June 2009 378

Advances in Detection of Breast Cancer : Dr. K. L. Chakraborti, Head, Department of Radiological Imaging Institure of Nuclear Medicine & Allied Science

Advances in diagnostic imaging, like Infrared Thermography, which helps in detecting signs of cancer at an extremely early stage is improving survival rates.


 

“Each time the breasts are exposed to an X-ray, the breast cancer risk increases by 2%. The pre-menopausal breast is highly sensitive to radiation Each 1-rad exposure increasing breast cancer risk by about 1% with a cumulative 10% increased risk for each breast over a decade. Mammography compresses breasts painfully and can lead to spread of cancer cells.”

Breast care presents a challenge to the entire health care delivery system, payor and provider alike. Its relative importance extends far beyond its cost in that one in eight women in the US will become a victim of breast cancer during her life time and virtually every women has a relative or close acquaintance who has had breast cancer. Breast cancer is the second most common cancer in Indian women. According to the National Cancer Registry project report about 52,000 women develop breast cancer in India per year. This gives breast cancer a high emotional, political and media profile.

An early accurate diagnosis of breast cancer has a favourable prognosis than that of late detection and even at times totally curable. Most often women are referred for multiple diagnostic tests which can include X-ray mammography, galactography, ultrasound, colour Doppler Ultrasound study, CT Scan, MRI, PET/CT Scanning, fine needle aspiration, and in some cases open surgical biopsy. X-ray Mammography is considered as gold standard. But it involves ionising Radiation. Each time the breasts are exposed to an X-ray, the breast cancer risk increases by 2%. The pre-menopausal breast is highly sensitive to radiation. Each 1-rad exposure increasing breast cancer risk by about 1% with a cumulative 10% increased risk for each breast over a decade. Mammography compresses breasts painfully and can lead to spread of cancer cells.

Low specificity of current screening and diagnostic modalities appear to be responsible for such unnecessary testing of benign symptoms and results in anxiety to patients and excessive health care expenditure. Thus there is need for a cost effective means of safety, reducing the number of diagnostic procedures undergone by these women.

Moreover, the existing technologies detect only structural changes. It may take up to 8 to 10 years for tumour to grow to a sufficient size to be detectable. By this time the tumour may have achieved more than 25 doubling of malignant cell colony & may have already metastasized.

The application of non-invasive, non-ionising and radiation free, cost effective technique for breast diagnostics aimed at early tumour detection is a challenging task of current interest for biomedical electronics research.

 Noninvasive infrared (IR) is a promising application for such detection. IR comprises wavelengths of 1mm to longest wavelength of visible light from 5-6 microns to 14 microns wavelength. This range also known as radiant heat, discovered by English Astronomer Sir William Hershel in 1800. Normal human body temperature is 98.6 F. Most of our body heat is typically radiated away as far infrared at 8-10 micron wavelength. As it is more penetrating than visible light, such radiation is being used in many practical applications like infrared thermography. IR thermography is a physiological study. In order for Solid mass cancer tumours to grow, the circulation near the tumour becomes abnormal. These changes are such that the central nervous system loses control of the heating & cooling. These abnormal temperatures are detectable with highly advanced infrared cameras. Digital infrared sensing camera and high speed computer are used to measure the heat radiated from breast and adjacent areas.

The fact that the physiological changes preceed anatomical mammographic detection, allows us to react early in preventive mode in early stages of development of cancer itself. This is a surprising fact that though medical thermography has been in the use since early 1970’s and the modality was approved by the FDA in 1982 for breast cancer detection and risk assessment as an adjunct to mammography, the women population in India and even majority of the woman in Europe are unaware/unfamiliar with the breast thermography.

Presently breast thermography is extensively used in US and European countries as a first line screening procedure to assess breast health. Clinical Digital Thermography (DITI) is unique in it’s capability to detect physiological changes and metabolic processes.

The IR Thermography instrument is compact and consists of a scanning system and IR detector. The detectors mainly used are InSb or HgCdTe in case of cameras where liquid nitrogen is used for cooling whereas HgCdTe is mainly used for thermoelectric cooling. InSb detector size is about 9.6 x 7.2 cm2. The latest thermal camera has a highest resolution of 640 x 512 pixels. It can pick up a difference of 25 mK temperature difference. Addition of a G3 microscope lens provides a working distance of 35 mm (3.5 cm). The IR thermography of the breast is performed before and after the cold challenge. A highly skilled thermo logy reader analyses the before and after cold challenge scans in order to prepare a thermography report.

IR thermography is very cost effective, risk free and provides instant images. The resolution of the equipment has improved tremendously. In Europe, IR thermography fees for breast screening are $ 175 for the initial scan, $ 175 for the 3 month follow up & whole body scan is $ 400. In India effort should be taken up by the Govt, either to import a large number of machines & introduce in the Rural Primary Health Centre level or to procure the core elements (sensors) from manufacturers abroad and develop the system in India. Introduction of this cost effective, first line screening technique in early detection of breast cancer will prove to be a great boon to the Indian health care system.

Major benefits of thermography

Timeliness : early detection provides the best outcomes in improved survival rates
Inclusive : examines the full body including whole chest and armpit areas
Good for all breast types: young, dense, fibrocystic, women on HRT, etc.
Pregnant & teen-age women can be examined.
The method is precise, has no risk, no pain & it is a complementary first line detection modality.

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