1. Anatomy & Pathology of the Thyroid
Teresa M Bieker, MBA, RT, RDMS, RDCS, RVT Lead Diagnostic Medical Sonographer University of Colorado Hospital Denver Colorado

2. Objectives
Anatomy and Pathology of the thyroid and surrounding structures
Identify suspicious characteristics of thyroid nodules
Types and occurrences rates of thyroid cancers

3. Embryology of the Thyroid
Formation of the thyroid begins approximately at the 4th week of gestation
The two lobes are connected by the thyroglossal duct (at the level of the tongue)
By the 7th week, the thyroid should be descended to the level of the trachea

4. Anatomy of the Thyroid
Right and left lobes are located anterolateral to the trachea & esophagus
Right and left lobes are connected midline by the isthmus
Size (adults)
Length: 4-6cm
AP: cm
Isthmus: 4-6mm

6. Neck Muscles Strap muscles (anterior) Sternocleidomastoid (lateral)
sternohyoid
sternothyroid
omohyoid
Sternocleidomastoid (lateral)
Longus colli (posterior)

8. Neck Vessels Thyroid Vessels Major Neck vessels
superior thyroid arteries and veins
inferior thyroid arteries and veins
Major Neck vessels
carotid artery
jugular vein

9. Function of the Thyroid
Produce, store, secrete thyroid hormones
Thyroid hormones are important for:
Proper growth
Development
Metabolism
Body temperature
Heart rate/rhythm
Iodine metabolism: converts iodine from food into thyroid hormones

10. Thyroid Hormones TSH (Thyroid Stimulating Hormone)
T3 (Triiodothyronine)
T4 (Thyroxine)
Calcitonin
Antibodies
Thyroglobulin (TG)

11. Thyroid Hormones TSH: T4/T3: TSH/T4 work together
Stimulates the thyroid to produce T4 and then T3.
Controlled by the pituitary gland
T4/T3:
Produced by the thryoid
TSH/T4 work together

12. Thyroid Hormones Calcitonin Antibodies TG Produced by the thryoid
Helps to regulate calcium levels
Antibodies
Typically present in autoimmune thyroid diseases (Graves, Hashimoto’s) TG
Produced by thyroid tissue
Tumor marker

13. Indications for Neck Ultrasound
Palpable enlargement
Abnormal thyroid hormone levels
Palpable mass
Swelling in the neck
Asymmetry of the neck
Redness and/or tenderness
Difficulty swallowing
Post thyroidectomy evaluation

14. Scanning Technique Patient Position Supine with neck extended
Elevating the head 20o in larger patients may be helpful
Neck rotation
Transducer Frequency
7-15 MHz
Image optimization
Scanning Planes

15. Congenital Anomalies Pyramidal lobe Shape variations
10-40% of patients
Arises superiorly from isthmus
Shape variations
Missing isthmus
“H” shape
Ectopia (rare, follows embryological path)
Agenesis
One lobe
Complete

16. Pyramidal lobe

17. Agenesis of the Right Thyroid

18. Diffuse Thyroid Pathology
Hyperthyroidism (Grave’s Disease)
Hypothyroidism
Thyroiditis
Acute
Chronic

19. Hyperthyroidism (Grave’s Disease)
Overproduction of thyroid hormone
Low TSH, high T3, T4
Causes
Abnormal hormone production
Pituitary tumor
Thyroid nodule/neoplasm
Symptoms:
Increased metabolism
Weight loss, increased appetite
Nervous energy
Tremors
Excessive sweating
Palpitations
Heat intolerance
Fatigue
Exophthalmos

20. Hyperthyroidism (Grave’s Disease)
Sonographic Appearance:
Enlarged
Heterogeneous
Hypervascular
Treatment:
Radioactive iodine
Medication
Surgery

23. Hypothyroidism Under secretion of hormone production Causes Symptoms:
High TSH, low T3, T4
Causes
Low intake of iodine
Thyroid hormone failure
Pituitary disease
Symptoms:
Weight gain
Hair loss
Increased tissue around eyes
Intellectual and motor slowing
Cold intolerance
Constipation
Deep voice
Myxedema (coma, life threatening)

24. Hypothyroidism Sonographic appearance Variable in size and echogencity
Treatment
Medication

25. Acute/Subacute Thyroiditis
Rare, caused by bacterial infection
Painful, firm, enlarged thyroid, may see abscess
Patients have neck swelling, fever, pain
Subacute (de Quervain’s Disease)
Diffuse inflammatory disease
Painful enlarged thyroid
Thyroid appears large and hypoechoic

28. Chronic Thyroiditis-Hashimoto’s
Autoimmune disease, often resulting in hypothyroidism
Increased risk for papillary thyroid cancer
Symptoms
Cold intolerance, weight gain, fatigue
Sonographic appearance
Enlarged, hypoechoic, heterogenous thyroid with fibrous strands
May have scalloped edges
Multiple lymph nodes
“Burned out” thyroid late in disease
Treatment (medication)

31. Hashimoto’s Thyroiditis (early)

33. Hashimoto’s Thyroiditis (burn out)

34. Riedel’s Thyroiditis Rare
Thyroid tissue is replaced by dense fibrous tissue
Thyroid is hard (stone-like) and fixed
Can cause tracheal compression
Can treat with steroids and possible surgery

36. Benign Focal Thyroid Pathology
Colloid
Adenomas
Goiters
Cysts

37. Colloid Nodules
Colloid is product of the thyroid that consists of thyroglobulin and serves as a storage reservoir for thyroid hormones
Reservoirs can form within the thyroid and fill with colloid and colloid crystals
Anechoic with echogenic focus/foci with comet tail artifact
Overwhelmingly benign

38. Insert colloid pix

41. Adenomas Usually benign Single or multiple
Normal labs unless functioning
Sonographic appearance
Focal with smooth borders
May have hypoechoic “halo”
May have rim calcification
Range in size and echogenicity
Patients are usually asymptomatic

42. Adenoma

44. Goiter
Thyroid is enlarged (can have neck tightness difficulty swallowing)
Causes:
Iodine deficiency
Hereditary
Medications
Can be associated with Graves disease
Toxic vs Non Toxic Goiter:
Toxic: Nodules are functioning, causing changes in lab values
Non Toxic: non functioning

45. Goiter Sonographic appearance
Multiple nodules
Nodules vary in size and echogenicity
Heterogeneous gland
Treatment & Symptoms depend on thyroid size and hormone levels

46. Goiter

48. Cysts True cysts are uncommon
Cystic appearing lesions are usually degenerating adenomas or colloid nodules
Sonographic appearance:
display cystic characteristics
may have internal echoes and irregular walls
Alcohol ablation is a treatment option

49. Cysts

51. Malignant Pathology Papillary Carcinoma Follicular Carcinoma
Medullary Carcinoma
Huthle Cell Carcinoma
Anaplastic Carcinoma (Giant Cell)
Lymphoma
Metastasis to Thyroid

52. Papillary Carcinoma Most common type of thyroid cancer
Cause usually unknown, but more common in females
Symptoms:
Palpable nodule
Asymptomatic
Thyroid hormones can be normal or abnormal
Slow growing, least aggressive thyroid cancer
Spreads through lymphatic system

53. Papillary Carcinoma Sonographic appearance
One or multiple nodules with irregular borders
Typically hypoechoic, but can vary
Microcalcifications (strong sign)
Increased internal vascularity
May see multiple central or lateral lymph nodes
Treatment

57. Follicular Carcinoma Second most common thyroid cancer
More common in females
Not aggressive but can metastasize
Tends to spread through bloodstream
Sonographic appearance
One or multiple nodules with irregular borders
Vary in echogenicity, may have calcifications
Increased internal vascularity
Thick, irregular halo
Treatment

59. Medullary Carcinoma Often familial
More aggressive than papillary or follicular
Often secretes calcitonin
Likely to metastasize to lymph nodes
Sonographic appearance
Hypoechoic mass(s) that may contain multiple calcifications
May also have lymph node/liver metastases
Treatment

61. Hurthle Cell
Uncommon
Not aggressive but likely to metastasize (nodes, blood, lungs, bone)
Sonographic appearance is variable
Treatment

62. Anaplastic (Giant cell)
Least common, most aggressive, most lethal
Neck is tender, mass is hard and fixed
Rapidly growing
Invades neck muscles, vessels, trachea
Sonographic appearance
large hypoechoic mass
Treatment

65. Lymphoma Typically non-Hodgkin’s type
Rapidly growing, hypoechoic, lobulated mass
Prognosis varies depending on stage

66. Metastsis to Thyroid Typically from melanoma, breast and renal cell
Primary is typically diagnosed
Patients feels neck fullness, palpable mass
Sonographic appearance
Solid, homogeneous, hypoechoic without calcifications

67. Parathyroid Glands Anatomy Hormones Pathology Adenomas
Hypoparathyroidism
Hyperparathyroidism
primary
secondary

68. Parathyroid Anatomy Four parathyroid glands Normal glands are small
2 superior
2 inferior (more variable in location)
Normal glands are small
1 x 3 x 5 mm
Function
Produce parathyroid hormone which regulates blood calcium levels

69. Parathyroid Adenomas Typically just one gland is affected
Sonographic appearance
enlarged
round
homogeneous and hypoechoic
Treatment

71. Hypoparathyroidism Post thyroidectomy complication Clinical diagnosis
Symptoms:
Numbness at mouth, then into extremities
Seizures
Cardiac arrhythmias/arrest
Temporary or chronic
Treatment:
Calcium and Vitamin D supplements (IV and oral)

73. Primary Hyperparathyroidism
Usually caused by functioning adenomas
High calcium levels during routine lab work
Symptoms:
Often asymptomatic
Can develop fatigue, depression, weakness
Severe symptoms: constipation, confusion, painful bones, renal stones
Sonographic appearance
Enlarged
Round
Homogeneous and hypoechoic
Treatment

75. Secondary Hyperparathyroidism
Found in patients with chronic renal failure
unable to produce vitamin D leading to decrease in calcium levels. More parathyroid hormone is produced trying to increase calcium levels
Sonographic appearance
enlarged parathyroids, often bilateral
Uncommon (due to the success of dialysis)

76. Secondary Hyperparathyroidism

77. Salivary Glands Location Appearance Pathology Parotid Submandibular
Sublingual
Appearance
Pathology

78. Salivary Glands Parotid Submandibular Sublingual
Anterior to ear, largest gland, triangular
Submandibular
Deep to mandible
Sublingual
Under tongue, small, not seen well by ultrasound
Sonographic appearance
Homogeneous and echogenic

81. Salivary Gland Pathology
Susceptible to infection and inflammation
Patients can have swelling, pain, fever
Ultrasound helpful in identifying possible fluid collections or abscess

84. Other Neck Lesions Thyroglossal Duct Cyst Branchial Cleft Cyst
Carotid Body Tumor

85. Thyroglossal Duct Cyst
Congenital anomaly
Located midline, anterior to trachea
More commonly seen in children
Sonographic appearance
Anechoic to hypoechoic
Can contain debris or fluid level
Treatment

87. Branchial Cleft Cyst Fetal remnant
Located slightly to the right or left of midline and anterior to the sternocleidomastoid
Sonographic appearance
Anechoic to hypoechoic
Can contain debris or fluid level
Treatment

89. Carotid Body Tumor/Paraganglioma
Rare, typically benign, slow growing
Usually unilateral, located at carotid bifurcation, and fed by the ECA
Patients feel neck mass or have a sudden change in blood pressure
Sonographic appearance
Round, smooth borders
Typically hypervascular
Treatment

90. Carotid Body Tumor

91. Thyroid Nodule Summary
Benign Nodules:
Wider then tall
Cystic
Hyper/iso/hypoechoic
Thin halo
Well defined
Course calfications
Peripheral flow
Malignant Nodules:
Taller then wide
Hypoechoic
Thick, incomplete halo
Absent halo
Spiculated
Microcalcifications
Internal flow