THE BREAST JOURNAL
Official Journal of the American Society of Breast Disease,
The American Society of Breast Surgeons and The Senologic International Society
Shahla Masood, MD, FCAP, MIAC, Editor
July/August 1998
Volume 4, Number 4
Infrared Imaging of the Breast:
Initial Reappraisal Using High-Resolution Digital
Technology in 100 Succesive Cases of Stage I and II Breast Cancer
J.R. Keyserlingk MD *†, P.D. Ahlgren MD *†, E. Yu PhD † ‡, and N. Belliveau, MD†
* Department of Oncology, St. Mary's Hospital, Montreal, Quebec;
‡ Department of Radiotherapy, London Cancer Center, London, Ontario; and
† Ville Marie Breast and Oncology Center, Montreal, Quebec, Canada
Presented at the American Society of Clinical Oncology Meeting, May 17-20, 1997, Denver, Colorado.
Abstract: There is a general consensus that earlier detection of breast cancer should result in improved survival. Current breast imaging relies primarily on mammography. Despite better equipment and regulation, variability in interpretation and tisuue density still affect acuragy. A number of adjuvant imaging techniques are currently being used, including doppler ultrasound and gadolinium-enhanced MRI, which can detect cancer-induced neovascularity. In order to assess the potential contribution of currently available high-resolution digital infrared technology capable of recognizing minute regional vascular flow related temperature variation, we retrospectively reviewed the relative ability of our preoperative clinical exam, mammography, and infrared imaging to detect 100 new cases of ductal carcinoma in situ, stage I and II breast cancer. While the false-negative rate of infrared imaging was 17%, at least one abnormal infrared sign was detected in the remaining 83 cases, including 10 of the 15 patients, a slightly younger cohort, who had nonspecific mammograms. The 85% sensitivity rate of mamography alone thus increased to 95% when combining both imaging modalities. Access to infrared information was also pertinent when confronted with the relatively frequent contributory but equivocal clinical exam (34%) and mammography (19%). The average size of those tumors undetected by mammography or infrared mamography was 1.66 cm and 1.28 cm, respectively, while the false-positive rate of infrared imaging in concurrent series of 100 successive benign open breast biopsies was 19%. Our initial experience would suggest that, when done concomitantly with clinical exam and mammography, high-resolution digital infrared imaging can provide additional safe, practical, and objective information. Further evaluation, preferably in controlled prospective multicenter trials, would provide valuable data.
Key words: breast, cancer, detection, imaging, infrared
Our first-line strategy for the detection of breast cancer still-depends essentially on clinical examination and mammography. Limitation of the former, with its reported sensitivity rate below 65% is well recognized (1), and even the proposed value of breast self-examination is now being contested (2). With the current emphasis on earlier detection, there is an increasing reliance on better imaging. Mamography is still recognized as our most reliable and cost-effective imaging modality (3). However, variable interpretation (4) and tissue density, now proposed as a risk factor in itself (5) and seen in both younger patients and those on hormone replacement (6), prompted us to reassess currently available infrared technology, spearheaded by recent military research and development, as a potential complementary imaging strategy. This modality is capable of of quantitating minute temperature variations and and qualifying abnormal vascular patterns, potentially reflecting the regional angiogenesis, neovascularization, and nitric oxide-induced regional vasodilation (7) frequently associated with tumor initiation and progression and possibly early predictors of tumor growth rate (8,9). We thus acquired in July 1995 a new fully integrated infrared imaging station to compliment our mammography unit. To evaluate its reported ability to detect early tumor-induced metabolic changes (10), we limited our initial reappraisal to ductal carcinoma in situ (DCIS), stage I and II breast cancer patients.
PATIENTS AND METHODS
The charts of our first 128 patients who had their initial diagnosis of breast cancer as of August 1995 were reviewed to accumulate 100 successive cases who filled the following criteria: minimal evaluation included a clinical exam, mamography, and infrared imaging; definitive surgical management constituted the preliminary therapeutic modality and was carried out at one of our affiliated institutions, and the final staging consisted of either DCIS (n = 4), stage I (n = 42), or stage II (n = 54) invasive breast cancer. While 94% of these patients were referred to our Comprehensive Breast Center for the first time, 65% from family physicians and 29% from specialists, the remaining 6% had their diagnosis of breast cancer at a follow-up visit. Age at diagnosis ranged from 31 to 84 years with a mean of 53 years. The mean histologic tumor size was 2.5cm. Lymphatic, vascular, or neural invasion was noted in 28% and concomitant DCIS was present, along with the invasive component, in 64%. One third of the 89 patients who had axillary lymph node dissection had involved nodes and 38% of the tumors were histologic grade III. While most of these patients underwent standard four-view mammorgraphy, with additional views when indicated, at our accredited center using a GE DMR appartus, in 17 cases we relied on recent and adequate quality outside films. Mammograms were interpreted by our examining physician and radiologist, both having access to the clinical findings and, like the clinical exam, were considered suspicious if either noted findings indicative of carcinoma. The remainder were considered either contributory but equivocal or nonspecific. A nonspecific mammography required concordance with our examining physician, radiologist and the authors.
Our integrated infrared station consisted of a scanning mirror optical system containing a mercury-cadmium-telleride detector (Bales Scientific, CA) with a spatial resolution of 600 optical lines, a central processing unit providing multitasking capabilities, and a high-resolution color monitor capable of displaying 1024 X 768 resolution points and up to 110 colors or shades of gray per image. Infrared imaging took place in a draft-free, thermally controlled room, maintained at between 18°C and 20°C , after a 5 minute equilibration period during which the patient sat disrobed with her hands locked over her head. We requested that the patients refrain from alcohol, coffee, smoking, exercise, deoderant, and lotions 3 hours prior to testing. Four images, consisting of an anterior, an undersurface, and two lateral views, were generated simultaneously on the video screen by the examining physician, who would digitally adjust them to minimize noise and enhance detection of more subtle abnormalities prior to exact on-screen computerized temperature reading and infrared grading. Images were then stored on retrievable laser discs. Our grading scale relies on pertinent clinical information, comparing infrared images of both breasts and current with previous images (unavailable during this first series). An abnormal infrared image required the presence of atleast one abnormal sign (Table 1).
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