By
Dr Fahad albadr MD
CHAIRMAN OF RADIOLOGY
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Anatomy of the Thyroid Gland
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Location: ant neck at C5-T1, overlays 2nd – 4thtracheal rings
Average width: 12-15 mm (each lobe)
Average height: 50-60 mm long
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Thyroid Diseases
Thyrotoxicosis
Hypothyroidism
Thyroid nodules
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Thyrotoxicosis VSHyperthyroidism
Thyrotoxicosis: a group of symptoms andsigns due to elevated thyroid hormones in thebody of any cause.
Hyperthyroidism: a group of symptoms andsigns due to increased production of thyroidhormones by hyper functioning thyroidgland.
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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
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TFT and Thyroid scan
Thyrotoxicosis= suppressed TSH and elevatedT3/T4.
Based on TFT, the exact cause ofthyrotoxicosis can not be determined.
Thyroid scan is a very helpful tool indifferentiating between various causes ofthyrotoxicosis.
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Thyroid scan and uptake
Radioactive Iodine (RAI) is used for thyroidscan and uptake.
RAI is given orally.
Image and uptake are obtained after 24 hours
Follicular cell traps Iodine and organifys it tobe incorporated with thyroid hormone.
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Imaging findings
Symmetric or asymmetric lobes.
Homogeneous or inhomogeneous uptake
Nodules; cold or hot
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Thyroid Uptake Probe
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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%).
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Graves’ Disease
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Single Toxic Nodule
Single hot nodule (independent of TSH orautonomous).
Rest of thyroid gland is poorly visualized dueto low TSH level (TSH dependant).
24-hour RAI uptake is slightly elevated,usually around 20%.
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Toxic Nodule
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Hot Nodule
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Toxic Multi-Nodular Goiter
Mild inhomogeneous uptake in thyroid gland.
Multiple cold and hot nodules in both thyroidlobes.
24-hour uptake is mildly elevated, usuallybetween 20%-30%.
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Multi-nodular Goiter
• Cut surface of onelobe of thyroid glandshowing ill definednodules.• Focus of cysticdegeneration seen(blue arrow).• Some hemorrhage(red arrow) and somescarring.
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Multi-nodular Goiter
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Early Phase Sub-acuteThyroiditis
Inhomogeneous uptake could be mild orsevere. In some cases thyroid gland is notvisualized.
No significant focal abnormalities (nodules).
24-hour RAI uptake is low, usually < 5%.
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Sub-acute Thyroiditis
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Hypothyroidism
The main cause is chronic thyroiditis(Hashimoto’s thyroiditis).
TSH is elevated.
Thyroid scan does not have significantdiagnostic value in this entity.
However, if there is nodule/nodulesconfirmed by physical examination andultrasound, thyroid scan may be helpful.
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Thyroid Nodules
thyroid nodules are common, perhapsexisting in almost half the population
Nodules are usually found by physicalexamination or by ultrasound.
US is the first modality used to investigate apalpable thyroid nodule
scintigraphy is reserved for characterizingfunctioning nodules and for staging follicularand papillary carcinomas.
The patient is usually euthyroid.
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If the patient is hyperthyroid do nuclear scanotherwise do FNA.
FNA is the most accurate and cost-effectivemethod for diagnostic evaluationof thyroid nodules.
FNA have a sensitivity of 76%–98%,specificity of 71%–100%
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Frequency of Occurrence ofThyroid Malignancies
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Risk factorsfor 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 60years,
previous diagnosis of type 2 multipleendocrine neoplasia
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US features of thyroidnodules
there is some overlap between the US appearance ofbenign nodules and that of malignant nodules
certain US features are helpful in differentiatingbetween the two. These features include
1.micro-calcifications
2.local invasion
3.lymph node metastases
4.a nodule that is taller than it is wide
5.markedly reduced echogenicity.
Other features, such as the absence of a halo, ill-defined irregular margins, solid composition, andvascularity, are less specific but may be useful.
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US Features Associated withThyroid Cancer
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Thyroid microcalcifications
They are psammoma bodies, which are 10–100-μm round laminar crystalline calcificdeposits. They are one of the most specificfeatures of thyroid malignancy, with aspecificity of 85.8%–95% and a positivepredictive value of 41.8%–94.2%
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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
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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
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Local Invasion and Lymph NodeMetastases
US features that should arouse suspicionabout lymph node metastases include arounded bulging shape, increased size,replaced fatty hilum, irregular margins,heterogeneous echotexture, calcifications,cystic areas and vascularity throughout thelymph node instead of normal central hilarvessels at Doppler imaging
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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
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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
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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
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Margins, Contour, and Shape
A completely uniform halo around a nodule ishighly suggestive of benignity, with aspecificity of 95%
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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
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Vascularity
papillary thyroid carcinomas had someintrinsic blood flow
avascular nodule is very unlikely to bemalignant.
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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
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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
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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
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Hypoechoic Solid Nodule
Marked hypoechogenicity is very suggestiveof malignancy.
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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
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Nonspecific US Features
The size of a nodule is not helpful forpredicting or excluding malignancy. There is acommon but mistaken practice of selectingthe largest nodule in a multinodular thyroidfor FNA.
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Number of Nodules
Although most patients with nodularhyperplasia have multiple thyroid nodulesand some patients with thyroid carcinomahave solitary nodules, the presence ofmultiple nodules should never be dismissedas a sign of benignity.
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Interval Growth of a Nodule
In general, interval growth of a thyroidnodule is a poor indicator of malignancy.Benign thyroid nodules may change in sizeand appearance over time.
The exception is clinically detectable rapidinterval growth, which most commonlyoccurs in anaplastic thyroid carcinoma butalso may occur in lymphoma, sarcoma, and,occasionally, high-grade carcinoma.
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Recommendations for Thyroid Nodules1 cm or Larger in Maximum Diameter
Society of Radiologists in UltrasoundConsensus Conference Statement
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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
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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
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Role of color Doppler US. (a) Transverse gray-scale image of predominantly solid thyroidnodule (calipers).
papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
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Transverse US images of mostly cystic thyroid nodule with a mural component containingflow.
The lesion was benign at cytologic examination
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
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US features of malignant lymphnode
rounded bulging shape
increased size,
replaced fatty hilum
irregular margins
heterogeneous echotexture
calcifications
cystic areas
vascularity throughout the lymph node instead ofnormal central hilar vessels at Doppler imaging
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Abnormal cervical lymph nodes.
metastatic papillary carcinoma
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
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Abnormal cervical lymph nodes.
metastatic papillary carcinoma.
Frates M C et al. Radiology 2005;237:794-800
©2005 by Radiological Society of North America
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US-guided FNA Technique
The needle may be introduced parallel orperpendicular to the transducer, and theneedle tip should be carefully monitoredduring the procedure.
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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
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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
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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
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Clinical history:
Slow onset (months), painless
ThyroidOphthalmopathyGraves’ Disease
Patterns of muscle involvement in thyroidopthalmopathy:
Bilateral (85%), Unilateral (5%), Normalmuscles (10%)
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ALL muscles involved is most common scenarioof extraocular muscle enlargement.
If only individual muscles involved, typically thenare inferior and medial recti muscles
Lateral rectus muscle: last to become involved;rarely/never the only muscle involved
Muscle enlargement characteristically involvesthe body of the muscle, sparing the tendinousattachment to the globe.
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Coronal imaging is the method of choice forassessing muscle thickness
Patients need not be hyperthyroid (some areeuthyroid)
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Renal osteo-dystrophy :
1- Seen in setting of chronic, end-stage renaldisease.
Related to combination of secondaryhyperparathyroidism and osteomalacia.
2-Osteopenia is most common finding; however,10-20% of patients also exhibit osteosclerosis.
3-Characteristic finding of osteosclerosis is"Rugger jersey spine"
Bands of hazy sclerosis that parallels thevertebral body endplates
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4- Additional signs ofhyperparathyroidism such asresorption of secondarytrabeculae, cortical thinning,subperiosteal bone resorption, orbrown tumors are often present.
Both axial and appendicularskeleton involved.
Increased risk for pathologicfracture.
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Typical subperiosteal bone resorption atthe radial aspects of the middle phalanges(small arrows) with bone resorption at themargins of the distal interphalangeal joints(arrowheads) and paraarticular soft tissueswelling of the proximal interphalangealjoint (thin arrows).
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