Download Thyroid

Thyroid disease
By
Dr Fahad
Anatomy of the Thyroid Gland
Location: ant neck at C5-T1, overlays 2nd
– 4th tracheal rings
 Average width: 12-15 mm (each lobe)
 Average height: 50-60 mm long

Thyroid Diseases
 Thyrotoxicosis
 Hypothyroidism
 Thyroid
nodules
Thyrotoxicosis VS
Hyperthyroidism
Thyrotoxicosis: a group of symptoms and
signs due to elevated thyroid hormones in
the body of any cause.
 Hyperthyroidism: a group of symptoms
and signs due to increased production of
thyroid hormones by hyper functioning
thyroid gland.

Causes of Thyrotoxicosis
Hyperthyroidism
1- Diffuse toxic goiter (Graves’ disease)
2- Single toxic nodule
3- Toxic multi-nodular goiter
 Early phase sub-acute thyroiditis
 Exogenous thyroid hormone intake

Thyroiditis and exogenous thyroid
hormone intake
Early phase sub-acute thyroiditis:
inflammation of thyroid gland that leads
to release of stored thyroid hormone due
to follicular cell destruction. In acute
stage, the patient is thyrotoxic.
 Exogenous thyroid hormone intake:
1- By mistake
2- with weight loss pills

Thyrotoxicosis and TFT



TSH is always suppressed in
thyrotoxicosis.
TSH is the most sensitive test for
thyroid function and it is the screening
test for thyroid dysfunction.
If TSH is abnormal, T3 and T4 levels can
be obtained in order to determine the
severity of the disease. T3 and T4 are
usually elevated in thyrotoxicosis.
TFT and Thyroid scan
Thyrotoxicosis= suppressed TSH and
elevated T3/T4.
 Based on TFT, the exact cause of
thyrotoxicosis can not be determined.
 Thyroid scan is a very helpful tool in
differentiating between various causes of
thyrotoxicosis.

Thyroid scan and uptake
Radioactive Iodine (RAI) is used for
thyroid scan and uptake.
 RAI is given orally.
 Image and uptake are obtained after 24
hours
 Follicular cell traps Iodine and organifys it
to be incorporated with thyroid
hormone.

Imaging findings
Symmetric or asymmetric lobes.
 Homogeneous or inhomogeneous uptake
 Nodules; cold or hot

24-hour RAI uptake
Measure photons in the given RAI by a
special probe (uptake probe) just before
taking RAI.
 After 24 hours, measure photons in the
neck (thyroid gland).
 Calculate % of photons concentrated in
thyroid gland.
 Normal range of 24 RAI uptake is 10%30%

Thyroid Uptake Probe
Increase uptake
Hyperthyroidism
 Iodine starvation
 Thyroiditis
 Hypoalbominemia
 lithium

decrease uptake
Hypothyroidism
 Thyroid hormon therapy, PTU ,Lugol’s
solution
 Medication(contrast , multivitamins )
 Thyroiditis

Diffuse Toxic goiter (Graves’ Disease)
Diffuse enlargement of thyroid gland.
 Homogeneous uptake.
 No significant focal abnormalities
(nodules).
 24-hour RAI uptake is elevated, usually >
35% (mean of 40%).

Graves’ Disease
Single Toxic Nodule
Single hot nodule (independent of TSH or
autonomous).
 Rest of thyroid gland is poorly visualized
due to low TSH level (TSH dependant).
 24-hour RAI uptake is slightly elevated,
usually around 20%.

Toxic Nodule
Hot Nodule
Toxic Multi-Nodular Goiter
Mild inhomogeneous uptake in thyroid
gland.
 Multiple cold and hot nodules in both
thyroid lobes.
 24-hour uptake is mildly elevated, usually
between 20%-30%.

Multi-nodular Goiter
• Cut surface of one
lobe of thyroid gland
showing ill defined
nodules.
• Focus of cystic
degeneration seen
(blue arrow).
• Some hemorrhage
(red arrow) and some
scarring.
Multi-nodular Goiter
Early Phase Sub-acute Thyroiditis
Inhomogeneous uptake could be mild or
severe. In some cases thyroid gland is not
visualized.
 No significant focal abnormalities
(nodules).
 24-hour RAI uptake is low, usually < 5%.

Sub-acute Thyroiditis
Hypothyroidism
The main cause is chronic thyroiditis
(Hashimoto’s thyroiditis).
 TSH is elevated.
 Thyroid scan does not have significant
diagnostic value in this entity.
 However, if there is nodule/nodules
confirmed by physical examination and
ultrasound, thyroid scan may be helpful.

Thyroid Nodules
thyroid nodules are common, perhaps
existing in almost half the population
 Nodules are usually found by physical
examination or by ultrasound.
 US is the first modality used to investigate
a palpable thyroid nodule
 scintigraphy is reserved for characterizing
functioning nodules and for staging
follicular and papillary carcinomas.
 The patient is usually euthyroid.

If the patient is hyperthyroid do nuclear
scan otherwise do FNA.
 FNA is the most accurate and costeffective method for diagnostic evaluation
of thyroid nodules.
 FNA have a sensitivity of 76%–98%,
specificity of 71%–100%

Frequency of Occurrence of
Thyroid Malignancies
Risk factors for thyroid cancer
family history of thyroid cancer,
 a history of head and neck irradiation,
 male sex,
 age of less than 30 years or more than 60
years,
 previous diagnosis of type 2 multiple
endocrine neoplasia

US features of thyroid nodules
there is some overlap between the US
appearance of benign nodules and that of
malignant nodules
 certain US features are helpful in differentiating
between the two. These features include

1.
2.
3.
4.
5.

micro-calcifications
local invasion
lymph node metastases
a nodule that is taller than it is wide
markedly reduced echogenicity.
Other features, such as the absence of a halo, illdefined irregular margins, solid composition, and
vascularity, are less specific but may be useful.
US Features Associated with
Thyroid Cancer
Thyroid microcalcifications

They are psammoma bodies, which are
10–100-μm round laminar crystalline
calcific deposits. They are one of the most
specific features of thyroid malignancy,
with a specificity of 85.8%–95% and a
positive predictive value of 41.8%–94.2%
Figure 2a. Papillary thyroid carcinoma in a 42-year-old man.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Figure 2b. Papillary thyroid carcinoma in a 42-year-old man.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Local Invasion and Lymph
Node Metastases

US features that should arouse suspicion
about lymph node metastases include a
rounded bulging shape, increased size,
replaced fatty hilum, irregular margins,
heterogeneous echotexture, calcifications,
cystic areas and vascularity throughout
the lymph node instead of normal central
hilar vessels at Doppler imaging
Figure 5a. Anaplastic thyroid carcinoma in an 84-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Figure 5b. Anaplastic thyroid carcinoma in an 84-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Figure 7b. Papillary carcinoma and cystic lymph node metastasis in a 28-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Margins, Contour, and Shape

A completely uniform halo around a
nodule is highly suggestive of benignity,
with a specificity of 95%
Figure 9. Follicular adenoma in a 30-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Vascularity

Chan et al (18) reported that all papillary
thyroid carcinomas in their study had
some intrinsic blood flow, and they
concluded that a completely avascular
nodule is very unlikely to be malignant.
Figure 11a. Renal cell carcinoma metastases to the thyroid in a 69-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Figure 11b. Renal cell carcinoma metastases to the thyroid in a 69-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Figure 12. Follicular adenoma in a 36-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Hypoechoic Solid Nodule

Marked hypoechogenicity is very
suggestive of malignancy.
Figure 13. B cell lymphoma of the thyroid in a 73-year-old woman with Hashimoto thyroiditis.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Nonspecific US Features

The size of a nodule is not helpful for
predicting or excluding malignancy. There
is a common but mistaken practice of
selecting the largest nodule in a
multinodular thyroid for FNA.
Number of Nodules

Although most patients with nodular
hyperplasia have multiple thyroid nodules
and some patients with thyroid carcinoma
have solitary nodules, the presence of
multiple nodules should never be
dismissed as a sign of benignity.
Interval Growth of a Nodule
In general, interval growth of a thyroid
nodule is a poor indicator of malignancy.
Benign thyroid nodules may change in size
and appearance over time.
 The exception is clinically detectable
rapid interval growth, which most
commonly occurs in anaplastic thyroid
carcinoma but also may occur in
lymphoma, sarcoma, and, occasionally,
high-grade carcinoma.

Recommendations for Thyroid Nodules
1 cm or Larger in Maximum Diameter
Society of Radiologists in Ultrasound
Consensus Conference Statement
Punctate echogenicities in thyroid nodules.
papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
Figure 4. Benign thyroid nodule in a 51-year-old woman.
Hoang J K et al. Radiographics 2007;27:847-860
©2007 by Radiological Society of North America
Punctate echogenicities in thyroid nodules.
colloid crystals in a benign nodule
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US images of thyroid nodules of varying parenchymal composition (solid to cystic).
papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US images of thyroid nodules of varying parenchymal composition (solid to cystic).
proved to be benign at cytologic examination
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US images of thyroid nodules of varying parenchymal composition (solid to cystic).
proved to be benign at cytologic examination
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US images of thyroid nodules of varying parenchymal composition (solid to cystic).
proved to be benign at cytologic examination
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US images of thyroid nodules of varying parenchymal composition (solid to cystic).
FNA of this presumed benign lesion was not performed because the
nodule appears entirely cystic
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
Role of color Doppler US. (a) Transverse gray-scale image of predominantly solid thyroid
nodule (calipers).
papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
Role of color Doppler US. (a) Transverse gray-scale image of predominantly solid thyroid
nodule (calipers).
papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
Transverse US images of mostly cystic thyroid nodule with a mural component containing
flow.
The lesion was benign at cytologic examination
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
Transverse US images of mostly cystic thyroid nodule with a mural component containing
flow.
The lesion was benign at cytologic examination
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US features of malignant lymph
node
rounded bulging shape
 increased size,
 replaced fatty hilum
 irregular margins
 heterogeneous echotexture
 calcifications
 cystic areas
 vascularity throughout the lymph node
instead of normal central hilar vessels at
Doppler imaging

Abnormal cervical lymph nodes.
metastatic papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
Abnormal cervical lymph nodes.
metastatic papillary carcinoma.
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
US-guided FNA Technique

The needle may be introduced parallel or
perpendicular to the transducer, and the
needle tip should be carefully monitored
during the procedure.
Figure 7a. Parallel positioning of the fine-gauge needle for thyroid nodule biopsy.
Kim M J et al. Radiographics 2008;28:1869-1886
©2008 by Radiological Society of North America
Figure 7b. Parallel positioning of the fine-gauge needle for thyroid nodule biopsy.
Kim M J et al. Radiographics 2008;28:1869-1886
©2008 by Radiological Society of North America
Figure 8a. Perpendicular positioning of the fine-gauge needle for thyroid nodule biopsy.
Kim M J et al. Radiographics 2008;28:1869-1886
©2008 by Radiological Society of North America
Figure 8b. Perpendicular positioning of the fine-gauge needle for thyroid nodule biopsy.
Kim M J et al. Radiographics 2008;28:1869-1886
©2008 by Radiological Society of North America
Radiopharmaceuticals



Radioactive Iodine 131 (scan and uptake)
used for therapy
Radioactive Iodine 123 (scan and uptake) is
the radioisotope of choice. The 13.3-hour
half-life, the 159-keV principal photon, and
the absence of particulate emission allow for
good imaging with modest patient exposure.
However, this isotope is cyclotron produced
and relatively expensive, and the short halflife necessitates frequent shipments from the
producer.
Free Tc99m (scan only)
Ablation of Benign Thyroid
diseases with I131
Graves’ disease is ablated with 10-15 mCi
of I131.
 Toxic nodular goiter (single nodule or
multinodular) is ablated with 25-30 mCi
of I131

Ablation of Thyroid cancer with
I131
This is effective in differentiated thyroid
cancer only(papillary and follicular thyroid
cancers).
 Both are originated from follicular cell
which is the functional cell in thyroid
tissue (build thyroid hormone by utilizing
iodine).

Thyroid Cancer Ablation
Once follicular cell (benign or malignant)
takes up radioactive iodine I131, beta
particles will be emitted causing serious
damage to cell components. These cells
become nonfunctional and then die.
 Ablation is not helpful in medullary
thyroid cancer and anaplastic carcinoma.

Protocol
Total thyroidectomy is required before
ablation.
 100-200 mCi of I131 is needed for
ablation of remnant thyroid tissue post
total thyroidectomy.

Radiation Protection
Cancer patients should be isolated in special
room (leaded walls) to prevent others from
radiation coming from the patient.
 Isolation is usually for 2-3 days.
 Once the residual iodine is coming down to
30 mCi and less, the patient can be
discharged.
 Patient is followed up with thyroglobulin to
detect recurrence and if needed nuclear
scan

Remnant thyroid tissue
Remnant thyroid tissue with metastatic
cervical adenopathy
Remnant thyroid tissue with metastatic
cervical adenopathy
Thank you