Diagnostic tests: Breast ultrasound
| April 12, 2007
Diagnostic tests: Breast ultrasound
Breast ultrasound is an imaging test that uses painless high-frequency sound waves to help doctors evaluate whether a density that appears on a mammogram is a fluid-filled cyst, a solid mass, or a variation of normal breast tissue. A cyst is generally benign, and a solid mass may be either benign or malignant.
It is quite common for a routine screening mammogram to show an abnormality that does needs further definition. The radiologist may request additional studies to answer any uncertainty. Commonly, the next test is an ultrasound. So, don't be overly concerned if you are called back to the radiologist's office to undergo an ultrasound examination after completing your mammogram.
Ultrasound isn't used for routine screening because it can't show the entire breast at one time; it can only visualize small areas accurately. Also, it doesn't show as much small detail as a mammogram does.
It's important to keep in mind that 1%–2% of breast cancers elude both ultrasound and mammography. So if there is a persistent change that you or your physician can feel in your breast, a biopsy may be required even without any clear results from the ultrasound or mammogram.
To obtain good quality breast-imaging services and careful biopsies, your best choice is a breast health center or any medical facility that does many of these procedures and is accredited by the American College of Radiology. There are very important credentials that both the facility and the physician who is performing and interpreting the results of a mammogram are required to have to assure that the highest quality test is performed.
In some institutions, the mammogram is first read (interpreted) by one radiologist; it then is interpreted by a second radiologist. If the two physicians agree, a final report if issued. If there is a discrepancy in the two interpretations, the radiologists confer and determine the next course of action. This may include a third interpretation, or a repeat exam or getting an ultrasound exam as well.
Also, the machine that is taking the mammogram pictures must be tested and certified to be delivering the correct dose of radiation during the mammographic procedure.
Cyst or solid mass? If a density is a fluid-filled cyst, the ultrasound waves will go through it and a black "hole" or spot will appear on the ultrasound image. If it's a solid mass, the waves will echo off, and it will appear as a white spot.
Ultrasound is a relatively easy way to diagnose a simple cyst. A simple cyst is like a tiny water balloon; it contains only fluid and does not contain any portions of cells or tissue from the breast. Even so, the doctor may perform a needle aspiration to remove the fluid from the cyst, just to be certain that it is just a simple cyst. Often, the fluid is sent to a cytologist or pathologist to examine any cells that may have been removed with the fluid.
If a cyst doesn't appear to be "clear" on ultrasound, then it is called a complex cyst. A needle aspiration is usually performed to see if there may be cancer cells hiding in it. The complex cyst will collapse after it's drained, making it possible to see any abnormality that might have been concealed. Most complex cysts have irregular shapes or debris floating inside the fluid. Complex cysts need to be aspirated (have the fluid portion of the cyst removed) under ultrasound guidance. The ultrasound images can determine whether the cyst fully collapsed following drainage and whether there is any additional abnormality.
If the mass is solid, the ultrasound appearance of it may help determine whether the mass is benign or malignant. A benign mass is typically more horizontal ("lying down") and has a smooth outer border. A cancer is more vertical ("standing up"), with an irregular border. If there is any uncertainty, a fine needle aspiration or surgical biopsy should be performed.
Review Date: 2007-04-12
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