Thyroid ultrasound

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

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<ul><li> 1. Surah Al Baqarahverse 32 </li> <li> 2. Welcome to THYROID </li> <li> 3. By: Dr. Raham Bacha MD KMU MSc SonologyGold Medalist (UOL) The university of Lahore </li> <li> 4. OBJECTIVE INDICATION OF THYROID SCANNING THYROID ANATOMY SCANNING TECHNIQUES SONOGRAPHIC ANATOMY THYROID PATHOLOGIES CHARACTERIZATION OF THYRIOD NODULES DIFFUSE THYROID DISEASES </li> <li> 5. 1.Toconfirmpresenceofathyroidnodulewhenphysicalexaminationisequivocal. 2.Tocharacterizeathyroidnodule(s),i.e.tomeasurethedimensionsaccuratelyandtoidentifyinternalstructureandvascularization. 3.Todifferentiatebetweenbenignandmalignantthyroidmasses,basedontheirsonographicappearance. 4.Todifferentiatebetweenthyroidnodulesandothercervicalmasseslikelymphadenopathy, thyroglossalcystandcystichygroma. INDICATIONS </li> <li> 6. INDICATIONS 5.Toevaluatediffusechangesinthyroidparenchyma. 6.Todetectpost-operativeresidualorrecurrenttumorinthyroidbedormetastasestonecklymphnodes. 7.Toscreenhighriskpatientsforthyroidmalignancylikepatientswithhistoryoffamilialthyroidcancer,multipleendocrineneoplasia(MEN)andirradiatedneckinchildhood. 8.Toguidediagnostic(FNAcytology/biopsy)andtherapeuticinterventionalprocedures. </li> <li> 7. ANATOMY </li> <li> 8. ANATOMY </li> <li> 9. ANATOMY </li> <li> 10. Ultrasound Examination Technique Allpatientsareexaminedinsupinepositionwithhyperextendedneck,usingahighfrequencylineararraytransducer(7-15MHz)thatprovidesadequatepenetrationandhighresolutionimage. Scanningisdonebothintransverseandlongitudinalplanes.Realtimeimagingofthyroidlesionsisperformedusingbothgray-scaleandcolorDopplertechniques.Theimagingcharacteristicsofamass(viz.location,size,shape,margins, echogenicity,contentsandvascularpattern)shouldbeidentified. </li> <li> 11. Normal Anatomy Thenormalthyroidglandconsistsoftwolobesandabridgingisthmus.Thyroidsize, shapeandvolumevarieswithageandsex. Normalthyroidlobedimensionsare:18-20mmlongitudinal,10-12mmantero-posterior(AP)diameterand8-9mminwidth,innewborn;25mmlongitudinaland12-15mmAPdiameteratoneyearage;and40-60mmlongitudinal,20-30mminAPdiameterand13-18mmwidthinadultpopulation. </li> <li> 12. Thelimitsofnormalthyroidvolume(excludingisthmus,unlessitsthicknessis&gt;30mm)are10-15mlforfemalesand12-18mlformales. Therelationshipswithsurroundingstructuresare:sterno-cleido-mastoidandstrapmusclesanteriorly;trachea/esophagusandlonguscollimusclesposteriorly;andcommoncarotidarteriesandjugularveinsbilaterallyThyroidvolume(ml)=0.52 </li> <li> 13. ColorandpowerDopplerultrasound(US)areusefultoevaluatevascularityofthethyroidglandandfocalmasses.Thyroidglandisahighlyvascularstructuresuppliedbysuperiorandinferiorthyroidarteries.ThethyroidarteriescanbevisualizedoncolorDopplerexaminationwhiletheflowparametersfromthesevesselscanbemeasuredbyspectralDopplerexamination. </li> <li> 14. Normally,alowresistanceflowwithhighpeaksystolicvelocity(PSV)isdetectedinthesevesselsonspectralDoppleranalysis. ThenormalPSVinintrathyroidarteriesrangesbetween15-30cm/second,butitcanriseincertainpathologies(likeGraves'disease)toover100cm/sec </li> <li> 15. Congenital and Developmental Anomalies of Thyroid Gland Thethyroidglandprimordiumdevelopsfrommedianeminenceinthefloorofprimitivepharynx(apointlaterknownasforamencecumatthebaseoftongue)during4thweekofgestation.Fromforamencecum,theprimitiveprimordiumdescendsthroughanteriormidlineportionofthenecktoreachitsfinalpositionbelowthyroidcartilageby7thweekofgestation. </li> <li> 16. Duringthisdescent,thedevelopingthyroidglandretainsanattachmenttothepharynxbyanarrowepithelialstalkknownasthyroglossalduct.Thisductusuallybecomesobliteratedby8th-10thweekofgestation. Thyroidhormonesynthesisnormallybeginsatabout11thweekofgestation </li> <li> 17. Occassionally,restsofthyroidtissuemayremainalongthecourseofthyroglossalduct, givingrisetoanadditionalthyroidlobe,thepyramidallobe,attachedtodistalendofthethyroglossalductandleftsideofisthmus(seenin50%ofpopulation).Persistenceofthyroglossalductresultsinformationofthyroglossalcyst,whichclinicallypresentsasmidlineneckswellingorlump,usuallyfoundatlevelofhyoidboneorthyroidcartilage. </li> <li> 18. Onultrasound,thecystappearsasawell-definedanechoictohypoechoiclesionwithposterioracousticenhancement.Internalechoesmaybeseenwithinthecystduetohemorrhageorinfection. </li> <li> 19. Ectopicthyroidrepresentsanarrestinusualdescentofpartorallofthethyroidtissuealongthenormalpathway.Ectopicthyroidglanddevelopsmostcommonlyatsublingual(midlineatforamencecum), suprahyoidorinfrahyoidposition.USGshowspresenceofanectopicthyroidtissueandthenormalthyroidglandmayormaynotbepresentatnormalposition. </li> <li> 20. EctopicthyroidmaybeeasilydetectedonCTandradionuclidescans.Congenitalagenesisorhypoplasia(unilobartypeorofisthmus)ofthethyroidglandmayoccurduetodevelopmentalfailureofallorpartofthyroidgland.OnUSG,agenesisofisthmusischaracterizedbyabsenceofisthmuswiththelaterallobespositionedindependentlyoneithersideofthetrachea. </li> <li> 21. Diseases of Thyroid Gland Theincidenceofallthyroiddiseasesishigherinfemalesthaninmales.Nodularthyroiddiseaseisthemostcommoncauseofthyroidenlargement.Majorityofpatientswiththyroiddiseasepresentwithmidlineneckswelling, occasionallycausingdysphagiaandhoarsenessofvoice. </li> <li> 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 </li> <li> 23. Thyroid Nodule(s) Nodularitywithinthyroidisnormal.Theincidenceanddevelopmentofnodulescorrelatedirectlywithageofthepatientandisregardedasapartofnormalmaturationprocessofthethyroidgland.TheincidenceofthyroidnodulesisveryhighonUSG, rangingfrom50%to70%.Thyroidcanceraccountsforlessthan7%cases.Althoughthereissomeoverlapbetweenultrasoundappearanceofbenignandmalignantnodules,certainUSGfeaturesarehelpfulindifferentiatingthetwo. </li> <li> 24. Themostcommoncauseofbenignthyroidnoduleisnodularhyperplasia.Thyroidadenomasareothercommonbenignneoplasmsofthyroidthataremostlysolitarybutmayalsodevelopasapartofmultinodularmasses.Iso-orhyper-echogenicityofthethyroidnoduleinconjunctionwithaspongiformappearanceisthemostreliablecriterionforbenignityofthenoduleongray-scaleultrasoundand. </li> <li> 25. Other features to characterize nodule size 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. </li> <li> 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 thats why most of the hypoechoic nodules are benign </li> <li> 27. "Ringdown"or"comet-tail"artifactisatypicalsignofbenigncysticcolloidnodule.Perinodularfloworspoke-and-wheel-likeappearanceofvesselsoncolorDopplerexaminationischaracteristicofabenignthyroidnodule. However,thisflowpatternmayalsobeseeninthyroidmalignancy.Acompleteavascularnoduleisveryunlikelytobemalignant. </li> <li> 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</li></ul>

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