Deck 23: The Thyroid and Parathyroid Glands

Question 1

The thyroid gland is composed of follicles filled with a substance called

A) thyrotropin.
B) parafollicular cells (C cells).
C) colloid.
D) none of the above

Answer 1

C
The thyroid is composed of follicles filled with colloid, which is secreted by the cuboidal epithelioid cells lining the periphery of the follicle.

Question 2

The sonographic appearance of the normal parathyroid glands generally is

A) hyperechoic compared with the thyroid gland.
B) mixed echogenicity with calcifications.
C) anechoic with through transmission.
D) hypoechoic compared with the thyroid gland.

Answer 2

D
The parathyroid glands generally appear as flat, hypoechoic structures posterior to the thyroid gland and anterior to the longus colli muscle.

Question 3

The average weight of the thyroid gland is approximately

A) 25g.
B) 40g.
C) 15g.
D) 10g.

Answer 3

A
The thyroid gland weighs approximately 25 g.

Question 4

The thyroid is an endocrine gland that secretes three hormones, which are

A) triiodothyronine (T4), thyroxine (T5), and calcitonin.
B) triiodothyronine (T3), thyroxine (T4), and calcium oxide.
C) thyroxine (T4), triiodothyronine (T3), and calcitonin.
D) triiodothyronine (T3), thyroxine (T7), and iron.

Question 5

The superior thyroid artery is a branch of the :

A) common carotid artery.
B) internal carotid artery.
C) external carotid artery.
D) vertebral artery

Question 6

The secretion of triiodothyronine (T₃), thyroxine (T₄), and calcitonin is regulated by the

A) pituitary gland only.
B) hypothalamus only.
C) hypothalamus and pituitary gland.
D) parafollicular cells (C cells).

Question 7

The high resolution sonography recommended for evaluation of parathyroid adenomas is

A) 3.5 to 5 MHz.
B) 5 MHz only.
C) 4.5 MHz.
D) 7.5 to 15 MHz.

Question 8

Which statement is NOT true about the thyroid gland?

A) It lies anterior to the trachea.
B) It is composed of right and left lobes only.
C) A pyramidal lobe is present in approximately 15% to 30% of the population.
D) It is composed of right and left lobes connected across the midline by the isthmus.

Question 9

Which statement is NOT true about the sonographic appearance of the neck muscles and the esophagus?

A) The esophagus appears hypoechoic with an echogenic center representing mucosa.
B) The infrahyoid muscles, or strap muscles, are hypoechoic relative to the thyroid gland.
C) The sternocleidomastoid muscle is hypoechoic compared with the thyroid gland.
D) The longus colli muscle is hyperechoic compared with the thyroid gland.

Question 10

When ultrasound fails to identify abnormal parathyroid glands preoperatively, and in patients considered for repeat surgery, which test(s) is/are commonly used?

A) Selective venous sampling
B) Arteriography and magnetic resonance imaging (MRI)
C) Computed tomography only
D) Scintigraphy, SPECT, and MRI

Question 11

Which statement is NOT true about the parathyroid glands?

A) Most people (about 80%) have four parathyroid glands located in a symmetric position contiguous with the thyroid gland.
B) The parathyroid glands generally are situated anterior to the thyroid gland.
C) The parathyroid glands may be intrathyroidal.
D) Approximately 15% of parathyroid glands are ectopic.

Question 12

Which statement is NOT true about the parathyroid glands?

A) Normal adult parathyroid glands generally are not seen with sonography.
B) The parathyroid glands are situated posterior to the thyroid gland and anterior to the longus colli muscle.
C) Normal parathyroid glands almost always can be seen, especially in young patients.
D) A prominent longus colli muscle may be mistaken for a parathyroid adenoma.

Question 13

Which statement is NOT true about the parathyroid glands?

A) They generally have a multilobulated shape.
B) Ectopic locations include the carotid bulb and retroesophageal, thymus, and intrathyroidal locations.
C) Normal parathyroid glands measure approximately 5 to 7 mm in length, 3 to 4 mm in width, and 1 to 2 mm in thickness.
D) Approximately 15% to 20% of parathyroid glands are ectopic.

Question 14

The mathematical method for calculating thyroid volume is based on the ellipsoid formula with a correction factor, which is:

A) Length ´ Width ´ Thickness ´ 0.72 for each lobe.
B) Length ´ Width ´ Thickness ´ 0.62 for each lobe.
C) Length ´ Width ´ Circumference ´ 0.52 for each lobe.
D) Length ´ Width ´ Thickness ´ 0.52 for each lobe.

Question 15

Which statement is NOT true about the thyroid gland?

A) Thyroid volumes increase with age and body weight, as well as in patients with acute hepatitis and those living in regions deficient in iodine.
B) It is an endocrine gland that secretes triiodothyronine (T3), thyroxine (T4), and calcitonin.
C) It is an exocrine gland that secretes triiodothyronine (T3), thyroxine (T4), and iron.
D) The normal mean thyroid volume is 18.6 ± 4.5 ml (± SD), which converts to a 18.6-g gland.

Question 16

Which statement is NOT true about parathyroid gland physiology?

A) When serum calcium levels are low, PTH raises serum calcium by releasing calcium from the bone and decreasing calcium absorption in the liver.
B) The parathyroid glands maintain homeostasis of blood calcium by promoting calcium absorption into the blood and preventing hypocalcemia.
C) The parathyroid glands secrete parathyroid hormone, also called PTH or parathormone.
D) Hypercalcemia (calcium levels greater than 10.2 mg/dl in adults and 10.7 mg/dl in children) is an indication for localizing abnormal parathyroid glands.

Question 17

The sonographic appearance of the normal thyroid gland is uniformly

A) echogenic with medium level echoes, similar to the testes and liver.
B) heterogeneous with medium to high level echoes.
C) hyperechoic with high level echoes.
D) hypoechoic with medium level echoes.

Question 18

The superior and inferior parathyroid glands are supplied by the

A) superior thyroid artery and vein.
B) inferior thyroid artery only.
C) venous plexus only.
D) separate small branches of the superior and inferior thyroid arteries and by branches from the longitudinal anastomoses between these vessels.

Question 19

Neck muscles located anterolateral to the thyroid gland include all of the following except the

A) sternothyroid (ST) and sternohyoid (SH).
B) sternocleidomastoid muscle (SCM).
C) longus colli muscle (LCM).
D) omohyoid (OH) and thyrohyoid (TH).

Question 20

Which statement is NOT true about the thyroid gland?

A) It measures approximately 4 to 6 cm in length, 2 to 3 cm in anteroposterior (AP) diameter, and 1.5 to 2 cm in width.
B) In cross-section, it is outlined anteriorly by the longus colli muscle and the internal jugular vein.
C) The isthmus measures approximately 2 to 6 mm in AP diameter.
D) It plays a major role in growth and development and regulates basal metabolism through the synthesis, storage, and secretion of thyroid hormones.

Question 21

Which statement is NOT true about imaging of the parathyroid glands?

A) High resolution (7.5 to 15 MHz) linear transducers are routinely used to image abnormal parathyroid glands.
B) In a patient with a thick neck, a lower frequency (e.g., a 4 to 8 MHz convex transducer) may be required to enhance acoustic visualization.
C) In examinations for inferior parathyroid adenomas, the swallow maneuver briefly elevates the thyroid gland, permitting acoustic access to the most inferior aspect of the gland.
D) Sonography routinely is performed on patients with normal calcium levels.

Question 22

Which statement is NOT true about the sonographic appearance of the normal thyroid gland?

A) It is more echogenic than contiguous muscles and vascular structures.
B) It is uniformly echogenic with medium level echoes, similar to the liver and testes.
C) Anechoic, 1- to 2-mm tubular structures represent the thyroid arteries and veins.
D) It is more uniformly hypoechoic than contiguous muscles and vascular structures.

Question 23

Which statement is NOT true about the size and shape of the thyroid gland?

A) The right lobe often is slightly larger than the left lobe.
B) Shorter, obese patients tend to have oval lateral lobes measuring less than 3.5 cm.
C) Tall, thin patients have elongated lateral lobes that can measure up to 7 to 8 cm in the longitudinal plane.
D) Thyroid gland measurements have a wide range of variability.

Question 24

Which statement is NOT true about the parathyroid glands?

A) The typical sonographic appearance of a parathyroid adenoma is an oval, hyperechoic, structure without through transmission.
B) Primary hyperparathyroidism is caused by a solitary parathyroid adenoma in 80% to 90% of cases.
C) Most people have four parathyroid glands located posterior to the thyroid lobe and anterior to the longus colli muscle.
D) The most common indication for parathyroid imaging is hypercalcemia.

Question 25

The major neurovascular bundle is located posterolateral to the thyroid gland and consists of the common carotid artery, internal jugular vein, and vagus nerve. ____

Question 26

Which neck muscle(s) is/are located posterior to the thyroid gland?

A) Longus colli muscle
B) Omohyoid and thyrohyoid muscles
C) Sternocleidomastoid muscle
D) Sternothyroid and sternohyoid muscles

Question 27

Which statement is NOT true about the adult thyroid gland?

A) It plays a major role in growth and development and regulates basal metabolism through the synthesis, storage, and secretion of thyroid hormones.
B) In cross-section, it is outlined posterolaterally by the CCA and the IJV.
C) The isthmus measures approximately 2 to 6 mm in AP diameter.
D) The thyroid parenchyma is composed of connective tissue and masses of chief cells.

Question 28

The presence of an extrathyroidal artery leading to an abnormal parathyroid gland aids the detection of an otherwise inconspicuous parathyroid adenoma ____

Question 29

Which statement is NOT true about the parathyroid glands and parathyroid adenomas?

A) Approximately 35% of parathyroid glands are ectopic.
B) Ectopic locations for parathyroid glands include the carotid bulb, as well as retroesophageal space, the thymus and perithymic tissues, and within the thyroid gland.
C) Current state-of-the-art color flow imaging of parathyroid adenomas demonstrates intraparenchymal hypervascularization in approximately 90% of cases.
D) Normal cervical structures, such as the longus colli muscle, esophagus, and small extrathyroidal arteries and veins, can mimic parathyroid adenomas.

Question 30

Patients with secondary hyperparathyroidism develop hypercalcemia. ____

Question 31

Which statement is NOT true about the thyroid gland?

A) It is connected across the midline by the isthmus.
B) It is composed of right and left lobes.
C) It lies anterior to the trachea.
D) In cross-section, it is outlined posterolaterally by the common carotid artery (CCA) and internal jugular vein (IJV), and anteriorly by the longus colli muscle.

Question 32

Most parathyroid adenomas appear in the area of an anatomic "triangle" formed by the thyroid gland, longus colli muscle, common carotid artery, and internal jugular vein. ____