1. Thyroid, Parathyroid, and Neck
Tanya Nolan

2. Thyroid Gland Anatomy

3. Anatomic Variations Thyroglossal Duct Cyst Athyrosis Pyramidal Lobe
Thyroglossal duct fails to involute completely
Athyrosis
Absence of Thyroid gland
Pyramidal Lobe
Absence of Isthmus
Ectopic Gland

4. Neck Anatomy

5. Normal Anatomy

6. Normal Anatomy

7. Function and Physiology
Maintains body metabolism, growth, and development
synthesis, storage, & secretion of thyroid hormones
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 7

8. Thyroxine (T4) Iodine + Tyrosine (amino acid)
Combines with protein thyroglobulin & stored.
Increases carbohydrate burn
Breaks down proteins for energy
Regulates fat metabolism
Accelerates body growth (especially nervous tissue)
Increases nervous system reactivity 8

9. Calcitonin
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? 9

10. Thyroid Stimulating Hormone (TSH)
Produced by the anterior pituitary gland
Regulated by the thyrotropin-releasing factor (TRF) produced by the hypothalmus
TRF regulated by the basal metabolic rate. 10

11. 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
>TRF inhibited 11

12. Lab Tests Nuclear Medicine
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? 12

13. Lab Tests Triiodothyronine (T3) Serum Thyroxine (T4) Serum Calcitonin
Normal RIA ng/dl; RU: 25-35% relative uptake
Serum Thyroxine (T4)
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
Elevated levels of calcitonin are diagnostic of medullary carcinoma of the thyroid
Serum Thyroid Stimulating Hormone
Normal Serum TSH < 5mU/ml
TSH level is indicative of thyroid reserve. It is the most accurate test for primary hypothyroidism 13

14. Indications for Sonographic Examination
Palpable enlargement
Abnormal Thyroid Hormone Level(s)
Palpable mass in neck / thyroid
Swelling of neck
Asymmetry of neck
Redness and/or tenderness

15. Sonographic Technique
Equipment
High frequency ( MHz or higher) linear
Transducer
Patient Position
Supine with neck extended
Views
Longitudinal and Transverse images of bilateral lobes & Transverse view of the isthmus
Demonstrate relational anatomy 15

16. Normal Thyroid Adult Thyroid 40-60 mm long 13-18 mm AP
Newborn: mm long; 8-9 mm AP
Age 1: 25 mm long; mm AP
Adult Thyroid
40-60 mm long
13-18 mm AP
Isthmus 4-6 mm AP

17. Nontoxic Goiter Simple, Colloid, or Multinodular Causes
Enlargement of entire gland without producing nodularity and without evidence of functional disturbance (euthyroid)
Causes
Lack of Iodine
Compensatory increase of TSH = follicular cell hypertrophy
Sporatic Goiter
Diffuse, Uninodular, or multinodular
Ingestion of Substances, hereditary enzyme defects
Simple Goiters may evolve = Multinodular Goiters
Calcification, Degeneration, Fibrosis, and Hemorrhage 17

18. Thyrotoxicosis / Hyperthyroidism
Over secretion of thyroid hormones
Clinical Signs
Dramatic increase in metabolic rate
Weight Loss
Increased appetite
Nervous energy
Tremor
Excessive sweating
Heat intolerance
Cardiac Palpitations
Exopthalmos (protruding eyes)
Causes
Abnormal hormone secretion (entire gland out of control)
Localized neoplasm caused by overproduction of hormones
Grave’s disease 18

19. Toxic Multinodular Goiter “Grave’s Disease”
Clinical Signs
Women over 30
Hypermetabolism
Exopthalmos
Cutaneous formations (periorbital and dorsum of feet)
Causes
Autoimmune
hyperthyroidism
Sonographic Findings
Diffuse enlargement
Hypoechoic without
palpable nodules
Markedly increased
vascularity (“thyroid
inferno”) 19

20. Hypothyroidism Lack of secretion of thyroid hormones Clinical Signs
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
Causes
Primary = Thyroid hormone failure
Secondary = Diseases of the hypothalmus or pituitary
Treatment
Synthetic thyroid hormone can reverse the condition 20

21. Thyroiditis
Most common cause of primary hypothyroidism in iodine rich areas of the world
Inflammation of the thyroid causing swelling and tenderness
May be associated with lymphoma
Causes
Infection
Autoimmune
Types
De Quervains
Hashimoto’s 21

22. Hashimoto’s De Quervain’s Clinical Signs Usually viral
Sonographic Findings:
Increased Vascularity with Color Doppler
Texture is course and homogenous with multiple ill-defined hypoechoic areas separated by thick fibrous strands
Over time, the gland becomes fibrotic, ill-defined, and heterogeneous
Clinical Signs
Usually viral
Diffuse enlargement
Tenderness / mild to severe pain
Transient hyperthyroidism
Gradual or fairly abrupt onset
Hashimoto’s
Increased risk for malignant disease
Most common form of thyroiditis
Autoimmune – chronic inflammation
possibly asymmetric
Painless
may develop mild pain over time
Eventual hypothyroidism
Young – middle aged females 22

23. 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

24. Benign Masses Cysts and Cystic Nodules
Sonographic Appearance
Purely anechoic areas (serous / colloid fluid), well-defined walls, & distal enhancement.
Fluid levels (hemorrhage)
FNA / Ethanol Injection
Degenerative Colloid Cysts 24

25. Benign Masses Adenomas
Most common solid thyroid mass
Encapsulated nodule
compression of adjacent tissues
fibrous encapsulation
Clinical Features
Most patients euthyroid or hyperthyroid
Slow growing – must be 0.5 – 1 cm to be palpated
Sonographic Appearance
Variable sonographic appearance
Follicular carcinoma is indistinguishable from an adenoma 25

26. Adenomas 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)

27. Malignant Masses 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
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

28. Papillary Carcinoma Most common thyroid malignancy
Sonographic Findings
Hypoechoic
Microcalcifications
Hypervascularity
Possible cervical
lymph node metastasis

29. Medullary Carcinoma C - Cells
Clinical Findings
Hard, bulky mass
Abnormal serum calcitonin levels
Sonographic Findings
Solid mass
Calcifications
Lymphadenopathy

30. Metastasis to Lymph Nodes
Normal
How does the appearance of a normal lymph node differ from an abnormal lymph node?

31. Anaplastic (Undifferentiated) Carcinoma
Clinical signs
> 50 years of age
Hard, fixed
Rapid growth
Pain, pressure, tenderness
Locally invasive
Sonographic Findings
Hypoechoic mass, possibly irregular
Diffuse glandular involvement
Invasion of surroundings

32. Features of Benign/Malignant Nodules
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

33. Parathyroid Gland Physiology
4 small masses on posterior surface of the lateral lobes
Physiology
Monitors Calcium Metabolism
Produces Parathyroid Hormone
Serum Calcium Low
PTH Secreted
Releases calcium from bones
Changes intestinal tract absorption

34. Parathyroid Gland
Texture similar to overlying thyroid (size <4 mm glands are usually not seen)
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.

35. Parathyroid Pathology
Primary Hyperparathyroidism
Increased function of parathyroid gland
Adenomas
Most common cause of primary hyperparathyroidism
Benign and usually less than 3 cm
Carcinoma
Most small, irregular, & firm; may adhere to surrounding structures.
Secondary Hyperparathyroidism
Chronic hypocalcemia
renal failure, vitamin D deficiency, or malabsorption syndromes
PTH secretion to compensate for renal insufficiency and intestinal malabsorption.

36. Neck Masses Thyroglassal Duct Cyst
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
Palpable midline mass
Pain associated with hemorrhage or infection
Sonographic Findings
Cystic mass in the midline anterior to the trachea
Internal echoes caused by hemorrhage or infection
Oval, spherical

37. Brachial Cleft Cyst Anterior to CCA
Along the border of the sternocleidomastoid muscle
Definite separation from the thyroid gland

38. Cystic Hygroma
Congenital lymphatic malformation of posterolateral neck
Webbed neck
Sonographic Findings
Thin walled, cystic multiloculated mass

39. Thyroid Scan