ANN ARBOR, Mich. -- When a woman feels a lump in her breast or gets mammogram results that show a possible problem, she often faces weeks of uncertainty until a biopsy comes back with the verdict -- is it cancer, or just a harmless cyst?
Now, a new medical imaging approach being developed at the University of Michigan Health System may give patients and doctors a way to tell even before biopsy if most masses inside the breast are malignant or benign. It may also provide a way to detect tumors long before a mammogram or breast self-exam could, and to track a tumor's response to treatment faster.
Called 3-D color Doppler ultrasound, the technique uses sound waves and sophisticated computerized equipment to allow doctors to see how quickly blood is moving in the vessels around a suspicious area - and to see that area in three dimensions. Because cancer cells grow rapidly and need extra blood to feed their spread, the technique can distinguish between tumors and benign masses. It can also pick up signals of increased blood flow and formation of new blood vessels in a cancerous area before any other imaging method can.
The researchers, from the U-M Department of Radiology, reported the latest results of their initial clinical trials at a recent meeting of the American Institute of Ultrasound in Medicine.
In a study of 38 women, 20 of whom had malignancies confirmed by biopsy, they were able to tell the difference between tumors and benign masses 100 percent of the time by combining 3-D color information on blood flow with a conventional ultrasound image of the same region, and taking into consideration the woman's age. They also reported success in tracking the changes in tumor blood flow over the course of pre-surgery chemotherapy in five breast cancer patients.
"We're hoping to add 25 percent to 50 percent more information to current ultrasound images, increasing the chances of being right when we try to discriminate benign from malignant masses," says Paul Carson, Ph.D., a U-M professor of radiology and bioengineering who leads the group developing the technology. "While we do not expect ultrasound to replace either mammography or biopsy, we see great potential for complementary use to benefit patients."
Carson's colleague, U-M breast imaging specialist and associate professor of radiology Marilyn Roubidoux, M.D., adds, "Mammography only finds about 85 percent of all cancers, so we need additional methods of detection. In the immediate future, I see this technique as useful for patients who have mammogram results that are extremely complicated for the radiologist to interpret. In these cases, finding a small tumor is like trying to find a seagull in a cloudy sky. Our approach can help find the seagulls that are hiding in the clouds."
The preliminary results from the technique's first trials are encouraging. Now, the researchers are analyzing results from another 40 patients. They also will work with physicians in the U-M Comprehensive Cancer Center to test the approach on more women who will soon be participating in a trial of a new chemotherapy regimen. The 3D ultrasound measurements of vascularity, or blood flow measure, are not yet available as part of routine mammogram appointments at the U-M.
With this research, the U-M team is improving on existing ultrasound techniques, which have been used for several years but do not provide three-dimensional information or reproducible data on blood vessels and flow. The new approach relies on sophisticated computer methods, developed by U-M scientists, that allow two different kinds of images to be made and then compared.
The first is a conventional gray-and-white ultrasound image similar to those made during pregnancy. It gives basic information about the breast tissue, which is full of ligaments, ducts and other structures that vary from woman to woman and must be distinguished from suspicious masses. Like all ultrasound images, it is made by sending focused high-frequency sound waves from a hand-held wand into the body, and then measuring the echoes that bounce off structures within the tissue and come back to the scanner.
The second ultrasound image, though, is made with a twist: the returning sound waves are measured for how much they change after bouncing off blood as it moves through vessels. This effect, called Doppler shift, is similar to what happens when a train blows its whistle as it approaches and then moves away from a person standing in a station. The bystander hears high-pitched, then low-pitched, sound waves as the train passes. Doppler ultrasound has been used for several years to get a general sense of blood flow and even color images.
Now, the U-M researchers have improved upon this method of "hearing" blood flow with ultrasound, by measuring the Doppler signal levels related to the volume and speed of blood flow throughout suspicious areas in the breast.
They've created an attachment for the conventional hand-held ultrasound wand that records its precise position in three dimensions as it is moved slowly across the breast. They have developed software that can take the results from a series of these side-to-side blood flow scans, combine them into a three-dimensional picture, and provide reproducible measurements related to blood flow.
"The new technology helps us be precise about the blood flow in the breast, which needs to be accurately measured so it can be a reliable indicator of whether a mass might be cancerous or harmless," says Roubidoux. The clinical trial results suggest that the new methods are better than regular gray scale or color flow Doppler imaging.
While the new 3D color Doppler ultrasound can detect blood vessels that the X-rays in a mammogram simply can't see, it isn't foolproof for every kind of breast cancer. Masses can also be distinguished by the amount of calcium in them, but ultrasound can't reveal calcium. That's why, Carson says, the new technique should be an addition to -- not a substitute for -- existing techniques. Women should still examine their breasts regularly and have annual mammograms after age 40.
Perhaps someday, he projects, ultrasound may also be used in routine detection alongside mammograms. But even before then, he sees the new approach as a powerful ally for patients if a suspected problem turns up and needs further checking before biopsy, if a mammogram is unclear, or if a lump turns out to be breast cancer and the doctor needs to track how well a treatment is working. And in the fight against breast cancer, women and doctors need every ally they can find.
The U-M research on 3D color Doppler ultrasound is supported by the National Cancer Institute of the National Institutes of Health, and by the U.S. Army, under its Breast Cancer Research Program. Besides Carson and Roubidoux, researchers on the team include Gerald LeCarpentier, Ph.D., Pamela Bhatti, MS, J. Brian Fowlkes, Ph.D, Aaron Moskalik, MS, Jochen Krücker, Dipl-Phys, Nancy Thorson, BA, and Charles Meyer, Ph.D.