ULTRASOUND IN

THYROID LESIONS

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DR RAJ BUMIYAFirst Year ResidentDept. of RadiodiagnosisS.S.G. Hospital, Baroda.

24/03/2011

Clinical applications of high resolution usg. 1. Detection of thyroid and other cervical masses

before and after thyroidectomy.

2. Differentiation of benign from malignant masses.

Ultrasound detects the presence, size, site, number, characteristics of thyroid nodules .

3. FNA Guidance 2

Technique

With high frequency transducer(7.5 to 15Mhz)Examination-supine position with neck

extended.

A small pad may be placed under the shoulders to provide better exposures of neck.

Lower pole imaging is enhanced– by asking the pt. to swallow, so the gland moves upward.

Examined thoroughly in transverse and longitudinal planes.

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Multiple oblique and angled projections may be

taken if necessary.

Examined: SUPERIORLY: to identify Submandibular

adenopathyINFERIORLY : to identify Supraclavicular

adenopathy

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Normal ultrasound anatomy of thyroidIt is located anterior

and lateral to trachea below the level of thyroid cartilage and above the sternal notch. (infrahyoid compartment)

DIVISION : RIGHT AND LEFT LOBES, ISTHMUS PYRAMIDAL LOBE (10-40

%)

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Normal thyroid parenchyma has homogenous medium to high level echogenicity & bounded by a thin hyperechoic line(the thyroid capsule).

Landmarks to be identified:

Midline -Trachea and oesophagus.

Laterally- Common Carotid artery, IJV Anterolaterally:Strap muscles of the neck

The superior thyroid Vessels are found at upper pole of each lobe and inferior thyroid vein is found at lower pole whereas the inferior thyroid artery is located posterior to lower third of each lobe.

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Anteriorly-Sternohyoid & omohyoid muscles, As hypoechoic bands.Lateral- Sternocleidomastoid As large oval band Posterior- Longus colli muscle

Recurrent laryngeal nerve & inferior thyroid artery pass in the angle between trachea, oesophagus & thyroid lobe.

On longitudinal scans, recurrent laryngeal nerve & inferior thyroid artery may be seen as hypoechoic bands between the thyroid lobe & oesophagus on left , thyroid lobe & longus colli on right.

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Oesophagus –laterally & towards the left Target appearance on transverse plane Peristaltic movements On swallowing.

Trachea PosteriorlyIdentified by lack of sound transmission and ring

down artifacts.

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Inferior thyroid artery along the posterior surface

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Inferior thyroid vein branchesseen at the lower pole

NORMAL DIMENSIONS OF THYROID LOBES A-P LENGTHNEWBORN 8-9mm 18-20mmINFANT 12-15mm 25mmADULT 13-18mm 40-

60mm

Normal Mean Thyroid Volume (LxWxTHICKNESSx0.52) : 18.6±4.5

MALE-UPTO 23gm IS NORMALFEMALE- UPTO 22gm IS NORMAL.

Mean thickness of isthmus – 4 to 6mm

A-P diameter is most precise because relatively independent of possible dimensional asymemetry between two lobes.

When AP diameter- > 2cm --- Enlarged gland.

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CONGENITAL ABNORMALITIES

AGENESIS/HYPOPLASIA

ECTOPIC

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EMBRYOLOGYThyroid gland is originated from epithelial

cells of floor of pharynx.

It descends from pharynx & remains connected to pharynx through a tract,known as thyroglossal duct.

The gland reaches to its normal location by 7 weeks of gestational age.

Then after duct involutes.15

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THYROID AGENESISUSG : Abnormal echogenic tissue in the expected location of the thyroid, without any normal flow on color Doppler imaging. There is no evidence of ectopic thyroid tissue. Pertechnetate scintigraphy demonstrates no functioning thyroid tissue.

Sonography of the thyroid in this 1 yr. old female child revealed congenital absence of the entire thyroid. Note the empty fossae where the right and left lobes would normally lie. The carotid artery and jugular vein of both sides are seen in the color doppler images. These ultrasound and color doppler images suggest congenital agenesis of the thyroid. 18

ECTOPIC THYROID

The thyroid gland develops as a median angle from a diverticulum of the foramen cecum.

Normally, it descends to its typical location anterior to the cervical trachea via the thyroglossal duct. Anomalies of descent can lead to a lingual or sublingual position of the gland.

Nuclear medicine scintigraphy with sodium iodine-123 or pertechnetate-99m is used to evaluate the neck for the presence of thyroid tissue.Diagnosis of lingual thyroid is made when uptake is seen at the tongue base but not in the thyroid bed.

Further evaluation can be done using CT & MRI imaging.19

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CT image- round mass at tongue base which enhances after contrast administration.  A pertechnetate-99m scan shows uptake corresponding to mass at tongue base without uptake in the thyroid bed. 

Thyroid disordersThyroid disorders can be divided into

Nodular thyroid disease

Diffuse thyroid disease.

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Nodular thyroid disease

Hyperplasia and goiter

Adenoma

Carcinoma

Lymphoma

Metastases22

Hyperplasia and Goitre:Etiology:Iodine deficiency, dishormonogenesis(familial),poor

utilization of Iodine.

F:M-3:1 ,more between 35-50 years.

Hyperplasia leads to an overall increase in size or volume of the gland.

Hyperplastic nodules often undergo liquefactive degeneration with the accumulation of blood, serous fluid and colloid substance, reffered to as hyperplastic,adenomatous, or colloid nodules.

Coarse and perinodular calcification occur. 23

SonographyMost   hyper plastic or adenomatous nodules are isoechoic

compared to normal thyroid tissue.As Size of the mass increases, it may become hyperechoic.Less frequently hypo echoic SPONGE—like OR HONEY COOMB

CYSTIC pattern is seen.When nodule is hyperechoic or isoechoic, a thin peripheral

hypoechoic halo is commonly seen-due to perinodular blood vessels and edema or compression of adjacent normal parenchyma.

Perinodular, intranodular vascularity on colour Doppler.

DEGENERATIVE CHANGES:Purely anechoic -due to serous/colloid fluid.Echogenic fluid/moving fluid-fluid levels due to hemorrhage.Bright echogenic foci with comet tail artifacts due to dense

colloid material/microcrystals.Eggshell(thin peripheral) or coarse calcification.

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Sonogram of the left lobe of the thyroid gland in the transverse plane showing a rounded lobe of a goiter. L=enlarged lobe, I= widened isthmus,T=trachea,C=carotid artery,J=jugular vein, S=Sternocleidomastoid muscle, m=strap muscles, E=esophagus.

Hyperplastic nodules

Oval homogenous isooechoic nodule with well defined peripheral halo.

Multiple hyperechoic nodules

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Cystic degenerative changes in adenomatous nodules

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Adenoma F:M – 7:1Solitary or as a part of multinodular goiter.Sonography

Hyperechoic, iso or hypoechoic solid masses .Have Peripheral hypoechoic halo which is thick

& smooth- due to fibrous capsule and blood vessels.

Typical spoke and wheel type of appearance on color doppler.

D/D : FOLLICULAR CARCINOMA— where vascular and capsular invasion are hallmarks.

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Isoechoic solid mass with thick irregular complete halo. Power doppler – spoke and wheel like appearance FOLLICULAR ADENOMA

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multiple nodular densities in cervical region that are palpable on physical examination.CT scan obtained 9 months before sonogram shows absent left thryoid lobe and enlarged right thryoid lobe with small low-attenuation lesion.

Carcinoma:Most primary thyroid cancers are of epithelial

origin and are derived from either the follicular or the parafollicular cells.Most are well differentiated.

Papillary carcinoma- 75-90% . Medullary/Follicular/anaplastic car. -10-25% Papillary cancer3rd and 7th decade.F>MThe major route of spread is through lymphatics

to nearby cervical lymph nodes.Distant metastasis is rare (2-3%) and occurs to

mediastinum and lungs.HISTOLOGY: PSAMMOMA BODIES

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SonographyHypoechoic nodules with microcalcifications (tiny punctuate hyperechoic foci with or without

acoustic shadowing).

Disorganized hypervascularity on color doppler,Mostly in well encapsulated form.

Cervical lymphnode metatasis which may contain tiny punctate echogenic foci due to microcalcifications.

Cystic lymph node metatasis in neck occur almost exclusively with papillary carcinoma.

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Hypoechoic solid nodule with punctate calcification

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Isoechoic nodule & punctate echogenic foci within it

Two rounded hypoechoic nodes – typical of metastasis to cervical nodes

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Hetrogenous oval nodes containing microcalcifications

Longitudinal and transverse sonographic images of the thyroid gland reveal a normal left lobe and thyroid isthmus. Multiple small punctate calcifications are seen scattered through the mass in right lobe.

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Punctate echogenicities in thyroid nodules. (a) Sagittal US image of nodule containing multiple fine echogenicities with no comet-tail artifact. These are highly

suggestive of malignancy.FNA and surgery confirmed papillary carcinoma. (b) Transverse US image of nodule containing cystic areas with punctate echogenicities

and comet-tail artifact consistent with colloid crystals in a benign nodule.

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Role of color Doppler US. (a) Transverse gray-scale image of Predominantly solid thyroid nodule (b) Addition of color Doppler modeshows

marked internal vascularity,indicating increased likelihood that nodule is malignant. This was a papillary carcinoma.

Woman with history of papillary thyroid cancer - underwent thyroidectomy & radioiodine ablation. Two years later, patient presented with thyroglobulin level of 6.1 ng/mL (TSH suppressed) and negative findings on 131I WBS. 18F-FDG PET (A) demonstrates small foci of increased 18F-FDG uptake corresponding to small lymph nodes in right lower neck on CT (B). These are clearly visualized on fused 18F-FDG PET/CT (C) and were subsequently proven to be thyroid cancer metastases.

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Follicular Carcinoma5 -15% (2 variants-widely invasive and minimally

invasive)Hematogenous spread to bone/lung/brain/liver

Sonography:Cant be differentiated from follicular adenoma

So treatment for both is surgical excision.Hypoechoic nodule with irregular tumor marginsThick, irregular halo.Tortuous or chaotic arrangement of internal

blood vessels on color doppler.PATHOLOGY: Vascular & capsular invasion.

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WIDELY INVASIVE FORM MINIMALLY INVASIVE FORM

-Not well encapsulated -Invasion of vessels and adjacent thyroid is more easily demonstrated.-Metastasis is in 20-40% cases

-Well encapsulated-No gross invasion seen. Only focal histologic invasion noted.-5-10% cases.

Heterogenous solid mass with peripheral and internal flow – follicular carcinoma

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Medullary Carcinoma

only 5 % thyroid cancer. Derived from parafollicular or C cells secretes calcitonin.- useful serum marker.

Frequently familial and Associated with MEN II syndrome.

Bilateral in 90% of familial cases.High incidence of metastatic to lymphnodes.

Sonography

- Similar to papillary carcinoma-hypoechoic solid mass with calcifications(often, but coarse than papillary carcinoma).

-Local invasion and cervical lymphadenopathy are also more common.

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Heterogenous nodule with multiple punctate foci of calcification within it – medullary carcinoma

Isoechoic nodule & punctate echogenic foci within it

Longitudnal color and power doppler – intranodular hypervascularity

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Anaplastic thyroid carcinoma

Occurs in elderly < 5% tumors worst prognosis Presents as a rapidly enlarging mass extending beyond

gland and invading adjacent structures.

Show aggressive local invasion of muscle and vessels.

Sonography

Hypoechoic masses often seen to encase or invade blood vessel and neck muscles(CT or MRI demonstrates the tumor more accurately owing to their large size) .

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Longitudnal scan – solid hypoechoic mass extending into the upper mediastinum – anaplastic carcinoma

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Aggressive thyroid cancer in left neck with spread to lungs

Lymphoma4% of all thyroid malignancies.Mostly non-Hodgkin’s typeElder females In 70-80% cases arises from pre-existing chronic

lymphocytic thyroiditis(HASHIMOTO’S thyroiditis) with subclinical or overt hypothyroidism.

Sonography Markedly Hypoechoic lobulated mass .Hypovascular or show blood vessels with chaotic

distribution and arteriovenous shunts.Large areas of cystic necrosis may occur as well as

encasement of adjacent neck vessels. Adjacent thyroid parenchyma heterogenous due to

associated chronic thyroiditis. 47

Nodule within a cystic lesion. No flow within the nodule

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Isotope scan of thyroid demonstrating a photopenic area within the left lobe. Axial contrast enhanced CT of the same patient shows a solid mass within

left lobe of thyroid . Lymphoma was proven by biopsy.

Differentiation

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Feature Benign malignant

Internal contentsPurely cysticCystic with thin septaeMixed solid and cysticComet tail artifact

++++++++++++++

+++++

EchogenicityHyperechoicIsoechoichypoechoic

++++++++++

++++++

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Feature Benign malignant

HaloThin Thick incomplete

+++++

+++++

MarginWell definedPoorly defined

+++++

+++++

CalcificationEggshellCoarse calcificationMicrocalcification

+++++++++

++++++

+ rare (<1%)++ low probability (<15%)+++ intermediate probability(16 to 84%)++++ high probability (>85%)

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Feature Benign malignant

DopplerPeripheral flowInternal flow

+++++

+++++

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Sagittal image of predominantly cystic nodule (calipers), which proved to be benign at cytologic examination.

Sagittal image of predominantly solid nodule , which proved to be benign at cytologic examination.

Transverse US images of mostly cystic thyroid nodule with a mural component containing flow. (a) Gray-scale image shows predominantly cystic nodule with small solid-appearing mural component (b) Addition of color Doppler mode demonstrates flow within mural component , confirming that it is tissue and not debris. US-guided FNA can be directed into this area. The lesion was benign at cytologic examination.

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Peripheral coarse calcification with acoustic shadowing – favours benign nature

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Peripheral egg shell calcification

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HYPERPLASTIC NODULAR

Iso/hyperechoichypoechoic-honey

coombThin peripheral haloPeri & intranodular

vascula.

ADENOMA

Hyper/iso/hypoechoicThick peripheral halo

Spoke wheel Appearance

LYMPHOMA

ElderNHL

Dyspnoea,DysphagiaHashimoto’s thyroditis

Hypovascular/chaotic vasc.

METS

Homogenous Hypoechoic

No calcification

Primary-Rcc/breast/Melanoma

CARCINOMA

PAPILARY

3RD,7TH DecadePsammoma bodies

Cervical LNHYPERECHOIC

PUNCTATECALCIFICATIONDisorganised

hypervascularityCystic LN Mets

FOLLICULAR

HyperechoicThick irregular

haloTortous vesselsHematogenous

spreadTo

Bone/lung/brain/liver

MEDULARY

FamillialMEN type-2Calcitonnin

LN METS-HIGHHYPOECHOIC

COARSE CALCIFICA

ANAPLASTIC

ElderAggressiveInvasion=

muscles,vesselsWorst prognosis

Evaluation of nodules incidentally detected by sonographyNodules<1.5cm : followed by palpation at

time of next physical examinaton

Nodules > 1.5cm : evaluation usually by FNA

Any nodule with malignant features like–microcalcifications, irregular margin , thick halo , or internal flow: FNA

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Biopsy guidance INDICATIONS

Nonpalpable suspected nodule with inconclusive physical examination.

Patients at high risk of developing thyroid cancer, normal gland by physical examination but sonography demonstrates a nodule.

Previous non diagnostic / inconclusive biopsy.

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DIFFUSE THYROID DISEASE

1.THYROIDITIS CHRONIC AUTOIMMUNE

LYMPHOCYTIC THYROIDITS(HASHIMOTO’S THYROIDITIS)

SUBACUTE GRANULOMATOUS THYROIDITIS

(DE QUERVAIN’S DISEASE)

ACUTE SUPPURATIVE THYROIDITIS

2.ADENOMATOUS OR COLLOID GOITRE

3. GRAVE’S DISEASE

SILENT/PAINLESS

THYROIDITIS

INVASIVE FIBROUS

THYROIDITIS

Diffuse Thyroid diseaseCharacterised by Generalized enlargement of

gland and no palpable nodules.

Diagnosis is usually based on clinical and laboratory finding and occasion by FNA.

Sonography helpful when underlying disease

causes asymmetric thyroid enlargement.

Sonographic diagnosis of diffuse thyroid disease is made when isthmus may be up to 1 cm or more thickness. 62

Diffuse enlargement of the isthmus and both lobes

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Diffuse enlargement – heterogenous gland with multiple nodules

ACUTE SUPPURATIVE THYRODITISRare inflammatory disease caused by bacteria

affecting children.Sonography useful in selected cases to detect

thyroid abscess-ill defined hypoechoic mass with debris and/or septa and gas.

SUBACUTE GRANULOMATOUS THYROIDITIS(DE QUERVAIN’S)

Spontaneously remitting inflammatory disease probably caused by viral infection.

C/F :fever, enlargement of gland ,Tenderness

Sonography – enlarged hypoechoic gland with normal or decreased vascularity due to edema.

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Ill defined hypoechoic area – focal area of subacute thyroiditisresolved after 4 wks of medical therapy

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Sagittal sonogram of left lobe of thyroid shows solid, predominately hyperechoic, poorly marginated nodule in lower pole

corresponding to palpable abnormality.Fine-needle aspiration of this lesion was consistent with thyroiditis.Background of thyroid was heterogeneous,with

geographic regions of hypoechogenicity.

Chronic autoimmune lymphocytic (Hashimoto’s) thyroiditis

As a painless diffuse enlargement of thyroid often associated with hypothyroidism.genetic tendency . F:M – 8 : 1 .Young woman are affected.Lymphocytic infiltration of thyroid gland.

Sonography Diffuse coarsened hypoechoic glandular

enlargement67

Multiple discrete hypoechoic micronodules of 1-6 mm size is strongly suggestive of chronic

thyroiditis. Surrounded by multiple linear echogenic fibrous

septations- giving pseudo lobulated appearance.

Normal or hypovascular.Occasionally hypervascular .

Often Cervical lymphadenopathy may be present.

In end stage, atrophy of gland occurs when thyroid gland is small with ill defined margins and heterogenous echotexture with absent blood flow.

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Various appearances of Hashimoto’s disease

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Nodule was predominantly hyperechoic, with both solid and cystic-appearing Fine-needle aspiration of this 28 mm palpable nodule was consistent with

lymphocytic thyroiditis.

Sagittal sonogram of right lobe obtained at time of diagnosis of left-sided thyroid carcinoma shows 11-mm hypoechoic solid nodule with ill-defined margins (delineated by electronic calipers) in upper pole of right lobe. Sonographically guided fine-needle aspiration of this nodule and surgical pathology findings were

consistent with lymphocytic thyroiditis.

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Painless thyroiditis Thyroid enlargement in early phase followed by

hypothyroidism.Clinical findings are similar to subacute thyroiditis Histologic and sonographic pattern of chronic

autoimmune thyroiditis.

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Graves disease Diffuse abnormality of thyroid gland with

associated thyrotoxicosis Sonography

Diffusely hypoechoic or inhomogenous texture

Color Doppler shows hypervascular pattern known as “thyroid inferno”.

Spectral Doppler shows peak velocities exceeding 70cm/sec.

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Graves’ disease – diffuse hypervascularity and peak systolic velocity of 80cm\sec

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Pinhole images from a Tc-99m pertechnetate thyroid exam demonstrate diffuse thyroid enlargement with decreased background activity.

Invasive fibrous thyroiditis(Riedel’s struma)

FemaleTends to progress to complete destruction

USG Diffusely enlarged thyroid gland Inhomogenous parenchymal echo texture

May have associated mediastinal or retroperitoneal fibrosis or sclerosing cholangitis.

D/D : From Anaplastic thyroid carcinoma….by biopsy.

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Role of CT and MRI in thyroid disorders To demonstrate- Extent of local invasion - regional LN metastasis

To determine recurrence following Surgery.

Detection of retrosternal & retrotracheal extension of the thyroid enlargement.

Confirm the location of mass within the gland, evaluating nodal disease and assessing the airway.

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CT signs suggesting the thyroid origin of mediastinal mass include

Intimate association of the superior pole of mass with thyroid gland & close proximity to the trachea.

Hyperdensity of lesion compared to surrounding tissue.

Presence of calcification.

Persistent enhancement of the mass.

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Differentiation of benign and malignant primary thyroid masses is impossible on imaging, although the associated lymphadenopathy, vocal cord paralysis and bone or cartilage invasion obviously suggests malignancy.

MRI helps to differentiate scar from residual or recurrent tumor.

Tumor - hypointense to isointense on T1WI iso to hyperintense on T2WI scar - hypointense on both T1 and T2WI.

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GOITER -Enhancing heterogenous soft tissue mass orignated in thyroid and causing deviation of the trachea

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Large heterogenous soft tissue mass replacing the thyroid with speck of calcification,causing deviation of the trachea–medullary carci.

Cystic metastasis from thyroid carcinoma

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Role of radionuclide thyroid scintigraphyTo determine functional status of the nodules.

Nodules may be cold, warm or hot depending on the uptake of tracer as compared to the normal thyroid tissue.

Thyroid nodules concentrate less radioiodine (only 1%) than normal thyroid tissue hence appear cold.

Most cold nodules are adenomas, colloid nodules or foci of thyroiditis or rarely intrathyroid lymphnodes, lymphoma or metastases.

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Approximately 10 to 20 % of cold solitary thyroid nodules are malignant.

Cold nodules further require FNAC or biopsy.

The demonstration of hot nodule on scintigraphy is not synonymous with autonomy, as it often represents spared focus of normal thyroid tissue in gland otherwise involved in destructive process.

The more important role is of 131 I whole body scintigraphy to identify most functioning metastases, usually in the neck, lungs or bone, following total thyroidectomy.

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TYPES USG RADIOACTIVE IODINE UPTAKE

HASHIMOTO’S HYPOECHOIC THYROIDITIS COARSENED VARIABLE MICRONODULATION

SUBACUTE HYPOECHOIC GRANULOMATOUS N/HYPOVASCULAR DECREASED

GRAVE’S DISEASE INHOMOGENOUS INCREASED HYPERVASCULAR

INVASIVE FIBROUS INHOMOGENOUS VARIABLE EXTRATHYROID INFLAMMATION VESSEL ENCASEMENT 87

MCQs

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1. GIVE THE DIAGNOSIS

2. Egg cell calcifications are more common in which type of tumor?

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3.Which type of carcinoma has such appearance ?

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4. GIVE THE DIAGNOSIS

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5.GIVE THE DIAGNOSIS

THANK YOU

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