Fluorescence Spectroscopy for Biomedical Diagnostics
In the past several decades, fluorescence spectroscopy has had a dramatic effect on many different fields of research. One field that has seen significant advancements is biomedical diagnostics. Within this field, fluorescence spectroscopy has been applied to the analysis of many different types of samples, ranging from individual biochemical species (e.g., NADH, tryptophan) to organs of living people. These studies have given rise to new methods for the early or noninvasive diagnosis of various medical conditions, including tooth decay, atherosclerosis, heart arrhythmia, cancer, and many others.*
The medical condition that has seen the largest effort toward fluorescence-based analyses and truly demonstrates the potential of fluorescence-based diagnoses is cancer. Fluorescence spectroscopy and imaging have been investigated for the diagnosis of almost every type of cancer and early neoplastic difference found in humans. The detection of early neoplastic changes is important from an outcome viewpoint because, once invasive carcinoma and metastases have occurred, treatment is difficult. At present, excisional biopsy followed by histology is considered the “gold standard” for diagnosis of early neoplastic changes and carcinoma. In some cases, cytology rather than excisional biopsy is performed. These techniques are powerful diagnostic tools because they provide high-resolution spatial and morphological information of the cellular and subcellular structures of tissues. The use of staining and processing can enhance contrast and specificity of histopathology. However, both of these diagnostic procedures require physical removal of specimens, followed by tissue processing in a laboratory. These
procedures incur a relatively high cost because specimen handling is required; more importantly, diagnostic information is not available in real time. Moreover, in the context of detecting early neoplastic changes, excisional biopsy and cytology can have unacceptable false negative rates often arising from sampling errors.