High Yield Imaging · Ultrasound clinical deep dive

Thyroid & Neck Ultrasound

The neck is a superficial, high-frequency playground — and thyroid ultrasound is one of the highest-volume studies in the department. This deep dive runs from probe choice and the systematic survey, through the full ACR TI-RADS points system with its FNA size thresholds, into nodule pathology, diffuse thyroid disease, parathyroid localisation, cervical node levels, and the salivary and congenital neck masses that turn up in the same field of view.

Educational reference only. Risk-stratification points and size thresholds here follow the ACR TI-RADS (2017) white paper; other systems (ATA 2015, EU-TIRADS 2017, K-TIRADS 2021) assign features and thresholds differently, and the correct system is the one your service has adopted. TI-RADS is an integrated pattern-plus-points judgement, not a single feature, and never replaces cytology, the reporting radiologist or MDT decision-making. Sonographic features suggest probability, not diagnosis. Always confirm against the current primary source and local protocol.

1 · Technique & normalprobe · volume · echogenicity · survey 2 · ACR TI-RADSpoints · TR1–5 · FNA thresholds 3 · Nodule patternscolloid · papillary · follicular 4 · Diffuse diseaseGraves · Hashimoto · goitre 5 · Parathyroid & nodesadenoma · levels · benign vs malignant 6 · Salivary & neck massesparotid · cysts · abscess 7 · Pro trackreporting · FNA · workflow

Technique & normal appearances

The thyroid sits 1–3 cm deep — the domain of a high-frequency linear array. Patient supine, neck extended over a pillow/roll under the shoulders. Scan both lobes and the isthmus in transverse and longitudinal planes, then sweep the lateral neck compartments. Use the strap muscles and common carotid as internal landmarks.

Transverse survey at mid-gland. Normal thyroid parenchyma is homogeneous and hyperechoic relative to the adjacent strap muscles. Trachea (air, dirty shadow) medially, common carotid and IJV laterally, longus colli posteriorly — the bed in which a parathyroid adenoma hides.

Probe & settings

Transducer: High-frequency linear array, 7.5–15 MHz (12–15 MHz for detail; drop to 7–9 MHz or add a curvilinear probe for a large/substernal goitre or deep node).
Position: Supine, neck extended over a shoulder roll; turn the chin away from the side scanned. Sitting/swallowing manoeuvres help assess substernal extension and fixation.
Optimise: Focal zone at the gland, adequate depth to see longus colli, harmonics on, spatial compounding for margins. Add colour/power Doppler for vascularity; measure with the smallest reliable calipers.

Normal dimensions & volume

Parameter	Typical adult normal	Note
Lobe length (cranio-caudal)	4–6 cm	Longitudinal plane, pole to pole
Lobe AP & transverse	1.3–2.0 cm each	AP > ~2 cm suggests enlargement
Isthmus thickness	< 3–5 mm	Measured AP over the trachea
Total gland volume	~7–11 mL (women), ~8–15 mL (men)	Upper limit ~18 mL used by many labs; population/iodine-dependent

Lobe volume (mL) = Length × Width × Depth × 0.523 → gland volume = right + left lobe

The 0.523 (≈ π/6) ellipsoid correction factor is the same one used for prostate and other organ volumes. Some labs use 0.479–0.52; the isthmus is usually excluded unless prominent.

Echogenicity reference. Grade thyroid echogenicity against the strap muscles (and secondarily the submandibular gland). Normal parenchyma is clearly brighter than strap muscle. “Hypoechoic” nodules are darker than parenchyma; “very hypoechoic” are darker than the strap muscles — a distinction that scores differently in TI-RADS.

Vascularity

Normal parenchyma shows sparse, orderly colour flow. Diffuse hypervascularity (“thyroid inferno”) points to Graves; nodular internal vascularity is assessed but — unlike older Chammas patterns — is not part of ACR TI-RADS scoring.

Systematic neck survey

Both lobes + isthmus — transverse then longitudinal; document dimensions, echogenicity, any nodules with location, size (3 planes) and TI-RADS features.
Retrotracheal / substernal — sweep inferiorly with swallowing; note if the lower pole is not seen (report as limitation).
Central compartment (level VI) — pretracheal/paratracheal nodes, especially in known thyroid cancer.
Lateral compartments (levels II–IV, and V) — along the IJV/carotid; assess nodes for hilum, shape and vascularity.
Parathyroid beds — posterior to the poles, anterior to longus colli, in the setting of hypercalcaemia.
Salivary glands & midline — submandibular/parotid if symptomatic; midline for thyroglossal duct cyst.

Free

The full reporting & FNA workflow is in the Pro track

This overview is free. Pro members get the structured report template, TI-RADS worksheet, FNA technique and Bethesda correlation, and the post-thyroidectomy surveillance protocol.

Structured thyroid report skeleton
TI-RADS scoring worksheet (printable)
US-guided FNA technique & safety
Bethesda categories & management
Node mapping for cancer staging
Reporting pitfalls & medico-legal notes

See the Pro track →

Nodule assessment & ACR TI-RADS

ACR TI-RADS scores five categories. You may pick one point value from each of composition, echogenicity, shape and margin, and add all applicable echogenic-foci points. Sum the total, map to a TR level, then apply the size threshold to decide FNA versus follow-up versus no action.

The points system

Category	Feature	Points
Composition pick one	Cystic or almost completely cystic	0
	Spongiform	0
	Mixed cystic and solid	1
	Solid or almost completely solid	2
Echogenicity pick one	Anechoic	0
	Hyperechoic or isoechoic	1
	Hypoechoic	2
	Very hypoechoic (darker than strap muscle)	3
Shape pick one	Wider-than-tall	0
Shape pick one	Taller-than-wide (on transverse image)	3
Margin pick one	Smooth	0
	Ill-defined	0
	Lobulated or irregular	2
	Extrathyroidal extension	3
Echogenic foci add all that apply	None / large comet-tail artifact	0
	Macrocalcifications	1
	Peripheral (rim) calcifications	2
	Punctate echogenic foci (microcalcifications)	3

Composition scored 0 for cystic/spongiform stops there for those two — a purely cystic or spongiform nodule is TR1. “Very hypoechoic” is judged against the strap muscles, not just the parenchyma. Large comet-tail (>1 mm) = benign colloid, scores 0; punctate foci without comet tail are the malignant microcalcification pattern.

Total points → TR level → action

Level	Points	Risk category	FNA threshold	Follow-up (no FNA)
TR1	0	Benign	No FNA	None
TR2	2	Not suspicious	No FNA	None
TR3	3	Mildly suspicious	FNA if ≥ 2.5 cm	Follow at ≥ 1.5 cm
TR4	4–6	Moderately suspicious	FNA if ≥ 1.5 cm	Follow at ≥ 1.0 cm
TR5	≥ 7	Highly suspicious	FNA if ≥ 1.0 cm	Follow at ≥ 0.5 cm

Reporting rule: report and manage up to the 2 highest-scoring nodules per TR level (ACR white paper), not every tiny nodule. Follow-up imaging is at defined intervals (e.g. TR3 at 1, 3, 5 yr; TR4 at 1, 2, 3, 5 yr; TR5 annually to 5 yr). A nodule below its FNA threshold but above its follow-up threshold is surveilled, not aspirated.

Watch-outs. Extrathyroidal extension, suspicious cervical nodes, or a history of neck irradiation lower the threshold to biopsy regardless of the tidy points. Microcalcifications in a solid hypoechoic taller-than-wide nodule is the classic papillary quartet and easily reaches TR5.

Worked example

Solid (2) + very hypoechoic (3) + taller-than-wide (3) + lobulated margin (2) + punctate foci (3) = 13 points → TR5. At 1.1 cm this crosses the ≥ 1.0 cm TR5 threshold → recommend FNA.

How other systems differ

ATA 2015

Pattern-based (not points): benign → very-low → low → intermediate → high suspicion, with size cut-offs for FNA (e.g. ≥ 1 cm high-suspicion, ≥ 1.5 cm low/intermediate, ≥ 2 cm very-low/spongiform). Endocrine-society favourite.

EU-TIRADS 2017

Five categories (1 normal → 5 high risk) driven by pattern; high-risk features are the same “big four” (marked hypoechogenicity, irregular margin, microcalcification, taller-than-wide). FNA generally ≥ 1 cm for EU-TIRADS 5, ≥ 1.5 cm for 4, ≥ 2 cm for 3.

K-TIRADS

Korean system; pattern + component. FNA thresholds are larger (e.g. ≥ 1 cm high-suspicion, ≥ 1.5 cm intermediate, ≥ 2 cm low). Tends to biopsy fewer small nodules than early ACR practice.

Common thread

All four converge on the same malignant features — solid, hypoechoic, irregular margin, taller-than-wide, microcalcifications — and all use the nodule size to gate biopsy. They differ mainly in how they combine features and where the size cut-offs sit.

Nodule patterns & pathology

TI-RADS scores features; pathology gives them meaning. These are the archetypal sonographic patterns — benign colloid/spongiform through the four main thyroid cancers and their aggressive cousins.

Benign patterns Thyroid cancers Cystic change & pitfalls

Colloid nodule benign

Appearance: Iso/hyperechoic, often mixed cystic-solid; comet-tail artifacts from inspissated colloid crystals are the giveaway (bright foci with a V-shaped reverberation trail).
TI-RADS: Usually TR1–TR2; comet-tail scores 0 for foci.

Spongiform nodule benign

Appearance: Aggregation of multiple microcystic spaces occupying > 50% of the nodule — a “bag of bubbles”. Essentially always benign.
TI-RADS: Composition scores 0 → TR1, no FNA.

Hyperplastic / multinodular goitre nodules benign

Appearance: Multiple nodules of mixed echogenicity, often with cystic change, a “giraffe-skin”/halo pattern; peripheral egg-shell macrocalcification is common in long-standing disease.
Caveat: Score each dominant/suspicious nodule on its own merits — cancer can hide in a busy MNG.

Papillary thyroid carcinoma (PTC) most common

Pattern: Solid, hypoechoic, taller-than-wide, irregular/lobulated margin, punctate microcalcifications — the classic quartet; readily TR5.
Spread: Lymphatic → look hard at levels III/IV/VI nodes; cystic nodal metastases with punctate foci are characteristic.

Follicular carcinoma imaging-poor

Pattern: Often iso/hyperechoic, solid, with a thick irregular halo; frequently looks bland. Cannot be distinguished from follicular adenoma on US or cytology — diagnosis needs capsular/vascular invasion on histology.
Spread: Haematogenous (lung, bone) rather than nodal.

Medullary carcinoma (MTC) C-cell

Pattern: Solid hypoechoic mass, often with coarse/dense calcifications (amyloid); may be multifocal in MEN2. Raised calcitonin/CEA.
Spread: Early nodal (central then lateral) and haematogenous.

Anaplastic carcinoma aggressive

Pattern: Large, rapidly growing, markedly hypoechoic infiltrative mass with extrathyroidal extension, encasing vessels/trachea; nodal and distant disease at presentation. Elderly patients.

Primary thyroid lymphoma Hashimoto link

Pattern: Very hypoechoic (almost anechoic, “pseudocystic”) lobulated mass with posterior enhancement, arising on a background of Hashimoto thyroiditis; rapid enlargement. Diagnosed by core biopsy, not FNA.

Cystic degeneration

Benign nodules commonly undergo haemorrhagic/cystic change. Anechoic areas with layering debris, thin septa and comet-tail foci favour benign colloid. Beware the partially cystic nodule with an eccentric solid mural component that has microcalcifications, lobulated margins or vascularity — that solid part can be PTC and should be scored/aspirated on its own.

Reading pitfalls

Comet-tail vs microcalcification: comet-tail = benign colloid (score 0); non-shadowing punctate foci = suspicious (score 3).
Taller-than-wide is judged on the transverse image and is most meaningful in small nodules.
A thick, irregular, incomplete halo is more worrying than a thin complete one.
Isthmus nodules and those abutting the capsule need careful extrathyroidal-extension assessment.

Diffuse thyroid disease

Not everything is a nodule. Diffuse change in parenchymal echogenicity, texture and vascularity tells its own story — and correlates with thyroid function tests and antibodies.

Hyperthyroid Hypothyroid / autoimmune Painful / goitre

Graves disease

Grey-scale: Diffusely enlarged gland, diffusely hypoechoic and heterogeneous (lymphocytic infiltrate).
Doppler: “Thyroid inferno” — markedly increased, diffuse pulsatile colour flow throughout the gland; raised peak systolic velocity in the inferior thyroid artery.
Correlates: Hyperthyroid, TRAb positive; helps distinguish Graves from destructive/low-uptake thyroiditis when scintigraphy is unavailable.

Hashimoto (chronic lymphocytic) thyroiditis

Grey-scale: Heterogeneous, hypoechoic, coarsened parenchyma with micronodulation (1–6 mm hypoechoic nodules separated by echogenic septa) and fibrous echogenic bands; gland may be enlarged early, atrophic late.
Pseudonodules: Islands of relatively spared parenchyma mimic nodules — the classic “give-away” that they follow the texture, lack a discrete margin and have no suspicious features.
Doppler / correlates: Variable flow (can be increased in “hashitoxicosis”); anti-TPO positive. Raises baseline risk of primary thyroid lymphoma and papillary carcinoma — score any discrete suspicious nodule normally.

Subacute (de Quervain) granulomatous thyroiditis

Grey-scale: Ill-defined, geographic hypoechoic areas (“map-like”), often migrating between lobes; painful, tender on transducer pressure; post-viral.
Doppler: Normal or reduced flow in affected areas (unlike the hypervascular Graves) — helps differentiate. Usually self-limiting.

Simple / multinodular goitre

Grey-scale: Diffuse or nodular enlargement; assess total volume, substernal extension (scan with swallowing), tracheal deviation/compression, and score dominant nodules with TI-RADS.
Reporting: Note the largest nodule, any suspicious nodule, tracheal narrowing and whether the lower poles are fully imaged.

Parathyroid & cervical lymph nodes

Parathyroid adenoma

Setting: Primary hyperparathyroidism (raised calcium + raised/inappropriate PTH). Single adenoma ~85% of cases; localisation is for the surgeon, not diagnosis.
Grey-scale: Discrete, oval, markedly hypoechoic nodule posterior to the thyroid, anterior to the longus colli, often medial to the common carotid; separate from thyroid parenchyma by a bright echogenic line/capsule.
Doppler: Polar vessel sign — a prominent extrathyroidal feeding artery (branch of the inferior thyroid artery) entering at a pole, with a peripheral vascular arc. A hypervascular pattern helps separate it from a lymph node.
Locations: Inferior glands near the lower pole (commonest); superior glands more posterior. Ectopic sites: retrotracheal, intrathyroidal, thyrothymic tract, mediastinum — a normal US does not exclude an adenoma.

Localisation pearl: US is combined with Tc-99m sestamibi scintigraphy (± SPECT/CT) and increasingly 4D-CT. Concordant US + sestamibi enables minimally invasive parathyroidectomy with intraoperative PTH monitoring.

Mimics. A cervical lymph node (has a hilum), an exophytic posterior thyroid nodule, oesophagus (peristalsis, target sign on transverse — ask the patient to swallow), and longus colli muscle. Colour Doppler and swallowing manoeuvres sort most of these out.

Cervical lymph node assessment

Benign node keeps its oval shape, thin cortex and central fatty hilum with hilar vascularity. Malignant nodes become round, lose the hilum, thicken the cortex (often eccentrically), and gain peripheral/mixed vascularity, cystic change or microcalcification.

Feature	Benign / reactive	Suspicious / malignant
Shape (S/L ratio)	Oval, S/L < 0.5	Round, S/L > 0.5
Hilum	Echogenic fatty hilum present	Loss/absent hilum
Cortex	Thin, uniform	Thick (> 3 mm), eccentric/focal
Echotexture	Homogeneous, iso/hypoechoic	Cystic necrosis; hyperechoic (PTC met)
Calcification	None	Punctate microcalcification
Vascularity (Doppler)	Hilar / central	Peripheral / mixed, chaotic
Borders / matting	Well-defined, discrete	Extracapsular spread, matted, fixed

The single most useful benign sign is a preserved fatty hilum with hilar flow; the most specific malignant signs are cystic change, microcalcification, loss of hilum and peripheral vascularity — the last is due to tumour-driven angiogenesis. Cystic and microcalcified lateral nodes strongly suggest PTC metastasis.

Neck node levels (I–VI)

Level	Location	Typical drainage
I (Ia/Ib)	Submental / submandibular	Floor of mouth, lip, anterior tongue, submandibular gland
II	Upper jugular (skull base → hyoid)	Oropharynx, oral cavity, parotid
III	Mid jugular (hyoid → cricoid)	Larynx, hypopharynx, thyroid
IV	Lower jugular (cricoid → clavicle)	Thyroid, hypopharynx, cervical oesophagus
V (Va/Vb)	Posterior triangle	Nasopharynx, scalp, thyroid
VI	Central compartment (pretracheal/paratracheal)	Thyroid, larynx, hypopharynx

Levels VI (central) and III/IV then II (lateral) are the key stations in thyroid cancer surveillance. Map and measure suspicious nodes, mark the level, and consider US-guided FNA with a washout for thyroglobulin (or calcitonin for MTC).

Salivary glands & other neck masses

The same linear probe and the same field of view pick up salivary and congenital neck pathology. A quick mental map keeps you from calling a branchial cleft cyst a node.

Salivary glands

Sialolithiasis

Echogenic focus with posterior acoustic shadowing in a duct, usually the submandibular (Wharton) duct (~80–90% of stones); look for proximal ductal dilatation. Scan during salivary stimulation.

Sialadenitis

Acute: enlarged, hypoechoic, hypervascular gland ± dilated ducts, abscess if focal fluid collection. Chronic: small, heterogeneous, atrophic gland. Autoimmune (Sjögren) → multiple small hypoechoic/cystic foci, “leopard-skin/salt-and-pepper” pattern.

Pleomorphic adenoma commonest tumour

Well-defined, hypoechoic, lobulated mass with posterior enhancement, usually in the parotid; may calcify. Slow-growing; small risk of malignant transformation over time.

Warthin tumour 2nd commonest

Well-defined hypoechoic mass with cystic/anechoic spaces, often in the parotid tail; frequently bilateral/multifocal; smokers. Increased internal vascularity.

Malignant salivary features: ill-defined/irregular margins, infiltration, heterogeneity, associated suspicious nodes. Small (< 2 cm) parotid tumours are hard to characterise on US alone — FNA/core and MRI often follow.

Congenital & inflammatory neck masses

Thyroglossal duct cyst

Midline (or paramedian), infrahyoid anechoic/hypoechoic cyst, embedded in or deep to the strap muscles, moving with tongue protrusion/swallowing. Internal echoes if infected/proteinaceous. A solid mural nodule raises the rare thyroglossal-duct carcinoma.

Branchial cleft cyst

Second-cleft is commonest: lateral cyst at the mandibular angle, anterior to sternocleidomastoid, posterolateral to the submandibular gland, lateral to the carotid space. Anechoic when uncomplicated; debris/pseudosolid when infected.

Neck abscess

Complex, thick-walled collection with internal debris/septa, posterior enhancement and peripheral hypervascularity with an avascular necrotic centre; ± gas (dirty shadowing). Often from suppurative adenitis. US guides aspiration/drainage.

Other

Lipoma (compressible, striated, mid-echogenicity), lymphatic/venous malformation (cystic ± fluid-fluid levels), carotid body tumour (splaying of the carotid bifurcation, hypervascular), and nerve sheath tumours. Correlate location with the level anatomy.

Free

Neck-mass work-up algorithm & report phrases are in the Pro track

Pro members get the age-based cystic-neck-mass algorithm (branchial cleft vs necrotic node vs abscess), the salivary-mass decision tree, and copy-paste report impressions for each entity.

See the Pro track →

Pro track — reporting, FNA & workflow

The free tabs cover the imaging. The Pro track turns it into a defensible report and a safe procedure.

What Pro members get

Structured thyroid & neck report template (dimensions, echogenicity, per-nodule TI-RADS, node map)
Printable TI-RADS scoring worksheet with the interval-follow-up calendar
US-guided FNA: consent, technique, sample handling, anticoagulation checks, complications
Bethesda I–VI categories with malignancy risk and management
Post-thyroidectomy surveillance protocol (bed + node levels, thyroglobulin washout)
Parathyroid localisation checklist (US + sestamibi + 4D-CT concordance)
ATA / EU-TIRADS / K-TIRADS quick-convert reference card
Neck-mass differential algorithms & report impression phrase-bank

What Pro will include →

Free preview. Two things every report should state: (1) the TR level, size in 3 planes and location of each managed nodule with an explicit FNA/follow-up recommendation, and (2) a clear limitation line if the lower poles or a substernal component were not fully imaged. Everything else in the template builds on those two.

References & further reading

Tessler FN, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. J Am Coll Radiol 2017;14(5):587–595.
American College of Radiology. TI-RADS — Clinical Resources. acr.org/Clinical-Resources/Reporting-and-Data-Systems/TI-RADS.
Haugen BR, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid 2016;26(1):1–133.
Russ G, et al. European Thyroid Association Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules (EU-TIRADS). Eur Thyroid J 2017;6(5):225–237.
Ha EJ, et al. 2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules (K-TIRADS). Korean J Radiol 2021;22(12):2094–2123.
The Radiology Assistant. TI-RADS — Thyroid Imaging Reporting and Data System. radiologyassistant.nl/head-neck/ti-rads.
Radiopaedia. Thyroid Imaging Reporting and Data System (ACR TI-RADS). radiopaedia.org.
Radiopaedia. Thyroid gland (normal ultrasound). radiopaedia.org.
Chaudhary V, Bano S. Thyroid ultrasound. Indian J Endocrinol Metab 2013;17(2):219–227.
Ha EJ, Baek JH. Applications of machine learning and deep learning to thyroid imaging: normal appearances & volume. (normal dimension/volume reference).
Moon WJ, et al. Benign and malignant thyroid nodules: US differentiation — multicentre retrospective study. Radiology 2008;247(3):762–770.
Hoang JK, et al. US features of thyroid malignancy: pearls and pitfalls. RadioGraphics 2007;27(3):847–860.
Frates MC, et al. Management of thyroid nodules detected at US: SRU consensus statement. Radiology 2005;237(3):794–800.
Ahuja AT, et al. Ultrasound of malignant cervical lymph nodes. Cancer Imaging 2008;8(1):48–56.
Radiopaedia. Cervical lymph node (ultrasound features of malignancy). radiopaedia.org.
Som PM, et al. Imaging-based nodal classification for evaluation of neck metastatic adenopathy (levels I–VI). AJR 2000;174(3):837–844.
Kamaya A, et al. Sonographic features of parathyroid adenomas. Ultrasound Q 2006.
Radiopaedia. Parathyroid adenoma (polar vessel sign). radiopaedia.org.
Johnson NA, et al. Parathyroid imaging: technique and role in the preoperative evaluation of primary hyperparathyroidism. AJR 2007;188(6):1706–1715.
Bhatia KSS, et al. Ultrasound of thyroid diffuse disease (Graves, Hashimoto, de Quervain). Clin Radiol.
Radiopaedia. Hashimoto thyroiditis / Graves disease / subacute thyroiditis (ultrasound). radiopaedia.org.
Bialek EJ, et al. US of the major salivary glands: anatomy and spatial relationships, pathologic conditions, and pitfalls. RadioGraphics 2006;26(3):745–763.
Ahuja AT, Evans RM. Practical Head and Neck Ultrasound. Cambridge University Press.
Koeller KK, et al. Congenital cystic masses of the neck: radiologic-pathologic correlation. RadioGraphics 1999;19(1):121–146.
Grant EG, et al. Thyroid Ultrasound Reporting Lexicon: White Paper of the ACR Thyroid Imaging, Reporting and Data System (TIRADS) Committee. J Am Coll Radiol 2015;12(12):1272–1279.

High Yield Imaging · Thyroid & Neck Deep Dive. Educational content — not a substitute for formal training, local protocols, cytology or a reporting physician. Thresholds and points follow the cited primary sources and may be updated; always confirm against the current guideline in use at your service.

Calculators for this topic

Ellipsoid volume