diagnostic imaging of salivary, parathyroid and thyroid glands

Head & NeckSalivary, Parathyroid and

Thyroid Glands

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Salivary, Parathyroid and Thyroid Glands

a) Salivary Glandsb) Parathyroid Glandsc) Thyroid Gland

a) Salivary Glands :1-Sialolithiasis2-Sialosis3-Sialoadenitis4-Sjogren Disease5-Cystic Salivary Lesions6-Parotid Tumors

1-Sialolithiasis : (Calculi)a) Incidenceb) Locationc) Radiographic Features

a) Incidence :-Refers to formation of concrements (sialoliths)

inside the ducts or parenchyma of salivary glands and most commonly occurs in the submandibular glands and their ducts

-Most common disease of salivary glands accounting for approximately 50% of all major salivary gland pathology

-Disease of adults , typically between 30 and 60 years of age , there is a male predilection 

b) Location :-Submandibular gland , 80% :Most calculi are radiopaque (80%-90%)-Parotid , 20% :50% of calculi are radiopaque

c) Radiographic Features :-Radiopaque calculi can often be seen on

plain films or CT-Radiolucent calculi are best demonstrated

by sialography, typically shows a contrast filling defect and ductal dilatation

-U/S : stones appear as strongly hyperechoic lines or points with distal acoustic shadowing represent stone

CT+C of the neck demonstrates a stone (blue arrow) in the submandibular region of a dilated Wharton's Duct (red arrow)

RT Wharton duct stone

LT Wharton duct

RT Wharton duct stone

Submandibular duct (Wharton duct), lateral-oblique conventional sialography confirms the presence of a 2-mm calculus (arrowhead), the proximal portion of the Wharton duct is better visualized because of retrograde filling of the ductal system (arrow)

Lateral-oblique conventional sialography shows a filling defect that corresponds to a small calculus (arrow)

Parotid gland duct (stensen duct), AP conventional sialography obtained shows a filling defect that suggests a small calculus (arrow)

Submental US image confirms the diagnosis of a 3-mm calculus (arrowhead), crosshairs indicate lateral borders of the stone, SMG = submandibular gland, W = Wharton duct

Transverse US image confirms the diagnosis of a 3-mm calculus (arrow), crosshairs indicate borders of stone. S = dilated Stensen duct

MRI (Transverse 3D-EXPRESS source image) shows a 3-mm calculus (large arrow) in the right Wharton duct at the level of the posterior edge of the mylohyoid muscle. Small arrow points to the normal opposite Wharton duct

MR sialography shows 2-4-mm stones (arrowheads) within the anterior third of the Wharton duct and shows ductal dilatation and associated sialodochitis with a small diverticular outpouching (arrow)

2-Sialosis :-Recurrent noninflammatory enlargement of

parotid gland (acinar hypertrophy, fatty replacement)

-Causes :1-Cirrhosis2-Malnutrition, alcoholics3-D.M.4-Drugs (thiourea, reserpine, phenylbutazone &

heavy metal)

-Radiographic Features :1-Sialography :-Sparse peripheral ducts2-U/S :-Reveals enlarged, hyperechoic salivary glands with a

poorly visible deep lobe but without focal lesions or increased blood flow

3-CT &MRI :-Normal or enlarged gland-Normal density throughout most of the disease-End stage glands may be diffusely dense and large

(a) MRI showing normal parotid gland, (b) MRI showing bilateral enlarged parotids in sialosis

3-Sialoadenitis :a) Incidenceb) Etiologyc) Radiographic Features

a) Incidence :-Refers to inflammation of the salivary

glands-It may acute or chronic and has a wide

range of causes-The submandibular glands are the most

commonly affected

b) Etiology :1-Acute Sialoadenitis :-Bacterial or viral-Abscess may form2-Chronic (Recurrent) Sialoadenitis :-Recurrent infection due to poor oral hygiene-Sialography : multiple sites of peripheral ductal

dilatation-Small gland3-Granulomatous Inflammation :-Causes : sarcoid , TB , actinomycosis , cat-

scratch disease & toxoplasmosis-Produces intraglandular masses indistinguishable

from tumors , biopsy is therefore required

HRUS images show bilateral diffusely hypoechoic parotid gland with small hypoechoic nodular lesions in a patient of granulomatous parotitis

Non-contrast T1 axial images show intraparotid adenopathy (white arrows) with altered appearance in a case of tuberculosis of left parotid gland

c) Radiographic Features :1-Sialography2-U/S3-CT4-MRI

1-Sialography :-Sialography is contraindicated in acute sialadenitis

because it can worsen the infection

2-U/S :-In acute sialadenitis the affected gland appears enlarged,

hypoechoic and hyperaemiac-In chronic infective forms the affected gland appears

atrophic and diffusely hypoechoic with irregular margins, the ultrasound appearances have been likened to that of a “cirrhotic” liver, may contain multiple small, oval, hypoechoic areas

Power Doppler US image shows an acutely inflamed right submandibular gland (arrows) containing a stone (arrowhead), the gland is enlarged and hypoechoic with rounded edges and increased blood flow

Power Doppler US image shows chronic inflammation of the left submandibular gland (arrowheads), the gland is inhomogeneous with decreased parenchymal echogenicity but without increased blood flow, arrows = stones

Gray-scale US image shows an acutely inflamed right parotid gland (arrows) in a 5-year-old child, the gland is enlarged and inhomogeneous with multiple small, oval, hypoechoic areas (arrowheads)

3-CT :-Enlarged salivary gland with abnormal attenuation,

indistinct margin and vivid contrast enhancement with associated adjacent fat stranding and/or thickening of deep cervical fascia that is typically unilateral

-Dilated duct from sialolithiasis or stenosis-Enlarged intra or extra-glandular lymph nodes may

also be seen but this is non-specific and can occur in other conditions such as malignancy

-Abscesses are hypodense fluid collections which may or may not be loculated

Acute submandibular sialadenitis, (a) Axial CT+C shows inflammation and asymmetric enhancement of the right submandibular gland, (b) Axial CT+C shows dilatation of the main submandibular duct, which contains a sialolith (arrow)

CT+C shows hypodense, enlarged right submandibular gland with calculus (thick white arrow) and thickening of adjacent fascia (thin white arrow)

Coronal and sagittal CT images show an enlarged left submandibular gland with two well-defined rim enhancing fluid collections in the anterior aspect of the gland, representing abscesses, there is adjacent subcutaneous fat stranding

Acute suppurative parotiditis, CT+C shows marked enlargement of the right parotid gland, glandular parenchyma demonstrates diffuse enhancement, and irregular areas of low attenuation are seen, a finding indicative of intraparotid abscesses

4-MRI :-The salivary gland is often enlarged-The affected gland can range from well defined to poorly

defined-Signal characteristics in majority of cases tend to be

heterogenous*T1 :Acute : low signalChronic : inhomogenous low signal*T2 :Acute : high signalChronic : low to intermediate due to fibrosis*T1+C :Vivid contrast enhancement

Acute right-sided parotitis, T1+C, fat-saturated shows marked enhancement of the right parotid gland (thick and thin arrows) compared with the left, the superficial subcutaneous tissue is also inflamed

T1+C shows severe parotitis on left side (white arrows)

4-Sjogren Disease :a) Incidenceb) Clinical Picturec) Radiographic Features

a) Incidence :-It is a chronic autoimmune disorder

involving mainly the salivary and lacrimal glands 

-It is the 2nd commonest autoimmune disorder after rheumatoid arthritis

-More in females, F:M = 9:1-Patients typically present around the 4th to

5th decades

b) Clinical Picture :-Sicca complex : dry eyes

(keratoconjunctivitis sicca) & xerostomia (dry mouth)

-Bilateral parotid enlargement-Systemic disease : rheumatoid arthritis

c) Radiographic Features :1-Sialography2-U/S3-CT4-MRI

1-Sialography :-Sialography patterns :1-Punctate : normal central and peripheral ductal

system, punctate (1 mm) parenchymal contrast collections

2-Globular : normal central system, peripheral duct system does not opacify, larger (>2 mm) extraductal collections

3-Cavitary : >2 mm extraductal collections4-Destructive : ductal structures not opacified

MR sialogram of the normal parotid gland duct in a healthy volunteer, main duct and intraglandular ducts are well seen.

MR sialography in a patient with Sjogren syndrome, diffuse areas of punctate high signal intensity 1 mm or less in diameter are distributed through the duct (stage 1 punctate appearance)

MR sialogram in a patient with Sjogren syndrome, areas of spherical high signal intensity 1 to 2 mm in diameter are evident (stage 2, globular appearance)

MR sialogram in a patient with Sjogren syndrome, large and irregular areas of high signal intensity up to 1 cm in diameter are noted (stage 3, cavitary appearance)

MR sialogram in a patient with Sjogren syndrome, the main duct shows marked dilatation and irregular branching (stage 4, destructive appearance)

MR Sialography: sialoadenitis classification in Sjogren syndrome. Stage I (A), stage II (B), stage III (C), stage IV (D)

2-U/S :-Early : enlarged and hyperechoic-Late : multicystic or reticular pattern within an

atrophic gland

3-CT & MRI :-Parotid gland enlargement (lymphoepithelial

proliferation), 50%-Parenchymal heterogeneity, cystic degeneration

& fatty replacement

Gray-scale (a) and power Doppler (b) US images show advanced-stage Sjögren syndrome in the parotid gland, the gland has an inhomogeneous structure with multiple small, oval, hypoechoic areas (arrowheads) and increased blood flow, the position of the US probe is shown in the inset diagram

Sialography (A and B) and sonography (C and D) of the parotid glands in patients who presented with sicca syndrome (dry eyes and dry mouth), normal glands (A and C), and glands affected by Sjogren syndrome (B and D) are shown for comparison, sialography of the parotid glands with Sjogren syndrome shows characteristic globular (B) staining patterns, sonography of the parotid glands with Sjogren syndrome shows irregular echogenicity and multiple hyperechoic bands and hypoechoic areas in the gland (D)

Sjögren disease, while both parotid glands (arrowheads) show cystic changes in and enlargement of the gland on this coronal T2, the left side also shows periparotid adenopathy (arrow)

5-Cystic Salivary Lesions :a) Mucus Retention Cystb) Ranulac) Mucocele d) Benign lymphoepithelial cysts (BLCs)e) Cystic tumors (Warthin's)

a) Mucus Retention Cyst :-True cyst with epithelial lining

Parotid retention cyst

b) Ranula :1-Incidence2-Types3-Radiographic Features4-Differential Diagnosis

1-Incidence :Retention cyst from sublingual glands in floor of

mouth

2-Types :a) Simple Ranula :-Confined to the sublingual spaceb) Plunging Ranula :-Also known as diving ranula or cervical ranula-As a simple ranula enlarges it dissects along facial

planes beyond the confines of the sublingual space

Simple ranula

Plunging ranula, CT+C shows a non-enhancing, water-density mass from the right sublingual space displacing the tongue to the left, a large component of the mass extends posterolaterally into the submandibular space (small arrow), It is non-enhancing, homogenous, smoothly-marginated, and without internal septations, smooth tapering anteriorly into the sublingual space, forming the “tail sign” (large arrow)

3-Radiographic Features :-The key to diagnosing a ranula, especially

in cases where they are large and have dissected some distance away form their origin is identification of a connection to the sublingual space, this may be no more than a thin tail of fluid or a significant local fluid collection

a) U/S :-Thin walled cystic lesion and can be

imaged both from the skin or trans-orally with a small probe

-If infected the walls are thicker and the fluid content more echogenic

b) CT & MRI :-Like branchial cleft and thyroglossal cysts

US shows space occupying mass with 62×25 mm, which was cyst like with capsule

CT scan shows a large mucous retention cyst arising from the sublingual gland (ranula)

Plunging ranula

Plunging ranula, CT+C shows a cystic attenuation lesion (arrows) in the floor of the mouth with a characteristic 'tail sign' extending into the submandibular space

Simple ranula, (a) In the right sublingual gland, the hyperintense lesion (arrow) on this transverse T2 could represent a pleomorphic adenoma or a cyst, (b) The absence of enhancement on this fat-saturated, T1+C suggests a cystic lesion, in this case a simple ranula of the sublingual gland

Plunging ranula, (A) Axial T1 and the (B) Coronal T2 show a cystic lesion having a fluid signal in the floor of the mouth

c) Mucocele :-Extravasation cyst-Results from ductal rupture and mucous

extravasation-Not a true cyst, composed of granulation

tissue

Mucocele of submandibular gland, (a) Noncontrast axial CT image shows a hypodense lesion in the left submandibular region, (b) CT+C image shows a mucocele of submandibular gland on left side

d) Benign lymphoepithelial cysts (BLCs) :-HIV+ patients -Associated adenopathy and lymphoid

hyperplasia -They typically present as bilateral parotid

cysts, superficial in location, in lymph nodes

HIV-related lesions, CT+C depicts a right-sided parotid cyst (straight arrow) and multiple small nodules in the left parotid gland (curved arrow) in this patient who was HIV positive

e) Cystic tumors (Warthin's) :1-Incidence2-Radiographic Features

1-Incidence :-They are the 2nd most common (up to 10% of all

parotid tumors) benign parotid tumor (after pleomorphic adenoma) and are the commonest bilateral or multifocal benign parotid tumor

-It typically occurs in the elderly (6th decade)-Usually solitary, unilateral, and slow growing -Bilateral in 10%-Male > female-Has a greater tendency to undergo cystic change

(~30%) than any other salivary gland tumor-Accumulation of pertechnetate

2-Radiographic Features :a) US :-Well-defined, lobulated, intermediate signal intensity mass

with cystic areas

b) CT :-Classic appearance is a cystic lesion posteriorly within the

parotid with a focal tumor nodule-Relatively well defined-Cystic changes appear as intra lesional lower attenuation-No calcification

Gray-scale US image shows the typical appearance of a Warthin tumor (arrows), the lesion, which is located in the lower pole of the parotid gland, is oval, well defined, hypoechoic, and inhomogeneous with multiple irregular anechoic areas (arrowheads) and posterior acoustic enhancement

CT+C shows a tumor with well defined margins and heterogenous contrast enhancement with multifocal cystic portion

RT warthin tumor

c) MRI :-Well defined and can be bilateral. *T1 : low to intermediate signal with cyst

containing cholesterol components containing focal high signal 2

*T2 : heterogenous and variable signal intensity

*T1+C : usually no contrast enhancement

(a) STIR shows the tumor with moderate-to-high signal intensity, the high-signal-intensity area is a cystic lesion (*); the area showed no enhancement on contrast-enhanced images (c, region of interest 2), (b) T1 shows a hypointense tumor, (c) Fat suppression T1+C shows solid (region of interest 1) and cystic (region of interest 2) tumor in the inferior pole of the parotid gland

Bilateral Warthin tumors, bilateral parotid masses (arrows) are seen on this transverse, contrast material-enhanced, fat-saturated T1, the multiplicity and location at the tail of the parotid gland (near the lower mandible) are typical features of this tumor

Bilateral parotid Wartin tumor, cervical MRI: axial (a, b) unenhanced T1, (c) T2 and (d) T1+C fat-saturated : two intraparotid masses, the right mass is ovoid and well circumscribed with an intermediate signal on T1 and intermediate and homogeneous signal on T2.The left mass is lobuled and heterogenous with high signal areas on T1, low signal intensity on T2 and a moderate contrast enhancement

6-Parotid Tumors :a) Benign : 80 %1-Pleomorphic adenoma (most common), 70%2-Warthin's tumor 3-Rare : oncocytoma, hemangioma & adenomab) Malignant : 20 %1-Mucoepidermoid carcinoma, 5%2-Carcinoma arising from pleomorphic adenoma, 5%3-Adenoid cystic carcinoma (cylindroma), 2%4-Adenocarcinoma, 4%5-SCC, 2%6-Oncocytic carcinoma, 1%

-Pleomorphic Adenoma : (Mixed Tumor)a) Incidenceb) Locationc) Radiographic Featuresd) Differential Diagnosis

a) Incidence :-The most common salivary gland tumors-Account for 70-80% of benign salivary

gland tumors and are especially common in the parotid gland

b) Location :-Parotid gland : 84% , commoner in the

superficial lobe-Submandibular gland : 8%-Minor salivary glands : 6.5% , widely

distributed including the nasal cavity , pharynx , larynx & trachea

-Sublingual glands : 0.5%

c) Radiographic Features :1-U/S2-CT3-MRI

1-U/S :-Typically hypoechoic-May show a lobulated distinct border +/-

 posterior acoustic enhancement -Useful in guiding biopsy (both FNAC and

core biopsies) but needs to be carried out with care to avoid facial nerve damage

Gray-scale US image shows the typical appearance of a pleomorphic adenoma (arrows), the lesion is hypoechoic and lobulated with distinct borders and posterior acoustic enhancement

US image shows an inhomogeneous pleomorphic adenoma (arrows)

Power Doppler US image shows a pleomorphic adenoma (arrows) in the lower pole of the parotid gland, no blood vessels are visible in the lesion

2-CT :-Well-circumscribed encapsulated mass-Calcification in a parotid mass is very

suggestive of pleomorphic adenoma-Moderate enhancement

Submandibular pleomorphic adenoma, CT+C shows that the pleomorphic adenoma (A) arises in the right submandibular gland. The attenuation characteristics leave little indication as to whether the lesion is benign or malignant

Pleomorphic adenoma in the parotid gland in a 29-year-old woman, (a) Transverse early phase helical CT scan shows a well-defined mass (arrows) in the superficial lobe of the right parotid gland. There is mild enhancement of the tumor, (b) Transverse delayed phase scan shows homogeneous and strong enhancement of the tumor (arrows)

Axial CT (encircled area enlarged) showing, (a) well-defined, hypodense, heterogeneous mass in the left parotid gland (white arrow) with poorly defined anteromedial margin (black arrow); (b) variable areas of low attenuation seen on the posterior aspect of the superficial lobe (white arrow)

3-MRI :*T1 : low*T2 : high, often have a rim of decreased signal intensity on

T2 representing the surrounding fibrous capsule*T1+C : homogenous enhancement-MRI characteristics that suggest malignancy :1-Irregular margins2-Heterogeneous signal3-Lymphadenopathy4-Adjacent soft tissue or bone invasion5-Facial perineural spread

Pleomorphic adenomas, (a) T1 shows the mass (P) to be well highlighted against the normal hyperintensity of the parotid gland, the margination is not particularly sharp, yet the diagnosis was pleomorphic adenoma, (b) The mass (P) is hyperintense T2, (c) The mass (P) enhances on this T1+C, though it has a central nonenhancing component

Pleomorphic adenoma, (a) T2 shows that the lesion (*) is hyperintense, this may raise the question of a cyst versus a pleomorphic adenoma, (b) With administration of a gadolinium-containing contrast agent and fat saturation, the mass (*) is seen to enhance avidly on this coronal T1+C, compatible with a solid mass

Pleomorphic adenoma of the superficial lobe of the left parotid gland. Cerical MRI, Coronal (a) T1 and (b) fat-supressed T2 : well circumscribed intra parotid mass with low and heterogenous intensity on T1 and a very high signal on T2

Non-contrast T2 & T1 axial images (upper row) and T2 coronal & DW axial images (lower row) show pleomorphic adenoma of right parotid gland (white arrows)

d) Differential Diagnosis :-When in the parotid gland consider :1-Warthin tumor2-Mucoepidermoid carcinoma3-Myoepithelioma4-Adenoid cystic carcinoma (ACC)5-Parotid nodal metastasis6-Parotid non-Hodgkin lymphoma7-Intra parotid facial nerve schwannoma

-Malignant Tumors :1-Mucoepidermoid carcinoma2-Carcinoma arising from pleomorphic

adenoma3-Adenoid cystic carcinoma (cylindroma)4-Adenocarcinoma5-SCC6-Oncocytic carcinoma*Areas of necrosis due to infarction (rapid

growth)*Locally invasive and aggressive*Lymph node metastases

Mucoepidermoid carcinoma of the parotid gland, transverse CT scan shows an ill-defined mass (C) that has less attenuation than that of enhancing parotid tissue in the right parotid gland

(A) CT+C shows a heterogeneously enhancing lesion in the right the parotid gland in a case of Mucoepidermoid carcinoma, the (B) Axial CT scan in an adenoidocystic carcinoma shows a multi-cystic infiltrating lesion in the left parotid region

Mucoepidermoid carcinoma of the parotid gland, (a) T2 shows an intermediate-signal-intensity mass (arrow) slightly lower in intensity than that of the native parotid tissue, (b) The ill-defined nature of the mass (arrow), the diagnosis was high-grade Mucoepidermoid carcinoma

Parotid Mucoepidermoid carcinoma, cervical MRI: axial (a) T2 and (b) T1+C fat-saturated : ovoid and well-circumscibed mass of the right parotid gland, this lesion has an hetrogenous signal with predominantly low signal on T1 and high signal on T2, and enhances heterogeneously after injection of Gadolinium (b)

CT+C shows malignant pleomorphic adenoma of right parotid gland (white arrows)

Non-contrast T2 & T1 axial images (upper row) and T2 coronal & DW axial images (lower row) show pleomorphic adenoma of right parotid gland (white arrows)

CT+C shows enlarged left submandibular gland (thick white arrow) associated with destruction of the adjacent mandible (thin white arrow) in a case of adenoid cystic carcinoma

b) Parathyroid Glands :1-Hyperparathyroidism2-Parathyroid Adenoma3-Hypoparathyroidism

1-Hyperparathyroidism :a) Incidenceb) Typesc) Clinical Pictured) Effect of PTHe) Radiographic Features

a) Incidence :-Usually detected by increased serum

calcium during routine biochemical screening

-Incidence : 0.2% of the general population-Female > male

b) Types :1-Primaryhyperparathyroidism :-Adenoma, 80%-Hyperplasia, 20%-Parathyroid carcinoma, rare2-Secondary hyperparathyroidism :-Renal failure-Ectopic parathormone (PTH) production by

hormonally active tumors3-Tertiary hyperparathyroidism : results from

autonomous glandular function after long-standing renal failure

c) Clinical Picture :-GI complaints-Musculoskeletal symptoms-Renal calculi

d) Effect of PTH :-Increases vitamin D metabolism-Increases renal calcium reabsorption

(hypercalcemia)-Increases bone resorption-Decreases renal PO4 resorption

(hypophosphatemia)

e) Radiographic Features :1-Parathyroid :-Single parathyroid adenoma, 80%-Hyperplasia of all 4 glands, 20%2-Bone :-Osteopenia-Subperiosteal resorption (virtually pathognomonic)-Brown tumors-Soft tissue calcification3-Renal :-Calculi (due to hypercalciuria)

55-year-old woman with primary hyperparathyroidism due to large left superior adenoma, sonogram shows hypoechoic nodule suspected of being parathyroid medial to common carotid artery (arrow)

15-year-old girl with hyperparathyroidism due to parathyroid hyperplasia, sonograms show four slightly enlarged parathyroid glands (arrows): right superior (A), right inferior (B), left superior (C), and left inferior (D)

Subperiosteal resorption

Subperiosteal resorption that has resulted in severe tuftal resorption (white arrows) , also note the subperiosteal and intracortical resorption of the middle phalanges (black arrows)

Subperiosteal resorption that has resulted in severe tuftal resorption (arrows)

Brown tumor

Brown tumor

Brown tumor

Brown tumors

2-Parathyroid Adenoma :a) Incidenceb) Radiographic Features

a) Incidence :-Adenomas may consist of pure or mixed

cell types, with the most common variant composed principally of chief cells

-Some cases are associated with the multiple endocrine neoplasia (MEN) I syndrome

-80% single, 20% multiple

Diagram shows posterior view of typical locations of paired superior (white arrows) and inferior (arrowheads) parathyroid glands and their relationship to thyroid gland and surrounding structures, note close relationship parathyroid glands have with recurrent laryngeal nerves (black arrows), illustrating why nerve injury is a significant concern of endocrine surgeons, particularly with four-gland explorations

b) Radiographic Features :1-Detection :-US and scintigraphy are the best screening

modalities-Adenomas are hypoechoic on US-If US is negative, further evaluation with CT or

MRI may be helpful-Angiography is reserved for patients with negative

neck explorations and persistent symptoms

-Location :*Adjacent to thyroid lobes*Thoracic inlet*Prevascular space in mediastinum (not in posterior

mediastinum); the inferior glands follow the descent of the thymus (also a 3rd pouch derivative)

2-Angiography :-Adenomas are hypervascular-Arteriography is most often performed after

unsuccessful surgery and has a 60% success rate in that setting

-Venous sampling and venography: 80% success rate after unsuccessful neck explorations

Parathyroid adenoma : CT+C through the neck at the level of the thyroid gland reveals an enhancing nodule posterior to the inferior right thyroid lobe, compatible with a parathyroid adenoma

Axial CT images in noncontrast (A) early post-contrast (B) and delayed post-contrast (C) phases demonstrate an intrathyroidal lesion with subtle hypodensity on precontrast imaging and delayed enhancement, this enhancement pattern is seen less commonly than early enhancement and washout

A 63-year-old woman with primary hyperparathyroidism, CT demonstrates avidly enhancing lesions in the orthotopic superior location (arrows) bilaterally with rapid washout of contrast greater than that of the adjacent thyroid gland (A and D: noncontrast phase; B and E: initial postcontrast “arterial” phase; C and F: delayed postcontrast phase), this patient underwent bilateral exploration, and bilateral superior parathyroid adenomas were found at surgery

3-Hypoparathyroidism :a) Etiologyb) Typesc) Radiographic Features

a) Etiology :1-Idiopathic :-Rare; associated with cataracts, mental

retardation, dental hypoplasia, obesity, dwarfism2-Secondary :Surgical removal (most common)-Radiation-Carcinoma-Infection

b) Types :1-Hypoparathyroidism :-Surgical removal (most common cause)2-Pseudohypoparathyroidism :-End-organ resistance to PTH (hereditary)3-Pseudo-pseudohypoparathyroidism :-Only skeletal abnormalities (Albright's

hereditary osteodystrophy)

c) Radiographic Features :-Generalized increase in bone density, 10%-Calcifications in basal ganglia-Other calcifications: soft tissues, ligaments,

tendon insertion sites

Marked bone sclerosis with the presence of lines parallel to the cortex of the vertebral bodies giving rise to an image of a small copy of the vertebral body within the body, a sign called “bone within a bone”

C) Thyroid :1-Thyroid Nodule2-Thyroid Follicular Adenoma3-Thyroiditis4-Grave’s Disease5-Thyroid Cyst6-Ectopic Thyroid7-Thyroid Cancer8-Photopenic Areas in Radionuclide Thyroid

Scanning

1-Thyroid Nodule :-Benign nodule versus Malignant nodulea) Nodule Charactersb) Peripheral Haloc) Nodule Margind) Calcificatione) Doppler Flowf) Metastases

Transverse US image shows the homogeneous echogenicity of the normal thyroid tissue and the normal thickness of the isthmus

A. Malignant, longitudinal US image of papillary thyroid carcinoma in 42-year-old woman shows marked hypoechogenicity, spiculated margin, microcalcifications, and taller-than-wide shape for nodule, B. Suspicious for malignancy, longitudinal US image of papillary thyroid carcinoma in 42-year-old woman shows marked hypoechogenicity, smooth margin, and ovoid shape, C. Borderline, transverse US image of nodular hyperplasia in 60-year-old woman shows macrocalcification in peripheral portion of nodule, patient underwent right lobectomy of thyroid, despite benign cytology upon US-guided fine-needle aspiration, for pathologic confirmation. D. Probably benign, longitudinal US image of benign nodule in 57-year-old woman shows isoechogenicity and smooth margin. E. Benign, longitudinal US image of benign nodule in 46-year-old woman shows ovoid shape, isoechogenicity, and smooth margin

a) Nodule Characters :1-Benign :-Cystic nodule +/- debris +/- septations-Posterior acoustic shadowing-Hyperechoic halo-Comet tail artifact (colloid nodule)-Multiple isoechoic nodules (MNG)-Multiple hypoechoic nodules (Hashimoto thyroiditis)-Intermediate : a solid well defined nodule +/- cystic

components

2-Malignant :-Solid nodules-No posterior acoustic shadowing-In a solid hyperechoic nodule the incidence

of malignancy is 5%-In a solid isoechoic nodule the incidence of

malignancy is 25%-In a solid hypoechoic nodule the incidence

of malignancy is 65%

Cystic lesion with mural nodule, the mural nodule has a homogenous echotexture

Thyroid nodule in longitudinal and transverse planes within calipers that has a homogeneous echogenicity is also isoechoic to the surrounding thyroid gland parenchyma

Malignant thyroid nodule demonstrating two suspicious ultrasound features - marked hypoechogenicity (compared to strap muscle) and taller than wide (AP diameter > transverse diameter)

b) Peripheral Halo :1-Benign :-Thin uniform halo2-Malignant :-An incomplete , irregular or thickened halo

Transverse US image shows a predominantly solid 2.4-cm nodule with well-circumscribed margins and a surrounding halo (benign US features)

c) Nodule Margin :1-Benign :-Smooth regular margins2-Malignant :-An irregular , lobulated or poorly defined margind) Calcification :1-Benign :-This is generally absent (eggshell calcification may be

present)2-Malignant :-Microcalcification fine or coarse calcification ▶

(commonly papillary or medullary carcinomas)

Gray scale image of a benign nodule in a patient with thyrotoxicosis (within calipers), this nodule has a regular margin and is heterogeneous with no calcification, color Doppler revealed normal blood flow, final diagnosis was colloid goiter

Thyroid nodule with an irregular margin

Thyroid nodule with macrocalcifications

Thyroid nodule (within calipers) with microcalcifications

(a) Gray scale image of a malignant nodule with heterogeneous echogenicity and microcalcifications, (b) Color Doppler image of the same nodule demonstrates increased central blood flow

e) Doppler Flow :-Intranodular flow (usually malignant)f) Metastases :-Invasion of the adjacent tissues , enlarged

ipsilateral or bilateral cervical lymph nodes (malignant)

Thyroid nodule with central increased blood flow

Thyroid nodule with peripheral increased blood flow

2-Thyroid Follicular Adenoma :-Represents 5% of thyroid nodules-Appears as solid masses with surrounding

halo-Difficult to differentiate from follicular cancer

by cytology, thus, these lesions need to be surgically resected

Follicular adenoma in a 36-year-old woman, longitudinal color Doppler sonogram of the right lobe of the thyroid shows perinodular flow around a follicular adenoma

Follicular adenoma in a 30-year-old woman, transverse sonogram of the left lobe of the thyroid shows a follicular adenoma with a hypoechoic halo (arrows)

3-Thyroiditis :a) Typesb) Radiographic Features

a) Types :1-Subacute granulomatous thyroiditis (de

Quervain's) :-Postviral2-Subacute lymphocytic thyroiditis :-Autoimmune -Postpartum3-Hashimoto's thyroiditis :-Autoimmune

b) Radiographic Features :-Enlargement of thyroid-Hypoechogenicity

Acute thyroiditis in a 12-year-old female patient, who presented with acute onset fever, neck pain and swelling, transverse gray-scale ultrasound neck (a) shows bilaterally enlarged thyroid lobes with heterogeneous echo pattern, color Doppler sonogram (b) demonstrates increased parenchymal vascularity in both lobes of the thyroid

Diffuse Hashimoto's thyroiditis in a 35-year-old female patient, transverse gray-scale ultrasound neck (a) demonstrates diffuse enlargement of thyroid gland with heterogeneous echotexture, multiple tiny and discrete hypoechoic nodules (micronodules, arrows) and few linear echogenic septae (arrowhead) are also noted, color Doppler sonogram (b) demonstrates mildly increased parenchymal vascularity

4-Grave’s Disease : (Diffuse Goiter)a) Incidenceb) Clinical Picturec) Radiographic Findings

a) Incidence :-Autoimmune thyroid disease and is the

commonest cause of thyrotoxicosis-There a strong female predilection with the

F:M ratio of at least 5:1-Typically presents in middle age

b) Clinical Picture :1-Thyrotoxicosis2-Goiter3-Ophthalmopathy4-Dermopathy : pretibial myxedema

c) Radiographic Findings :1-U/S2-Scintigraphy

1-U/S :-Enlarged thyroid and can be hyperechoic

2-Scintigraphy :-Homogeneously increased activity in an

enlarged thyroid gland

5-Thyroid Cyst :-Fluid filled cavities (cysts) in the thyroid

most commonly result from degenerating thyroid adenomas

-Cysts are usually benign but they occasionally contain malignant solid components

6-Ectopic Thyroid :-This may occur anywhere from the foramen caecum (the

base of the tongue) and via the thyroglossal tract, to the pretracheal, mediastinal or pericardiac areas

-By far the most common location is near its embryological origin at the foramen caecum, resulting in a lingual thyroid, this accounts for 90% of all cases of ectopic thyroids

-Thyroglossal Duct Cyst : Like ectopic thyroids, thyroglossal duct cysts are found along the thyroglossal duct, they are the most common thyroglossal duct lesion, and approximately 20%-25% are suprahyoid in location

Normal adult neck, sagittal CT+C shows the normal anatomic course of the thyroglossal duct (magenta line), the thyroid primordium originates as the median thyroid anlage (•) at the foramen cecum (white arrow), the path of the primordial descent wraps anteriorly, inferiorly, and posteriorly to the hyoid bone (black arrow) and courses anteriorly to the thyrohyoid membrane and thyroid cartilage (arrowhead)

Arrows point to the ectopic thyroid tissue at the tongue base, above the epiglottis (arrowhead) on this sagittal-reformatted CT image

Lingual thyroid tissue at the base of the tongue of a 29-year-old woman, CT+C through the base of the tongue shows lingual thyroid tissue that contains multiple low-attenuation foci corresponding to thyroid nodules (white arrow) and calcification (black arrow), nodules within ectopic thyroid tissue are identical in appearance to nodules within orthotopic thyroid tissue

Incidentally discovered thyroglossal duct cyst at the base of the tongue of a 13-month-old boy with transverse myelitis, (a) Sagittal T1+C shows a round, well-circumscribed, nonenhancing low-signal-intensity lesion (arrow) at the foramen cecum, (b) Axial T2 depicts the cystic high-signal-intensity nature of the thyroglossal duct cyst (arrow)

Sagittal T2 (a) and T1+C (b) MR images show a thyroglossal duct cyst 

Thyroid ectopia at the base of the tongue in two patients, (a) Sagittal CT+C of a 22-year-old woman with a history of dysphagia shows lingual thyroid tissue that obscures the epiglottic vallecula (white arrow) and displaces the epiglottis (black arrow) posteriorly and inferiorly, (b) Sagittal CT+C of a 3-month-old male infant shows a thyroglossal duct cyst in the base of the tongue that obscures the epiglottic vallecula (white arrow) and displaces the epiglottis (black arrow)

Long-standing palpable mass, which had recently enlarged, in the anterior portion of the neck of a 48-year-old man, CT+C depicts a thyroglossal duct cyst (black arrow) within the infrahyoid portion of the neck, the histopathologic findings from fine-needle aspiration of the associated enhancing nodule (white arrow) disclosed a thyroid carcinoma, papillary type

7-Thyroid Cancer :a) Incidenceb) Typesc) Stagingd) Radiographic Features

a) Incidence :-A malignant tumor arising from the thyroid

or parafollicular C cells-It is an uncommon tumor (accounting for

0.5% of all cancer deaths)

b) Types :1-Papillary, 60 %2-Follicular, 25 %3-Medullary, 5 %4-Anaplastic, 10 %5-Epidermoid, < 1 %6-Other (Lymphoma & Mets), < 1 %

Papillary thyroid carcinoma, transverse sonogram of the right lobe of the thyroid demonstrates punctate echogenic foci without posterior acoustic shadowing, findings indicative of microcalcifications (arrows)

Papillary carcinoma and cystic lymph node metastasis in a 28-year-old woman, longitudinal sonogram of the right lobe of the thyroid shows an irregular hypoechoic tumor with microcalcifications

Follicular carcinoma in a 60-year-old woman, (a) Transverse sonogram of the left lobe of the thyroid shows a partially cystic tumor with solid internal projections (arrows) and thick walls, (b) Color Doppler sonogram (shown in black and white) depicts increased vascularity in the solid parts of the tumor (arrow)

Medullary thyroid carcinoma in a 32-year-old man, (a) Transverse sonogram of the right lobe of the thyroid shows a large nodule with coarse calcification and posterior acoustic shadowing (arrows), (b) Axial CT shows the nodule with an internal focus of coarse calcification (arrows)

Anaplastic thyroid carcinoma in an 84-year-old woman, (a) Transverse sonogram of the left lobe of the thyroid shows an advanced tumor with infiltrative posterior margins (arrows) and invasion of prevertebral muscle, (b) Axial CT+C shows a large tumor that has invaded the prevertebral muscle (arrows)

B cell lymphoma of the thyroid in a 73-year-old woman with Hashimoto thyroiditis, transverse sonogram of the left lobe of the thyroid shows a large heterogeneous mass (between calipers) with marked hypoechogenicity when compared with the strap muscles (SM), a normal isthmus (arrow) also is visible. IJV = internal jugular vein

Renal cell carcinoma metastases to the thyroid in a 69-year-old woman, (a) Longitudinal sonogram of the right lobe of the thyroid 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

c) Staging :-T :*T1 :T1a : nodule < 4 cmT1b : nodule > 4 cm*T2 : nodule with partial fixation*T3 : nodule with complete fixation

-N :*N1 : Regional nodes1a : ipsilateral1b : contralateral1c : bilateral 2c*N2 : Fixed regional lymph nodes-M :*Mo : no mets*M1 : distant metastases

d) Radiographic Features :1-U/S2-Scintigraphy3-CT4-PET-CT5-MRI

1-U/S :-A hypoechoic nodule with an irregular ill-

defined border-Cervical adenopathy-Destruction of any adjacent structures

Papillary carcinoma and cystic lymph node metastasis in a 28-year-old woman, (a) Longitudinal sonogram of the right lobe of the thyroid shows an irregular hypoechoic tumor with microcalcifications, (b) Longitudinal sonogram of the right neck shows a cystic nodal metastasis with internal septation and foci of calcification (arrows), (c) CT+C shows the metastasis (arrow)

2-Scintigraphy : -Cold nodule (hypofunctioning)

3-CT :-This is not routinely used-it can assess metastatic nodal involvement , the

presence of distant metastases-Thyroid nodules appear as low attenuation lesions

(particularly after IV contrast medium)

There is a 1 cm solid primary tumor in the right lobe of the thyroid with fine calcifications (arrow), simple cyst (arrowheads) that actually represents a right nodal metastasis

4-PET-CT :-This is used for detecting recurrent or

metastatic disease

5-MRI :-This can be used for the detection of

recurrent disease

8-Photopenic Areas in Radionuclide Thyroid Scanning :

a) Localized :1-Colloid cyst2-Adenoma3-Carcinoma4-MNG

5-Local Thyroiditis (may show increased uptake) :-Acute-De Quervain’s-Hashimoto’s-Riedel’s6-Vascular7-Abscess8-Artefact

b) Generalized :1-Concurrent medication2-Hypothyroidism3-Ectopic hormone production4-De Quervain’s thyroiditis5-Ectopic thyroid