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Thermography (also called thermal imaging or infrared imaging) was approved by the U.S.
Food and Drug Administration (FDA) in 1982 as a supplement to mammography
in helping to detect breast cancer. Thermography can help determine whether a local
abnormality in breast tissue temperature is present, which may indicate the presence of
disease. Though thermography is FDA approved, the exam has not gained acceptance in
the medical community as a necessary or effective tool in breast cancer detection.
According to the American College of Radiology, thermography has not shown value as a
screening, diagnostic, or adjunctive imaging tool.
While thermography may be appealing to some women because it is a pain-free exam, most
physicians do not recommend thermal imaging. Scientific research over the last 20 years
has shown that thermography is not reliable for detecting breast cancer. In 1977, the
Beahrs Committee of the National Cancer Institute (NCI) recommended that thermography be
discontinued as a routine screening modality in the NCI’s Breast Cancer Detection
Demonstration Project.
Since then, studies have failed to show a clear benefit of thermal imaging in helping
to detect breast cancer. In their 1998 document, "Evaluation of Common Breast
Problems: Guidance for Primary Care Providers," Barbara Smith, MD, PhD and her
colleagues wrote, "currently, thermography has no role in breast cancer screening or
diagnostic evaluation." Several other reports have drawn similar conclusions. That is
not to say that improved thermography technology may not one day aid in the breast cancer diagnostic process (see computerized thermal
imaging sections below); however, at the moment, thermography is not widely accepted as an
effective means of detecting breast cancer.
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Inside view of computerized
thermal imaging system with
mirrors that deflect infrared
waves from a patient's breast
to a camera below. Image
courtesy of CTI, Inc. |
Computerized thermal imaging (CTI) is a new, non-invasive imaging method that is being
developed using the principles of traditional thermography but with the addition of
digital image reconstruction. Computerized thermal imaging (CTI) is a heat sensing and
processing system that uses a thermal sensitive camera to capture a digital image based on
heat radiating from the body. A computer-assisted interpretation of the digital image
helps to determine whether a local abnormality in breast tissue temperature is present,
which may indicate the presence of disease. To date, CTI is only available for eligible
women who participate in CTI clinical trials; the technology has not been approved by the
U.S. FDA.
Currently, clinical trials are being conducted at five hospitals across the United
States to determine whether the CTI technology may be useful as an adjunct (supplement) to
mammography in the breast cancer diagnostic process.
The main component of the CTI technology is the highly sensitive, high-speed infrared
camera. The camera is designed to detect infrared heat given off by the body. After the
radiologist has acquired images of the breast tissue, the CTI system uses sophisticated
image analysis algorithms and a computer to reconstruct the images to show individual heat
patterns. These images differentiate between normal and abnormal heat patterns. The CTI
examination consists of the patient being positioned on a special examination bed with the
breast suspended in an opening in the top of the bed. The thermal camera is located inside
of the bed, focused at the examination area. The physician will use the thermal camera to
take a series of images of the breast. The procedure is then repeated with the
patient’s other breast. As with traditional thermography, no radiation or breast
compression is used during CTI.
After the breast images have been taken, they are analyzed by a computer algorithm and
displayed for interpretation by the physician. Breast images are displayed in different
colors (red, orange, and yellow) on a computer monitor for the physician to review. Any
suspicious area (abnormal heat area) is marked on the digital breast image. The
radiologist may then decide whether further breast imaging is necessary. The CTI
technology is designed to electronically store the digital breast images and provide the
patient with an electronic copy of the images, which may be helpful if she visits another
imaging facility.
Malignant (cancerous) image:
The left image is the raw thermal image. The right image is a
magnified view of the processed image that corresponds to the area of suspicion selected
by the green square in the left image. This image shows a very high probability of
malignancy (cancer). This patient was rated a BIRAD 4 (suspected
malignancy, biopsy recommended) by mammography and confirmed to have ductal
carcinoma in situ by biopsy. Images courtesy of Computerized Thermal Imaging, Inc.
The computerized thermal imaging (CTI) technology is currently being tested in clinical
trials to determine its effectiveness. The manufacturer of CTI technology recently
received acceptance from the FDA for module three of its premarket approval application
(PMA). This is the third of five modules to be submitted. Each of the five modules
contains a portion of the data needed for FDA review. Currently, CTI technology is being
evaluated in clinical trials at five U.S. medical facilities:
- USC/Norris Comprehensive Cancer Center, Los Angeles, California
- Providence Hospital, Washington, DC
- Mt. Sinai Medical Center, Miami Beach, Florida
- St. Agnes Hospital, Baltimore, Maryland
- Lahey Center, Boston, Massachusetts
The clinical trials will determine whether the addition of the CTI technology to
mammography and clinical breast exams helps differentiate between normal and malignant
(cancerous) breast tissue.
Though computerized thermal imaging (CTI) may provide a pain-free breast imaging exam
and has the potential to detect cancer by identifying abnormal heat patterns in breast
tissue, there are some limitations to the technology. Since CTI is based on the principles
of thermography, it may give false-positive results as thermography often does. A false
positive result indicates cancer when no cancer is present. Thermography has a false
positive rate of approximately 25%. However, CTI uses more advanced technology and a
different exam process than thermal imaging. Thus, clinical trials may find that false
positive results are less likely with CTI.
In addition, CTI cannot detect microcalcifications
(tiny calcium deposits that may indicate the presence of cancer). Tumors that contain
calcifications may be more difficult to remove completely. Microcalcifications can only be
seen reliably with mammography. Approximately 50% of the breast cancers detected by
mammography appear as a cluster of microcalcifications. Other imaging exams, including
thermography, do not provide the fine detail (spatial resolution) that is available with
conventional x-ray mammography. However, adjunct exams (such as ultrasound,
MRI, etc.,) may be beneficial in some cases because they
provide excellent contrast resolution, which may make some abnormalities such as cysts
easier to see since these areas "stand out" more from surrounding tissue.
Cost is another limitation of the CTI technology. The manufacturer of CTI technology is
only seeking FDA approval for the exam to be used in addition to mammography to help
screen for breast cancer. Because mammography will have to be performed regardless of
whether or not thermal imaging is done, many physicians question whether CTI technology
will drastically change how breast cancer is detected. Many facilities that perform breast
imaging tests to screen for breast cancer may be unable or unwilling to acquire additional
costly imaging technology if they do not see a significant benefit to the patient.
Mammography is currently the only FDA approved exam to help screen for breast cancer in
women who show no signs or symptoms of the disease. Screening
mammography is recommended on an annual basis for all women once they reach 40 years
of age. If a suspicious region is detected with screening mammography or by physical exam,
the physician may order diagnostic mammography (involves
more views than screening mammography) and/or other breast imaging exams.
Other imaging exams FDA approved as supplements to mammography for diagnosis include:
To help detect breast cancer at an early stage when the chances for successful
treatment are the greatest, women should follow the guidelines set by the American Cancer
Society:
- All women between 20 and 39 years of age should practice monthly breast
self-exams and have a physician performed clinical
breast exam at least every three years.
- All women 40 years of age and older should have annual screening mammograms, practice
monthly breast self-exams, and have yearly clinical breast exams. The clinical breast exam
should be conducted close to and preferably before the scheduled mammogram.
- Women with a family history of breast cancer or those who test positive for the BRCA1 (breast cancer gene 1) or BRCA2
(breast cancer gene 2) mutations may want to talk to their physicians about beginning
annual screening mammograms earlier than age 40, as early as age 25 in some cases.
- The American College of Radiology’s "Radiological Practice & Ethics"
document is available online at http://www.acr.org/governance/council_digest/radiol_prac.html
- The report, "Evaluation of Common Breast Problems: Guidance for Primary Care
Providers," by Barbara Smith, MD, PhD et al., is published in the January/February
1998 issue of CA – A Cancer Journal for Physicians (Vol. 48, No. 1). To learn
more about this report, please visit http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve
&db=PubMed&list_uids=9449933&dopt=Abstract
- The Susan G. Komen Breast Cancer Foundation provides information on thermal imaging at http://www.breastcancerinfo.com/news/html/102700b.asp
- The Pacific Chiropractic and Research Center provides information on breast thermal
imaging at http://www.breastthermography.com/
- Computerized Thermal Imaging, Inc., the manufacturer of CTI technology, provides
information on using thermal imaging to help detect breast cancer at http://www.cti-net.com/ Images found in
this article are courtesy of Computerized Thermal Imaging, Inc.
- To learn more about breast cancer diagnosis, please visit http://www.imaginis.com/breasthealth/menu-diagnosis.asp
Updated: May 4, 2008 |
