Shanshan Xu
Published: 2012
Total Pages: 174
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Optical imaging has enjoyed a large following in cancer in general and breast cancer in particular (i.e., diffuse optical imaging, DOI and diffuse optical tomography, DOT). Optical imaging biomarkers emerge from modeling specific near-infrared (NIR) absorption signatures that are sensitive indicators of important molecular concentration and disposition. We have developed Diffuse Optical Spectroscopic Imaging (DOSI) by increasing spectral information content for the purpose of increasing access to molecular targets and states. Malignancy-specific optical imaging biomarkers may be important because the above-mentioned changes in tumor hemoglobin, water and lipids are a necessary but not a sufficient condition to classify therapeutic response. We note that for all therapeutic imaging assessments (i.e., mammography, ultrasound, MRI, PET) that the same case is true for their respective contrast mechanisms. By a novel spectral analysis method, we have discovered the presence of absorption signatures that are unique to malignant lesions. A reproducible absorption spectrum (Specific Tumor Component, STC) with several distinct spectral features emerges when compared with the normal absorption spectra (the flat line near zero) measured from the normal tissue of these subjects plus an additional 21 patients without any evidence of malignancy. These data demonstrate the existence of a spectral signature that acts as an optical biomarker for malignancy. We are not aware of any other such biomarker that combines high specificity with ease of application in the imaging field. This DOSI-measured malignancy-specific biomarker STC provides an ideal non-invasive surrogate biomarker for breast lesion detection and differentiation. Although STC offers both spectroscopic and quantitative information for breast malignancy, this method relies on complicated data analysis and lacks of standardization. Thus, it is still far from a clinical reality. In order to carry out a quantitative assessment of its potential in becoming a standardized clinical detection modality for tumor detection/prediction/prognosis, the longitudinal temporal stability of signatures must be evaluated and the detection limit must be set. The overall clinical goal is to evaluate the possibilities for STC detection method to become a future clinical practice. Building the linkage between pre-existing detection modalities (pathological biomarkers, DCE-MRI) and novel spectral signature detection is essential. The medical interpretation of the findings from conventional tools will shed light on the understanding and further employment of STC biomarker. Similarly, STC detection with a high diagnosis sensitivity and specificity could be very well an adjunct method for traditional modalities.