On the left is an ultrasound image of breast scan, which shows a tumorous growth as a large, dark spot. On the right is an elastograph of the same breast. The elastograph gives a clearer image of the tumor and shows it to be larger than the sonogram reveals. It also captures a second, smaller tumor (to the left of the larger one) that didn't show up on the sonogram.

Image courtesy ALGOR, Inc.

December 6, 2006

When most of us hear the word "tumor," our heart skips a beat. But a tumor doesn't necessarily mean the C-word. In fact, if you want to get technical about it, a tumor is simply "an abnormal growth of tissue" or "a swelling." The human body is a complex system that produces countless abnormal growths or swellings that are totally harmless. But when someone discovers a breast lump and a doctor can't automatically determine it's harmless by palpation (a method of feeling the lump with the fingers to determine its characteristics), the next step is often a biopsy.

A biopsy is an invasive procedure that can cost up to $1,000 depending on the method used to extract the questionable tissue and how much of the tissue is extracted, and the result can take up to two weeks to come back. Overall, under the best of circumstances, there's a lot of anxiety involved. But a procedure that's been in the research phase for almost a decade could possibly change all that. Elastography, a twist on the traditional ultrasound technique of using sound waves to create a picture of what's going on inside the body, can determine if a growth is malignant or benign in an instant.

As it turns out, even with the huge variety of harmless tumors the body can produce, they all have one thing in common: They're a lot softer than cancerous tumors. In the case of a breast tumor, a benign one is anywhere from five to 100 times more flexible than a malignant one. Elastography takes advantage of this characteristic to quickly diagnose breast cancer without the use of a needle or a scalpel. It's sort of like mechanical palpation taken to the next level: digital, extremely reliable, and unaffected by the depth of the tumor.

To understand elastography, we need to first understand ultrasound. If you've read How Ultrasound Works, you know that this medical imaging technique uses the echoes produced by high-frequency sound waves to construct an image of the inner body. When a sound wave hits an object, it's reflected -- this is the "echo" that an ultrasound machine captures. Depending on how and when the sound waves are echoed as they penetrate the body, the machine can put together a picture of what the sound waves are hitting. Ultrasound has tons of applications besides the imaging of tumors -- those fuzzy pictures of fetuses in the womb are created by ultrasound, for example. Ultrasound images are called sonograms.

So the software that processes traditional ultrasound creates a sonogram based on the echoes of sound waves when they penetrate the skin and hit various masses and tissues inside the body. Elastography does this, too, but it adds another dimension to the mix: compression.

An elastograph is a picture much like an ultrasound image except that it's the combination of two views instead of just one. In elastography, the ultrasound technician first takes a regular ultrasound image and then takes a compression image. In the case of elastography of the breast, the technician pushes slightly on the breast with the ultrasound emitter in order to compress the breast tissue. As we already discussed, the normal breast tissue and any benign growths are going to be much more elastic than a malignant tumor, so they're going to depress a lot more easily. A malignant tumor is hardly going to depress at all. The second picture in elastography captures the echoes of the sound waves in this compressed state. Since a malignant tumor behaves so differently from a benign tumor under compression, the computer-generated combination of the first image with the compression image is going to reveal a lot more information than the first image alone. In a small elastography study whose results were revealed at a radiology conference in 2006, elastographs correctly identified benign versus malignant tumors with a nearly 100 percent success rate.

While elastography has a ways to go before doctors abandon biopsies in favor of sound waves, it has a lot going for it. Experts estimate a cost of $100 to $200 for the procedure, and it's completely non-invasive. Also, since the results are right there for the doctor to analyze on the spot, diagnosing a tumor as cancerous or harmless can happen in one visit. There's no need for a second appointment to get your results after a week or two of sleepless nights.

Researchers are also studying elastography for diagnosing prostate cancer, cirrhosis of the liver (in which the liver characteristically hardens) and heart irregularities, among other applications.

For more information on elastography and related topics, check out the following links:

Sources

  • Brown, Darla. "New Imaging Technology Deciphers Tumors." Distinctions. The University of Texas Health Science Center at Houston. Oct. 2003. http://distinctions.uthouston.edu/archive/2003/oct/tumor.html
  • "'Elastogram' instantly diagnoses breast cancer." MSNBC.com. Dec. 1, 2006. http://www.msnbc.msn.com/id/15990645/
  • Ophir, Jonathan, MD. "New Medical Imaging Technique Improves Chances of Early Cancer Detection." Algor. June 16, 1998. http://www.algor.com/news_pub/cust_app/cancer/cancer.asp