The document discusses thyroid ultrasound techniques, anatomy, pathologies, and diseases. It provides details on: 1. Indications for thyroid ultrasound including evaluating nodules, diffuse changes, and post-operative evaluation. 2. Techniques including using a high-frequency linear probe in transverse and longitudinal planes with color Doppler. 3. Common pathologies include multinodular goiter, Hashimoto's thyroiditis, Graves' disease, and thyroid cancers. Features helpful for characterizing benign versus malignant nodules are described.

1. قالو سُبحانك ل ا ع لام لنا
ال اما عا لمتنا انك انت العليمُ الحكيم
Surah Al Baqarahverse 32

2. اسلام علیکم
Welcome to THYROID

3. By: Dr. Raham Bacha
MD KMU
MSc SonologyGold Medalist (UOL)
The university of
Lahore

5. OBJECTIVE
•INDICATION OF THYROID SCANNING
•THYROID ANATOMY
•SCANNING TECHNIQUES
•SONOGRAPHIC ANATOMY
•THYROID PATHOLOGIES
•CHARACTERIZATION OF THYRIOD NODULES
•DIFFUSE THYROID DISEASES

6. 1.Toconfirmpresenceofathyroidnodulewhenphysicalexaminationisequivocal.
2.Tocharacterizeathyroidnodule(s),i.e.tomeasurethedimensionsaccuratelyandtoidentifyinternalstructureandvascularization.
3.Todifferentiatebetweenbenignandmalignantthyroidmasses,basedontheirsonographicappearance.
4.Todifferentiatebetweenthyroidnodulesandothercervicalmasseslikelymphadenopathy, thyroglossalcystandcystichygroma.
INDICATIONS

7. INDICATIONS
5.Toevaluatediffusechangesinthyroidparenchyma.
6.Todetectpost-operativeresidualorrecurrenttumorinthyroidbedormetastasestonecklymphnodes.
7.Toscreenhighriskpatientsforthyroidmalignancylikepatientswithhistoryoffamilialthyroidcancer,multipleendocrineneoplasia(MEN)andirradiatedneckinchildhood.
8.Toguidediagnostic(FNAcytology/biopsy)andtherapeuticinterventionalprocedures.

9. ANATOMY

10. ANATOMY

11. ANATOMY

12. Ultrasound Examination Technique
Allpatientsareexaminedinsupinepositionwithhyperextendedneck,usingahighfrequencylineararraytransducer(7-15MHz)thatprovidesadequatepenetrationandhighresolutionimage. Scanningisdonebothintransverseandlongitudinalplanes.Realtimeimagingofthyroidlesionsisperformedusingbothgray-scaleandcolorDopplertechniques.Theimagingcharacteristicsofamass(viz.location,size,shape,margins, echogenicity,contentsandvascularpattern)shouldbeidentified.

13. Normal Anatomy
Thenormalthyroidglandconsistsoftwolobesandabridgingisthmus.Thyroidsize, shapeandvolumevarieswithageandsex. Normalthyroidlobedimensionsare:18-20mmlongitudinal,10-12mmantero-posterior(AP)diameterand8-9mminwidth,innewborn;25mmlongitudinaland12-15mmAPdiameteratoneyearage;and40-60mmlongitudinal,20-30mminAPdiameterand13-18mmwidthinadultpopulation.

14. Thelimitsofnormalthyroidvolume(excludingisthmus,unlessitsthicknessis>30mm)are10-15mlforfemalesand12-18mlformales.
Therelationshipswithsurroundingstructuresare:sterno-cleido-mastoidandstrapmusclesanteriorly;trachea/esophagusandlonguscollimusclesposteriorly;andcommoncarotidarteriesandjugularveinsbilaterallyThyroidvolume(ml)=퐿×푊×퐷×0.52

19. ColorandpowerDopplerultrasound(US)areusefultoevaluatevascularityofthethyroidglandandfocalmasses.Thyroidglandisahighlyvascularstructuresuppliedbysuperiorandinferiorthyroidarteries.ThethyroidarteriescanbevisualizedoncolorDopplerexaminationwhiletheflowparametersfromthesevesselscanbemeasuredbyspectralDopplerexamination.

20. Normally,alowresistanceflowwithhighpeaksystolicvelocity(PSV)isdetectedinthesevesselsonspectralDoppleranalysis. ThenormalPSVinintrathyroidarteriesrangesbetween15-30cm/second,butitcanriseincertainpathologies(likeGraves'disease)toover100cm/sec

21. Congenital and Developmental Anomalies of Thyroid Gland
Thethyroidglandprimordiumdevelopsfrommedianeminenceinthefloorofprimitivepharynx(apointlaterknownasforamencecumatthebaseoftongue)during4thweekofgestation.Fromforamencecum,theprimitiveprimordiumdescendsthroughanteriormidlineportionofthenecktoreachitsfinalpositionbelowthyroidcartilageby7thweekofgestation.

22. Duringthisdescent,thedevelopingthyroidglandretainsanattachmenttothepharynxbyanarrowepithelialstalkknownasthyroglossalduct.Thisductusuallybecomesobliteratedby8th-10thweekofgestation. Thyroidhormonesynthesisnormallybeginsatabout11thweekofgestation

23. Occassionally,restsofthyroidtissuemayremainalongthecourseofthyroglossalduct, givingrisetoanadditionalthyroidlobe,thepyramidallobe,attachedtodistalendofthethyroglossalductandleftsideofisthmus(seenin50%ofpopulation).Persistenceofthyroglossalductresultsinformationofthyroglossalcyst,whichclinicallypresentsasmidlineneckswellingorlump,usuallyfoundatlevelofhyoidboneorthyroidcartilage.

26. Onultrasound,thecystappearsasawell-definedanechoictohypoechoiclesionwithposterioracousticenhancement.Internalechoesmaybeseenwithinthecystduetohemorrhageorinfection.

27. Ectopicthyroidrepresentsanarrestinusualdescentofpartorallofthethyroidtissuealongthenormalpathway.Ectopicthyroidglanddevelopsmostcommonlyatsublingual(midlineatforamencecum), suprahyoidorinfrahyoidposition.USGshowspresenceofanectopicthyroidtissueandthenormalthyroidglandmayormaynotbepresentatnormalposition.

28. EctopicthyroidmaybeeasilydetectedonCTandradionuclidescans.Congenitalagenesisorhypoplasia(unilobartypeorofisthmus)ofthethyroidglandmayoccurduetodevelopmentalfailureofallorpartofthyroidgland.OnUSG,agenesisofisthmusischaracterizedbyabsenceofisthmuswiththelaterallobespositionedindependentlyoneithersideofthetrachea.

29. Diseases of Thyroid Gland
Theincidenceofallthyroiddiseasesishigherinfemalesthaninmales.Nodularthyroiddiseaseisthemostcommoncauseofthyroidenlargement.Majorityofpatientswiththyroiddiseasepresentwithmidlineneckswelling, occasionallycausingdysphagiaandhoarsenessofvoice.

30. Broadly the thyroid diseases are classified into three categories:
•(i) benign thyroid masses,
•(ii) malignant tumors of thyroid gland, and
•(iii) diffuse thyroid enlargement

31. Thyroid Nodule(s)
Nodularitywithinthyroidisnormal.Theincidenceanddevelopmentofnodulescorrelatedirectlywithageofthepatientandisregardedasapartofnormalmaturationprocessofthethyroidgland.TheincidenceofthyroidnodulesisveryhighonUSG, rangingfrom50%to70%.Thyroidcanceraccountsforlessthan7%cases.Althoughthereissomeoverlapbetweenultrasoundappearanceofbenignandmalignantnodules,certainUSGfeaturesarehelpfulindifferentiatingthetwo.

32. Themostcommoncauseofbenignthyroidnoduleisnodularhyperplasia.Thyroidadenomasareothercommonbenignneoplasmsofthyroidthataremostlysolitarybutmayalsodevelopasapartofmultinodularmasses.Iso-orhyper-echogenicityofthethyroidnoduleinconjunctionwithaspongiformappearanceisthemostreliablecriterionforbenignityofthenoduleongray-scaleultrasoundand.

33. 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.

34. 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

39. "Ringdown"or"comet-tail"artifactisatypicalsignofbenigncysticcolloidnodule.Perinodularfloworspoke-and-wheel-likeappearanceofvesselsoncolorDopplerexaminationischaracteristicofabenignthyroidnodule. However,thisflowpatternmayalsobeseeninthyroidmalignancy.Acompleteavascularnoduleisveryunlikelytobemalignant.

42. 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.

43. Histologically,malignanttumorsofthethyroidareclassifiedaspapillarycarcinoma(60-80%),follicularcarcinoma(20-25%), medullarycarcinoma(4-5%),anaplasticcarcinoma(3-10%),lymphoma(5%)andmetastases.Theoverallsensitivityofthyroidultrasoundfordiagnosingamalignantnoduleis83.3%.

44. USGfeaturespredictiveofmalignantnodulesincludepresenceofmicrocalcifications(<2mm),localinvasion,lymphnodemetastases, markedhypoechogenicity,irregularmargins, solidcomposition,absenceofahypoechoichaloaroundthenodule,size>1cm,taller- than-wide-shape,andanintranodularvascularity

45. Multiplicityofthenoduleisnotanindicatorofbenignity.Theincidenceofmalignancyissameinsolitarynodulesasitisinmultiplenodules.Intervalgrowthofnodulesisanon- specificcharacteristic.Microcalcificationsaremostcommonlyfoundinpapillaryandmedullarycarcinomathyroidandintheirmetastases(lymphnodeorhepatic).

46. OnUSG,microcalcificationsappearaspunctuatehyperechoicfociwithorwithoutposterioracousticshadowing.Rarely, microcalcificationscanbefoundinfollicularandanaplasticthyroidcarcinomasandcertainbenignlesionslikefollicularadenoma, multinodulargoitreandHashimoto'sthyroiditis.

47. Other features to characterize nodule
•Margins
•Margins may be smooth, speculated, micro-labulated, or Ill defined. Spiculatedmargins are strongly suggestive of malignancy.

48. 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.

50. 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)

51. Localinvasionofadjacentstructuresandmetastasestoregionalcervicallymphnodesarehighlyspecificsignsofthyroidmalignancy.Theyoccurmorefrequentlyinmedullarycarcinoma(50%cases)thanpapillarycarcinoma(40%cases).Althoughpatientswiththyroidcarcinomamaypresentwithmultiplelevelnodaldisease,theanterolateralgroup(levelII,IIIandIV)havegreatestriskofmetastaticdisease.
Lymph nodes involment.

52. USneckplaysanintegralroleinthemanagementofcervicalmetastasesfromthyroidcarcinoma(rangingfromselectiveremovaltoacomprehensiveneckdissection)byevaluatingnodalmetastaseswithrespecttonodelevel. Anaplasticthyroidcarcinomaandlymphomaarehighlyaggressivetumors,earlyandextensivelocalinvasioniscommonwiththesetumors. Lymphnodemetastasisisrareinfollicularthyroidcarcinoma,eveninhighlyinvasivecases.

53. Themostcommonpatternofvascularityinthyroidmalignancyismarkedintrinsichypervascularity.OncolorDopplerexamination,moreflowisdemonstratedinthecentralportionofthetumorthaninthesurroundingthyroidparenchyma

54. Increasedvascularitywithdistortionofsinusfatisseenwithinthemetastaticlymphnodes. Thyroidlymphomasarehypo-vascularwithchaoticvessels;however,neckvesselencasementmaybepresent.

57. Metastasestothethyroidglandareinfrequent.Themainprimarytumorsspreadingtothethyroidglandaremalignantmelanoma(39%ofcases),breastcarcinoma(21%ofcases)andrenalcellcarcinoma(10%ofcases).Sonographically,metastasespresentasasolitaryormultiplehypoechoichomogeneousmass(es)withoutcalcification.

58. Thyroidnodule(s)withsuspiciousUSGfeaturesshouldbeinvestigatedfurtherwithFNAbiopsy.Moreover,thework-upofasymptomaticthyroidnodules(incidentalomas)mustbeweighedagainsthighprevalenceofbenignthyroidnodulesandlowmortalityratefromsmallthyroidcarcinomas.

59. Diffuse Thyroid Diseases
Thecommonconditionsthatpresentasdiffuseenlargementofthethyroidglandincludemultinodulargoitre,Hashimoto's(lymphocytic) thyroiditis,de-Quervain'ssubacutethyroiditisandGraves'disease.Thesonographicfeaturesoftheseprocessesmaybesimilarbuttheyhavedifferentbiochemicalprofileandclinicalpresentations. Hence,intheseconditions,ultrasoundfindingsshouldbeviewedinrelationtoclinicalandbiochemicalstatusofthepatient..

60. Multinodulargoitre(MNG)isthecommonestcauseofdiffuseasymmetricenlargementofthethyroidgland.Femalesbetween35-50yearsofagearemostcommonlyaffected.Histologically,colloidoradenomatousformofMNGiscommon.Theultrasounddiagnosisrestsonthefindingofmultiplenoduleswithinadiffuselyenlargedgland. AdiffuselyenlargedthyroidglandwithmultiplenodulesofsimilarUSappearanceandwithnonormalinterveningparenchymaishighlysuggestiveofbenignity,therebymakingFNAbiopsyunnecessary.
Multinodulargoitre(MNG)

63. Mostofthenodulesareiso-orhyper-echoicinnature;whenenlargedprovideheterogeneousechopatterntothegland.ThesegoitrousnodulesoftenundergodegenerativechangesthatcorrespondtotheirUSGappearances: cysticdegenerationgivesanechoicappearancetothenodule,hemorrhageorinfectionwithinthecystisseenasmovinginternalechoes/septations,colloidaldegenerationproducescomet-tailartifact,whiledystrophiccalcificationisoftencourseorcurvilinear.

64. Vascularcompressionduetofollicularhyperplasialeadstofocalischemia,necrosisandinflammatorychange.TheassessmentofnodulevascularityisveryusefulindifferentiatingMNGfrommultifocalcarcinoma.Nodulewithintrinsicvascularityandotherfeaturesofmalignancycanbetargetedforbiopsy,inpreferencetoothernodules.

67. •Graves'disease(thyrotoxicosis)isanautoimmunediseasecharacterizedbythyrotoxicosis.
•Femalesbetween20and50yearsaremostcommonlyaffected.
•Ongray-scaleUSG,thyroidisdiffuselyenlarged(2-3timesitsnormalsize),hypoechoicandheterogeneous.
•Colorflowimagingrevealsaspectacular"thyroidinferno"withmarkedhypervascularity
•Thispatterndemonstratesextensiveintra-thyroidflowbothinsystoleanddiastole.

68. IncontrasttoHashimoto'sthyroiditis, returnofnormalthyroidappearanceispossibleatthetimeofremission.TheultrasoundpictureofGraves'diseasemaybeindistinguishablefromHashimoto'sthyroiditisandde-Quervain'sthyroiditis; however,clinicalpicturevariessignificantlybetweenthesethreeconditions.

70. Hashimoto'sthyroiditis(chroniclymphocyticthyroiditis)isanautoimmunedisorderleadingtodestructionoftheglandandresultshypothyroidism.Itoccurspredominantlyinfemalesover40yearsofage. Painless,diffuseenlargementofthyroidglandisthemostcommonclinicalpresentation.Clinically, Hashimoto'sthyroiditismaypresentwithformationofgoitrewithorwithoutdisturbanceofthyroidfunction.

71. Childrenwithhypothyroidismusuallyhavegrowthfailureanddelayedpuberty.DiagnosisofHashimoto'sthyroiditisisconfirmedbydemonstrationofserumthyroidantibodiesandantithyroglobulinantibodies.ThecharacteristicUSappearanceisfocalordiffuseglandularenlargementwithcoarse,heterogeneousandhypoechoicparenchymalechopattern.

77. Presenceofmultiplediscretehypoechoicmicronodules(1-6mmsize)isstronglysuggestiveofchronicthyroiditis.Fineechogenicfibrousseptaemayproduceapseudolobulatedappearanceoftheparenchyma.ColorDopplermaydemonstrateslighttomarkedlyincreasedvascularityofthethyroidparenchyma. Increasedvascularityseemstobeassociatedwithhypothyroidism,likelyduetotrophicstimulationofthyroid- stimulatinghormone.

78. SmallatrophicglandrepresentsendstageHashimoto'sthyroiditis.Occasionally,nodularformofHashimoto'sthyroiditismayoccur; withinasonographicbackgroundofdiffuseHashimoto'sthyroiditisorwithinnormalthyroidparenchyma.Bothbenignandmalignantnodulesareknowntoco-existwithinabackgroundofdiffuseHashimoto'sthyroiditis; onultrasound,hyperechoicnodulesaremorelikelytobebenign,whereashypoechoicnodulesaremorelikelytobemalignant

83. However,aPETscanorFNACmayberequiredtodifferentiatethem.TheabnormalthyroidultrasoundpictureinHashimoto'sthyroiditisneverimprovesandremainsunchangedforrestofthepatient'slife.Hashimoto'sthyroiditisisassociatedwithanincreasedriskofthyroidmalignancieslikefollicularorpapillarycarcinomaandlymphoma.Moreover,inpatientsofHashimoto'sthyroiditis,USGexaminationmayrevealpresenceofperithyroidalsatellitelymphnodes,especiallythe"Delphian"nodejustcephaladtotheisthmus

86. TheseperithyroidallymphnodesareextremelyusefulindiagnosisofthethyroiditiswhencorrelatedwithUSG,clinicalandlaboratoryfindings.However,itshouldbekeptinmindthattheselymphnodesmayalsocorrespondtounderlyingmalignantprocesses, likethyroidmalignancyandlymphoma,inpatientswithHashimoto'sthyroiditis.Indoubtfulcases,FNAbiopsymayberequiredtodifferentiatebetweenbenign(reactionary/inflammatoryorigin)andmalignantlymphnodes

87. De-Quervain'sthyroiditis(subacutegranulomatousthyroiditis) characteristicallypresentswithpainfulswellinginlowerneck,feverandconstitutionalsymptoms,typicallyfollowingaviralillness. Theremaybefeaturesofthyrotoxicosisorhypothyroidismdependingonphaseoftheillness.Initiallythereisthyrotoxicosis,followedbyhypothyroidism.USGexaminationshowscharacteristicfocalhypoechoicareas(maplike) andenlargementofoneorboththyroidlobes.

88. LevelVIchainlymphnodes(pre-tracheal,thepreferentialsiteofthyroiddrainage)arefoundtobeenlargedinmajorityofpatients.ColorDopplersonographyshowsdecreaseorabsentbloodflowwithinabnormalmap-likehypoechoicareas.Completerecoveryischaracteristicandoccursinweekstomonths.Inrecoveryphase,thyroidappearancereturnstonormal.

90. Acutethyroiditis(suppurative/infectiousthyroiditis)israreandoccursduetosuppurative(pusforming)infectionofthethyroid.Inchildrenandadults,themostcommoncauseisinfectionofpyriformsinusfistula(acongenitalbranchialpouchabnormality). Inelderly,longstandinggoitreanddegenerationinthyroidmalignancyareriskfactors.

91. Clinically,patientpresentswithacuteonsetfever,thyroidpain,asymmetricswellingofthegland(predominantlyleftsided)andregionallymphadenopathy(levelVIcervicalchainlymphnodes).OnUSG,theinvolvedlobeappearsheterogeneousandhypoechoic. Abscessandcystformationmaybeseen. Rarely,retropharyngealabscess,trachealobstruction,jugularveinthrombosisandmediastinitismaycomplicateacutethyroiditis

94. Riedel'sthyroiditis(chronicfibrousthyroiditis/invasivefibrousthyroiditis)istheraresttypeofinflammatorythyroiddisease.Thethyroidglandisgraduallyreplacedbyfibrousconnectivetissueandbecomesextremelyhard.Itmayencasetheadjacentvesselsormaycompress,displaceordeformshapeofthetrachea.Onultrasound,Riedel'sthyroiditismaypresentasadiffusehypoechoicprocesswithill-definedmarginsandmarkedfibrosis

95. Diagnostic Pitfalls
Cysticcomponentsofthyroidmalignanciesmaybemistakenforbenigncystorcysticdegenerationinabenignnodule.Acarefulultrasoundassessmenttodemonstratesolidcomponentwithvascularityorsolidexcrescencewithmicrocalcificationswillbeofhelpindifferentiatingtheselesions.

96. Diagnostic Pitfalls
Cysticorcalcifiedlymphnodemetastasesadjacenttothethyroidglandmaybemistakenforbenignnoduleinmultinodularthyroiddisease.Incompleterimofthyroidparenchymaaroundthemassandlackofmovementofthemasswiththethyroidglandduringswallowingfavorsextrathyroidlymphnodalmetastasis.Cysticmetastaticnodesaremorecommoninpapillarycarcinomathyroid,whilecalcifiedmetastaticnodesarefoundbothinpapillaryandmedullarycarcinomathyroid.

97. Diagnostic Pitfalls
Diffuselyinfiltrativehypervascularthyroidcarcinomalikepapillaryorfollicularcarcinomamaybemistakenforautoimmunethyroiddisease(suchasGraves'diseaseorHashimoto'sthyroiditis);similarlymultifocalcarcinomamaybemistakenforbenignmultinodulargoitre.Asdescribedearlier,diffusethyroidenlargementwithmultiplenodulesofsimilarUSappearanceandwithnonormalinterveningparenchymaishighlysuggestiveofbenignity. USfeaturesthatsuggestmalignancyincludeirregularornodularenlargementofthethyroidgland,localinvasionandnodalmetastases.Co-existingautoimmunethyroiddiseaseandthyroidcarcinomacanfurthercomplicatethesituation

98. Therapeutic Application
US-guidedpercutaneousethanolinjection(EPI)isusedforsclerosationofautonomousandtoxicthyroidadenomas.Post-injectionfollow-upultrasoundscandemonstratessignificantreductioninnodulesizeongray-scaleimaging,andmarkedreductionorcompleteabsenceofintranodularflowoncolorandpowerDopplerexamination.Periodicneckultrasoundisthemostsensitivemethodfordetectingrecurrenceofthyroidcarcinomasafterthyroidectomy.

99. Advanced Ultrasound Techniques in Thyroid Imaging
Ultrasoundelastographyisadynamictechniquethatestimatesstiffnessoftissuesbymeasuringthedegreeofdistortionunderexternalpressure.Thyroidglandelastographyisusedtostudyhardness/elasticityofthethyroidnoduletodifferentiatemalignantfrombenignlesions.Abenignnoduleissofteranddeformsmoreeasily,whereasthemalignantnoduleisharderanddeformslesswhencompressedbyultrasoundprobe.

100. Advanced Ultrasound Techniques in Thyroid Imaging
Theelastographytechniqueutilizesexternalcompressiontodifferentiatemalignantthyroidnodulesfrombenignlesions.Itdeterminestheamountoftissuedisplacementatvariousdepths,byassessingtheultrasoundsignalsreflectedfromthetissuesbeforeandaftercompression.Dedicatedsoftwarethenprovidesanaccuratemeasurementoftissuedistortionanddisplaysitvisuallyasanelastographicimage.

101. Advanced Ultrasound Techniques in Thyroid Imaging
Theelastographicimage(elastogram)displayedovertheB-modeimageinacolorscale,indicateslocaltissueelasticityas(i)verysoftinbluecolorfortissuewithgreatestelasticstrainand(ii)veryhardinredcolorfortissuewithnostrain.Real-timeshearelastographyisalatesttechnique;thatcharacterizesandquantifiestissuestiffnessbetterthanconventionalelastography.

102. Advanced Ultrasound Techniques in Thyroid Imaging
CysticlesionsandcalcifiednodulesareexcludedfromUSelastographicevaluation.USelastographyhelpsincharacterizingacytologicallyindeterminatenoduleasmalignantorbenignwithhighaccuracythatisalmostcomparabletoFNACandobviatestheneedofunnecessaryFNAexamination.ThemajorlimitationofUSelastographyisthatitcannotassessthelesionswhicharenotsurroundedbyadequatenormaltissue.

103. Advanced Ultrasound Techniques in Thyroid Imaging
Contrast-enhancedultrasound(CE-US)isanewlydevelopedtechniquethathelpsincharacterizingathyroidnodule.OnCE-US,enhancementpatternsaredifferentinbenignandmalignantlesions.Ringenhancementispredictiveofbenignlesions,whereasheterogeneousenhancementishelpfulfordetectingmalignantlesions. However,overlappingfindingsseemtolimitthepotentialofthistechniqueinthecharacterizationofthyroidnodules.Useofspecificcontrast(e.g.SonoVue)andpulseinversionharmonicimagingfurtherimprovestheefficacyofultrasoundindiagnosingamalignantthyroidnodule.

104. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules
Severalstudieshavebeenconductedtoevaluatetheroleofultrasoundusingelastographyandcontrastagentinthecharacterisationofthyroidnodules.

105. 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%

106. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules
Anotherstudy(samplesize90)wasdonebyYHongetal.in2009toevaluatethediagnosticutilityofreal- timeultrasoundelastographyindifferentiatingbenignfrommalignantthyroidnodules.Accordingtothisstudy,elastographyyieldedasensitivityof88%, specificityof90%,PPVof81%andNPV93%

107. 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.

108. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules
Anotherstudy(samplesize72)hasbeendonerecentlybyMGiustietal.in2012,inwhichtheyhaveevaluatedtheroleofultrasound,elastographyandCE-USinscreeningofthyroidnodules.TheyfoundthattheultrasoundscoreshowedhighspecificityandPPVwhencomparedwithelastographyandCE-US.BothelastographyandCE-USwereexpensive,timeconsumingandoflimitedutilityinselectingpatientsforthyroidectomy

109. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules
Inshort,somestudiesshowveryhighsensitivityandspecificityofUSelastography;intherangeof85-90%. Onthecontrary,therearestudieswhichshowitssensitivityaslowas65%andless(comparefromthesensitivityofgray-scaleUSwhichisintherangeof90to95%).

110. Current Status of US Elastographyand CE-USG in Characterisationof Thyroid Nodules
Thus,althoughelastographyandCE-USappearpromisingimagingtechniques,theyneedtobestandardized.Atpresent, theyseemtobeexpensive,timeconsumingandoflimitedutilityinselectingpatientsforsurgery.LargerprospectivestudiesareneededtoestablishthediagnosticaccuracyandcosteffectivenessofthesetechniquesoverconventionalgrayscaleandcolorDopplerimaging

111. Conclusion
High-resolutionUSGhasimprovedinthepastfewyearsandhasbecomeaveryvaluablediagnostictoolintheevaluationofthyroiddiseases.Recentadvancesinthyroidultrasoundhavefurtherimprovedthediagnosticaccuracy

112. 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.

113. •.