Thyroid scan planes : – Transverse plane of the neck – Oblique plane of the neck. – Scanning recommendations: when performing an EED, the window range is adjusted so that the entire thyroid gland can be examined, the appropriate value of the pulse repetition frequency (PRF) should also be used, for example, 0.06 m / s. 

Ultrasound anatomy of the thyroid gland

• The thyroid gland is scanned in the plane of the transverse section, in the anteroposterior direction (the picture obtained differs from the shape of the “butterfly”, which is presented in anatomy textbooks and in isotopic images).

• Ultrasound anatomy: the trachea is determined directly behind the thyroid gland. The esophagus is defined posteriorly and to the left of the trachea and posteriorly of the left lobe of the thyroid gland. The main blood vessels of the neck pass posteriorly and laterally with respect to the lobes of the thyroid gland.

Normal picture : the thyroid gland is covered with a capsule, which is clearly delimited from the surrounding tissues. It has a granular homogeneous echo structure and is hypoechoic in relation to the surrounding muscles.

Normal sizes : length 40-70 mm, width 10-30 mm, depth 10-20 mm (for each lobe). The width of the isthmus is less than 5 mm.
• Total volume: <25 ml in men, <20 ml in women.
• Volume measurement: length • width • depth • 0.5 (for thyroid lobe).

Thyroid Tips

– Sensor: 5.0-7.5 MHz.
– In each maximum measurement, a picture is taken in the longitudinal plane, then as the sensor moves above the skin, serial transverse pictures are taken.
– Parathyroid glands are detected with ultrasound only if they are enlarged (each of the glands is located posterior to the upper and lower poles of the thyroid gland).

Note : pain during the study may indicate thyroiditis.

– The indication for ultrasound of the thyroid gland may be its functional disorder (hyper- or hypothyroidism) or goiter. In many cases, the results of the study are ambiguous and difficult to interpret. This chapter discusses data that deserves special attention.

– An ultrasound examination of the thyroid gland must necessarily include an assessment of the parathyroid glands. Sometimes they should be differentiated with thyroid nodules. In case of adenoma or hyperplasia, the parathyroid glands look like hypoechoic nodules located posterior to the thyroid gland in the region of its upper or lower poles.

Classification and review : changes in the thyroid gland detected by ultrasound can be classified as diffuse or delimited:
• Diffuse changes: may be associated with a change in the size or echogenicity of the gland.
• Delimited changes: range from anechoic (cysts) to extremely echogenic (calcifications).