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Last Updated: 12/22/16

Ultrasound

Ultrasound (US) uses sound waves with frequencies above those humans can hear. A transducer sends sound waves traveling into the body which are reflected back from organs and tissues, allowing a picture to be made of the internal organs. Ultrasound can show tumors, and can also guide doctors doing biopsies or treating tumors. Most people know about US images when a woman is pregnant, for example — boy or girl. As with diagnostic MRI, there is no harmful radiation from diagnostic US. (Keep in mind, both MRI and US can be used for treatment under certain conditions - but this very uncommon currently.) Unfortunately, while US is very useful for imaging certain body parts, it is not as useful as other imaging techniques for looking at the brain, lungs or an entire abdomen or pelvis. Because masses can sometimes be tiny and far from the skin surface, we usually need CT, MRI and / or PET to find these places of suspect tumor spread.

PET scan
Ultrasound image of the liver; dark areas by arrows show possible tumors. Image courtesy of Dr.Thomas Shawker, National Cancer Institute.