Thyroid ultrasound uses ultrasonic waves to identify the shape of the thyroid and its internal structure and its relation with surrounding tissues.
As the most sensitive method among image diagnostics for thyroid currently used, this can recognize all thyroid nodules of approximately 1-2 mm or more.
To check a nodule on the thyroid gland with hands, it must be at least 1-1.5 cm in size, and sometimes, one larger than that may not be touched.
But the ultrasound can identify the presence, location and nature of a very small nodule that can't be touched and distinguish whether the nodule is cystic.

Since the outer surrounding tissue of the thyroid can be seen, if thyroid cancer spreads out into the surrounding tissue, you can look at the condition in some degree and the local recurrence after surgery.

But the method is very sensitive, so even all small and minor lumps can be found.
In fact, almost 40 to 50 percent of the population has small thyroid lumps, but most or all of them don't cause health problems.
When lumps are discovered, patients are unnecessarily worried about the possibility of cancer. Thus, it is not always good to early find out abnormalities.
However, the thyroid ultrasound is first implemented for those who are suspected to have a thyroid disease.