Moving Pictures — Ultrasound Video Loop May Someday Supplement Mammography for High-Risk Screening
By Kathy Hardy
Vol. 9 No. 10 P. 20
The investigational automated ultrasound system captures 2,000 to 5,000 images of breast tissue and links them together in a “moving loop” of streaming video.
When the Pap smear was first developed in the 1920s, the fear of cervical cancer was considerable, and there was great hope in the new test. Today, this procedure, commonly performed during a woman’s annual gynecological exam, gives peace of mind.
Kevin M. Kelly, MD, director of breast imaging at Huntington Memorial Hospital and the Hill Breast Center, both located in Pasadena, Calif., hopes to see a parallel between the Pap smear’s role in reducing cervical cancer deaths and an investigational ultrasound device’s potential to reduce the number of breast cancer deaths, particularly for at-risk women with dense breast tissue.
“I’m working toward having ultrasound breast imaging become as accepted as the Pap smear,” Kelly says. “In 1965, women had a fear of cervical cancer. Now, it’s virtually gone. There is no fear of cervical cancer. I’m working toward a day when breast cancer will be considered in the same way cervical cancer is considered today.”
In pursuit of this goal, Kelly has invented SonoCiné, an investigational ultrasound device that conducts computerized ultrasound exam guidance. While traditional ultrasound produces approximately 30 permanent images, SonoCiné captures 2,000 to 5,000 images of breast tissue and links them together in a “moving loop.” A sonographic video streams to a computer, with images remaining in the same format as if they were viewed on the ultrasound monitor with no data compression. Kelly says this allows radiologists to better identify cancerous tissue pattern distortions.
The Hill Breast Center has performed approximately 6,000 SonoCiné exams, with more than 80 cancerous nodules discovered in about 55 patients. SonoCiné, Inc. is in the FDA-approval process, seeking 501(k) clearance that would allow it to market its label claims and enter into negotiations with distributors for commercialization purposes. Currently, however, it is not reimbursed by health insurance plans.
Kelly says the next step is premarket approval, which is the most stringent type of device marketing application required by the FDA. SonoCiné must receive FDA approval of its premarket approval application prior to marketing the device.
During an FDA-approved, multicenter clinical trial completed in 2001, 500 high-risk women, defined as having either dense breast tissue or a family history of breast cancer, underwent ultrasound screening with SonoCiné. During the study, 20 cancers were discovered; 18 of those were found with SonoCiné and 15 with mammography. Three cancers found by SonoCiné were not discovered with either mammography or physical exam. While specific findings from this study are pending, the conclusion suggests that SonoCiné is a complement to, not a replacement for, mammography.
“Early results appear to show a significant increase in the number of cancers found,” Kelly says, “and the size of the cancers found is smaller. That’s significant as well.”
Kelly bases the significance of these findings on a study released in 2004, led by Elena B. Elkin, PhD, on the effect of changes in tumor size on breast cancer survival in the United States from 1975 to 1999. Within each stage category in the study, the proportion of smaller cancerous tumors increased significantly over time. As more smaller cancers are discovered, breast cancer survival rates may improve. This improvement, according to the study, has coincided with important advances in both screening and treatment.
“The Elkin paper looks at the reduction in size and shows that the survival rate of patients with breast cancer improves as smaller cancers are discovered,” Kelly says.
Participants in the multicenter trial paid for their exam costs, which Kelly says ranged anywhere from $250 to $400, depending on the center. “Having women pay for the exam, rather than paying them to participate in the study, ensured that they really wanted to be involved,” he says. “They were motivated to undergo the ultrasound imaging.”
How It Works
A SonoCiné ultrasound scan takes about 30 minutes to complete. The transducer is computer guided rather than handheld, as is the case with traditional ultrasound scanning. The robotic arm is programmed to gently move up and down over the breasts in slow, steady overlapping rows. The technologist must provide the correct skin pressure and angle of inclination for the transducer, while the SonoCiné system provides uniform speed and position. The transducer moves across the skin at 0.8 millimeters per second, with images collected at 800-micron intervals. With this automated scanning method, any fluctuations that can occur with handheld transducer scans are reduced.
“I always knew ultrasound imaging was good enough to see small lesions,” Kelly says. “It’s the human who’s having the trouble seeing. You need to control the transducer. You need to control the images in the stage I want them. With SonoCiné, you review the images, eliminate duplicates, and end up with the images you need.”
Patients undergoing the scan wear a thin, tight-fitting camisole to hold the breasts in place. The camisole is covered with gel for ultrasound transmission, with gel pads placed over the nipples to reduce any obscuring shadow. This also helps identify the nipple as a reference point in the sonogram.
Once each unique image is transferred for viewing, SonoCiné’s technology allows radiologists to adjust the brightness and contrast of the images for a more precise analysis. The image size is reduced without loss of resolution, increasing the contrast between cancerous and normal tissue.
When considering how to configure this new system, Kelly considered what was best for the physicians. Although SonoCiné has 3D capabilities, he based the device on 2D compatibility. He notes that new technology is often developed based on manufacturers’ specifications instead of the needs of the physicians who will use it. “You need to make the technology compatible with what the physician already does,” Kelly says.
Next, he determined how to obtain unique images that are clear and can be viewed in a way that the reader would have time to assimilate them. “Magnifying the images isn’t necessarily the best way to view ultrasound,” he says. “You still have the same image; it’s just displayed larger. You’re just spreading it out into a larger image, but you don’t really improve the visibility.”
Kelly’s medical career began in the 1970s after two years as a lieutenant commander in the U.S. Public Health Service Center Bureau of Radiological Health. His focus on breast imaging began after his military service, but he knew even before then that mammography could benefit from other imaging methods.
“As early as the 1970s, they knew the problem with mammography,” he says. “A woman would get her annual breast mammography screening and three months later come back and there would be a mass. It was discouraging to see this.”
He became involved with ultrasound in 1993 when stereotactic methods were being introduced. It was at that time Kelly realized lesions could be viewed better with ultrasound than with mammography in women with dense breast tissue.
“I would review the images and concluded that ultrasound was good,” he says. “You could tell the difference between solid and fibrocystic masses. It was clear 10 to 12 years ago, and I could see a lot of cancers with ultrasound that I couldn’t feel at all.”
Kelly is quick to point out that SonoCiné, as with other ultrasound technology, should be used in conjunction with routine mammography. The x-ray exam can help pinpoint where potential masses exist, enabling SonoCiné to focus on those particular areas.
“You’re using a diagnostic tool for detection,” Kelly says, referring to the use of ultrasound as a breast screening tool. “It’s like using a wrench as a hammer.”
He goes on to explain that diagnosis is the method of determining the nature of the disease through analysis, while detection is the “aha” phenomenon of discovering the disease.
“Ultrasound is good at diagnosis,” he says. “I thought if you took ultrasound and designed a system for scanning and viewing ultrasound, you could change it from a diagnostic tool to a detection tool.”
When considering other alternatives to supplementing mammography in the breast cancer screening process, Kelly says SonoCiné’s preliminary findings indicate that ultrasound offers little negative effect on the patient while providing viable results.
“This is a low-cost alternative in the detection of breast cancer,” he says. “MRI has been useful, but it’s an expensive process and requires a contrast injection to view the lesions. Not everyone is comfortable with the injection.”
Women also like ultrasound because there is no radiation involved, he says, and it’s also painless because no breast compression is necessary. Finally, the process is simple and can be easily performed on an annual basis, the same as with mammography.
Kelly has observed that European women more readily accept ultrasound as a supplement to routine breast mammography. In addition, he has found acceptance of ultrasound imaging in developing countries, including China.
“They perform fewer mammograms in China,” he says. “Women there are more likely to have dense breasts, and the thin layers imaged with ultrasound technology better detect cancers in women with dense breast tissue.”
As ultrasound grows in popularity, Kelly believes women will increasingly accept SonoCiné as a reliable supplemental procedure to routine mammography. “Women get a lot of assurance out of this screening,” he says. “This is another level of assurance that everything is alright.”
— Kathy Hardy is a freelance writer based in Phoenixville, Pa., and a frequent contributor to Radiology Today.