Biomedical Imaging: Principles and Applications

Chapter 9

Infrared and Raman Spectroscopic Imaging

Gerald Steiner

Clinical Sensoring and Monitoring, Faculty of Medicine Carl Gustav Carus, Dresden University of Technology, Dresden, Germany

9.1 Introduction

Infrared and Raman spectroscopic imaging are relatively new techniques that reveal the biochemical composition of cells, tissue, and even organs. Advances in instrumentation have made these imaging modalities a tool of choice for an increasing number of medical applications. The greatest benefit of these techniques lies in their high molecular sensitivity combined with a spatial resolution of less than 1 μm. Another advantage is their ability to probe samples under in situ conditions, which allows new insights into living cells without the need for fixation, stains, or markers.

Both infrared and Raman spectroscopy probe vibrations of the atoms within a molecule; hence, infrared and Raman spectra are summarized as vibrational spectra. The infrared spectral region is divided into three subregions, the sort-wavelength Near-Infrared (NIR) region, the Mid-Infrared (MIR or simply IR) region, and the Far-Infrared (FIR) region. The last region recently attracted some interest under the new name terahertz (THz) region. By far, the most important region is the IR region. NIR spectroscopy has also become an interesting tool in clinical medicine. NIR spectra result from overtones and combinations of fundamental vibrations occurring in the IR spectral range. Raman spectra of biomolecules ...