Thyroid Flashcards
1
Q
What divides the anterior and posterior triangles of the neck?
A
Sternocleidomastoid
2
Q
What are the boundaries of the anterior triangle of the neck?
A
anterior: median line of the neck
posterior: anterior margin of sternocleidomastoid
base: inferior border of the mandible , which is a line from the inferior border of the mandible to the mastoid process.
the roof of platysma muscle and subcutaneous tissues;
the floor, formed by the pharynx, larynx and thyroid gland;
the apex which is the jugular notch; and
3
Q
What are the triangles that make up the anterior triangle of the neck?
A
digastric (submandibular) triangle
muscular triangle
carotid triangle
submental triangle (half, only because there is only one submental triangle)
4
Q
What are the muscles that divide the anterior triangle of the neck?
A
anterior and posterior bellies of digastric muscle and superior belly of omohyoid muscle.
5
Q
What are the contents of the anterior triangle of the neck?
A
glandular structures (such as the thyroid and parathyroid glands) and lymphatics. The carotid triangle in particular contains the carotid vessels and associated veins and nerves.
6
Q
What are the boundaries of the posterior triangle of the neck?
A
anterior: posterior border of sternocleidomastoid
posterior: anterior border of trapezius
inferior: middle third of the clavicle
roof: skin, superficial fascia and the investing layer of deep cervical fascia
floor: prevertebral fascia overlying splenius capitis, semispinalis capitis, levator scapulae, scalenus medius and scalenus anterior
7
Q
What muscle divides the posterior triangle?
A
The inferior belly of the omohyoid that crosses the triangle divides it into an inferior supraclavicular and superior occipital triangle.
8
Q
What are the contents of the posterior triangle?
A
mostly vessels and nerves that connect the neck and the upper limb. It also contains superficial and deep lymph nodes.
9
Q
Describe the pyramidal lobe
A
(Lalouette’s pyramid) may be seen in 10-40 percent of cases, extending upward from the isthmus or the left lobe to the suprahyoid region.
10
Q
What attaches the thyroid to the cricoid cartilage?
A
a ligamentous band (ligament of berry).
11
Q
What divides the thyroid gland into lobules?
A
A thin fibrous capsule surrounds the thyroid and sends septa into the gland dividing it into lobules made up of 20-40 evenly dispersed follicles
12
Q
What are thyroid follicles made of?
A
simple cuboidal epithelial cells that are referred to as follicular cells and produce the glycoprotein, thyroglobulin
13
Q
What is the role of thyroid follicular cells?
A
convert thyroglobulin into T4 and T3
14
Q
What do Parafollicular cells, or C cells do?
A
found in the follicular epitheliumThey secrete the hormone calcitonin which controls calcium metabolism
15
Q
What are some symptoms of thyroid enlargement?
A
Obstruction
difficulty swallowing (dysphagia)
compression of large blood vessels, lymphatics and nerves in the neck and upper thorax.
sensation of tightness or pain in the anterior neck
discomfort when swallowing
compression of blood vessels may inhibit the return of blood from the neck and head and may even result in superior vena cava syndrome.
16
Q
What are some effects if thyroid enlargement is due to malignancy?
A
If enlargement is due to malignancy that invades nearby structures there may be:
Pain
hoarseness of the voice if laryngeal nerves are affected
coughing up of blood if the trachea is invaded
17
Q
Where are the superior parathyroids usually located?
A
remain associated with the posterior aspect of the middle to upper portion of the thyroid gland.
18
Q
Where are the inferior parathyroids usually located?
A
majority (>60%) come to rest at or just inferior to the posterior aspect of the lower pole of the thyroid
19
Q
Why are the inferior parathyroids more variable in location?
A
arise from the paired third branchial pouches, along with the thymus
Both migrate caudally along with the thymus.
Making them more variable in location than the superior glands
20
Q
What is the role of the thyroid?
A
maintains body metabolism and growth development by synthesising, storing and secreting thyroid hormones. parafollicular cells (C-cells) make up a small amount of the thyroid gland composition, occurring mainly in small clusters between follicles produce the hormone calcitonin which is involved in calcium homeostasis, decreasing the release of calcium from the bone to lower blood calcium levels.
21
Q
What is the role of the parathyroid glands?
A
synthesise the hormone parathormone (PTH)
major role of PTH (along with vitamin D and calcitonin) is to maintain blood calcium levels.
22
Q
What does PTH do in bone?
A
increased reabsorption to mobilise calcium and phosphate (increases levels of P and Ca in the blood)
23
Q
What does PTH do in the kidneys?
A
in the kidneys, increased tubular reabsorption of calcium and tubular secretion of phosphate (increases Ca in the blood and P in the urine)
24
Q
What does PTH do in the gut?
A
in the gut, increased absorption of dietary calcium, magnesium and phosphate and reduced loss of calcium in faeces. (increases Ca and P in blood)
25
What does a rise in blood calcium do to PTH?
Depresses secretion
26
What does a fall in blood calcium do to PTH?
Increases it
27
What are the advantages of thyroid FNA?
```
minimal materials (usually a very simply procedure)
inexpensive
quickly performed
local anaesthetic often not used
minimal discomfort (usually)
small bruise only (usually)
```
28
What are the disadvantages of thyroid FNA?
sample may be inadequate ( reduced if pathologist is present to check sample )
false positive/false negative/equivocal aspirates
dependence of cytopathology expertise
specific tissue-related potential pitfalls.
29
What are the advantages of thyroid core biopsy?
inexpensive
relatively atraumatic
may obviate the need for open biopsy
higher diagnostic yield (though there is some varying opinion about this)
30
What are the disadvantages of thyroid core biopsy?
greater chance of local haemorrhage due to larger bore needle used
tracheal perforation and other complications as there is probably reduced control of the needle depth with this procedure compared to FNA.
potential for facial nerve damage
possibility of tumour seeding, but very little evidence.
31
What is hyperthyroidism?
excessive secretion of thyroid hormones T3 and T4, often termed thyrotoxicosis.
32
What are some causes of hyperthyroidism?
Graves' disease
idiopathic nodular hyperplasia of the thyroid (toxic goitre)
tumours, such as hyperfunctioning thyroid adenoma and metastatic thyroid carcinoma
subacute or acute thyroiditis
choriocarcinoma or hydatidiform mole
overdose of thyroid hormone
33
What are some symptoms of hyperthyroidism?
```
mostly related to the abnormally high metabolic rate
warm and sweaty
increased pulse rate and blood pressure
Tachycardia
Tremor
muscle weakness
weight loss
Restlessness
Anxiety
Amenorrheoa and exophthalmos may also occur, especially in Graves' disease.
```
34
What is the treatment for hyperthyroidism?
Treatment is often with anti-thyroid drugs for Graves' disease. If this is not effective or the cause is due to tumour or nodular hyperplasia, then a subtotal thyroidectomy is usually performed.
35
What is hypothyroidism?
reduced circulating thyroid hormones. This usually results from a functional failure of the thyroid gland.
36
What are some causes of hypothyroidism?
developmental defects, such as congenital thyroid aplasia
postoperative thyroidectomy, for example, after removal of tumour
thyroiditis, often autoimmune such as Hashimoto's thyroiditis
iodine deficiency where dietary iodine is low
deficiency of TRH from the hypothalamus
37
What are some symptoms of hypothyroidism?
```
Usually related to a low metabolic rate
Low BMR
Bradycardia
Shortness of breath
Lethargy
Mental sluggishness
Weight gain
Constipation
Cold sensitivity
Cretinism occurs in utero or infancy usually due to congenital aplasia. It will result in mental and physical retardation unless detected and treated with thyroid hormones. This is usually a routine test for all newborns
```
38
What is the treatment for hypothyroidism?
Standard treatment for hypothyroidism involves daily use of the synthetic thyroid hormone
39
What is hyperparathyroidism?
Excessive secretion of parathormone
40
What does hyperparathyroidism cause?
Hypercalicemia
41
How does hyperparathyroidism cause hypercalcemia?
bone reabsorption and calcium mobilisation from the skeleton, which can cause the bone to be very susceptible to fracture
increased renal tubular reabsorption and retention of calcium
enhanced gastrointestinal calcium absorption
42
What are some causes of hyperparathyroidism?
```
Primary
parathyroid adenoma (80-90%)
hyperplasia (10-20%)
carcinoma (less than 1%)
Secondary
associated with renal failure and vitamin D deficiency
```
43
What are some symptoms of hyperparathyroidism?
elevated serum calcium
Hypophosphatasia
hypercalciuria
possible nephrocalcinonsis or renal calculi
possible bone deformities in severe cases
44
What is the treatment for hyperparathyroidism?
Remove one or more of the glands.
45
What are the risk factors for hyperparathyroidism?
Most cases are sporadic
Prior external neck radition (small amount of cases)
Long term lithium therapy
Hereditary (multiple endocrine neoplasia syndrome (MEN I))
Familial syndromes such as familial hypocalciuric hypercalcemia
46
What is the prevalence of primary hyperparathyroidism?
common endocrine disease 1 to 2 per 1000 population.
Women are affected 2-3:1 particularly after menopause.
Most >50 years
rare <20 years
47
What are the laboratory diagnoses?
elevated serum calcium
Hypophosphatasia
Hypercalciuria
PTH level that is “inappropriately high” for the corresponding serum calcium level confirms the diagnosis
48
When should PTH within normal limits still be suspicious for primary hyperparathyroidism and why?
in a hypercalcemic patient, the diagnosis of primary hyperparathyroidism should still be suspected, since hypercalcemia from other nonparathyroid causes (including malignancy) should suppress the glandular function and decrease the serum PTH level.
49
What are the later clinical presentations of hyperparathyroidism?
Because of earlier detection by increasingly routine laboratory tests, the later “classic” signs of hyperparathyroidism, such as “painful bones, renal stones, abdominal groans, and psychic moans,” are often not present.
Many patients are diagnosed before severe manifestations of hyperparathyroidism, such as nephrolithiasis, osteopenia, subperiosteal resorption, and osteitis fibrosis cystica.
50
What are the early clinical presentations of hyperparathyroidism?
In general, patients rarely have obvious symptoms unless their serum calcium level exceeds 12 mg/dL. However, subtle nonspecific symptoms, such as muscle weakness, malaise, constipation, dyspepsia, polydipsia, and polyuria, may be elicited from these otherwise asymptomatic patients by more specific questioning.
51
What is hypoparathyroidism?
This is a functional disorder that results in reduced secretion of parathormone.
52
What are some causes of hypoparathyroidism?
inadvertent removal of the glands
congenital absence of the glands
autoimmune disease, causing atrophy
rare syndromes
53
What are some symptoms of hypoparathyroidism?
tetany, which is an increased excitability of the neuromuscular tissues and muscle contraction (stiffness, cramps, spasms, convulsions, hyperexcitability, depression).
The heart action may also become irregular.
54
What is the treatment for hypoparathyroidism?
Usually injections of synthetic parathormone.
55
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
Feeling hot, increased sweating, weight loss, enlargement of the thyroid gland, rapid heart rate and palpitations, anxiety and restless hyperactivity.
T3 and T4 will be elevated above normal ranges. TSH will be decreased due the feedback mechanism not requiring further TSH secretion in the presence of increased T3 and T4 circulating in the blood. RAIU could be also performed, but the other tests are more specific as hyperthyroidism does not always cause high iodine uptake
Most likely cause:
Graves’ disease which accounts for up to 85% percent of thyrotoxicosis presentations and can cause diffuse hyperplasia of the thyroid gland.
56
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
Cold intolerance, facial and extremity oedema, lethargy, weight gain, bradycardia, constipation, hair loss
```
Hypothyroidism induces changes expected of a hypometabolic state across the systems and processes effected by thyroid hormone such as the above. Facial and extremity oedema in the context of hypothyroidism indicate the condition is severely advanced and is termed myxedema.
Laboratory tests
TSH
T4
T3
RAIU
```
TSH will be elevated above the normal range as it is further secreted due to low circulating levels of T3 and T4. This is a sensitive early marker. A RAIU test could be also performed and would show reduced iodine uptake.
Most likely cause:
Hashimoto's thyroiditis is the most common cause, clinically presenting with reduced thyroid function and the symptoms of myxedema due to reduced metabolic rate.
57
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
Prominent, irregular neck swelling, difficulty in swallowing, occasional neck pain.
A patient with the described clinical features is presenting with common features of multi-nodular goitre.
Laboratory tests
RAIU
TSH
T3
T4
These may all show normal levels, unless there is a dominant functional adenoma that will cause an elevation of the RAIU, T3 and T4 tests, with a reduction in the TSH levels. Usually these goitres are euthyroid in nature.
58
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
History of renal calculi, unilateral (mild) neck swelling.
A patient with the described clinical features is presenting with common features of parathyroid adenoma.
Laboratory tests:
Serum calcium
PTH
Hyperparathyroidism caused by a single adenoma will result in unilateral neck swelling and nephrolithiasis, if it is uncontrolled. Possible but unlikely differentials include multiple gland enlargement and multiple adenomas.
59
What are some congenital anomalies of the thyroid gland?
Mostly very rare
agenesis of one lobe or the whole gland;
hypoplasia; and
ectopic thyroid tissue
60
Briefly describe congenital hypothyroidism
relatively common disorder occurring in about 1 in 3000 to 4000 live births.
Cause may be
Dysgenesis
Dyshormonogenesis
pituitary or hypothalamic hypothyroidism)
clinically important because prognosis and therapy differ.
Early initiation of therapy can prevent mental retardation and delayed bone development.
61
What are some congenital abnormalities of the parathyroid?
```
agenesis of some or all of the glands (congenital or post-surgical); and
ectopic positions (multiple variations).
```
62
Define goitre
Goitre is an enlargement of the thyroid gland. The definition of goitre is age and sex dependent.
63
List some causes of goitre
```
ses:
non-toxic simple goitre (e.g. from iodine deficiency)
Graves disease
multinodular goitre
Hashimoto thyroiditis
thyroid cancer
goitrogens
drugs: lithium, amiodarone, etc.
diet: cabbage, sprouts, etc.
depositional disease, e.g. amyloidosis
miscellaneous, e.g. Plummer-Vinson syndrome
```
64
List some causes of nodular thyroid disease
Hyerplastic/Colloid nodules are by far the most common
Adenoma (follicular) most commonly encountered neoplasm
Haemorrhage, usually into an adenoma, which often appears suddenly with pain
cysts (true epithelial cysts are rare)
multinodular thyroid
Abscess
Papillary thyroid cancer (PTC) is the most common thyroid cancer
Follicular thyroid cancer (FC) is the second most common thyroid cancer
Medullary thyroid carcinomas (MTC) arise from the parafollicular or C cells of the thyroid and account for approximately 5% of all thyroid cancer
poorly differentiated PTC (uncommon)
anaplastic thyroid carcinoma (uncommon)
focal region of thyroiditis (rare)
intrathryoidal parathyroid adenoma (rare)
metastatic disease (rare) (breast, kidney, melanoma)
Lymphoma
65
What lesion features allow you to confidently diagnose thyroid malignancy?
If extension of a lesion beyond the thyroid capsule or metastatic cervical lymphadenopathy is identified on imaging
66
What are some nodular features that have a high correlation with thyroid malignancy?
marked hypoechogenicity, infiltrative and/or lobulated margins, microcalcifications, and a taller-than-wide shape.
67
What are some nodular features that are highly likely benign?
Nearly entirely cystic and spongiform nodules are highly likely to be benign.
68
Give the ultrasound appearance for a hyperplastic/colloid nodule
Usually well demarcated and smooth walls and increased through transmission of sound.
Mostly isoechoic but may become hyperechoic because of the numerous interfaces between cells and colloid substance.
mixed echo texture, with low-level echoes of haemorrhage and necrosis.
may have a hypoechoic peripheral rim, with egg-shell calcifications.
Commonly have a spongiform appearance.
69
Relate ultrasound appearance to degenerative processes in hyperplastic nodules
Purely anechoic areas are caused by serous or colloid fluid.
Echogenic fluid or moving fluid-fluid levels correspond to hemorrhage.
Bright echogenic foci with comet-tail artifacts are likely caused by microcrystals or aggregates of colloid substance, which may also move slowly, like snowflakes, within the fluid collection.
Thin, intracystic septations probably correspond to attenuated strands of thyroid tissue and appear completely avascular on color Doppler ultrasound.
These degenerative processes may also lead to the formation of calcifications, which may be either thin, peripheral shells (“eggshell”) or coarse, highly reflective foci with associated acoustic shadows, scattered throughout the gland.
70
Why are Intracystic solid projections, or papillae problematic in imaging?
Intracystic solid projections, or papillae, usually containing color Doppler signals, may appear similar to the rare cystic papillary thyroid carcinoma (PTC). In some cases, sonography and color Doppler imaging cannot differentiate the septations of colloid hyperplastic nodules from the vegetations seen in papillary carcinomas.
71
Define a follicular adenoma
Adenoma (or it may be termed follicular adenoma) is a benign, solid tumour composed of thyroid follicles encapsulated with fibrous tissue.
72
What is the incidence of follicular adenoma?
5% to 10% of all nodular disease
| Women 7:1
73
What is the differential for follicular adenoma?
difficult to differentiate between a follicular adenoma and a follicular carcinoma
cytologic features of follicular adenomas are generally indistinguishable from those of follicular carcinoma
Vascular and capsular invasion are the hallmarks of follicular carcinoma
identified by histologic rather than cytologic analysis. Needle biopsy is therefore not a reliable method to distinguish between follicular carcinoma and cellular adenoma
As such tumors are usually surgically removed
74
Classic ultrasound appearance of a follicular adenoma?
solid masses
hyper, iso or hypo- echogenicity
smooth peripheral halo resulting from the fibrous capsule and blood vessels, which can be readily seen by color Doppler imaging.
Often, vessels pass from the periphery to the central regions of the nodule, sometimes creating a “spoke and wheel” appearance.
increased flow within if hyperfunctioning exists
75
What is the incidence of malignant thyroid nodules?
rare (approximately 1-3% of thyroid nodules are malignant) with a higher incidence in females over 40.
76
What are the risk factors for thyroid malignancy?
early exposure of thyroid gland to irradiation; and
prolonged exposure to high levels of TSH, for example, Hashimoto's thyroiditis.
All have a greater female than male predominance.
77
What are some ultrasound features associated with malignancy?
```
Capsular invasion
Coexisting metastatic lymphadenopathy
Markedly hypoechoic
Entirely or nearly entirely solid
Taller than wide
Infiltrative or lobulated margin
Puncatate echogenic foci
Irregular or interrupted peripheral calcifications
```
78
What is the aetiology of papillary thyroid carcinoma carcinoma?
Most malignant nodules are papillary in type (50-70%).
Sub-types include: follicular (most common), diffuse sclerosing (children/young adults), encapsulated.
PTC peaks in both the third and the seventh decades of life.
Women are affected more often than men.
Distant metastases are very rare (2%-3%)
least aggressive, slow growing, non-functioning, and spread to cervical lymph nodes.
79
What is the prognosis of PTC?
respond well to treatment, often even the presence of adjacent nodal metastases does not adversely affect the patient's progress. Recurrences may develop.
Poorer prognosis is associated with: older patients, male, masses larger than 3cm with large solid areas, and extracapsular invasion.
80
What is the usual patient presentation for PTC?
a hard mass, hoarseness, pressure symptoms, and often no symptoms.
81
What are the ultrasound features of PTC?
```
relatively distinctive
predominantly hypoechoic
may be chaotic internal blood flow
mostly solid
vary in size
Septae may have vascularity
Punctate calcifications
Microcalcifications
Some will have irregular macrocalcifications distributed throughout, others may have irregular peripheral calcifications.
A peripheral halo may be present, often incomplete (representing encapsulation), otherwise they will have ill-defined, irregular margins
```
82
How would you extend the exam when PTC is suspected?
They usually spread locally to the adjacent cervical lymph nodes, but you should also look for adjacent spread to strap muscles, trachea, oesophagus and recurrent laryngeal nerve.
83
What is the characteristic lymphadenopathy for PTC?
nodes hyperechoic relative to muscle
distribution along cervical chain and pre/para-tracheal nodes
punctate calcifications are present in approximately 50 percent of cases
chaotic internal blood flow may be present
cystic necrosis in 25 percent with thick, vascular walls
84
How would you perform post surgical follow up on the thyroid?
Look for recurrence in the thyroid bed (similar to the primary tumour) and adjacent nodal regions. You must be aware that granulomatous change at the previous surgical site may mimic tumour recurrence, with appearances such as ill-defined, solid mass, hypoechoic with echogenic shadowing foci, though these foci will be larger and more dense than those associated with the primary papillary carcinoma. This is termed a suture granuloma.
85
Discuss the aetiology of Follicular carcinoma?
Next most common after PTC (10-15% of all thyroid carcinomas).
It is more common in females.
very difficult to differentiate between malignant folkicular carcinoma and benign follicular adenoma on ultrasound and even via FNA.
If a follicular lesion is found on FNA it needs to be surgically removed as only by assessment of the capsule of the mass to look for invasion or breaching of the capsule - can a malignant lesion be identified.
There is an increased incidence in areas of low iodine.
It spreads via the bloodstream to lung, bone, liver and brain, nodal metastases are uncommon.
It may be multiple and some have iodine uptake.
86
Describe the ultrasound appearance of follicular thyroid carcinoma
No unique sonographic features allow differentiation of follicular carcinoma from adenoma.
predominantly solid (if present, the cystic portion is small).
homogeneous in 70 percent of cases.
usually hyperechoic, encapsulated with a peripheral halo often thick and partial (capsular invasion may be seen).
rarely calcify.
characterised by an internal, chaotic nodular flow pattern with/without perinodular flow.
Features that suggest follicular carcinoma are rarely seen but include irregular tumor margins, a thick irregular halo, and a tortuous or chaotic arrangement of internal blood vessels on color Doppler imaging
87
Discuss the aetiology of medullary carcinoma
arises from the parafollicular C-cell which secretes calcitonin.
1-5% of thyroid carcinoma and is relatively rare.
often familial (20%), or with a past history of hypercalcaemia or phaeochromocytoma.
slow growing, but metastasises early, with a survival rate of 55 percent at five years.
spreads to the lymph nodes, then via the blood stream.
88
What is the ultrasound appearance of medullary carcinoma?
oma and is seen most often as a hypoechoic solid mass.
usually irregular margins but may appear well-circumscribed but with no capsule.
Thick irregular halo
may be focal or multi-focal, even diffuse affecting both lobes.
have granular ( usually centrally positioned) echogenic foci, larger and denser than in papillary carcinoma (80-90%) and they exhibit posterior acoustic shadowing.
are characterised by prominent, chaotic vessels within the tumour.
are associated with MEN (multiple endocrine neoplasia), which are biologically aggressive. Therefore you should also examine the adrenal glands for enlargement.
89
What is the aetiology of anaplastic (undifferentiated) carcinoma
typically a disease of elderly persons
one of the most lethal and aggressive of solid tumors
10% of all thyroid cancers
worst prognosis of thyroid Ca, with a 5-year mortality rate of more than 95%.
is usually inoperable with extra-capsular spread.
metastasises to adjacent and distant nodes in 80 percent of cases.
a rapidly enlarging mass invading adjacent structures
Often hx nodular goitre
90
What are the main characteristics used in assessing thyroid nodules?
Composition – solid, cystic, mixed, spongiform
Echogenicity compared with normal thyroid tissue – hyper, iso, hypoechoic., very hypoechoic
Shape - wider than tall, taller than wide
Margination – smooth, well-defined, ill defined, lobulated, irregular, extrathyroid spread
Echogenic foci – None or comet tail artifacts, macrocalcifications, peripheral/rim calcifications ( "egg shell"- smooth and regular or irregular and incomplete) or punctate echogenic foci (microcalcifications)
abnormal lymphadenopathy
Additional features - minor:
co-existing multinodularity – solitary or multiple nodules - BUT remember that a malignant nodule may be present among benign ones
vascularity – peripheral, internal, chaotic flow, mixture.
91
What is the role of characterisation of thyroid nodules?
help us determine whether the lesion may be benign or malignant
this is not always possible, especially in the case of follicular lesions
biopsy of the lesion is the only fully effective method of determining if a lesion is malignant or benign.
Your role as a sonographer in thyroid imaging is to determine which nodules require an FNA.
92
What are nodule features with very low risk of malignancy?
Entirely cystic
Spongiform
Mixed cystic and solid with concentric solid portions
Large comet tail artefact
93
What are nodule features associated with malignancy?
```
Capsular invasion
Coexisiting metastatic lymphadenopathy
Marked hypoechoic echogenicity
Entirely or nearly entirely solid
Taller than wide shape
Infiltrative or lobulate margin
Punctate echogenic foci
Irregular or interrupted peripheral calcifictions
```
94
What are some features that favour both benign and malignant nodules?
```
Cystic appearances
Peripheral (eggshell) calcification
Intracystic solid projections, or papillae, usually containing color Doppler signals
A peripheral halo
Vascularity
```
95
Elaborate on the ambiguous nature of cystic appearances
argely associated with hyperplastic nodules that have undergone extensive cystic degeneration or haemorrhage. Pathologically, true epithelial-lined cysts of the thyroid gland are rare. Cystic appearances may also be present with papillary carcinoma of the thyroid.
96
Elaborate on the ambiguous nature of Peripheral (eggshell) calcification
was previously thought to indicate a benign nodule, but malignant nodules may have the appearance
97
Elaborate on the ambiguous nature of Intracystic solid projections
or papillae, usually containing color Doppler signals, may appear similar to the rare cystic papillary thyroid carcinoma (PTC). In some cases, sonography and color Doppler imaging cannot differentiate the septations of colloid hyperplastic nodules from the vegetations seen in papillary carcinomas
98
Elaborate on the ambiguous nature of A peripheral halo
may be present in hyperplastic/colloid nodules, follicular adenoma, follicular carcinoma and at times papillary carcinoma.
99
Elaborate on the ambiguous nature of blood flow
Blood flow within cancer is often, but not always, increased.
100
Discuss differentiating between Benign follicular adenoma and follicular carcinoma
Both Benign follicular adenoma and follicular carcinoma commonly present as a solid, homogenous, hyperechoic nodule with peripheral halo and an internal, chaotic nodular flow pattern. It is very difficult to differentiate between malignant and benign follicular lesions on ultrasound and even via FNA. If a follicular lesion is found on FNA it needs to be surgically removed.
Medullary thyroid cancer can also present this way.
101
What do diffuse thyroid conditions typically cause?
```
thyroid enlargement
alterations in parenchymal echogenicity
coarse echotexture
increased or decreased vascularity
surface contour changes.
```
102
What are some difficulties in imaging diffuse thyroid conditions?
There is significant overlap in the sonographic findings of these various entities, and the diagnosis is often established based on clinical presentation.
Recognition of diffuse thyroid enlargement on sonography can often be facilitated by noting the thickness of the isthmus, normally a thin bridge of tissue measuring only a few millimeters in AP dimension. With diffuse thyroid enlargement, the isthmus may be up to 1 cm or more in thickness.
103
What are some causes of diffuse thyroid disease?
chronic lymphocytic thyroiditis (Hashimoto disease)
Graves disease
subacute granulomatous thyroiditis (de Quervain disease)
acute suppurative thyroiditis
Silent (subacute lymphocytic) thyroiditis (can be post partum)
Drug-induced thyroiditis
104
What is the aetiology of hashimotos?
most common type of thyroiditis
autoimmune disease with a familial predisposition
usually affecting young or middle-aged women
Patients develop antibodies to their own thyroglobulin as well as to the major enzyme of thyroid hormonogenesis, thyroid peroxidase.
increased risk for development of non-Hodgkin's lymphoma
may be associated with other autoimmune diseases.
Both benign and malignant thyroid nodules may coexist with chronic lymphocytic thyroiditis, and FNA is often necessary to establish the final diagnosis.
105
What is the patient presentation of hashimotos?
hypothyroid symptoms
smooth, rubbery, painless swelling of the thyroid gland.
Some present as hyperthyroid early on and then develop hypothyroid symptoms later
106
What is the ultrasound appearance of hashimotos?
Typically diffuse, coarsened, parenchymal echotexture, generally more hypoechoic than a normal thyroid
most cases the gland is enlarged
Micronodulation - Multiple, discrete hypoechoic micronodules from 1 to 6 mm in diameter are strongly suggestive of chronic thyroiditis
107
What is the appearance of end stage hashimotos?
end stage of chronic thyroiditis is atrophy, when the thyroid gland is small, with poorly defined margins and heterogeneous texture caused by progressive fibrosis
Blood flow signals are absent.
Discrete thyroid nodules may also develop (for example, follicular lesions)
associated cervical lymphadenopathy may be visualised.
108
What is De Quervain's thyroiditis (sub-acute thyroiditis)
spontaneously remitting inflammatory disease
probably caused by viral infection.
may be mildly enlarged and be hyperfunctioning initially
then hypofunctional in the later stages (two to four months)
usually returning to normal function at six months
There is a poorer prognosis if the nodules remain beyond six months.
109
What is the patient presentation of De Quervain's thyroiditis (sub-acute thyroiditis)
```
Fever
Tender neck
enlargement of the gland
Dysphagia
lethargy
```
110
What is primary atrophic thyroiditis?
Often appears only at old age.
The patient has demonstrable anti-thyroid anti-bodies.
Patients with focal or diffuse Hashimoto's or De Quervain's thyroiditis may progress to this.
It appears as a small, echogenic gland with little/no vascularity.
111
What is Graves disease?
common diffuse abnormality of the thyroid
complex autoimmune disease
occurs 10 times more in women than men.
biochemically characterized by hyperfunction (thyrotoxicosis).
112
What is the patient presentation of graves disease?
generalised thyroid enlargement
| thyrotoxicosis.
113
What is the ultrasound appearance of graves disease?
diffusely enlarged thyroid.
usually hypoechoic and coarse texture.
possible lobulated surfaces of the gland, with no discrete nodules
massive increase in gland vascularity – 'thyroid inferno'.
possible increased velocities in the inferior thyroid artery (>150cm/s).
gland size is usually proportional to the vascular activity, as function returns to normal, then the vascular pattern also regresses
114
When are the parathyroid glands examined on ultrasound?
Only examined directly to find a parathyroid tumour causing hyperparathyroidism as shown by blood tests that show an increase in circulating calcium, phosphate and parathormone levels.
Parathyroid disease is examined via ultrasound often inadvertently when a neck mass is detected, as this may be one of the causes of the mass.
Ultrasound plays an often limited role in finding enlarged parathyroid glands, as nuclear medicine studies are often preferred due to the many variations of parathyroid gland positions.
115
List 4 parathyroid diseases
adenoma (usually affects only one gland but may be multiple)
cyst (more common in women and usually occurs in one of the inferior glands)
hyperplasia (affects all four glands equally
carcinoma (usually affects only one gland
116
What shape are the glands in parathyroid adenoma?
oval or bean shaped (a glands enlarge, they dissect between longitudinally oriented tissue planes in the neck and acquire a characteristic oblong shape)
often asymmetry in the enlargement (the cephalic and/or caudal end can be more bulbous, producing a triangular, tapering, teardrop or bilobed shape)
117
What are the echogenicity of glands in parathyroid adenoma?
substantially less than normal thyroid tissue.
majority of parathyroid adenomas are homogeneously solid
Occasionally heterogeneous appearance, with areas of increased and decreased echogenicity.
118
What is the vascularity of parathyroid adenoma?
may demonstrate a hypervascular pattern
A finding described in parathyroid adenomas is a vascular arc, which envelops 90 to 270 degrees of the mass
may aid in confirming the diagnosis by allowing for differentiation from lymph nodes, which have a central hilar flow pattern.
119
What is the usual size of parathyroid adenoma?
Most parathyroid adenomas are 0.8 to 1.5 cm long but can be as big as 5cm.
120
Discuss parathyroid cysts
(more common in women and usually occurs in one of the inferior glands).
are more frequently seen in women than men
may be present in the neck or anterior mediastinum
may, when large, compress the oesophagus, trachea and recurrent laryngeal nerve
95% of cases occur below the level of the inferior thyroid border; 65% involve inferior parathyroid glands
are well defined and thin walled; the cyst fluid has high parathormone but low T3 and T4 levels
121
Discuss parathyroid hyperplasia
(affects all four glands)
tends to be more spherical than adenomas
may show the presence of calcification.
all 4 glands are hyperplastic to varying degrees
glands generally smaller in size than those in patients with parathyroid adenomas
Hyperplastic parathyroid glands consequently are generally not as readily visible sonographically
122
Discuss parathyroid carcinoma
(usually affects only one gland)
appearances are similar to those in parathyroid adenoma
except that there may be demonstrable invasion of adjacent structures
plus immobility on swallowing.
Metastases to adjacent nodes are seen in 21–28% of cases.
usually larger than adenomas
measure more than 2 cm compared with about 1 cm for adenomas
also frequently have a lobular contour, heterogeneous internal architecture, and internal cystic components
large adenomas may also have these features.
123
What is the difficulty in scanning parathyroid adenoma and cancer?
In many cases, carcinomas are indistinguishable sonographically from large, benign adenomas.
124
Discuss Nuc Med scanning of the thyroid
Thyroid isotope scanning with 99m-Tc is used in thyroid disease, mainly to quantify thyroid function by measuring thyroid uptake. It is also used to identify functional ectopic thyroid tissue and to assess a nodule's functional state compared to the rest of the gland.
Hot lesions have increased iodine uptake and have little risk of malignancy (1-4%), for example, functioning adenoma.
Warm lesions have the same function as the normal thyroid (usually adenomatous) and have a slightly increased risk of malignancy (approximately 10%).
Cold lesions have little or no uptake. Most are benign, such as non-functional adenomas or those with internal cystic degeneration or haemorrhage. There is a greater risk of malignancy (10-25%).
125
Discuss nuc med scanning of the parathyroid
provides good localisation of hyperfunctional parathyroid glands and adenomas.
IMportant to localise as failure during parathyroidectomy to remove the adenoma will result in any later operation being technically more difficult than the first operation, with a higher associated morbidity
126
Discuss CT or the parathyroid
very useful, especially with mediastinal and retroparathyroid glands
A high signal intensity is noted on the T2-weighted images due to the high degree of cellularity and sinusoidal dilatation of the glands.
127
Discuss MRi scanning of the the thyroid and parthyroid
MRI would currently be the most sensitive non-invasive modality for such applications and is very useful in the post-operative neck as it appears to be less impaired by scar tissue and has superb contrast resolution
