AACE 2017

Principles of Endocrine NeckSonography Course™

ANATOMY and ULTRASOUND PATHOLOGY

Neck Anatomy Derived from endodermal

tissue at base of tongue

Named after the thyroid cartilage (Greek: Shield)

1st gland to develop – day 24

Embryonal remnants form Thyroglossal duct; pyramidal lobe; lingual thyroid

Fuse with C-cells (neural crest origin)

C-cells scattered through posterior/superior lobes

Wharton 1656: “purpose is to… beautify the neck…particularly in females”

Thyroid Embryology

• Initial descent occurs anterior to

pharyngeal gut

• Connected to the base of tongue via

thyroglossal duct. Obliterates entirely in

7-10th week of gestation

• Remnants:

Thyroglossal duct cyst

Lingual thyroid (base of tongue)

Thyroid Anatomy

• Largest endocrine

gland (20 - 25 g)

• Fills tracheo-

esophageal space

• Overlies RLN

bilaterally

• Parathyroids

typically lie at each

pole

Thyroid Ultrasonography

• Extension of physical exam

• To the thyroidologist as the stethoscope/

echocardiogram to the cardiologist

• “Real time” information to the clinician

• Very sensitive tool. Can detect nodules

only 2-3 mm in size. Lacks specificity

Thyroid Ultrasonography

Advantages

Painless

No radiation or contrast material

Less expensive than CT / MRI

May use in pregnancy

Most sensitive modality for thyroid

nodules

Best imaging for guided FNA

Isthmus Sternohyoid muscle

Sternothyroid muscle

Omohyoid muscle

tracheaSternocleidomastoid muscle

Internal jugular vein

Carotid artery

esophagus

Parathyroid gland

Longus colli muscle

Normal Thyroid – Composite View

CA

SCMStrap

TrachIJ

EsophLCM

R Lobe L Lobe

Normal Thyroid – R Transverse

High

Mid

Low

Normal Thyroid – L Transverse

High

Mid

Low

Appearance of

the Esophagus (post thyroidectomy)

Normal Thyroid – R Sagittal

Lateral

Mid

Medial

Thyroid Echogenicity

Normal thyroid: High intensity

homogeneous echo pattern

with little identifiable internal

architecture

Muscles located anteriorly

and anterolaterally are less

echogenic (“hypoechoic”)

Hashimoto’s thyroiditis - Note heterogeneous (hypoechoic) echotexture

Diffuse Goiter

Normal isthmus <0.5cm

Measurement of ThyroidWidth and Depth

Measurement of ThyroidLength

Volume = p/6(WxDxL)

Pyramidal Lobe

Som et al, AJR 174:837 2003

Surgical Levels of the Neck

Typical location of Parathyroid Glands

Summary

Ultrasound is an anatomic imaging tool, whose utility requires a thorough understanding of neck anatomy

Ultrasound does not generate pre-defined image planes, and is therefore highly operator dependent

Ultrasound is a functional imaging tool, through inquisition of blood flow patterns by Doppler

Ultrasound is a real-time imaging tool, which permits accurate localization of biopsy needles

Nodular Disease (more to come later)

Benign Malignant

Diffuse Goiter Iodine deficient Organification Defects Thyroiditis/Graves Riedel’s Struma Lymphoma, Metastatic Disease (nonthyroid primary)

Miscellaneous Malformations Vascular anomalies

Causes of Diffuse Thyroid Disease

Patterns of Hashimoto’s Thyroiditis

Nodules versus Pseudonodules

Doppler Evaluation of Thyrotoxicosis

Ultrasound Follow-up of Thyroiditis

Euthyroid- normal TSH, most common form

Atrophic

Goitrous

Typical Hashimoto’s US changes

50% with positive anti-TPO abs

Hypothyroid- high TSH

Atrophic, Fibrotic

Goitrous

90% with anti-TPO abs

Hyperthyroid- Hashitoxicosis

Goitrous with immune-mediated thyroid hormone spillage

Mild tenderness if any Typical echo heterogeneity with reactive LN’s +/- fibrosis Positive TG or anti-TPO abs and no thyroid stimulating

immunoglobulins High TG Modest vascularity compared to Graves’ gland

Transient TSH suppression

May have a history of previous hypothyroidism US shows typical Hashimoto’s changes in a normal sized or

enlarged gland

Hyperthyroid

Soft diffuse goiter

TSI elevated with anti-TPO abs negative or low titer

US shows hypervascular, hypoechoic, hyperplastic gland with less LN enlargement than Hashimoto’s

RAIU usually quite elevated

Associated eye and skin manifestations

Hypothyroid after RAI or gland burnout

Firm/rubbery, atrophied gland, often with nodules

US shows densely hypoechoic, diffusely heterogenoeusappearance with hypovascularity, scarring/fibrosis

Graves Disease, Hashitoxicosis and Hashimoto’s

Graves’ and Hash exhibit different antibody profiles but commonly there is antibody overlap

Graves’ ultrasonographic appearance is classically an enlarged, hypervascular diffusely hypoechoic gland, but unadulterated Graves’ is infrequent

Typical Hashitoxicosis or Hashimoto’s ultrasonographic appearance is heterogeneous with scarring

Vascularity– all patterns possible

Mildly Hypoechoic and Heterogeneous

Micronodular

Swiss Cheese

Macropseudonodular

Profoundly hypoechoic and developing fibrosis

Hyperechoic

Bonavita JA, Mayo J, Babb J et al. AJR: 2009, 193:207-213.

Speckled – be careful here

Multiple prominent nodes in central and lateral neck

Matted clustered nodes Often with abnormal shape and loss of hilar line

Location

Delphic area on and above the isthmus

Paratracheal nodes below the thyroid and at the lower poles

Typically enlarged gland with heterogeneity

May be hypoechoic or iso/hyperechoic

Increased blood flow in contrast to thyroiditis which usually has low flow

Detect nodules not felt on palpation and not seen on I-123 scan Cancer in Graves may have more aggressive biology

May be cost effective to do US in all GD patients

Cappelli C et al, Eur J Rad 2008; 65;99-103

Note the resemblance to speckled Hashimoto’s

Lymph nodeRight neckCompartment III

Note the resemblance to speckled Hashimoto’s

Note the resemblance to speckled Hashimoto’s

Bonavita JA, Mayo J, Babb J et al. AJR: 2009, 193:207-213.

Note the resemblance to speckled Hashimoto’s

Echogenicity of “nodule” similar to the unaffected thyroid parenchyma

No vascular shadow / ring / halo

Nodule shrinks with time and continued observation

Margins vague or absent

“Nodule” often not seen well in in one of the two views

Linear fibrosis often seen around “nodule”, and in the rest of the thyroid

There may be a higher prevalence of PTC in patients with Hashimoto’s Thyroiditis

The heterogeneous echotexture may make identifying nodules more difficult

In general, sonographic appearance of PTC in CLT is same as seen in normal thyroids

May be tendency towards denser calcification

If there is doubt, perform FNA Gul K, Dirikoc A, Kiyak G et al. Thyroid 2010; 20:873-8.Fiore E, Rago T, Latrofa F, et al. Endocr Relat Cancer. 2011;18(4):429-37

Anderson L, Middleton W, et al. AJR: 195, 216-222, 2010.Ohmori N, Miyakawa M, Ohmori K, et al. Intern Med 2007;46(9):547-50

Autoimmune thyroiditis is very common and has myriad forms Hypoechoic and heterogeneous US pattern is the most

common

Autoimmune thyroiditis represents a broad spectrum of thyroid disease

Thyroid nodules are common in autoimmune glands and knowing which ones to biopsy is key to being a competent thyroidologist

Thyroid cancer is not uncommon in autoimmune glands

Progressive growth of a goiter or of (pseudo)nodules should raise suspicion for a neoplastic process

Rare form of autoimmune thyroiditis

May present as a systemic disease characterized by fibrosis and lymphocytic infiltration of the retroperitoneum, mediastinum, biliary system, and orbits

Only 30% are hypothyroid

Some have hypocalcemia due to infiltration of parathyroids

Considered to be the most severe manifestation of IgG4 disease

Avoid surgery, except for diagnostic biopsy or debulking when needed

Infiltrative and hypoechoic

Diffuse or focal hypoechoic areas with irregular boundaries

Hold off on FNA if clinical suspicion suggests non-Hashimotoid thyroiditis- RTC 6-8 weeks Hyperthyroid Fever, past viral infection (6-8 weeks) and thyroid

tenderness suggest sub-acute (findings will resolve)

In thyrotoxic patient the absence of flow suggests thyroiditis, but high intensity flow can be seen in either Graves or thyroiditis of any causality

Extremely tender gland- often dramatic

Varying degree of goiter Preexisting and inflammatory

Systemic toxicity- FUO common Can masquerade as endocarditis, vasculitis

Transient thyrotoxic phase

Subsequent hypothyroid phase 95% recovery

Often focal, or multifocal

Painless, postpartum variants

At presentation

Six month follow-up

Six Weeks Later

Doppler used to help differentiate Type 1 vs Type 2 Amiodarone Induced Thyrotoxicosis

Graves’ Disease – Thyroid Inferno

Destructive Thyroiditis –

Usually Low Vascularity

Can Doppler be used to distinguish painless/postpartum thyroiditis from Graves’?

Arises in thyroid already affected by Hashimoto’s thyroiditis

Ultrasonographic appearance deeply hypoechoic.

Appearance not significantly different than in Hashimoto’s

Rapid growth of goiter should raise suspicion

Diagnosis by cytology and flow cytometry

Image courtesy of Woody Sistrunk, MD, FACE

NODULAR LYMPHOMA

Malformations

Hemiagenesis

Thyroglossal Duct Cyst

Vascular

Varicosities

Hemangioma

Anatomical Variants

Hemiagenesis of Left Lobe

SCM SCM

C C

strapstrap

R lobe

Hashimoto’s with Hemiagenesis

Multinodular Goiter ???

SAGITTAL TRANSVERSE

Thyroglossal Duct Remnant Hyoid

Sistrunk Procedure

SAGITTAL LEFT THYROID TRANS LEFT THYROID

L THY TIPTHYMUS

ESOPHC SPINE

THYMUS

ESOPH

Muscle

Biopsy Proven Scar Tissue

Transverse Longitudinal

C

TR

J

Lateral Thyroid Rest

Rim of normal

thyroid tissue

Metastatic Squamous Cell Carcinoma

Transverse Longitudinal

Hemangioma

Tubercle of Zuckerkandl

Superior Parathyroid

Gland

Tubercle of Zuckerkandl

Transverse Longitudinal

Diffuse Thyroid Disease is a common finding in Clinical Thyroidology

AITD often mimics nodular thyroid disease

Careful ultrasound can help distinguish nodules that need FNA from those that can be observed

Doppler findings are variable, but may be helpful in the evaluation of thyrotoxicosis