Ultrasound imaging, also called ultrasound scanning or sonography, is a method of obtaining images of internal organs by sending high-frequency sound waves into the body. The reflected sound waves produce echoes that are displayed and recorded as a real-time, visual image. No ionizing radiation (x-ray) is involved in ultrasound imaging.

Because ultrasound images are captured in real-time, they can show movement of internal tissues and organs, and enable physicians to see blood flow. As a result, ultrasound can help to diagnose a variety of conditions and to assess organ damage following illness. Ultrasound imaging can help a physician determine the source of pain, swelling, or infection in many parts of the body.

Ultrasound is a painless, useful way of examining many of the body's internal organs, including the thyroid. 

A physician may use an ultrasound examination of the neck to help diagnosis a lump in the thyroid or a thyroid that is not functioning properly. The thyroid gland is located in front of the neck just below the Adam's apple and is shaped like a butterfly, with two lobes on either side of the neck connected by a narrow band of tissue. It is one of nine endocrine glands located throughout the body that make and send hormones into the bloodstream. These hormones target specific body functions and affect virtually every organ, tissue and cell in the body.

The thyroid gland produces thyroid hormones. Thyroid hormones set the rate at which your body carries on its necessary functions (metabolic rate). Some of the functions controlled by thyroid hormones include heart rate, cholesterol level, body weight, energy level, muscle strength, skin condition and vision.

The most common diseases of this gland result when the thyroid becomes overactive or underactive. An overactive thyroid, also called hyperthyroidism and Grave's disease, produces more thyroid hormone than is needed. The underactive thyroid, called hypothyroidism, does not produce enough hormone. Other common conditions of the thyroid include an enlarged thyroid, often called a goiter, and lump in the gland.

You will need to extend your neck to gain appropriate access, which may be mildly uncomfortable.