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 in your breast, a biopsy may be required even without any clear results from the ultrasound or mammogram.

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 are 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.

Next >> Magnetic Resonance Imaging (MRI)

In This Article:
Detecting Breast Cancer
Breast Self-Exam and Clinical Exam
Mammography
Breast Ultrasound
Magnetic Resonance Imaging (MRI)
Breast Ductogram
Breast Biopsy

From the Harvard Health Publications Special Health Report, Breast Cancer: Strategies for Living. Copyright 2004 by the President and Fellows of Harvard College. Illustrations by Harriet Greenfield, M.A., and Jesse Tarantino. All rights reserved. Used with permission of StayWell. Harvard Medical School does not endorse products.
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