Chemistry Reference
In-Depth Information
21.4.2.4 Image analysis
Biodiagnosis by IR images has been applied during the last two decades in several physician evaluations. The
main fields are; cancer, dentistry, neurology, cardiovascular, drug delivery, ophthalmic, surgery, respiratory
and tissue analysis. The main signals obtained in IR medical imaging are due to the thermal effect of the IR ray
on the organ, bio-fluid or tissue sample. There are several criteria which must be taken into account in order to
obtain more useful images. The main concerns in this area are to enable the analyst to recognise the inter-
relations between the IR image signals and pathological or medical nature of them, and also to provide the
standard models of known samples in order to be able to interpret the qualitative data in to quantifiable clinical
information. Breast cancer is diagnosed by the IR imaging process. Of course the chemometric techniques are
really effective in obtaining the most useful clinical results. Wavelet data processing and ANN have been
reported as high quality techniques in disease situation classification via IR imaging [93].
21.4.3
Cancer diagnosis by FTIR spectrometry
There are several reports indicating the diagnostic capabilities of IR spectrometry for detection of malignancy
in a tissue sample. Lung, ovarian, esophagus, colon, and gastric cancers among others have been successfully
detected via investigating the mid-IR spectrum of tissue samples. In this section we try to discuss the
capabilities of this technique in cancer diagnosis, comparing a multi step effort for diagnosis of cancer in
digestive organs of human: esophagus, gastric and colon. Colon, gastric and esophagus cancers are the main
malignant diseases in digestive system of human body respectively. Among these three diseases, colon cancer
is the highest ranked according to the mortality rates. Comparing all malignancies, colon cancer will be the
third leading cause of death (about 150 000 detected cases and 65 000 deaths in a year in the USA alone).
Early diagnosis of colon malignancy may provide about five years of survival in more than 90
%
of cases. If
colorectal cancer is detected at an early stage, then the five-year relative survival rate is 90
%
; however, only
about 37
of colorectal cancers are diagnosed in the early stages. Abnormal cell proliferation is known as the
main indicator for the initiation of colorectal malignancy which is identified by investigating the probable
presence of certain molecular markers in the crypt. Gastric malignancy related diseases are also common all
around the world. The main gastric diseases diagnosed by endoscopy and/or biopsy analysis are chronic
superficial gastritis, gastric carcinoma and chronic atrophic gastritis. Professional characterization of biopsy
samples obtained from stomach of the patient will dramatically affect the final diagnosed condition. On the
other hand, esophagus cancer is still one of the concerning malignant tumors which may be called as a
seriously dangerous disease. The approximated statistics of esophageal carcinoma is more than 1.5 million
per year in China alone. Fiber endoscopy is the lesion analyzing device used which can also obtain the lesion
sample for further pathologic inspections and is known as the best way to diagnose the disease.
Application of IR spectroscopic analyses or combination of the technology with microscopic accessories
has been highly powerful in the precise detection of malignant cases in tissue biopsies. To propose a useful
approach, one needs to study the cell lines in order to extract the demonstrated spectroscopic features. This
strategy would be an appropriate experimental system which provides the requirements to study the origin of
the spectroscopic changes observed hitherto and to apply the IR technology to other aspects of cancer biology.
In case of tissue samples, the same as all other biostructures, the splitting pattern is mostly found in the
1800-1000 cm
−1
spectral region displaying an extensive set of spectroscopic changes between malignant and
healthy tissue samples. As expected, most of the clinical reports dealing with cancer detection by IR
spectroscopy are based on experimental investigation of:
%
Isolated signal intensities
●
Signal position shift
●
Intensity ratio of correlated signals
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