Keck School of Medicine radiologists are conducting a flurry of clinical trials to look for answers to some of the most vexing challenges to women’s breast health: detecting tumors that are difficult to discover in dense breast tissue, and making breast cancer imaging more accessible and affordable.
“There’s a lot going on in our section—a lot of work to push technology forward in women’s imaging,” said Yuri Parisky, associate professor of clinical radiology and director of new technologies at the Harold E. and Henrietta C. Lee Breast Center at USC/Norris Comprehensive Cancer Center.
Breast cancer remains the most common cancer other than skin cancer among women. Although mammography has helped discover breast tumors in many women at an early, treatable stage, the disease continues to take its toll: Breast cancer trails only lung cancer as a leading cause of cancer death among American women.
With this in mind, USC radiologists—including Parisky and assistant professors of clinical radiology Linda Hovanessian and Pulin Sheth—are forging ahead on projects that focus exclusively on the breast.
Hovanessian, for one, is looking for answers to one of radiologists’ most difficult conundrums: how to better find and assess breast cancer early in young women, whose dense breast tissue can often hide suspicious lesions.
Older women who are on hormone replacement therapy also may have dense breasts.
Dense tissue complicates mammography. While fat appears black on a mammogram, cancer appears as a white mass, Hovanessian explained. Unfortunately, normal, dense glandular tissue also appears white on a scan—sometimes obscuring cancerous tissue.
“Mammography in fatty breast tissue provides 98 percent accuracy,” said Hovanessian, who specializes in women’s cancers. “But in dense breasts, accuracy goes down to 40 to 60 percent.”
Hovanessian believes ultrasound techniques can help. Ultrasound uses sound waves to form a picture, and some studies suggest it can find early breast cancers in dense breast tissue. That is why Hovanessian is involved in an extensive American College of Radiology Imaging Network (ACRIN) trial that will evaluate whether ultrasound should be used together with mammography as a screening method in women with dense breast tissue who are at high risk for breast cancer.
Ultrasound is also relatively inexpensive, widely available and well-tolerated by patients.
USC and about 21 other North American sites are recruiting 2,800 women for the study, which is sponsored by the National Cancer Institute and the Avon Foundation. All participants receive a mammogram and ultrasound each year for three years. Two radiologists look at each scan independently and then discuss the results.
“We look for an irregular shape, darkness of the lesion and shadowing on ultrasound,” said Hovanessian, who leads USC’s ACRIN trial site, which includes USC/Norris and LAC+USC Medical Center.
The study will cover the cost of the ultrasounds, but women must have insurance coverage for the mammography, or get their imaging at LAC+USC’s women’s facility (mammography is used routinely to screen for breast cancer, and is not part of the study itself.) Eligible high-risk women include those with a personal history of breast cancer or a strong family history of breast cancer, or those who have had a breast biopsy showing pre-cancerous cells.
In a separate, pilot study exclusive to USC/Norris, Parisky wants to see if existing technology can make mammography even more effective.
He and fellow radiologists are testing whether injecting a contrast agent into women undergoing digital mammography can provide more information about a woman’s cancer than mammography alone.
“We want to blend those two elements—contrast and mammography—to see if we can effectively determine the presence and characteristics of cancer,” Parisky said. “We’d like to see if it can give us information about whether a lesion is benign or malignant, as well as extent of disease.”
Radiologists routinely use contrast agents as a way to highlight cancer’s appearance on magnetic resonance imaging, or MRI, scans. “We know breast tumors have a greater blood supply than normal tissue, and the contrast is meant to pick that up,” Parisky said.
Bringing contrast to digital mammography could offer benefits, he noted. Clinics have much greater access to mammography than MRI, and mammography is more affordable than MRI.
In this study, Norris radiologists are using their Selenia unit, a digital mammography system produced by Hologic Inc., which is supporting the study.
Like traditional mammography, Selenia uses X-rays to create an image of women’s breast tissue. But instead of recording images on film, digital mammography records images electronically. That means radiologists can darken or lighten the images, manipulate them and share them electronically with other health experts.
Norris radiologists plan to recruit 20 women to participate. They will select patients known to have a suspicious lesion requiring biopsy. The team will perform digital mammography with contrast and try to identify the lesion and its characteristics from the scan; the team will then compare those findings with pathology results from the patient’s subsequent biopsy. Some patients also will undergo MRI.
And that is not all. Radiologists are also investigating other techniques.
One is tomosynthesis, which uses X-rays, like mammography. However, tomosynthesis takes pictures of the breast from different angles, resulting in a three-dimensional series of high-resolution slices through the breast. Through tomosynthesis, radiologists will be able to better see lesions or suspicious areas that would otherwise overlap each other on a traditional mammogram, Parisky explained.
And Pulin Sheth, USC/Norris director of breast imaging, will lead a study on DOBI Medical’s ComfortScan system, an experimental, non-invasive digital imaging system that uses light to highlight any areas of a woman’s breast with vascular abnormalities.
One of cancer’s hallmarks is that a tumor must surround itself with tiny blood vessels that bring it nourishment; the ComfortScan system aims to pinpoint those telltale blood-vessel hotspots.
Women simply stand in front of a machine featuring a panel of red light-emitting diodes and a silicone membrane. The membrane inflates around the breast and exerts gentle pressure while light shines through the breast tissue. The machine measures variations in the intensity of light transmitted through the breast.
For information on any of the breast imaging studies, please call project manager Tina Kiss at (323) 865-3228.
“This is an exciting time,” summed up Hovanessian, who credited Department of Radiology Chair Edward Grant. “He is really supportive of all of us and our research efforts to in radiology.”