Neck
a congenital diverticulum of the brachial cleft located directly below the angle of the mandible.
bulging of the eyeballs; associated with hyperthyroidism.
subacute thyroiditis secondary to a viral infection.
a pronounced swelling of the neck caused by an enlarged thyroid gland.
a multisystemic autoimmune disorder characterized by pronounced hyperthyroidism; usually associated with an enlarged thyroid and exophthalmos.
a progressive autoimmune inflammatory disorder of the thyroid gland; most common cause of hypothyroidism; associated with an increased risk of developing a thyroid malignancy.
an excessive amount of calcium in the blood; associated with hyperparathyroidism.
excessive function of the parathyroid glands; may lead to osteoporosis and nephrolithiasis.
hyperactivity of the thyroid gland; associated with Graves disease.
a deficiency of calcium in the blood; associated with hypoparathyroidism.
a condition of insufficient secretion of the parathyroid glands; associated with hypocalcemia and primary parathyroid dysfunction.
decreased activity of the thyroid gland; associated with Hashimoto disease.
neck muscles located on the anterior surface of the vertebral column, between the atlas and the third thoracic vertebra; commonly associated with whiplash injuries.
the most severe form of hypothyroidism; characterized by swelling of the hands, face, and feet; may lead to coma and death.
a transient thyroiditis seen following pregnancy.
lateral and superficial neck muscles that attach to the sternum, clavicle, and the mastoid process of the temporal bone; act to flex and rotate the head.
a group of long and flat muscles located anterior and lateral to each thyroid lobe; includes the sternohyoid, sternothyroid, and omohyoid muscles.
an embryonic remnant cyst located between the isthmus of the thyroid and the tongue.
Physiology
Function of the thyroid glands
• Maintain body metabolism, growth, and development.
• Iodine is processed to manufacture, store, and secrete hormones: thyroxine, triiodothyronine, and calcitonin.
• Secretion of thyroid hormones is primarily controlled by the thyroid-stimulating hormone produced by the pituitary gland.
Vasculature of the neck
Common carotid arteries
• Left originates from the aortic arch.
• Right arises from the innominate (brachiocephalic) artery.
• Ascend the anterolateral aspect of the neck.
• Lie medial to the internal jugular vein and lateral to the thyroid lobe.
• Course deep to the sternocleidomastoid muscles.
• Bifurcate into the external and internal carotid arteries.
Vertebral arteries
• Arise from the first segment of the subclavian artery.
• Provide blood to the posterior brain.
• Lie in the posterior neck, ascending through the transverse processes of the spine.
• Left and right vertebral arteries join to form the basilar artery at the base of the skull.
• Basilar artery terminates in the posterior aspect of the circle of Willis.
Vasculature of the thyroid glands
• The superior and inferior thyroid arteries supply arterial flow.
• Superior thyroid artery arises from the external carotid artery.
• Inferior thyroid artery arises from the thyrocervical artery.
• Superior, middle thyroid veins drain into the internal jugular vein; inferior thyroid vein drains into the innominate vein.
Size
• Isthmus—0.2 to 0.6 cm in height.
• Thyroid glands (adult)—4.0 to 6.0 cm in length, 2.0 cm in height, and 2.0 cm in width.
• Thyroid glands (pediatric)—2.0 to 3.0 cm in length, 0.2 to 1.2 cm in height, and 1 to 1.5 cm in width.
• Parathyroid glands—up to 6 mm in length, 2 mm in height, and 4 mm in width.
Sonographic appearance
• Thyroid lobes and isthmus appear as homogeneous solid structures demonstrating a medium-gray echo pattern.
• Sternocleidomastoid and strap muscles appear hypoechoic when compared with the normal thyroid gland.
• Longus colli muscles appear hyperechoic when compared with the normal thyroid gland.
• Parathyroid glands are flat, bean-shaped hypoechoic structures located posterior and medial to the thyroid lobes.
• Carotid arteries and jugular veins appear as anechoic tubular structures demonstrating internal vascular flow.
Technique
Preparation
Examination technique and image optimization
• Use the highest-frequency linear transducer possible to obtain optimal resolution for penetration depth.
• Focal zone(s) at or below the place of interest.
• Sufficient imaging depth to visualize structures immediately posterior to the region of interest.
• Increase the dynamic range setting when imaging the thyroid glands.
• Harmonic imaging can be used to reduce artifactual echoes within anechoic structures.
• Spatial compounding can be used to improve visualization of structures posterior to a highly attenuating structure.
• Use Doppler settings for low-flow to medium-flow states.
• Place the patient in a supine position with the neck extended.
• A pillow may be placed under the upper back to hyperextend the neck.
• Evaluate and document both thyroid lobes from the superior to inferior borders and the medial to lateral borders in two imaging planes.
• Document length, width, and height of each thyroid lobe.
• A convex abdominal transducer can be used to measure enlarged thyroid glands.
• Document thickness of isthmus.
• Document length, width, and height of any abnormality.
• Demonstrate color Doppler flow within each thyroid lobe.
• With multinodular goiters, include measurements of the largest nodules for serial comparison.
• Documentation and measurement of any abnormality in two scanning planes with and without color Doppler should be included.
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