SEATTLEWhen used as an adjunct to mammography and clinical
breast examinations, thermal imaging may help reduce the number of unnecessary
breast biopsies, according to Karleen Callahan, PhD, director of Clinical
Research for Breast Cancer at Computerized Thermal Imaging, Inc (CTI).
Dr. Callahan presented an exhibit about the CTI Breast Cancer
System 2100 (BCS 2100), an investigational thermal imaging device, at the 101st
Annual Meeting of the American Roentgen Ray Society (ARRS).
Dr. Callahan and her colleagues are analyzing the results of a
3½-year clinical study of the efficacy of the BCS 2100 as an adjunctive breast
imaging modality in the diagnostic setting. In this multicenter study, thermal
imaging was performed before biopsy in more than 2,100 women who had been
referred for biopsy because of mammographic findings and/or palpable findings.
The findings are likely to be particularly meaningful because
the patient population included women of a wide range of ages and ethnicities.
"Our clinical study pretty well reflects the demographics of the
country," Dr. Callahan said.
Thermal imaging provides physiologic information about
suspicious areas of the breast. The physiologic basis for thermal imaging for
cancer detection is the difference in infrared emissions of normal and
malignant tissues upon cooling. This difference results, in turn, from
differences in angiogenesis, vascular reactivity, the release of vasoactive
mediators, and metabolic activity.
Efforts to harness thermal disparities for breast cancer
detection date back to at least the 1970s, Dr. Callahan said. But that older
technology (called thermography) had limitations and did not prove effective
when used for breast cancer screening. The key changes have been an increase in
the camera sensitivity, the collection of data over a period of several
minutes, the addition of a cooling challenge, and the development of a
sophisticated computer model for analyzing the data. "We think that all of
the improvements will make thermal imaging a viable technique," she said.
A patient undergoing thermal imaging lies prone on the patented
BCS 2100 imaging table, and thermal data are collected from each breast over a
3-minute period that includes a cooling challenge (a stream of cold air blown
over the breast).
The radiologist identifies the region of interest from the
mammogram or the clinical breast exam and uses this region of interest to
localize the lesion on the thermal image. A proprietary algorithm analyzes
unique spatial and temporal characteristics in the data to generate a
likelihood of malignancy score for the lesion (see Figure).
Patient acceptance of the BCS 2100 has been very good, Dr.
Callahan said. "It’s not an uncomfortable procedure. There’s no breast
compression, and it’s not invasiveno contrast dyes and no radiation,"
she said. The entire exam takes only about 10 minutes.
Unblinding of the data from the clinical study should provide
detailed information about the performance of the BCS 2100, Dr. Callahan said.
For example, the data will help determine how effective the BCS 2100 is for
detecting specific types of malignancies, how well it discriminates between
malignant and benign neoplasms, and how well it performs for superficial vs
Thermal imaging may be particularly useful in women with
lesions that are probably benign (BI-RADS 3) or suspicious (BI-RADS 4) on
mammography, Dr. Callahan noted. "Right now, these patients often go to
biopsy. And yet, about 80% of the biopsies turn out to be benign," she
said. "Thermal imaging would provide further information to the doctor and
the patient as to whether they might want to proceed to biopsy or possibly go
to short-term follow-up."
To obtain premarket approval (PMA) of the BCS 2100, the company
is using the FDA’s modular approach, which divides the application into five
modules, each containing a portion of the total
data required. The FDA has accepted four modules for the BCS 2100, and the
final module was submitted last month.