click here." data-pin-do="buttonBookmark"> To view a comparision of CTLM and conventional mammography, click here.
A LARGE AREA of suspicious new blood-vessel growth supporting a cancer tumor is clear in an image made with computed tomography laser mammography (CTLM).
To view a comparision of CTLM and conventional mammography, click here.Image: IMAGING DIAGNOSTIC SYSTEMS, INC.
In a quiet exam room, Susan Conlan, 50, prepared for the mammogram that would help confirm whether her breast cancer had returned. She untied her robe, positioned herself on the machine and moved her arms out of the way. Ordinarily this is when a woman would begin to cringe--the moment before her breast is smashed onto a cold x-ray platform. But Conlan never felt a thing.
"I was extremely comfortable," Conlan recalls.
Conlan is one of the first patients in the country to test a gentler, radiation-free breast-imaging method called CT (computed tomography) Laser Mammography (CTLM). CTLM, developed by Florida-based Imaging Diagnostic Systems, Inc., is one of several experimental technologies (see sidebar) aimed at improving the accuracy of breast imaging, especially in distinguishing benign breast conditions from breast cancer. Like CTLM, another method, Computerized Thermal Imaging (CTI), also scans the tissue for the temperature differences that might indicate a growing tumor. Recent concerns over the sensitivity of standard x-ray mammography images and the competency of the human readers have underscored the need for better tests.
"Approximately 10 to 20 percent of the time, a mammogram is read negative when a breast cancer is present," says Susan Curry, a radiologist at the Women's Center for Radiology Orlando.
X-ray mammograms are recorded onto large, flat sheets of black-and-white photographic film. Because the anatomical images vary tremendously from woman to woman, they are difficult to read. What may be considered normal for one patient could indicate a need for concern for another. In addition, some breast changes are just too subtle to recognize. "When I had my cancer, the lump did not show on the mammogram," Conlan notes.
In Living Color
CTLM gives radiologists a colorful 3-D cross-sectional view of each breast. The bright green and white globes conjure the image of a lime Jell-O salad filled with fruit.
"We can look through the breast from the front, the side, the back and all the way through," explains Eric Milne, chief radiologist for Imaging Diagnostic Systems, Inc. The company is currently seeking approval by the U.S. Food and Drug Administration (FDA) as an adjunct to mammography. It plans to eventually push for the technique's use as a screening tool.
During an exam, a patient lies face down and suspends one breast through a hole in the table. Inside the console, a low-wavelength laser sweeps around the entire breast, a process that can take up to 15 minutes depending on breast size. The system calculates how the light is absorbed and uses the information to create an image. For some smaller-breasted women, it may be more difficult to make an image of the breast with this technique, as with mammograms, because they can't get as much tissue into the machine.
This physiological approach is based on the theory that malignant tumors sprout new blood vessels, a process called angiogenesis. Hemoglobin in the blood absorbs the CTLM laser light much more than surrounding tissue. The more blood flow, the whiter the image. The trick is deciphering which blood vessels are normal and which are not. Ordinary blood vessels in the breast tend to reveal themselves in a bicycle-spoke-like pattern.
While Milne declined to quantify how much the laser-based technique might improve the detection of breast cancer, he did say that the "incidence of false positives is much lower than that of mammography."
The CTLM test, which is expected to cost patients about $150, revealed that Conlan's most recent lump was much larger than x-rays indicated, prompting her doctor to recommend a biopsy.
Cutting Back on Biopsies
Millions of dollars are spent each year on breast biopsies, the majority of which reveal that nothing is wrong. Experts say more informative imaging could dramatically reduce the number of unnecessary procedures.