallyThyroidvolume(ml)=퐿×푊×퐷×0.52
  13. 13. ColorandpowerDopplerultrasound(US)areusefultoevaluatevascularityofthethyroidglandandfocalmasses.Thyroidglandisahighlyvascularstructuresuppliedbysuperiorandinferiorthyroidarteries.ThethyroidarteriescanbevisualizedoncolorDopplerexaminationwhiletheflowparametersfromthesevesselscanbemeasuredbyspectralDopplerexamination.
  14. 14. Normally,alowresistanceflowwithhighpeaksystolicvelocity(PSV)isdetectedinthesevesselsonspectralDoppleranalysis. ThenormalPSVinintrathyroidarteriesrangesbetween15-30cm/second,butitcanriseincertainpathologies(likeGraves'disease)toover100cm/sec
  15. 15. Congenital and Developmental Anomalies of Thyroid Gland Thethyroidglandprimordiumdevelopsfrommedianeminenceinthefloorofprimitivepharynx(apointlaterknownasforamencecumatthebaseoftongue)during4thweekofgestation.Fromforamencecum,theprimitiveprimordiumdescendsthroughanteriormidlineportionofthenecktoreachitsfinalpositionbelowthyroidcartilageby7thweekofgestation.
  16. 16. Duringthisdescent,thedevelopingthyroidglandretainsanattachmenttothepharynxbyanarrowepithelialstalkknownasthyroglossalduct.Thisductusuallybecomesobliteratedby8th-10thweekofgestation. Thyroidhormonesynthesisnormallybeginsatabout11thweekofgestation
  17. 17. Occassionally,restsofthyroidtissuemayremainalongthecourseofthyroglossalduct, givingrisetoanadditionalthyroidlobe,thepyramidallobe,attachedtodistalendofthethyroglossalductandleftsideofisthmus(seenin50%ofpopulation).Persistenceofthyroglossalductresultsinformationofthyroglossalcyst,whichclinicallypresentsasmidlineneckswellingorlump,usuallyfoundatlevelofhyoidboneorthyroidcartilage.
  18. 18. Onultrasound,thecystappearsasawell-definedanechoictohypoechoiclesionwithposterioracousticenhancement.Internalechoesmaybeseenwithinthecystduetohemorrhageorinfection.
  19. 19. Ectopicthyroidrepresentsanarrestinusualdescentofpartorallofthethyroidtissuealongthenormalpathway.Ectopicthyroidglanddevelopsmostcommonlyatsublingual(midlineatforamencecum), suprahyoidorinfrahyoidposition.USGshowspresenceofanectopicthyroidtissueandthenormalthyroidglandmayormaynotbepresentatnormalposition.
  20. 20. EctopicthyroidmaybeeasilydetectedonCTandradionuclidescans.Congenitalagenesisorhypoplasia(unilobartypeorofisthmus)ofthethyroidglandmayoccurduetodevelopmentalfailureofallorpartofthyroidgland.OnUSG,agenesisofisthmusischaracterizedbyabsenceofisthmuswiththelaterallobespositionedindependentlyoneithersideofthetrachea.
  21. 21. Diseases of Thyroid Gland Theincidenceofallthyroiddiseasesishigherinfemalesthaninmales.Nodularthyroiddiseaseisthemostcommoncauseofthyroidenlargement.Majorityofpatientswiththyroiddiseasepresentwithmidlineneckswelling, occasionallycausingdysphagiaandhoarsenessofvoice.
  22. 22. Broadly the thyroid diseases are classified into three categories: •(i) benign thyroid masses, •(ii) malignant tumors of thyroid gland, and •(iii) diffuse thyroid enlargement
  23. 23. Thyroid Nodule(s) Nodularitywithinthyroidisnormal.Theincidenceanddevelopmentofnodulescorrelatedirectlywithageofthepatientandisregardedasapartofnormalmaturationprocessofthethyroidgland.TheincidenceofthyroidnodulesisveryhighonUSG, rangingfrom50%to70%.Thyroidcanceraccountsforlessthan7%cases.Althoughthereissomeoverlapbetweenultrasoundappearanceofbenignandmalignantnodules,certainUSGfeaturesarehelpfulindifferentiatingthetwo.
  24. 24. Themostcommoncauseofbenignthyroidnoduleisnodularhyperplasia.Thyroidadenomasareothercommonbenignneoplasmsofthyroidthataremostlysolitarybutmayalsodevelopasapartofmultinodularmasses.Iso-orhyper-echogenicityofthethyroidnoduleinconjunctionwithaspongiformappearanceisthemostreliablecriterionforbenignityofthenoduleongray-scaleultrasoundand.
  25. 25. Other features to characterize nodule •size<1 cm, width > length. Size of the nodule is also helpful. The size of the nodule increase with age, so follow up is helpful. Although 90 percent of the benign nodules can also increase in volume by 50% in 5 years.
  26. 26. Other features to characterize nodule •Texture: thyroid nodules may either be hypo echoic, Isoechoicor hyperechoic. It may be solid, cystic or mixed. •Hyperechoic nodules with internal cystic areas are benign in nature. But hyper echoic nodule with thick external hollow is a sign of malignant nodule. But hyper echogenicity without thick peripheral hallow is a strong feature of benign nodule. •Malignant nodules are mostly hypoechoic but it is not necessary for all hypoechoic nodules to be malignant. Because most of the thyroid nodules are benign in nature that’s why most of the hypoechoic nodules are benign
  27. 27. "Ringdown"or"comet-tail"artifactisatypicalsignofbenigncysticcolloidnodule.Perinodularfloworspoke-and-wheel-likeappearanceofvesselsoncolorDopplerexaminationischaracteristicofabenignthyroidnodule. However,thisflowpatternmayalsobeseeninthyroidmalignancy.Acompleteavascularnoduleisveryunlikelytobemalignant.
  28. 28. Other features to characterize nodule •Calcification: calcification is common in benign as well as in malignant nodules but it is more probably malignant if found in solitary nodules. •Micro calcination <2mm is most commonly found in malignant nodule.
  29. 29. Histologically,malignanttumorsofthethyroidareclassifiedaspapillarycarcinoma(60-80%),follicularcarcinoma(20-25%), medullarycarcinoma(4-5%),anaplasticcarcinoma(3-10%),lymphoma(5%)andmetastases.Theoverallsensitivityofthyroidultrasoundfordiagnosingamalignantnoduleis83.3%.
  30. 30. USGfeaturespredictiveofmalignantnodulesincludepresenceofmicrocalcifications(<2mm),localinvasion,lymphnodemetastases, markedhypoechogenicity,irregularmargins, solidcomposition,absenceofahypoechoichaloaroundthenodule,size>1cm,taller- than-wide-shape,andanintranodularvascularity
  31. 31. Multiplicityofthenoduleisnotanindicatorofbenignity.Theincidenceofmalignancyissameinsolitarynodulesasitisinmultiplenodules.Intervalgrowthofnodulesisanon- specificcharacteristic.Microcalcificationsaremostcommonlyfoundinpapillaryandmedullarycarcinomathyroidandintheirmetastases(lymphnodeorhepatic).
  32. 32. OnUSG,microcalcificationsappearaspunctuatehyperechoicfociwithorwithoutposterioracousticshadowing.Rarely, microcalcificationscanbefoundinfollicularandanaplasticthyroidcarcinomasandcertainbenignlesionslikefollicularadenoma, multinodulargoitreandHashimoto'sthyroiditis.
  33. 33. Other features to characterize nodule •Margins •Margins may be smooth, speculated, micro-labulated, or Ill defined. Spiculatedmargins are strongly suggestive of malignancy.
  34. 34. Other features to characterize nodule •presence of hypoechoic halo •It is caused either by nodular capsule or by the compression of the thyroid tissue. •It may either be thin or thick and regular or irregular •Thin and regular is suggestive of benign •While thick and irregular more probability of malignancy.
  35. 35. Other features to characterize nodule •Vascularity •There are three paternof vascular distribution in the tumer. •Type one: absence of flow •Type two: peripheral vascularity •Type three: internal flow. ( associated with malignancy)
  36. 36. Localinvasionofadjacentstructuresandmetastasestoregionalcervicallymphnodesarehighlyspecificsignsofthyroidmalignancy.Theyoccurmorefrequentlyinmedullarycarcinoma(50%cases)thanpapillarycarcinoma(40%cases).Althoughpatientswiththyroidcarcinomamaypresentwithmultiplelevelnodaldisease,theanterolateralgroup(levelII,IIIandIV)havegreatestriskofmetastaticdisease. Lymph nodes involment.
  37. 37. USneckplaysanintegralroleinthemanagementofcervicalmetastasesfromthyroidcarcinoma(rangingfromselectiveremovaltoacomprehensiveneckdissection)byevaluatingnodalmetastaseswithrespecttonodelevel. Anaplasticthyroidcarcinomaandlymphomaarehighlyaggressivetumors,earlyandextensivelocalinvasioniscommonwiththesetumors. Lymphnodemetastasisisrareinfollicularthyroidcarcinoma,eveninhighlyinvasivecases.
  38. 38. Themostcommonpatternofvascularityinthyroidmalignancyismarkedintrinsichypervascularity.OncolorDopplerexamination,moreflowisdemonstratedinthecentralportionofthetumorthaninthesurroundingthyroidparenchyma
  39. 39. Increasedvascularitywithdistortionofsinusfatisseenwithinthemetastaticlymphnodes. Thyroidlymphomasarehypo-vascularwithchaoticvessels;however,neckvesselencasementmaybepresent.
  40. 40. Metastasestothethyroidglandareinfrequent.Themainprimarytumorsspreadingtothethyroidglandaremalignantmelanoma(39%ofcases),breastcarcinoma(21%ofcases)andrenalcellcarcinoma(10%ofcases).Sonographically,metastasespresentasasolitaryormultiplehypoechoichomogeneousmass(es)withoutcalcification.
  41. 41. Thyroidnodule(s)withsuspiciousUSGfeaturesshouldbeinvestigatedfurtherwithFNAbiopsy.Moreover,thework-upofasymptomaticthyroidnodules(incidentalomas)mustbeweighedagainsthighprevalenceofbenignthyroidnodulesandlowmortalityratefromsmallthyroidcarcinomas.
  42. 42. Diffuse Thyroid Diseases Thecommonconditionsthatpresentasdiffuseenlargementofthethyroidglandincludemultinodulargoitre,Hashimoto's(lymphocytic) thyroiditis,de-Quervain'ssubacutethyroiditisandGraves'disease.Thesonographicfeaturesoftheseprocessesmaybesimilarbuttheyhavedifferentbiochemicalprofileandclinicalpresentations. Hence,intheseconditions,ultrasoundfindingsshouldbeviewedinrelationtoclinicalandbiochemicalstatusofthepatient..
  43. 43. Multinodulargoitre(MNG)isthecommonestcauseofdiffuseasymmetricenlargementofthethyroidgland.Femalesbetween35-50yearsofagearemostcommonlyaffected.Histologically,colloidoradenomatousformofMNGiscommon.Theultrasounddiagnosisrestsonthefindingofmultiplenoduleswithinadiffuselyenlargedgland. AdiffuselyenlargedthyroidglandwithmultiplenodulesofsimilarUSappearanceandwithnonormalinterveningparenchymaishighlysuggestiveofbenignity,therebymakingFNAbiopsyunnecessary. Multinodulargoitre(MNG)
  44. 44. Mostofthenodulesareiso-orhyper-echoicinnature;whenenlargedprovideheterogeneousechopatterntothegland.ThesegoitrousnodulesoftenundergodegenerativechangesthatcorrespondtotheirUSGappearances: cysticdegenerationgivesanechoicappearancetothenodule,hemorrhageorinfectionwithinthecystisseenasmovinginternalechoes/septations,colloidaldegenerationproducescomet-tailartifact,whiledystrophiccalcificationisoftencourseorcurvilinear.
  45. 45. Vascularcompressionduetofollicularhyperplasialeadstofocalischemia,necrosisandinflammatorychange.TheassessmentofnodulevascularityisveryusefulindifferentiatingMNGfrommultifocalcarcinoma.Nodulewithintrinsicvascularityandotherfeaturesofmalignancycanbetargetedforbiopsy,inpreferencetoothernodules.
  46. 46. •Graves'disease(thyrotoxicosis)isanautoimmunediseasecharacterizedbythyrotoxicosis. •Femalesbetween20and50yearsaremostcommonlyaffected. •Ongray-scaleUSG,thyroidisdiffuselyenlarged(2-3timesitsnormalsize),hypoechoicandheterogeneous. •Colorflowimagingrevealsaspectacular"thyroidinferno"withmarkedhypervascularity •Thispatterndemonstratesextensiveintra-thyroidflowbothinsystoleanddiastole.
  47. 47. IncontrasttoHashimoto'sthyroiditis, returnofnormalthyroidappearanceispossibleatthetimeofremission.TheultrasoundpictureofGraves'diseasemaybeindistinguishablefromHashimoto'sthyroiditisandde-Quervain'sthyroiditis; however,clinicalpicturevariessignificantlybetweenthesethreeconditions.
  48. 48. Hashimoto'sthyroiditis(chroniclymphocyticthyroiditis)isanautoimmunedisorderleadingtodestructionoftheglandandresultshypothyroidism.Itoccurspredominantlyinfemalesover40yearsofage. Painless,diffuseenlargementofthyroidglandisthemostcommonclinicalpresentation.Clinically, Hashimoto'sthyroiditismaypresentwithformationofgoitrewithorwithoutdisturbanceofthyroidfunction.
  49. 49. Childrenwithhypothyroidismusuallyhavegrowthfailureanddelayedpuberty.DiagnosisofHashimoto'sthyroiditisisconfirmedbydemonstrationofserumthyroidantibodiesandantithyroglobulinantibodies.ThecharacteristicUSappearanceisfocalordiffuseglandularenlargementwithcoarse,heterogeneousandhypoechoicparenchymalechopattern.
  50. 50. Presenceofmultiplediscretehypoechoicmicronodules(1-6mmsize)isstronglysuggestiveofchronicthyroiditis.Fineechogenicfibrousseptaemayproduceapseudolobulatedappearanceoftheparenchyma.ColorDopplermaydemonstrateslighttomarkedlyincreasedvascularityofthethyroidparenchyma. Increasedvascularityseemstobeassociatedwithhypothyroidism,likelyduetotrophicstimulationofthyroid- stimulatinghormone.
  51. 51. SmallatrophicglandrepresentsendstageHashimoto'sthyroiditis.Occasionally,nodularformofHashimoto'sthyroiditismayoccur; withinasonographicbackgroundofdiffuseHashimoto'sthyroiditisorwithinnormalthyroidparenchyma.Bothbenignandmalignantnodulesareknowntoco-existwithinabackgroundofdiffuseHashimoto'sthyroiditis; onultrasound,hyperechoicnodulesaremorelikelytobebenign,whereashypoechoicnodulesaremorelikelytobemalignant
  52. 52. However,aPETscanorFNACmayberequiredtodifferentiatethem.TheabnormalthyroidultrasoundpictureinHashimoto'sthyroiditisneverimprovesandremainsunchangedforrestofthepatient'slife.Hashimoto'sthyroiditisisassociatedwithanincreasedriskofthyroidmalignancieslikefollicularorpapillarycarcinomaandlymphoma.Moreover,inpatientsofHashimoto'sthyroiditis,USGexaminationmayrevealpresenceofperithyroidalsatellitelymphnodes,especiallythe"Delphian"nodejustcephaladtotheisthmus
  53. 53. TheseperithyroidallymphnodesareextremelyusefulindiagnosisofthethyroiditiswhencorrelatedwithUSG,clinicalandlaboratoryfindings.However,itshouldbekeptinmindthattheselymphnodesmayalsocorrespondtounderlyingmalignantprocesses, likethyroidmalignancyandlymphoma,inpatientswithHashimoto'sthyroiditis.Indoubtfulcases,FNAbiopsymayberequiredtodifferentiatebetweenbenign(reactionary/inflammatoryorigin)andmalignantlymphnodes
  54. 54. De-Quervain'sthyroiditis(subacutegranulomatousthyroiditis) characteristicallypresentswithpainfulswellinginlowerneck,feverandconstitutionalsymptoms,typicallyfollowingaviralillness. Theremaybefeaturesofthyrotoxicosisorhypothyroidismdependingonphaseoftheillness.Initiallythereisthyrotoxicosis,followedbyhypothyroidism.USGexaminationshowscharacteristicfocalhypoechoicareas(maplike) andenlargementofoneorboththyroidlobes.
  55. 55. LevelVIchainlymphnodes(pre-tracheal,thepreferentialsiteofthyroiddrainage)arefoundtobeenlargedinmajorityofpatients.ColorDopplersonographyshowsdecreaseorabsentbloodflowwithinabnormalmap-likehypoechoicareas.Completerecoveryischaracteristicandoccursinweekstomonths.Inrecoveryphase,thyroidappearancereturnstonormal.
  56. 56. Acutethyroiditis(suppurative/infectiousthyroiditis)israreandoccursduetosuppurative(pusforming)infectionofthethyroid.Inchildrenandadults,themostcommoncauseisinfectionofpyriformsinusfistula(acongenitalbranchialpouchabnormality). Inelderly,longstandinggoitreanddegenerationinthyroidmalignancyareriskfactors.
  57. 57. Clinically,patientpresentswithacuteonsetfever,thyroidpain,asymmetricswellingofthegland(predominantlyleftsided)andregionallymphadenopathy(levelVIcervicalchainlymphnodes).OnUSG,theinvolvedlobeappearsheterogeneousandhypoechoic. Abscessandcystformationmaybeseen. Rarely,retropharyngealabscess,trachealobstruction,jugularveinthrombosisandmediastinitismaycomplicateacutethyroiditis
  58. 58. Riedel'sthyroiditis(chronicfibrousthyroiditis/invasivefibrousthyroiditis)istheraresttypeofinflammatorythyroiddisease.Thethyroidglandisgraduallyreplacedbyfibrousconnectivetissueandbecomesextremelyhard.Itmayencasetheadjacentvesselsormaycompress,displaceordeformshapeofthetrachea.Onultrasound,Riedel'sthyroiditismaypresentasadiffusehypoechoicprocesswithill-definedmarginsandmarkedfibrosis
  59. 59. Diagnostic Pitfalls Cysticcomponentsofthyroidmalignanciesmaybemistakenforbenigncystorcysticdegenerationinabenignnodule.Acarefulultrasoundassessmenttodemonstratesolidcomponentwithvascularityorsolidexcrescencewithmicrocalcificationswillbeofhelpindifferentiatingtheselesions.
  60. 60. Diagnostic Pitfalls Cysticorcalcifiedlymphnodemetastasesadjacenttothethyroidglandmaybemistakenforbenignnoduleinmultinodularthyroiddisease.Incompleterimofthyroidparenchymaaroundthemassandlackofmovementofthemasswiththethyroidglandduringswallowingfavorsextrathyroidlymphnodalmetastasis.Cysticmetastaticnodesaremorecommoninpapillarycarcinomathyroid,whilecalcifiedmetastaticnodesarefoundbothinpapillaryandmedullarycarcinomathyroid.
  61. 61. Diagnostic Pitfalls Diffuselyinfiltrativehypervascularthyroidcarcinomalikepapillaryorfollicularcarcinomamaybemistakenforautoimmunethyroiddisease(suchasGraves'diseaseorHashimoto'sthyroiditis);similarlymultifocalcarcinomamaybemistakenforbenignmultinodulargoitre.Asdescribedearlier,diffusethyroidenlargementwithmultiplenodulesofsimilarUSappearanceandwithnonormalinterveningparenchymaishighlysuggestiveofbenignity. USfeaturesthatsuggestmalignancyincludeirregularornodularenlargementofthethyroidgland,localinvasionandnodalmetastases.Co-existingautoimmunethyroiddiseaseandthyroidcarcinomacanfurthercomplicatethesituation
  62. 62. Therapeutic Application US-guidedpercutaneousethanolinjection(EPI)isusedforsclerosationofautonomousandtoxicthyroidadenomas.Post-injectionfollow-upultrasoundscandemonstratessignificantreductioninnodulesizeongray-scaleimaging,andmarkedreductionorcompleteabsenceofintranodularflowoncolorandpowerDopplerexamination.Periodicneckultrasoundisthemostsensitivemethodfordetectingrecurrenceofthyroidcarcinomasafterthyroidectomy.
  63. 63. Advanced Ultrasound Techniques in Thyroid Imaging Ultrasoundelastographyisadynamictechniquethatestimatesstiffnessoftissuesbymeasuringthedegreeofdistortionunderexternalpressure.Thyroidglandelastographyisusedtostudyhardness/elasticityofthethyroidnoduletodifferentiatemalignantfrombenignlesions.Abenignnoduleissofteranddeformsmoreeasily,whereasthemalignantnoduleisharderanddeformslesswhencompressedbyultrasoundprobe.
  64. 64. Advanced Ultrasound Techniques in Thyroid Imaging Theelastographytechniqueutilizesexternalcompressiontodifferentiatemalignantthyroidnodulesfrombenignlesions.Itdeterminestheamountoftissuedisplacementatvariousdepths,byassessingtheultrasoundsignalsreflectedfromthetissuesbeforeandaftercompression.Dedicatedsoftwarethenprovidesanaccuratemeasurementoftissuedistortionanddisplaysitvisuallyasanelastographicimage.
  65. 65. Advanced Ultrasound Techniques in Thyroid Imaging Theelastographicimage(elastogram)displayedovertheB-modeimageinacolorscale,indicateslocaltissueelasticityas(i)verysoftinbluecolorfortissuewithgreatestelasticstrainand(ii)veryhardinredcolorfortissuewithnostrain.Real-timeshearelastographyisalatesttechnique;thatcharacterizesandquantifiestissuestiffnessbetterthanconventionalelastography.
  66. 66. Advanced Ultrasound Techniques in Thyroid Imaging CysticlesionsandcalcifiednodulesareexcludedfromUSelastographicevaluation.USelastographyhelpsincharacterizingacytologicallyindeterminatenoduleasmalignantorbenignwithhighaccuracythatisalmostcomparabletoFNACandobviatestheneedofunnecessaryFNAexamination.ThemajorlimitationofUSelastographyisthatitcannotassessthelesionswhicharenotsurroundedbyadequatenormaltissue.
  67. 67. Advanced Ultrasound Techniques in Thyroid Imaging Contrast-enhancedultrasound(CE-US)isanewlydevelopedtechniquethathelpsincharacterizingathyroidnodule.OnCE-US,enhancementpatternsaredifferentinbenignandmalignantlesions.Ringenhancementispredictiveofbenignlesions,whereasheterogeneousenhancementishelpfulfordetectingmalignantlesions. However,overlappingfindingsseemtolimitthepotentialofthistechniqueinthecharacterizationofthyroidnodules.Useofspecificcontrast(e.g.SonoVue)andpulseinversionharmonicimagingfurtherimprovestheefficacyofultrasoundindiagnosingamalignantthyroidnodule.
  68. 68. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Severalstudieshavebeenconductedtoevaluatetheroleofultrasoundusingelastographyandcontrastagentinthecharacterisationofthyroidnodules.
  69. 69. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Astudy(doneon23thyroidnodules)wasconductedbyFSFerrarietal.in2008,todifferentiatebenignfrommalignantthyroidnodule,usingbothelastographyandCE-US.Elastographyyieldedasensitivityof88%, specificityof78%,positivepredictivevalue(PPV)of71%,negativepredictivevalue(NPV)of91%anddiagnosticaccuracy(DA)of82%;andCE-USyieldedasensitivityof100%,specificityof71%,PPVof69%, NPV100%andDAof83%
  70. 70. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Anotherstudy(samplesize90)wasdonebyYHongetal.in2009toevaluatethediagnosticutilityofreal- timeultrasoundelastographyindifferentiatingbenignfrommalignantthyroidnodules.Accordingtothisstudy,elastographyyieldedasensitivityof88%, specificityof90%,PPVof81%andNPV93%
  71. 71. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Arecentstudy(doneon703thyroidnodules)publishedbyMoonetal.in2012evaluatedthediagnosticperformanceofgray-scaleUSandelastographyindifferentiatingsolidthyroidnodules.Accordingtothestudy,thesensitivityandNPVfordifferentiatingbenignfrommalignantthyroidnodulesongrayscaleUSare91%and94.7%respectively,andonUSelastographyare65.4%and79.1%respectively.TheyconcludedthatelastographyaloneorincombinationwithgrayscaleUSisnotausefultoolindifferentiatingbenignfrommalignantthyroidnodules.
  72. 72. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Anotherstudy(samplesize72)hasbeendonerecentlybyMGiustietal.in2012,inwhichtheyhaveevaluatedtheroleofultrasound,elastographyandCE-USinscreeningofthyroidnodules.TheyfoundthattheultrasoundscoreshowedhighspecificityandPPVwhencomparedwithelastographyandCE-US.BothelastographyandCE-USwereexpensive,timeconsumingandoflimitedutilityinselectingpatientsforthyroidectomy
  73. 73. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Inshort,somestudiesshowveryhighsensitivityandspecificityofUSelastography;intherangeof85-90%. Onthecontrary,therearestudieswhichshowitssensitivityaslowas65%andless(comparefromthesensitivityofgray-scaleUSwhichisintherangeof90to95%).
  74. 74. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules Thus,althoughelastographyandCE-USappearpromisingimagingtechniques,theyneedtobestandardized.Atpresent, theyseemtobeexpensive,timeconsumingandoflimitedutilityinselectingpatientsforsurgery.LargerprospectivestudiesareneededtoestablishthediagnosticaccuracyandcosteffectivenessofthesetechniquesoverconventionalgrayscaleandcolorDopplerimaging
  75. 75. Conclusion High-resolutionUSGhasimprovedinthepastfewyearsandhasbecomeaveryvaluablediagnostictoolintheevaluationofthyroiddiseases.Recentadvancesinthyroidultrasoundhavefurtherimprovedthediagnosticaccuracy
  76. 76. Conclusion It is the imaging modality of choice for evaluating thyroid masses in children and pregnant females. Real time USG also helps to guide the diagnostic and therapeutic interventional procedures in various thyroid diseases.
  77. 77. •.

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