Infrared Spectroscopy, Microscopy, and Microscopic Imaging of Mineralizing Tissues: Spectra-Structure Correlations from Human Iliac Crest Biopsies

Abstract

Infrared microscopic images of the cortical region of human iliac crest biopsies have been obtained at ∼7 μm spatial resolution and 8 cm-1 spectral resolution with a 64×64 mercury-cadmium-telluride focal plane array detector coupled to a Fourier transform infrared microscope and a step scanning interferometer. Images of several spectral parameters provide information about the spatial distribution of the mineral (apatite) and protein (mostly collagen) components of the tissue. In addition, the image of a parameter known to reflect the crystallinity/perfection of the mineral phase, namely, the intensity ratio of bands at 1030 and 1020 cm-1 within the phosphate ν1,ν3 contour, revealed a progressive increase in the apatite crystal size/perfection from the osteonal center to the periphery. Finally, a detailed comparison of the spatial distribution of the I(1020)/I(1030) ratio for the same osteon obtained by array detection and by conventional point-by-point microspectroscopy revealed statistically identical behavior, thereby providing a validation of infrared imaging for structural analysis of apatite forming tissues. © 1999 Society of Photo-Optical Instrumentation Engineers.