Ch. 27

Question 1

Thyroid Gland consists of:

Answer 1

-Two lateral lobes
-Connecting isthmus

Question 2

Thyroid Gland secretes:

Answer 2

-Thyroxine (T4)
-Triiodothyronine (T3)
-Calcitonin

Question 3

Pyramidal Lobe

Answer 3

-Present in approximately 10%-40% of population
-Extends cephalad from isthmus
-May extend from the left or right side of the isthmus (more freq. on left)

Question 4

Normal Measurements

Answer 4

-Thyroid gland (adult)- 4.0-6.0 cm in length ; 1.3-1.8 cm in height ;1.5-2.0 cm in width
-Isthmus (adult)- 4.0-6.0 mm in height
-Thyroid gland (children)- 2.0-3.0 cm in length ; 0.2-1.2 cm in height ; 1.0-1.5 cm in width
-Parathyroid (adult)- 5.0-7.0 mm in length ; 1.0-2.0 mm in height ; 3.0-4.0 mm in width

Question 5

Sonographic Appearance of the Thyroid Glands

Answer 5

-Uniformly echogenic, with medium- to high-level echoes
-Thin, hyperechoic capsule
-Hyperechoic compared with
surrounding muscles

Question 6

Sonography

Answer 6

-Transducer Frequency
Multifocal zones
-Patient Position
-Limitations
-Echogenicity

Question 7

Scan Protocol

Answer 7

-Long
Lateral-medial
Measure
-Trans
Superior-Inferior
Measure
-Isthmus-trans
-Doppler

Question 8

Benign versus Malignant

Answer 8

No single sonographic criterion distinguishes benign thyroid nodules
-Internal consistency
-Echogenicity
-Margins
-Calcifications

Question 9

Physiology of Thyroid Glands

Answer 9

-Plays a major role in growth and development
-Regulates basal metabolism and controls various functions of the body, including memory, weight loss or gain, heart rate, cholesterol levels, skin conditions, and energy levels by the synthesis, storage, and secretion of thyroid hormones.
-Produces and secretes three hormones: T3, T4 and Calcitonin
-Secretion of these hormones is regulated by hypothalamus and pituitary gland.

Question 10

Sonographic Applications of Thyroid

Answer 10

Ultrasound examinations of thyroid glands are indicated for:
-Evaluation of location and characteristics of palpable neck masses, including enlarged thyroid gland
-Detecting recurrent carcinoma after thyroidectomy or regional nodal metastases in patients with proven or suspected thyroid carcinoma
-Ultrasound-guided thyroid procedures

Question 11

Parathyroid

Answer 11

-Four parathyroid glands (5x3x1mm)
-Normal circumstances (Sonographically, not always seen)
-Hyperparathyroidism (Women 2-3 times more than men) (Single Adenoma)
-Hypercalcemia

Question 12

Physiology of the Parathyroid Glands

Answer 12

-Parathyroid glands secrete parathyroid hormone (PTH), also called parathormone
-Primary function is to help maintain homeostasis of blood calcium concentration by promoting calcium absorption into the blood, preventing hypocalcemia

Question 13

Parathyroid Anatomy

Answer 13

-Typically located posterior to thyroid gland and anterior to LCM
-Majority of parathyroid masses appear in area of an anatomic “triangle” formed by thyroid gland, LCM, CCA, IJV

Question 14

Sonographic Applications of Parathyroid

Answer 14

Ultrasound examinations of the parathyroid glands are indicated for:
-Localization of parathyroid adenomas in patients with suspected primary or secondary hyperparathyroidism
-Assessment of number and size of enlarged parathyroid glands
-Localization of thyroid/parathyroid abnormalities or adjacent cervical lymph nodes for (FNA) biopsy

Question 15

Sonographic Appearance of the Parathyroid Glands

Answer 15

-Similar in echogenicity to thyroid
-Not generally identified with ultrasound unless they are abnormal