Vibrational Spectroscopic Imaging of Hard Tissues

Michael D. Morris, Matthew V. Schuimerich, Kathryn A. Dooley, and Karen A. Esmonde-White 

Chemical composition is an important contributor to bone quality, a term that encompasses the effects of architecture, composition and remodeling dynamics. An important advantage of infrared (IR) and Raman imaging in bone studies is that they allow the imaging of parameters that measure tissue quality and competence. These are usually measured as band height or band area ratios, and in some cases as band widths. Although measures of tissue properties are similar in both IR and Raman spectroscopy, the IR metrics have been validated with other techniques. 

Crystallinity is a metric related to mineral maturity, and is a measure of mineral crystalUte size, mineral maturity, and the amount of substitution into the apatitic lattice. Crystallinity increases when crystals are larger and more perfect (i.e., less substitution), and is directly proportional to the inverse width of the 002 reflection (c-axis reflection) in the powder X-ray diffraction pattern of bone mineral. Several features in the IR spectra of bone correlate with mineral crystaUiriity, including 

Infrared and Raman Spectroscopic Imaj ng. Edited by Reiner Saizer and Heinz W. Siesier Copyright 2009 WiLEY-VCH Veriag GmbH Co. KGaA, Weinheim iSBN 978-3-527-31993-0 

The carbonate phosphate ratio in the IR spectrum is calculated [10] from the area of the COl V2 components at 866 cm (labile carbonate), 871 cm (B-type carbonate), and 878 cm (A-type carbonate) and the area of the Vj V3 envelope. These correlations use earlier carbonate band assignments [12, 13]. 

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Connective tissues have often been reported in Raman and FT-IR images adjacent to epitheUum or carcinomas. Articular cartilage [15], ECM damage [16], and sarcoma, which is a neoplastic process originating within connective tissue [17], were studied by Raman spectroscopy. Applications of vibrational spectroscopic imaging to bone, which belongs to supportive connective tissue and is considered as hard tissue, are described in Chapter 4 of this book. 

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