Ultrasound of thyroid nodules

Ultrasound of thyroid nodules
Samir Haffar MD
Internal medicine – Ultrasound

Ultrasound of thyroid nodules
① Epidemiology & etiologies of thyroid nodules
② Ultrasound features of thyroid nodules
③ Ultrasound of cervical lymph nodes
④ Ultrasound systems for thyroid nodule risk stratification
⑤ Pseudo-nodules of thyroid
⑥ Fine needle aspiration of thyroid nodules

① Epidemiology & etiology of thyroid nodules

Epidemiology of thyroid nodules
• Very common: Palpation 4 – 8%, US 10 – 40%, autopsy 50%
Increases with age
• Malignancy risk: Patients younger than 20 or older than 60 years
History of neck irradiation
History of familial thyroid cancer
• Cancer prevalence: 10-13% no matter how many nodules at US
No decrease of cancer risk in multiple nodules
Cancer found in dominant nodules in 2/3 of cases
Frates MC et al. Ultrasound Quarterly 2006;22(4):231–238.
Most thyroid nodules are benign hyperplastic nodules
Thyroid cancer not common compared to very frequent benign nodules

Indications of thyroid ultrasound
• Patient with palpable thyroid nodule or with multinodular goiter
• High-risk patient for thyroid malignancy:
History of familial thyroid cancer
Multiple endocrine neoplasia (MEN) type II
Irradiated neck in childhood
• Patient with palpable cervical adenopathy suspicious for malignancy
• Follow-up and monitoring of thyroid nodules
Haugen BR et al. Thyroid 2016;26:1–133.
American thyroid association guidelines

Etiologies of thyroid nodules
Discrete lesion in thyroid distinct from surrounding thyroid parenchyma
• Benign thyroid nodules:
Cyst and pseudocyst
Hyperplastic adenomatous nodule (adenoma)
• Malignant thyroid nodules:
Papillary carcinoma: 75 – 80%
Follicular carcinoma: 10 – 20%
Medullary carcinoma: 3 – 5%
Anaplastic carcinoma: 1 – 2%
Lymphomas: < 5%
Metastasis: rare
Dighe M et al. Med Ultrason 2017;19:195–210.

② Ultrasound features of thyroid nodules

Different modes of medical ultrasonography
Mode What is measured What is displayed
B-mode Acoustic impedance Anatomy
Doppler Motion Vascular flow
Elastography Mechanical properties Tissue stiffness
Elastography: A Practical Approach. Barr RG Edit, Thieme Medical Publishers, New York, 2017.
The three modes are applied during ultrasound
examination for a more accurate diagnosis

Ultrasound features of thyroid nodules
Nodules Ultrasound features
Composition: Cystic: fluid-filled without solid component
Predominantly cystic: ≥ 50% cystic
Predominantly solid: ≥ 50% solid
Solid: entirely solid or almost completely solid
Echogenicity: Anechoic, hyperechoic, isoechoic, hypoechoic, very hypoechoic
Shape: Wider-than-tall, taller-than-wide
Margins: Regular, lobulated, irregular, extra-thyroidal extension
Peripheral halo: No halo, thin regular vascular, thick irregular avascular
Echogenic foci: Comet-tail artifact (colloid cyst)
Peripheral rim calcification (eggshell)
Macro-calcifications: > 1 mm
Micro-calcifications: ≤ 1 mm without acoustic shadowing
Vascular pattern: Peripheral, intranodular, peripheral & intranodular
Tessler FN et al. J Am Coll Radiol 2017;14:587–595.

Some ultrasound features are considered as benign
Other ultrasound features are suspicious for malignancy

Category Benign features Suspicious features
Composition Cystic predominantly cystic
Spongiform
Mixed cystic and solid
Solid or almost completely solid
Echogenicity Anechoic Hyperechoic
Isoechoic
Hypoechoic
Very hypoechoic
Shape Wider-than-tall Taller-than-wide
Margins Smooth or regular Lobulated or irregular
Extra-thyroidal extension
Halo Thin hypoechoic vascular halo Lack of hypoechoic halo
Thick irregular avascular halo
Echogenic foci No calcifications
Comet-tail artifacts (colloid cyst)
Macro-calcifications
Eggshell calcifications (rim)
Micro-calcifications
Vascularity Peripheral vascularity Intranodular vascularity
Peripheral & intranodular

Suspicious US features don’t have the same risk of malignancy
Some have lower risk of malignancy: hyperechoic, isoechoic, …
Other have higher risk of malignancy: hypoechoic, irregular margin, ..
Suspicious US features of thyroid nodules

US report of thyroid nodules should include
• Nodule location
• Nodule size in three dimensions
• Nodule sonographic features:
composition, echogenicity, shape, margin, halo, calcifications,
and vascularity
Cosgrove D et al. Ultrasound in Med & Biol 2016;

Drawing to locate and number thyroid nodules
Russ G et al. Eur Thyroid J 2017;6:225–237.
right lobe, longitudinal left lobe, longitudinal
anterioranterior
posterior posterior
caudalcaudalcranial cranial

Composition, echogenicity, shape, margin, peripheral halo,
calcifications and vascularity

Composition

Large anechoic cyst (arrow) without calcifications or ring down artifact
Most thyroid cysts are pseudocysts are hyperplastic nodules that
have undergone extensive degeneration, necrosis and hemorrhage
Dighe M et al. Med Ultrason 2017;19(2):195–210.
29 year old female with multiple known thyroid nodules
Difficult swallows due to mass like feeling in neck
Thyroid nodule
Composition / Completely cystic

Ahuja AT. Diagnostic Ultrasound: Head and Neck. 2104, Amirsys Publishing.
Large cystic thyroid nodule with internal debris mobile on Doppler
Posterior acoustic enhancement
esophagus
debris
cyst
Thyroid nodule
Composition / Hemorrhagic thyroid cyst

Large predominantly cystic nodule with internal debris and septa
Perinodular vascularity with no vascularity within septa
Power Doppler ultrasound of thyroid
septa
cyst
perinodular
vascularity
Thyroid nodule

Hemorrhagic thyroid cyst
Sharply defined fluid level: layering of debris in its dependent portion
Marked posterior enhancement
Absence of any intranodular vascularity
Longitudinal power Doppler US of thyroid lobe
posterior
enhancement
fluid level
Thyroid nodule

Hemorrhagic thyroid nodule with multiple mural nodules within
Mural nodules avascular on Doppler
Representing intra-nodular blood clots
Longitudinal ultrasound of thyroid lobe
mural nodule
Thyroid nodule

53-year-old male with incidental mass in right lobe seen on CT
Cystic mass with large ring down artifact (arrowheads)
consistent with benign colloid cyst
Transverse ultrasound of right lobe
Thyroid nodule
Composition / Colloid cyst

Multiple benign colloid cysts with ring-down artifact
in several cysts
Henrichsen TL et al. Radiol Clin N Am 2011;49:417–424.
Thyroid nodule
Composition /Colloid cyst

Thyroid nodule
Composition /Colloid cyst
Comet tail artifact also referred to as a ring-down artifact,
a stepladder artifact, or when a single comet tail is seen
within a small colloid cyst, a cat’s eye
In: Thyroid and parathyroid ultrasound and ultrasound-guided FNA.
Duick DS Edit, 4th edition, 2018, Springer International Publishing, Switzerland.
cat’s eye

Thyroid nodule
Composition / Spongiform nodule
Spongiform benign nodule with
internal microcystic appearance
involving more than 50% of the lesion
Classic spongiform or honeycomb pattern
Head and neck ultrasonography: essential and extended applications. Second edition, 2017.
Editor: LA Orloff – Plural Publishing Incorporation, San Diego, CA, USA.

Thyroid nodule
Composition / Predominantly cystic nodule
Transverse US of left lobe
Predominantly cystic nodule with small solid mural component
Flow within mural component (arrowheads): tissue and not debris
US-guided FNA directed into this area: benign lesion
Corresponding color Doppler US

Thyroid nodule
Composition / Predominantly solid nodule
Iso- to hyperechoic thyroid nodule
containing multiple cystic components
Gaitini D et al. Thyroid Ultrasound.
In: EFSUMB – European Course Book – Editor: Dietrich CF – 2011

Thyroid nodule
Composition / Completely solid nodule
Transverse US of left lobe
Completely solid thyroid nodule (calipers)
Marked internal vascularity on color Doppler mode
indicating increased likelihood that nodule is malignant
This was a papillary thyroid carcinoma

Echogenicity

Thyroid nodule
Echogenicity / Hyperechoic nodule
Russ G et al. Eur Thyroid J 2017;6:225–237.
Hyperechoic homogenous thyroid nodule
Oval shape and smooth margins – No any high-risk features
Risk of malignancy decreases as the echogenicity increases
Longitudinal ultrasound Transverse ultrasound

Die C et al. Insights Imaging 2016;7:77–86.
Markedly hyper-echogenic & heterogenous nodule
This is considered a suspicious nodule
Thyroid nodule

Thyroid nodule
Almost completely solid and hyperechoic nodule
Some small cystic components
Smooth margin – No calcifications

Thyroid nodule
Echogenicity / Isoechoic nodule
Isoechoic and completely solid nodule
Hypoechoic thin halo with peripheral vascularity on Doppler
Benign nodule at fine needle aspiration
Transverse US of right lobe Correspondent color Doppler

Thyroid nodule
Echogenicity / Hypoechoic nodule
Hypoechoeic nodule compared to thyroid gland (arrowheads)
Asterisk: strap muscle
Kwak JY et al. Radiology 2011;260(3):892–899.
Transverse US of left thyroid lobe

Suspicious hypoechoic nodule with signal lower than surrounding
thyroid tissue but higher than strap muscle above
Thyroid nodule
Echogenicity / Hypoechoic nodule
nodule
strap muscle
normal thyroid

Hypoechoic nodule with significant posterior acoustic enhancement
Presence of intra-nodular vascularity identifies this as a solid
nodule and not a cyst
Thyroid nodule
Echogenicity / Hypoechoic nodule or thyroid cyst
Correspondent color DopplerTransverse US of right lobe

Thyroid nodule
Echogenicity / Very hypoechoic nodule
Echogenicity of nodule less than that of strap muscle
Proved to be papillary thyroid carcinoma on histology

Thyroid nodule
Echogenicity / Very hypoechoic nodule
Grant EG et al. J Am Coll Radiol 2015;12:1272–1279.
Very hypoechoic 10-mm nodule (N) with smooth margin
Nodule less echogenic than adjacent strap muscles (S)
and isoechoic to common carotid artery (C)
Diagnosis: papillary thyroid carcinoma
Transverse ultrasound of left thyroid lobe

Shape

Thyroid nodule
Shape / Taller-than-wide nodule
Langer JE. Radiol Clin North Am. 2019;57(3):469–483.
Hypoechoic solid nodule of 1.3 cm
Larger in anteroposterior diameter than in width
Highly predictive of malignancy & noted in smaller cancers < 1 cm
Papillary thyroid carcinoma on surgery
Transverse image of left lobe

Margins

Thyroid nodule
Margin / Lobular margin of nodule
Suspicious hypoechoic nodule with lobular margin

Hypoechoic solid nodule with a lobulated margin (arrow)
Papillary thyroid carcinoma on FNA
Thyroid nodule
Margin / Lobular margin of nodule

Grant EG et al. J Am Coll Radiol 2015;12:1272–1279.
Thyroid nodule
Margin / Irregular margin of nodule
Heterogeneous 16-mm nodule with irregular margins
Angulated borders anteriorly
Diagnosis: papillary thyroid carcinoma
Longitudinal image of thyroid lobe

Markedly hypoechoic nodule which is taller than wide (arrow)
Presence of speculated margin (arrowheads )
Presence of microcalcifications (open arrow )
It demonstrates most of US features associated with malignancy
Thyroid nodule
Margin / Irregular spiculated margin of nodule
In: Ultrasound of the thyroid and parathyroid glands.
RA Sofferman & AT Ahuja (Eds), Springer Science+Business Media, 2012, New York.

Thyroid nodule
Margin / Extra-thyroidal extension of nodule
Longitudinal US of left thyroid lobe
Hypoechoic nodule with extrathyroidal extension into strap muscle
Loss of thin hyperechoic capsule (red arrow)
Highly reliable sign of malignancy and unfavorable prognostic sign
Papillary carcinoma on surgery

Thyroid nodule
Transverse ultrasound of thyroid
Extrathyroidal extension through anterior capsule (arrows)
Lack of clear margin with adjacent trachea posteriorly (dashed arrow)
Anaplastic carcinoma on surgery with tracheal invasion

Langer JE. Radiol Clin North Am 2019;57(3):469–483.
Thyroid nodule
Sagittal ultrasound of left thyroid lobe
3.5 cm solid hypoechoic nodule with microcalcifications
Along inferior aspect of lesion: normal thyroid capsule (dashed arrow)
Along superior aspect lesion: extra-thyroidal extension (arrows)

Peripheral halo

• Thin, regular and vascular halo
Generally forms margin for iso- and hyperechoic nodules
Found in about half of benign nodule
• Thick, irregular and avascular halo
Presence of fibrous capsule surrounding a neoplastic growth:
Follicular carcinoma or Hürthle cell carcinoma
Peripheral halo of thyroid nodules
Sonolucent ring that surrounds a nodule

Longitudinal US of thyroid lobe
Thyroid nodule
Halo / Thin regular and vascular halo
Halo corresponds with
peripheral vascularity
Coresponding color Doppler
Isoechoic nodule with thin regular halo
Cytology is benign

Thick, irregular, and incomplete halo
Surrounding solid iso- to hyperechoic nodule
Hürthle cell cancer on histology
Thyroid nodule
Halo / Thick irregular and incomplete halo
Transverse ultrasound of right thyroid lobe

Thyroid nodule
Halo / Thick avascular halo
Heterogeneous nodule with thick halo which without vascularity
Avascular halo is suspicious for a malignant nodule
and represents true capsule of the lesion
Longitudinal power Doppler ultrasound of thyroid lobe

Echogenic foci (calcifications)

Thyroid nodule
Echogenic foci / Ring down artifact
Cystic mass with large ring down artifact (arrowheads)
consistent with benign colloid cyst

Thyroid nodule
Echogenic foci / Macro-calcifications
Mixed solid & cystic nodule (calipers)
Central macro-calcification (arrow)
producing acoustic shadowing
Benign hyperplastic nodule
Sagittal US of thyroid lobe Transverse US of thyroid lobe
Solid hypoechoic nodule
Central dystrophic calcification
outlined by calipers
Medullary thyroid carcinoma

69-year-old woman with medullary thyroid carcinoma
Hypoechoic nodule with coarse central calcification
This is suggestive of medullary thyroid carcinoma
Thyroid nodule
Echogenic foci / Macro-calcifications

Thyroid nodule
Echogenic foci / Peripheral rim calcifications (eggshell)
Complete eggshell calcification
Acoustic shadowing produced by calcific ring
Twofold increase of cancer likelihood in case of eggshell calcification
CCA
trachea
eggshell

Thyroid nodule
Echogenic foci / Disrupted peripheral rim calcifications
Interrupted eggshell calcification around edges
Corresponds with localized invasion into surrounding thyroid

Coarse and disrupted calcification
Posterior acoustic shadowing partially obscures the nodule
Highly suspicious for malignancy – Papillary thyroid carcinoma on FNA
Editor: Orloff LA – Plural Publishing Incorporation, San Diego, CA, USA.
Thyroid nodule
Echogenic foci / Disrupted peripheral rim calcifications

Sagittal US image of thyroid nodule
Thyroid nodule (arrowheads) with micro-calcifications (arrow)
Papillary thyroid carcinoma on FNA and surgery
Threefold increase of cancer likelihood in case of microcalcifications
Microcalcifications almost exclusively appear in hypoechoic nodules
Thyroid nodule
Echogenic foci / Micro-calcifications (punctate echogenic foci)

Vascularity

Vascularity pattern of thyroid nodules
ACR TIRADS: American college of radiology – Thyroid imaging reporting and data system
ATA: American thyroid association – BTA: British thyroid association
FNA: fine needle aspiration
Nodular vascularity U classification
of BTA
FNA
Peripheral vascularity Benign nodule not required
Peripheral & intra-nodular vascularity Equivocal nodule required
Intra-nodular vascularity Malignant nodule required
Nodular vascularity included in U classification of BTA
and not included in K-TI-RADS, ATA & ACR TI-RADS

Benign nodule with peripheral vascularity on Doppler
Vascular haloes in benign nodules represent compressed vessels/
thyroid tissue & such nodules do not have true capsule around them
Thyroid nodule
Vascularity /Peripheral vascularity of nodule

Transverse US of thyroid nodule
Solid thyroid nodule with peripheral and internal vascularity
This was a papillary thyroid carcinoma
Increased vascularity in thyroid nodule is suggestive of malignancy
but should not be considered a pathognomonic feature
Thyroid nodule
Vascularity / Peripheral and intra-nodular vascularity

Thyroid nodule
Vascularity / Intranodular vascularity
Thyroid nodule with intra-nodular vascularity
Later confirmed to be papillary thyroid cancer

Nodules in Hashimoto thyroiditis
• Pseudo- nodules
• White-knight nodule
• Giraffe hide
• Papillary thyroid carcinoma: increased risk in Hashimoto thyroiditis
• Thyroid lymphoma: increased risk in Hashimoto thyroiditis

Hashimoto’s thyroiditis
Pseudonodules
Thin & thicker fibrous septa in hypoechoic thyroid
Creating pseudonodules and parenchymal coarsening
When it is unclear if a nodule is present, FNAC may be needed
FNAC: fine needle aspiration cytology
Sholosh B et al. Radiol Clin N Am 2011;49:391–416.
Sagittal ultrasound of thyroid lobe

white-knight nodule
Background thyroid: hypoechoic with micro-nodularity
features typical of diffuse Hashimoto thyroiditis
Well-defined homogenous hyperechoic nodule known as white-knight
Surgical removal demonstrated nodular Hashimoto thyroiditis
16-year-old boy with known Hashimoto thyroiditis

Giraffe hide
Background thyroid: hypoechoic with micro-nodularity
features typical of diffuse Hashimoto thyroiditis
Bright blocks separated by dark bands looking like a giraffe hide
This nodule is variation of echogenic nodule known as “white- knight”

Presence of multiple nodules is the norm
on ultrasound examination
With high-resolution ultrasound, it is quite
unusual to see a truly solitary nodule

Multiple thyroid nodules
Large anechoic cyst (arrow) without calcifications or ring down artifact
Two small hypoechoic nodules with multiple cystic components
Longitudinal ultrasound of left thyroid lobe

Sagittal ultrasound of right thyroid lobe
Multiple heterogeneous nodules in right lobe (arrows)
Some nodules show cystic component with comet-tail artifacts
Others are isoechoic with cystic elements
None of nodules show obvious features suspicious for malignancy

Multiple solid isoechoic non-calcified nodules

Malignancy in solitary & multiple thyroid nodules
1 Cochand-Priollet B et al. Am J Med 1994; 97(2):152–157.
2 Marqusee E et al. Ann Intern Med 2000; 133(9):696–700.
3 Papini E et al. J Clin Endocrinol Metab 2002; 87(5):1941–1946.
Malignancy
Solitary nodules Multiple nodules
Cochand-Priollet 1 13% 14%
Marqusee E 2 7% 9%
Papini 3 9% 6%
Malignancy is similar in solitary & multiple thyroid nodules

Thyroid cancers
1% of all malignancies
Average annual incidence 5/100.000 inhabitants
• Papillary thyroid carcinoma: 75 – 80%
• Follicular thyroid carcinoma: 5 – 10%
• Medullary thyroid carcinoma: 3 – 5%
• Anaplastic thyroid carcinoma: 1 – 2%
• Primary thyroid lymphoma: < 5%
• Thyroid metastasis

• Ultrasound:
Heterogeneous hypoechoic nodule
Irregular shape
Characteristic micro-calcifications
• Color Doppler:
Not useful to diagnose papillary cancer (useful in follicular cancer)
20% of malignant nodules have peripheral vascularity
Papillary thyroid carcinoma
most common thyroid cancer (75–80%)

Classic pattern of hypoechoic nodule with micro-calcifications
Mild internal vascularity on color Doppler
Transverse US and color Doppler of right lobe

Subtle hypoechoic nodule proved to be papillary thyroid carcinoma
Nodule easily blends in to adjacent hypoechoic thyroid on sagittal view
Multiple tiny hypoechoic nodules consistent with Hashimoto thyroiditis
Patient with long-standing Haschimoto’s thyroiditis
Transverse and sagittal US of right thyroid lobe

Patient with long-standing Haschimoto’s thyroiditis
Background thyroid: micronodules of Hashimoto’s thyroiditis
Papillary thyroid cancer (PTC) occurring in Haschimoto thyroiditis
Echogenicity of nodule similar to background thyroid
but microcalcifications within nodule facilitate its detection

Thrombosis of internal jugular vein
Patient with known papillary thyroid carcinoma
Thrombosis of left internal jugular vein (IJV)

Follicular thyroid carcinoma
5–10% of thyroid cancer
• More common in females than males
• Higher risk of distant metastases & mortality compared with PTC
• Ultrasound: follicular carcinoma similar to follicular adenoma
Adenoma: oval to round isoechoic or hypoechoic nodule
Carcinoma: irregular margins, thick halo & caotic vessels
• Doppler: characteristic high velocity pulsatile flow penetrating tumor
• FNA insufficient to distinguish benign & malignant follicular lesions
Follicular carcinoma dg by capsular or vascular invasion on histology
Follicular adenoma must be excised for definitive diagnosis

Benign follicular adenoma
Classic pattern of follicular benign adenoma
Homogeneous hypoechoic oval nodule with thin capsule
56-year-old woman with benign follicular adenoma

Ovoid solid predominantly hypoechoic thyroid nodule
Hypoechoic areas (arrowhead) within nodule are suspicious features
Marked intranodular vascular flow on power Doppler
Follicular carcinoma on histology
Follicular thyroid carcinoma
Longitudinal US of thyroid nodule
Correspondent color Doppler US

• Arise from parafollicular C-cells that secrete thyrocalcitonin
10-20% of patients have familial history of pheochromocytomas
Medullary carcinoma may be associated with MEN II-syndrome
• Ultrasound:
Solid hypoechoic nodule with central coarse calcification in 80-90%
• Doppler:
Chaotic intranodular vessels seen in tumor on color Doppler
3–5 % of thyroid cancer

Transverse ultrasound of left lobe
Well-defined solid hypoechoic nodules in left lobe
Central dense shadowing calcification in larger nodule
These were confirmed to be medullary thyroid carcinoma

37 year old male with incidentally detected nodule on CT scan
Transverse US & Doppler US of right lobe
Large hypoechoic predominantly solid nodule
Mild internal vascularity on color Doppler
FNA suspicious for medullary carcinoma confirmed on histopathology

• Highly aggressive form of thyroid cancer
Typically in elderly women in 6th to 7th decades of life
Large number of patients have history of multinodular goiter
• Ultrasound:
Hypoechoic nodule involving entire lobe, ill-defined margins, areas
of necrosis, microcalcifications, extracapsular spread, vascular
invasion, nodal or distant metastases
• Doppler: multiple small intra-nodular vessels
• Core biopsy may be required for diagnosis due to its fibrotic nature
Anaplastic thyroid carcinoma

Transvers ultrasound of thyroid bed
ill-defined hypoechoic nodule in thyroid isthmus
Tissue plane between tumor and trachea is lost (tracheal invasion)
Anaplastic carcinoma revealed by core needle biopsy

ill-defined heterogeneous hypoechoic nodule (arrows)
encasing left CCA (open arrow)
Anaplastic carcinoma on histology
Extrathyroid extension is better evaluated with CT or MR

Thyroid lymphoma
• Uncommon: < 5% of all thyroid malignancies
• Almost always in patients with underlying Hashimoto’s thyroiditis
• Classically presents with rapidly enlarging thyroid gland
• Ultrasound features:
Markedly hypoechoic nodule in background of chronic thyroiditis
Enhanced through transmission posterior to the lesion
• Treatment: Chemotherapy and external beam radiation
Surgery only if trachea markedly compressed by tumor
• Good prognosis when disease confined to thyroid gland

CECT: contrast enhanced computed tomography – PET: positron emission tomography
Thyroid lymphoma
Markedly hypoechoic large expansile masses in both lobes on US
Low density masses on CT scan
Intensely hypermetabolic masses on PET scan
Patient with Hashimoto thyroiditis & rapidly enlarging thyroid mass
Transverse US of thyroid CECT PET scan

Thyroid lymphoma
almost always in patients with underlying Hashimoto’s thyroiditis
Markedly hypoechoic nodule in isthmus
Increased through-transmission: finding suggesting lymphoma
Relative hypovascularity on color Doppler
Background thyroid: micronodules of Hashimoto’s thyroiditis

Asymmetrically enlargement of left lobe with preserved contour
Homogeneous & hypoechoic parenchyma of both lobes
with increased through-transmission (features suggestive of lymphoma)
Haschimoto thyroiditis: heterogeneous hypoechoic regions that attenuate sound
Thyroid lymphoma
Patient with long-standing Haschimoto thyroiditis & new neck swelling
Transverse ultrasound of thyroid

Thyroid metastasis
rare in daily clinical practice
• Generally associated with advanced stage of malignancy
• Main primary tumors spreading to thyroid gland:
malignant melanoma, breast carcinoma, renal cell carcinoma
• Difficult to distinguish from primary thyroid lesion
• No specific features on US:
Solitary/multiple hypoechoic nodules without calcifications
No specific information about color Doppler of metastases

Transverse US of right and left lobe
Several small hypoechoic nodules in right lobe
Large hypoechoic nodule in left lobe
Adenocarcinoma most probably from gastrointestinal origin on FNA
Thyroid metastasis
Gaitini D et al. Thyroid Ultrasound.
In: EFSUMB – European Course Book – Editor: Dietrich CF – 2011

Thyroid metastasis
Longitudinal in a patient with a known lung cancer
Solid hypoechoic noncalcified nodule (arrow) in lower thyroid pole
Lower pole is common location for large thyroid metastases
Presence of such a nodule in a patient with known cancer suggests
thyroid metastases unless proven otherwise

③ Ultrasound of cervical lymph nodes

Six zones of cervical lymph nodes
Zone I Submental triangle
Zone II Upper internal jugular chain nodes
Zone III Middle internal jugular chain nodes
between hyoid bone & cricoid cartilage
Zone IV Lower internal jugular chain nodes
from zone II to clavicle
Zone V Entire posterior triangle
between SCM, trapezius and clavicle
Zone VI hyoid bone superiorly
sternal manubrium inferiorly
carotid arteries laterally

Zones in dark blue are most common sites of metastatic papillary carcinoma
Zones in lighter blue are less frequent areas of metastatic papillary carcinoma
Six zones of cervical lymph nodes
RA Sofferman & AT Ahuja (Eds), 2012, Springer Science+Business Media, New York.

Pretracheal and paratracheal lymph nodes
Schematic transverse section at level of thyroid gland
Relationship of pretracheal and paratracheal lymph nodes
to adjacent structures

• Small: short axis < 5 – 8 mm
• Oval: short axis/long axis < 0.5
• Echogenic hilum
• Hilar vascularity or avascular hilum on Doppler
Ultrasound features of benign lymph nodes
At least 5–6 normal cervical nodes identified routinely by US
Ting M et al. Clinical Radiology 2003;58:351–358.

Normal cervical lymph node
Oval shape and echogenic hilum
Ahuja AT et al. AJR 2005;184:1691–1699.
Hypoechoic, elliptic, and elongated lymph node (arrows)
Arrowheads indicate echogenic hilus continuous with adjacent soft tissue

Richards PS et al. Cancer Imaging 2007;7:167–178.
oval shape & echogenic hilum
Normal elliptical node with echogenic hilum

Hilar vascularity
Vessels radiate out from the hilum

Ultrasound features of malignant lymph nodes
• Round shape
• Loss of echogenic hilum
• Cystic change in lymph node
• Microcalcifications
• Non-hilar vascularity
• Extracapsular spread

Ahuja AT et al. Cancer Imaging 2008;8:48–56.
Malignant lymph node
Round shape
Metastatic lymph node which is enlarged, hypoechoic, well-defined
and without echogenic hilum (arrows)

Enlarged node (calipers) with cystic component
Node proved to be metastatic papillary carcinoma
Cystic change

Metastatic cervical node (arrows) with intra-nodal cystic necrosis
which appears ill-defined and echolucent (arrowheads)
Cystic change

Cystic change
Cystic metastatic lymph node (arrow) from papillary carcinoma
Microcalcifications (arrowhead) within solid component
(open arrow) of metastatic node
Transverse ultrasound of left neck
CCA

Metastatic lymph node from papillary thyroid carcinoma (arrows)
Hyperechoic component within node which may be related
to intra-nodal deposition of thyroglobulin (arrowheads)
Hyperechoic component

Round heterogeneous hyperechoic node – Loss of echogenic hilum
Characteristic punctate calcification with fine acoustic shadowing
Compressed internal jugular vein (IJV)
CCA
collapsed IJV
lymph node
punctate
calcifications

Metastatic lymph node with peripheral vascularity (arrowheads)
Power Doppler ultrasound
Peripheral vascularity

Malignant lymph node with both peripheral (arrowheads)
and hilar vascularity (arrows)
Power Doppler ultrasound
Ahuja AT et al. Clinical Radiology 2003:58:359–366.
Peripheral & hilar vascularity

Metastatic lymph node
Mixed (peripheral and hilar) vascularity on power Doppler
Sagittal gray scale & power Doppler ultrasound
Peripheral & hilar vascularity

Extracapsular spread

④ Ultrasound systems for thyroid nodule
risk stratification

Reliable US systems are necessary to specifically
target nodules that require biopsy
Several published US systems for risk stratification

Some US systems for thyroid nodule risk stratification
2009 First TI-RADS
Horvath E et al. Clin Endocrinol Metab 2009;94(5):1748–51.
2011 Korean TI-RADS
2016 U classification of British Thyroid Association (BTA)
2016 American Thyroid Association (ATA)
Haugen BR et al. Thyroid 2016;26(1):1–133.
2017 ACR TI-RADS
ACR: American college of radiology
TI-RADS: Thyroid imaging reporting and data system
No one system has achieved universal acceptance
This leads to some confusion for practitioners of sonography

Korean TIRADS
Analysis of 1658 nodules > 1 cm that underwent FNA
Category Definition Ultrasound features FNA
1 Normal thyroid gland follow-up
2 Benign: 0% Cyst & colloid cysts
Spongiform grid nodule
follow-up
follow-up
3 Probably benign: < 5% No suspicious feature follow-up
4
4 a
4 b
4 c
Suspicious nodules: 5-80%
Low suspicion:
Intermediate suspicion
Moderate suspicion
1 suspicious feature
2 suspicious features
3-4 suspicious features
≥ 1.0 cm
≥ 1.0 cm
≥ 1.0 cm
5 Probably malignant: >80% 5 suspicious features ≥ 1.0 cm
6 Biopsy proven malignancy
Less complex TI-RADS stratifying malignancy risk

Suspicious ultrasound features in Korean TI-RADS
• Solid component
• Hypoechogenicity
• Marked hypoechogenicity
• Microlobulated or irregular margins
• Microcalcifications
• Taller-than-wide shape
Six ultrasound features

U classification of British Thyroid Association
Classification US features of thyroid nodule FNA
U1: benign thyroid not required
U2: indeterminate nodule Iso- or slightly hyperechoic nodule
Hypoechoic halo around nodule
Anechoic with ring-down sign (colloid)
Spongiform/honeycomb nodule
Complete eggshell calcification
Peripheral vascularity of nodule
not required
U3: equivocal nodule Markedly hyperechoic nodule
Nodule with cystic change
Peripheral & intra-nodular vascularity
required
U4: suspicious nodule Hypoechoic nodule
Disrupted eggshell calcification
Nodule with lobular margin
required
U5: malignant nodule Taller than wide nodule
Intra-nodular vascularity
required

American Thyroid Association (ATA) guidelines
for adult patients with thyroid nodules
FNAC: fine needle aspiration cytology – ETE: extra-thyroidal extension – F/U: follow-up
Category Risk of
malignancy
US features FNAC
High suspicion > 70 – 90% Microcalcifications, hypoechoic, irregular
Hypoechoic, irregular margin
Hypoechoic, taller-than-wide
Hypoechoic, irregular margin, ETE
Hypoechoic, interrupted rim calcifications
Irregular, suspicious lateral lymph node
≥ 1 cm
Intermediate suspicion 10 – 20% hypoechoic solid, regular margin ≥ 1 cm
Low suspicion 5 – 10% Hyperechoic solid, regular margin
Isoechoic solid, regular margin
Partially cystic, eccentric solid area
≥ 1.5 cm
Very low suspicion < 3% Spongiform
Partially cystic, no suspicious features
≥ 2 cm
or F/U
Benign < 1% Cyst no FNA

ACR TI-RADS

ACR TI-RADS
• Less concerning features are awarded less or no points
• More suspicious features are awarded higher points
• Add points of all categories to determine ACR TI-RADS level
ACR TI-RADS: American college of radiology – Thyroid imaging reporting and data system

Categories of nodule features in ACR TI-RADS
Category Ultrasound features Points
Composition:
choose only one
Cystic or almost completely cystic
Spongiform: > 50% of small cystic spaces
Mixed cystic and solid
0 point
0 point
1 point
2 points
Echogenicity:
choose only one
Anechoic
Hyperechoic or isoechoic
Hypoechoic
Very hypoechoic
0 point
1 point
2 points
3 points
Shape:
choose only one
Wider-than-tall
Taller-than-wide
0 point
3 points
Margins:
choose only one
Smooth or ill-defined
Lobulated or irregular
Extra-thyroidal extension
0 point
2 points
3 points
Echogenic foci:
all that apply
No echogenic foci or large comet-tail artifacts
Macrocalcifications
Peripheral (rim) calcifications
Punctate echogenic foci (microcalcifications)
0 point
1 point
2 points
3 points

ACR TI-RADS
ACR: American college of radiology
TIRADS: Thyroid imaging reporting and data system
TI-RADS Description Points FNA
TR1 benign 0 points no FNA
TR2 not suspicious 2 points no FNA
TR3 mildly suspicious 3 points FNA if ≥ 2.5 cm
TR4 moderately suspicious 4 – 6 points FNA if ≥ 1.5 cm
TR5 highly suspicious ≥ 7 points FNA if ≥ 1 cm

Advantages and disadvantages of ARC TI-RADS
• Advantages:
Standard terms (lexicon) for ultrasound reporting
Able to classify almost all thyroid nodules
Evidence based to the greatest extent possible
• Disadvantages:
High size threshold for FNA in mild & moderate suspicious lesions
Doesn't take into consideration thyroid nodule vascularity
Doesn't take into consideration elastography

Almost completely solid (2 points) – Hyperechoic nodule (1 point)
Smooth margin (0 point) – No calcifications (0 point)
Total: 3 points – ACR TR3: mildly suspicious – FNA if ≥ 2.5 cm
Classification of thyroid nodule by ACR TI-RADS

Completely solid (2 points) – hyperechoic (1 point)
Smooth margin (0 point) – No echogenic foci (0 point)
Total: 3 points – ACR TR 3: mildly suspicious – FNA if ≥ 2.5 cm

Longitudinal ultrasound of thyroid
Completely solid nodule (2 points) – Hypoechoic (2 points)
Lobulated margin (2 points) – Microcalcifications (arrows, 3 points)
Total: 9 points – ACR TR 5: highly suspicious – FNA if ≥ 1 cm
Papillary carcinoma on FNA
ACR: American college of radiology – FNA: fine needle aspiration – TR: TIRADS

Pseudo-nodules of thyroid
• Pyramidal lobe
• Zuckerkandl tubercle
• Pseudo-nodules in Hashimoto thyroiditis
• Parathyroid adenoma
• Osteophytes
Germano A et al. Clinical imaging 2019;58:114–128.

• Frequency: 10–30% of individuals
• Remnant of thyroglossal tract
Arises from isthmus & ascends towards hyoid bone
Anterior to thyroid cartilage on midline or slightly to left
• Rarely visualized on ultrasound: small anteroposterior diameter
Can be seen when hypertrophied such as in case of Graves disease
• More commonly detected in young: progressive atrophy in adulthood
Pyramidal lobe (Lalouette lobe)

pyramidal lobe
Transverse ultrasound: pyramidal lobe simulates a nodule
Longitudinal ultrasound: pyramidal shape can be assessed
Transverse US of thyroid Sagital US of thyroid

• Lateral ingress of embryologic thyroid tissue
• Located along posterior midportion of thyroid lobe
• Ranges from small round fragment to 2–3 cm oval structure
• Becomes prominent in the setting of diffuse thyroid disease
• It may be misinterpreted as a nodule & unnecessarily biopsied
• Surgically, the tubercule can be a marker of nearby trajectory
of recurrent laryngeal nerve
Tubercle of Zuckerkandl
Embryologic remnant in posterior aspect of thyroid lobe

Hyperechoic thyroid capsule separates body of thyroid
from tubercle of Zuckerkandl
Misinterpreted as thyroid nodule which does not have capsule
Transverse US of thyroid
In: Atlas of Thyroid Ultrasonography.
Halenka M & Fryšák Z (Edits), Springer International Publishing AG, Switzerland, 2017.
Sagittal US of left lobe
Zuckerkandl tubercle

Zuckerkandl tubercle
Zuckerkandl tubercle (arrows)
Longitudinal ultrasound of right lobe

Thin & thicker fibrous septa in hypoechoic thyroid
Creating pseudonodules and parenchymal coarsening
When it is unclear if a nodule is present, FNAC may be needed
Hashimoto thyroiditis

parathyroid adenoma
Histology-proven parathyroid adenoma (arrow)
located posteriorly to thyroid, compressing thyroid parenchyma
and mimicking a thyroid nodule

osteophytes
Osteophytes posterior to lateral lobes of thyroid gland
Mimicking calcified thyroid nodules (arrows)
Can be easily ruled-out with neck X-ray
Longitudinal ultrasound of thyroid

⑥ Fine needle aspiration of thyroid nodules

Indications for FNA according to US findings
FNA: fine needle aspiration – US: ultrasound
Gharib H et al. Endocrine Practice 2016;22 (Suppl 1):1–60.
FNA
Ultrasound findings

Indications of FNA in ACR TI-RADS
• TR3 (mildly suspicious nodules): if they are ≥ 2.5 cm
• TR4 (moderately suspicious nodules): if they are ≥ 1.5 cm
• TR5 (highly suspicious nodules): if they are ≥ 1 cm
• No FNA of nodules < 1 cm even if they are highly suspicious
This is in concordance with other guidelines
FNA of 5-9 mm nodules may be done in certain conditions:
Shared decision making between referring physician and patient

Fine needle aspiration of thyroid nodules
Advantages Inexpensive, widely available, easy to perform,
accurate (>90%) and cost-effective
Disadvantages Depends on skill of operator & cytopathologist
Complications Rare – no reported case of cutaneous
implantation of malignancy following FNA
False negative rate 0.5 – 11.8% (pooled rate 2.4%)
False positive rate 0 – 7.1% (pooled rate of 1.2%)
Non-diagnostic rate Vary among different centers
5% is the maximum acceptable limit

Bethesda system for reporting thyroid cytopathology
BSRTC
Category Management
I Nondiagnostic or unsatisfactory Repeat FNAC in 3 m
II Benign Ultrasound follow-up
III Atypia of undetermined significance or
Follicular lesion of undetermined significance
Repeat FNAC in 3 m
or surgery w/o repeat FNAC
IV Follicular neoplasm or
Suspicious for follicular neoplasm
Lobectomy or
Thyroidectomy if proven malig.
V Suspicious for malignancy Lobectomy or
Thyroidectomy
VI Malignant Thyroidectomy

Complication of thyroid fine needle aspiration
1–12% of patients
In: Thyroid ultrasound – From simple to complex. Editor: Sencha AN, Springer AG, 2019.
Hematoma Sub-capsular, interfacial, inter-muscular, subcutaneous
Pain in puncture region
Usually disappears within 2 – 5 days
Injury of CCA Hematoma in CCA wall with stenosis
Injury of IJV Partial or complete thrombosis of IJV
Nerve puncture Cervical plexus: neck, shoulder & upper extremity pain
Superior laryngeal nerve: choking specially with liquids
Inferior laryngeal nerve: hoarse voice
Trachea puncture Instant dry hoarse cough for 1 – 5 min
Insignificant subcutaneous emphysema possible
Esophageal puncture Oval lesion in posterior left lobe on transverse scan
Can be misinterpreted as nodule

Complications of fine needle aspiration
Subcapsular hematoma of thyroid

interfascial hematoma

hematoma within common carotid artery wall
CCA: common carotid artery
Transverse US of CCA Longitudinal color Doppler of CCA

thrombosis of internal jugular vein
Transverse US of left thyroid lobe
Partial thrombosis of left internal jugular vein (arrow)

Conclusion
• Thyroid nodules are very common
• Vast majority of nodules are benign, hyperplastic regions of
thyroid or benign adenomas
• Minority of nodules representing a malignancy
• Sonography serves as an effective tool in determining the
need for FNA to diagnose or exclude thyroid malignancy
especially in low-risk patients

Benign features of thyroid nodules in ACR TI-RADS
Langer JE. Radiol Clin North Am 2019;57(3):469–483.
Nodule Ultrasound features Points
Composition Cystic or almost completely cystic
Spongiform: > 50% of small cystic spaces
add 0 point
add 0 point
Echogenicity Anechoic: cystic or almost completely cystic add 0 point
Shape Taller-than-wide: assessed by visual inspection add 0 point
Margin Smooth add 0 point
Echogenic foci None
Large comet-tail artifacts: >1 mm in cystic parts
add 0 point

Suspicious features of thyroid nodules in ACR TI-RADS
Nodule Ultrasound features Points
Choose only one
Composition: Mixed cystic and solid & predominantly solid
add 1 point
add 2 points
Echogenicity: Hyperechoic or isoechoic: compared to thyroid
Hypoechoic: compared to thyroid
Very hypoechoic: compared to strap muscle
add 1 point
add 2 points
add 3 points
Shape: Taller-than-wide: assessed by visual inspection add 3 points
Margin: Lobulated or irregular
Extra-thyroidal extension: obvious malignancy
add 2 points
add 3 points
Choose all that apply
Echogenic foci: Macrocalcifications: causing acoustic shadowing
Peripheral rim calcifications: eggshell
Punctate echogenic foci: mirocalcifications
add 1 point
add 2 points
add 3 points
Add points from all categories to determine ACR TI-RADS level

Ultrasound of thyroid nodules

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