Thyroid, Parathyroid, and
Neck
Tanya Nolan
Thyroid Gland Anatomy
Anatomic Variations
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Thyroglossal Duct
Cyst
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Athyrosis
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Thyroglossal duct fails to
involute completely
Absence of Thyroid gland
Pyramidal Lobe
Absence of
Isthmus
Ectopic Gland
Neck Anatomy
Normal Anatomy
Normal Anatomy
Function and Physiology
Maintains body metabolism, growth, and
development
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synthesis, storage, & secretion of thyroid
hormones
1.
2.
3.
Thyroid gland traps iodine (used for synthesis)
Produces triiodothyronine (T3) & thyroxine (T4)
Thyroid hormone released into bloodstream via action
of thyrotopin (TSH) produced by the pituitary gland
Thyroxine (T4)
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Iodine + Tyrosine (amino acid)
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Combines with protein thyroglobulin & stored.
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Increases carbohydrate burn
Breaks down proteins for energy
Regulates fat metabolism
Accelerates body growth (especially nervous tissue)
Increases nervous system reactivity
Calcitonin
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Produced by parafollicular cells (C cells of
thyroid gland) in response to high calcium
levels
Decreases the concentration of calcium in
the blood by inhibiting bone break down (less
Ca absorbed)
What happens when blood
Calcium concentrations are
HIGH?
Thyroid Stimulating Hormone
(TSH)
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Produced by the
anterior pituitary gland
Regulated by the
thyrotropin-releasing
factor (TRF) produced
by the hypothalmus
TRF regulated by the
basal metabolic rate.
Feedback System
>Decreased Metabolic Rate
LOW OR HIGH Concentration of Thyroid
Hormone (Thyroxine)?
>Hypothalmus releases Thyrotropin-Releasing
Factor(TRF)
Thyroid Stimulating Hormone (TSH)
Released by __________?
>Increase in Thyroid Hormone
Blood Concentration Normal
Basal Metabolic Rate Normal
Lab Tests

Nuclear Medicine
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Most accurate for T3 & T4 levels.
Radioactive iodine injected into
the bloodstream & % of uptake
monitored by gamma camera.
HOT NODULE: A
hyperfunctioning nodule or
COLD NODULE: hypoactive
nodule.
What type of nodule is
MOST suspicious of
carcinoma?
Lab Tests
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Triiodothyronine (T3)
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Serum Thyroxine (T4)
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Normal Serum T4: 5-11 mg/dl.
Elevated levels seen in hyperthyroidism and acute thyroiditis.
Low levels are seen in hypothyroidism, myxedema, cretinism, chronic
thyroiditis, and occasionally in subacute thyroiditis.
Serum Calcitonin
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Normal RIA 80-160 ng/dl; RU: 25-35% relative uptake
Elevated levels of calcitonin are diagnostic of medullary carcinoma of
the thyroid
Serum Thyroid Stimulating Hormone

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Normal Serum TSH < 5mU/ml
TSH level is indicative of thyroid reserve. It is the most accurate test
for primary hypothyroidism
Indications for
Sonographic Examination
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Palpable enlargement
Abnormal Thyroid Hormone Level(s)
Palpable mass in neck / thyroid
Swelling of neck
Asymmetry of neck
Redness and/or tenderness
Sonographic Technique

Equipment
High frequency (7.5-15 MHz or higher) linear
Transducer
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Patient Position
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Supine with neck extended
Views
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Longitudinal and Transverse images of bilateral
lobes & Transverse view of the isthmus
Demonstrate relational anatomy
Normal
Thyroid
Newborn: 18-20
mm long; 8-9 mm
AP
Age 1: 25 mm
long; 12-15 mm AP
Adult Thyroid
40-60 mm long
13-18 mm AP
Isthmus 4-6 mm AP
Nontoxic Goiter
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Simple, Colloid, or Multinodular
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Enlargement of entire gland without
producing nodularity and without evidence of
functional disturbance (euthyroid)
Causes
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Lack of Iodine
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Sporatic Goiter
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Compensatory increase of TSH = follicular cell
hypertrophy
Diffuse, Uninodular, or multinodular
Ingestion of Substances, hereditary enzyme
defects
Simple Goiters may evolve =
Multinodular Goiters

Calcification, Degeneration, Fibrosis,
and Hemorrhage
Thyrotoxicosis / Hyperthyroidism
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Over secretion of thyroid hormones
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Clinical Signs
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Dramatic increase in metabolic rate
Weight Loss
Increased appetite
Nervous energy
Tremor
Excessive sweating
Heat intolerance
Cardiac Palpitations
Exopthalmos (protruding eyes)
Causes
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Abnormal hormone secretion (entire gland out of control)
Localized neoplasm caused by overproduction of hormones
Grave’s disease
Toxic Multinodular Goiter
“Grave’s Disease”
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Clinical Signs
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Causes
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Women over 30
Hypermetabolism
Exopthalmos
Cutaneous formations (periorbital and dorsum of feet)
Autoimmune
hyperthyroidism
Sonographic Findings
Diffuse enlargement
 Hypoechoic without
palpable nodules
 Markedly increased
vascularity (“thyroid
inferno”)
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Hypothyroidism
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Lack of secretion of thyroid hormones
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Clinical Signs
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Causes
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Myxedema (skin and tissue disorder)
Weight gain
Hair loss
Increased tissue around the eyes
Lethargy
Intellectual and motor slowing
Cold Intolerance
Constipation
Deep, husky voice
Primary = Thyroid hormone failure
Secondary = Diseases of the hypothalmus or pituitary
Treatment
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Synthetic thyroid hormone can reverse the condition
Thyroiditis
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Most common cause of primary hypothyroidism in
iodine rich areas of the world
Inflammation of the thyroid causing swelling and
tenderness
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Causes
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May be associated with lymphoma
Infection
Autoimmune
Types
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De Quervains
Hashimoto’s
De Quervain’s
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Clinical Signs
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Usually viral
Diffuse enlargement
Tenderness / mild to severe pain
Transient hyperthyroidism
Gradual or fairly abrupt onset
Hashimoto’s
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Increased risk for malignant disease
Clinical Signs
 Most common form of thyroiditis
 Autoimmune – chronic inflammation
 Diffuse enlargement
possibly asymmetric
 Painless
may develop mild pain over time
 Eventual hypothyroidism
 Young – middle aged females
Sonographic Findings:
1.
Increased Vascularity with
Color Doppler
2.
Texture is course and
homogenous with multiple
ill-defined hypoechoic
areas separated by thick
fibrous strands
3.
Over time, the gland
becomes fibrotic, illdefined, and
heterogeneous
Thyroid Disease and Pregnancy
• 2nd most common endocrinopathy that affects
women of reproductive age.
Increase TBG (Thyroid Binding Globulin)
Decreased TSH between weeks 8-14
Reduced plasma iodine
• Increased gland size in 13% women
• Post Partum Thyroiditis
Benign Masses
Cysts and Cystic Nodules
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Sonographic Appearance
Purely anechoic areas (serous / colloid fluid),
well-defined walls, & distal enhancement.
 Fluid levels (hemorrhage)
 FNA / Ethanol Injection
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Degenerative Colloid Cysts
Benign Masses
Adenomas
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Most common solid thyroid mass
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Encapsulated nodule
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Clinical Features
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compression of adjacent tissues
fibrous encapsulation
Most patients euthyroid or hyperthyroid
Slow growing – must be 0.5 – 1 cm to be palpated
Sonographic Appearance
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Variable sonographic appearance
Follicular carcinoma is indistinguishable from an
adenoma
Adenomas
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Well circumscribed; circular
shaped
Peripheral halo (edema of
compressed tissue)
Increased Color Flow
Cystic Degeneration
Rim Calcification
Homogeneous with variable
size; Hyperechoic
Slow growing unless
hemorrhage occurs
(sudden painful
enlargement)
Malignant
Masses
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Carcinoma of the thyroid is rare!
Risk of malignancy decreases with multiple nodules
A solitary thyroid nodule in the presence of cervical adenopathy
on the same side suggests malignancy
Clinical Findings
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Asymptomatic nodule
Hoarseness
History of exposure to low dose ionizing radiation
Solitary fixed, rapidly enlarging nodule in patient under 14 years or over
65 years of age
Papillary Carcinoma
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Most common thyroid malignancy
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Sonographic Findings
Hypoechoic
 Microcalcifications
 Hypervascularity
 Possible cervical
lymph node metastasis
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Medullary Carcinoma
C - Cells
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Clinical Findings
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Hard, bulky mass
Abnormal serum calcitonin
levels
Sonographic Findings
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Solid mass
Calcifications
Lymphadenopathy
Metastasis to
Lymph Nodes
Normal
How does the appearance of a
normal lymph node differ
from an abnormal lymph
node?
Anaplastic (Undifferentiated) Carcinoma
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Clinical signs
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> 50 years of age
Hard, fixed
Rapid growth
Pain, pressure,
tenderness
Locally invasive
Sonographic
Findings
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Hypoechoic mass,
possibly irregular
Diffuse glandular
involvement
Invasion of
surroundings
Features of Benign/Malignant Nodules
Feature
Internal Contents
Purely Cystic
Cystic with Thin Septa
Mixed Solid and Cystic
Comet Tail Artifact
Echogenicity
Hyperechoic
Isoechoic
Hypoechoic
Halo
Thin Halo
Thick Incomplete Halo
Margin
Well Defined
Poorly Defined
Calcification
Eggshell
Course
Microcalcifications
Doppler Flow Pattern
Peripheral
Internal
Benign
Malignant
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Parathyroid Gland
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4 small masses on posterior
surface of the lateral lobes
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Physiology
Monitors Calcium
Metabolism
 Produces Parathyroid
Hormone
 Serum Calcium Low
 PTH Secreted
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Releases calcium from
bones
Changes intestinal tract
absorption
Parathyroid Gland
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Texture similar to overlying
thyroid (size <4 mm glands are usually
not seen)
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Be careful to evaluate in sagittal
and transverse views so not to
mistake a muscle for
parathyroid!
Enlarged glands have
decreased echo texture and
appear elongated masses
between the posterior longus
coli and the anterior thyroid
lobe.
Parathyroid Pathology
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Primary Hyperparathyroidism
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Adenomas
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Most common cause of primary hyperparathyroidism
Benign and usually less than 3 cm
Carcinoma
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Increased function of parathyroid gland
Most small, irregular, & firm; may adhere to surrounding
structures.
Secondary Hyperparathyroidism
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Chronic hypocalcemia
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renal failure, vitamin D deficiency, or malabsorption syndromes
PTH secretion to compensate for renal insufficiency and
intestinal malabsorption.
Neck Masses
Thyroglassal Duct Cyst
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Congenital anomaly
Midline & anterior to
trachea
Remnant of tubular dev’t
of thyroid gland persisting
between the base of the
tongue and the hyoid
bone
Clinical Signs
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Palpable midline mass
Pain associated with
hemorrhage or infection
Sonographic Findings
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Cystic mass in the midline
anterior to the trachea
Internal echoes caused by
hemorrhage or infection
Oval, spherical
Brachial Cleft Cyst
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Anterior to CCA
Along the border of the
sternocleidomastoid
muscle
Definite separation from
the thyroid gland
Cystic Hygroma
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Congenital lymphatic
malformation of
posterolateral neck
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Webbed neck
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Sonographic Findings
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Thin walled, cystic
multiloculated mass
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Thyroid Scan