Ultrasound of Thyroid,parathyroid glands

and neck lymph nodes

Presenter : Dr.Sanjeeva Rao

Moderator : Dr.Kishore.V.HProf&HOD,Dept of Radiology

NMCH. NELLORE

EMBRYOLOGY First appears late in the 4th week of embryonic life as a

nodule of endoderm at the apex of the foramen caecum on the developing tounge

This nodule descends through the neck at the end of a slender thyroglossal duct, which breakdown by the end of 5th week

The thyroid continues its descent to reach its definitive position by the 7th week

Located in the anteroinferior part of neck (infrahyod compartment) outlined by muscle,trachea,esophagus,carotid arteries and jugular veins.

Extends from C-5 through T-1The thyroid gland is made up of two lobes

located along either side of the trachea and connected across the midline by the Isthmus

10-40% of normal patients have a small pyramidal lobe arising superiorly from the isthmus

supplied by R&L inferior thyroid artery,R&L superior thyroid artery .Drained by R & L superior, middle and inferior thyroid

veins

Muscular landmarks

a. Sternocleidomastoid muscles lie laterally

b. Longus colli (prevertebral)muscles lie posteriorly

c. “Strap” muscles lie anteriorly In adults mean length is 40 to 60 mm and the mean

anteroposterior diameter is 13 to18 mm. thickness of isthmus is 4 to 6 mm

Ultrasound of normal thyroid

Normal appearing thyroid in transverse view. Thyroid ishomogeneous and slightly hyperechoic. The lobes are bordered anteriorlyby the strap muscles (SM), posteriorly by the longus colli muscle(LC), medially by the trachea, and laterally by the sternocleidomastoidmuscle (SCM), carotid artery and jugular vein. A portion of the esophagus(ESO) protrudes behind the tracheal shadow against the medial borderof the left lobe

Ultrasound technique(High frequency trancducers:7.5to15.0MHz)

Patients are usually scanned in the supine position with the neck mildly hyperextended by an pillow

Both lobes are scanned individually in the transverse and in the longitudinal plane

Any specific abnormalities should be studied in both planes by rotating the transducer 90 degrees over the area

If the lobe is longer than the transducer, a “split screen technique” can be used to measure the length of lobe

Measurement of the thyroid (or a nodule) involves three measurements: the width, depth and length

THYROID ANOMALIES

Hemiagenesis of the thyroid

Aberrant Thyroid

Thyroglossal Duct cyst

THYROID ANOMALIES

Hemiagenesis of the thyroid

It is usually found when ultrasound is being done for some other cause, such as evaluation of a nodule in the contralateral lobe

Hemiagenesis of the left lobe. Ultrasound done to evaluatethe palpable nodule (N) in the right lobe reveals the thyroid ends atthe isthmus (arrow). The strap muscles (SM) have filled in the spacewhere the left lobe would be. Physical examination of the left neckwas normal

THYROID ANOMALIESAberrant Thyroid

can occur anywhere along the path of descent most common at the base of the tongue ‘lingual thyroid’

Resulting from failed bifurcation of two lobes

Failed bifurcation of the thyroid. This patient presented with an apparent “goiter” located 1 cm above the larynx. Ultrasound reveals a normal amount of thyroid tissue, and thyroid function was normal

THYROID ANOMALIES

Thyroglossal Duct cystSometimes the entire

thyroglossal duct persists, and protein material secreted by the lining epithelium may form a thyroglossal duct cyst that manifests itself clinically as a midline mass in the anterior aspect of the neck above the isthmus.

can form a sinusFluid filled Thyroglossal duct cyst in the midline.

Muscle anomaly

Patient was thought to have a nodule in the right lobe by physical examination. Ultrasound revealed enlargement of the strap muscle in the right neck (arrow) causing asymmetry; no nodule is present

Thyroid pathologies NODULAR DESEASES:

Goiter/hyperplasia , Thyroid adenoma , Thyroid malignancy( Papillary ca,Follicular ca, Anaplastic ca,Medullary ca,Thyroid primary lymphoma)

DIFFUSE DESEASES: Graves’ disease, acute suppurative thyroiditis,subacute(De Quervain)thyroiditis ,Chronic autoimmune thyroiditis,Silent thyroiditis,Riedels thyroiditis

NODLAR DISEASES

In thyroid nodular deseases sonography has five major applications;

1)Detection of nodules

2)Deffrentiation of goiter/hyperplasia from other thyroid nodular deseases

3)Preoperative determination of the extent of known thyroid malignancy

4)Detection of residual,recurrence

5)Guidance of FNAC for nan palpable nodules

Each thyroid nodule has to be studied :Echogenicity compared with normal

parenchymaPresence calcifiacations/cystic changesPattern of marginsPresence of echo-poor haloAmont and distribution of blood flow

Goiter/hyperplasia80% of nodular desease is due to hyperplasiaWhen single or multiple hyperplastic nodules

lead to global enlargement of the gland the term Goiter is used(either single or multinodular)

Sonographically; most hyperplastic nodules are Isoechoic with well defined margins

Cystic changes are present in 60-70% of cases

Typical comet tail artefacts seen with in nodules

Macro calcifications are present in “old”nodules These Calcificatoins are typicallycurvilinear, annular or dismorphic with posterior shadowing

Doppler:

- usually less vascularised than normal parenchyma

-Exception of rapidly growing hyperplastic lesions in yong patients

Isoechoic with thin regular halo cystic with multiple comet-tail artefacts and small internal cystic change

AdenomaRepresents 5-10% of all nodular deseaseCommon in femalesVarious subtypes of Follicular adenoma

1.Fetal adenoma 2.Hurthle cell adenoma 3.Embryonal adenoma

Sonography:

>commonly solid masses

>May be hypoechoic,isoechoic or hyperechoic

>Thick and smooth hypoechoic halo

Doppler imaging:

>blood flow from perifery to the center of the nodule called”Spoke and wheel” appearance

Thyroid adenoma shows peripheral

Vascularity with Spoke and wheel appearance

,blood flow towards the centre of the mass

Thyroid malignancyPapillary carcinoma

Most common thyroid malignancy(60-70%)Common in females ,Slow growth and good prognosisSonography: >Hypoechogenicity

>Intralesional punctate calcifications

>Hypervascularity

>Cerivical lymph node metastases which contain punctate microcalcifications

Follicular carcinomaAccounts for 5-15% of thyroid cancersAssociated with hyperplastic/adenomatous

thyroid nodules in 60-70% of casesSignificant criteria: Capsular & vascular invasionSonography: solid,homogenous, hyperechoic or isoechoic Thick irregular capsule,tortuous perinodular and

intranodular blood vessels….signs of extra capsular spread

Isoechogenicity,perilesional and internal blood suply features of Follicular carcinoma

Anaplastic carcinomaRepresents 5-10% of all thyroid carcinomasMostly occurs in elderyHighly aggressive,invades adjucent structuresSonography: Diffusely hypoechoic with area of necrosis (78%) Dense amorphous calcifications (58%) Irregularities of the boundaries and the early

invasion of the thyroid capsule Infirtation if adjacent structures

Large anaplastic carcinoma with irregular margins, posterior extracapsular growth and infiltration of the laryngeal recurrent nerve(arrow)

Medullary carcinomaAccounts only 5% of all thyroid carcinomasMay be familial, assoc with MEN llA syndromeMulticentric and/or bilateralPrognosis worse than Follicular carcinomasSonography : >similar to papillary carcinoma>Hypoechogencity,iregular margins ,

microcalcifications(calcified amyloid deposits)>Hypervascularity with irregular blood vessels

A large hypoechoic nodule with thick halo and scatterd microcalcifications. Pathological diagnosis confirms Medullary carcinoma

Thyroid primary lymphoma 4% of all thyroid malignancies Rare,Mostly of Non-Hodgkin’s type Rapidly growing,may cause symptoms such as

dyspnea and dysphagia 70-80% cases arises from preexisting Chronic

thyroiditisSonography:

>Hypoechoic,lobulated,nearly avascular mass

>Cystic necrosis&encasement of great vessels of neck

>Adjacent thyroid parenchyma may heterogenous due chronic thyroiditis

Metastases Metastases to thyroid are infrequent Spread by hematogenous or lymphatic route Commonly from Melanoma(39%)breast(21%)

&RCC(10%) Solitary well cecumscribed nodules&diffuse involvement

Renal cell carcinoma metastases shows a round hypoechoic nodule (arrows) and an irregular-shaped hypoechoic nodule (arrowheads). (b) Color Doppler sonogram of the round nodule shows increased internal vascularity.

Feature BENIGN MALIGNANT

INTERNAL CONTENTS

Purely cystic High probability Rare

Cystic with thin septa High probability Rare

Comet tail artefact Intermediate probability Rare

ECHOGENICITY

Hyperechoic High Rare

Isoechoic Intermediate Low

Hypoechoic Intermediate Intermediate

HALO

Thin halo High Low

Thick incomplete halo Rare Intermediate

MARGIN

Well defined Intermediate Low

Poorly defined Low Intermediate

Rare :<1%Low :<15%Intermediate: 16 to 84 %High :>85%

CALCIFICATION

Egg shell calcification High probability Rare

Coarse calcification Intermediate Rare

Microcalification Low HIGH

DOPPLER

Preipheral flow pattern Intermediate Low

Internal flow pattern Low Intermediate

Grading of colour doppler flow mapping(Fukunari N, Nagahama M, Sugino K et al (2004) Clinical evaluation of color Doppler imaging for the differential diagnosis of thyroidfollicular lesions)

Grade1 nodules had no flow detectable. Grade 2 nodules had only peripheral flow,

without intranodular flow. Grade 3 nodules had low velocity central

flow.Grade 4 nodules had highintensity central

flow.

Grade 1 Doppler flow. Grade 1 lesions have no intranodular flow and no flow to the periphery

Grade 2 Doppler flow. Grade 2 lesions have peripheral flow only, without intranodular flow

Grade 3 Doppler flow. Great 3 lesions have low to moderate velocity central flow

Grade 4 Doppler flow. Grade 4 lesions have high-intensity central blood flow

Diffuse thyroid desease

Diagnosis usually made on the basis of clinical & lab findings

On occasion by FNA

Sonography is seldom indicated

DIFFUSE THYROID DESEASEAcute suppurative thyroiditisRare inflammatory desease(bacterial infection)Usually affects childrenSononography: useful to detect development of

the frank thyroid Abscessill defined,hypoechoic,heterogenous mass with

internal debris with or with out septa & gasAdjacent inflamatory nodes are often present

Sub acute granulomatous thyroiditis (De-Qearvain’s)Spontaneous remitting inflamatory desease

probably caused by Viral infectionClinical findings : fever,enlargement of gland and

painful on palpation

Sonography: May enlarged and hypoechoic with normal or

decreased vascularityDiffuse edema may present

This patient had a painful upper right lobe with elevated sedimentation rate typical of deQuervain’s thyroiditis.Note the line of demarcation (arrow) between the inflamed upper lobe and normal appearing lower lobe

Chronic autoimmune lymphocytic thyroiditis(Hashimoto’s thyroiditis

Occures usually in yong or middle aged womanPainless,diffuse enlargemant of thyroid gland

Sonography: >Diffuse coarse echopattern

>Hypoechoic Micronodules (+ve predictive value 90%)

>Fibrotic septations with pseudolobulated appearance

>Doppler imaging: “Thyroid inferno”

Hashimoto’s lymphocytic thyroiditis. The echo pattern is heterogeneous, hypoechoic micro nodules with interspersed discrete white lines representing fibrosis .

Also called “Swiss cheese” appearence

Hashimoto’s thyroiditis (hashitoxicosis) has intenseblood flow (thyroid inferno)

Grave’s deseaseCommon diffuse abnormality

Biochemically charecterised by hyperfunction

Diffusely hypoechoic in young patients (due to extensive lymphocytic infiltration)

Color doppler shows ‘Thyroid inferno”

Graves’ disease has been described as the“thyroid inferno,” typically showing very intense blood flow

Riedel’s strumaRarest type of inflammatory thyroid deseaseAlso called Invasive fibrous thyroiditisPrimarily affects women and tends to complete

destruction of the glandMay assoc with mediastinal or retroperitoneal

fibrosis or sclerosing cholangitisDiffusely enlarged & inhomogenous echopatternThe primary reason for sonography was to check for

extra thyroid extension with encasement of adjacent vessels

Para thyroid glands

Parathyroid glands These are two pairs(superior&inferior) Superior parathyroids develop from 4th pharyngeal poch Inferior parathyroids develop from 3rd pharyngeal pouch Measure 3-10 mm x 2-6 mm x 1-4 mm Lie between posteromedial thyroid lobes and carotid sheath

Close proximity to: a. Tracheoesophageal groove

b. longus colli muscles

Supplied by inferior thyroidartery & from anastamosis of sup&inf thyroid arteries

TECHNIQUE OF PARATHYROID ULTRASOUNDThe patient should be made to lie flat on a firm table

with one or two pillows placed under the shoulders to enable full extension of the neck

The structures of the neck should be carefully studied in two or more axis at multiple levels of the neck

Most common cause of primary hyperparathyroidism

>Adenoma,Hyperplasia,and carcinomaSecondary hyperparathyroidism usually a response

to chronic hypocalcemia in uraemic patients

Superior parathyroid adenoma seen in longitudinal view

Inferior parathyroid adenoma seen in longitudinal view.

Parathyroid adenoma indenting the posterior capsule of the thyroid gland.

Double inferior parathyroid adenoma in panoramic view

False positive Para thyroid adenoma:

Cervical lymph node

Prominent blood vessel

Esophagus

Longus colli muscle

Thyroid nodule False negative:

Miniamally enlarged adenomas

Multinodular thyroid goiters

Some ectopic adenomas

Parathyroid hyperplasia

Large hypoechoic parathyroid hyperplasia

on right side & small lesion on left side

capsulated parathyroid hyperplasias

> Para thyroid carcinoma with mild hypoechogenicity &irregular margins

NECK LYMPH NODES Neck lymph nodes are classified into:

> Submental,Submandibular,Parotid,facial,Deep

Cervical,Spinal accessory,Transverse cervical, retropharyngeal,occipital and matoid

Topographic classification based on 7 “levels”

> Level I incudes submental&submandibular

>Level II,III,IV deeep cervical ,nodes deep to SCM muscle and upper spinal accessory chain

>Level v Transverse cervical chain

>Level VI Anterior cervical chain

>Level VII Nodes in superior mediastinum

Once LN detected define whether benign or malignantSize,echogenic hilum,level of echogenicity,necrosis,

extracapsular spread,vascularity and calclfications should be evaluated

In inflammatory conditions: Diffuse,homogenous and preserve their normal oval shape

In malignancy: greater transverse diameter,rounded, asymmetric morphology, thin echogenic hilum

Cystic necrosis seen in TB nodes

Doppler: Benign LN shows Hilar flow&central vacular pattern

Malignant LN shows Aberrant vessels with course entering from the nodal capsule

Malignant LN have higher PI&RI than benign LN

Hyperplastic lymphnode of neck with elongated shape,cenral hilum

Central hilar blood suply

Typical metastatic adenopathy :rounded,isoechoic,with both perilesional&intralesional vascularity

Rounded hypoechoic TB node with macrocalcification and poor vascular supply