Ultrasound
Ultrasound works using the same principles as sonar, which is used by bats and some marine vessels for the purpose of locating objects. As the Mayo Clinic explains, ultrasonography works by transmitting high frequency sound waves into the body using a device called a transducer. These sound waves travel into the body and are bounced back when they hit internal structures, such as the thyroid. The ultrasound transducer also works as a detector, so it is able to detect and measure the reflected sound waves. Based on this information, the ultrasound machine is able to generate an image of the thyroid.
Procedure
Radiology Info explains that for an ultrasound examination of the thyroid, most patients are told to lie on an adjustable examination table. A radiologist or a technician then applies a water-based gel onto the patient's throat. This helps eliminate any air between the transducer and the patient's skin, which makes it easier for the sound waves to penetrate the patient's skin. The technician then places the transducer onto the gel-covered area and moves it around to get ultrasound signals from different angles. Sometimes the images from the ultrasound are displayed in real time on a monitor by the machine; other times, the ultrasound images need to be reviewed after the scan is complete.
Interpretation
Thyroid problems can be detected using ultrasound by measuring the size of the thyroid as well as looking for any irregularities in the surface of the thyroid. An unusually large prostate could be the result of inflammation (thyroiditis) or to compensate for poor thyroid function. Ultrasonography can also be used to look for thyroid tumors that could be a sign of thyroid cancer. However, one of the disadvantages of using ultrasonography to diagnose thyroid problems is that it can only detect the presence of thyroid tumors; it cannot determine if they are cancerous or not.
