An ultrasound uses high-frequency sound waves that are transmitted through breast tissue from a hand-held unit called a transducer. These sound waves bounce off breast tissues. The "echoes" created as a result are then recorded by a computer that makes an image of the breast tissue and displays it on a monitor. No radiation is used, and very little pressure is required.
Ultrasounds produce sharp, high-contrast images. In dense breast tissue, the ultrasound can create an image that often allows a doctor to distinguish between a fluid-filled cyst and a solid mass. Mammograms do not make this distinction as accurately, though they are better than ultrasounds at detecting microcalcifications (which can be an early sign of breast cancer).
Ultrasound imaging requires a skilled operator who can examine suspect areas of the breast by positioning the transducer in several positions. The operator must decide when to reposition the transducer, or the patient, in order to get the best images.
Often, breast abnormalities that are suspected to be cancerous after a mammogram can be identified as benign with a follow-up ultrasound examination. Benign breast abnormalities can include cysts and plugged milk ducts. If your doctor sends you for an ultrasound, it doesn't always mean that you have cancer -- just that a clearer picture of your breast is needed.
What Can be Seen on an Ultrasound
- Can't image areas deep inside the breast
- Requires a well-trained and experienced operator
- Equipment can sometimes have problems
- May have trouble distinguishing between abnormality and surrounding tissue
- Cannot show microcalcifications
- High-contrast images
- Can image nonpalpable masses (lumps that you can't feel)
- No compression, pain-free
- No radiation
- Less expensive than CAT scan or Breast MRI
Ultrasound can also be used to guide a surgeon during a breast biopsy, so the most accurate tissue sample can be taken. Your surgeon can also use an ultrasound to guide the needle during an aspiration of a cyst in order to remove fluid. Lymph nodes can be imaged by ultrasound because they make a characteristic image which distinguishes them from malignant tumors.
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Imaginis.com. Breast Cancer Diagnosis. Ultrasound Imaging of the Breasts. Last Updated: July 2007. http://www.imaginis.com/breasthealth/ultrasound.asp