Fourier transform infrared imaging spectroscopy of collagen deposition after myocardial infarction

Detection and characterization of the increase in deposition of fibrillar collagen cardiac fibrosis after myocardial infarction (MI) is of great interest to investigators and clinicians. Since conventional staining techniques to visualize collagen deposition in cardiac tissue sections are accompanied by significant limitations, we have developed a new Fourier Transform Infrared Imaging Spectroscopy (FT-IRIS) methodology for collagen assessment. Collagen deposition in heart tissue sections of a rat model of myocardial infarction was mapped using the infrared absorbance band centered at 1338cm^-1, which arises from collagen amino acid side chain vibrations. This distribution map was compared to conventional staining techniques. Comparison of the size of the collagen scar in heart tissue sections as measured with this methodology and that of trichrome staining showed a strong correlation (R=0.93). A Pearson correlation model between local intensity values in FT-IRIS and immuno-histochemical staining of collagen type I also showed a strong correlation (R=0.86). This study demonstrates that FT-IRIS methodology can be utilized to visualize cardiac collagen deposition.