Improved model for myocardial diffuse reflectance spectra by including mitochondrial cytochrome aa3, methemoglobin, and inhomogenously distributed RBC
2011 (English)In: Journal of Biophotonics, ISSN 1864-063X, EISSN 1864-0648, Vol. 4, no 4, 268-276 p.Article in journal (Refereed) Published
Hemo- and myoglobin oxygen saturation and cytochrome aa3 oxidation was locally assessed using calibrated diffuse reflectance spectroscopy in fourteen patients undergoing coronary artery bypass grafting. Diffuse spectral reflectance data, recorded with a handheld fiberoptic probe with a single source-detector separation, was analyzed using an empirical light transport model relating the absorption and reduced scattering coefficients to the measured spectrum. The absorption coefficient has previously been modeled as a sum of hemoglobin and myoglobin, fat, and water. In this study, inclusion of cytochrome aa3 and the sum of methemoglobin and metmyoglobin improved the spectral fit, especially in the wavelength regions where their absorption is prominent. On average, the extended model increased the mean R2 from 0.96 to 0.99 and displayed 4% units higher saturation levels. After aorta cross-clamping, the sum of hemo- and myoglobin oxygen saturation increased while cytochrome aa3 oxidation decreased slightly. Opposite trends were observed during cardiac arrest. At reperfusion, the saturation increased compared to the levels found at cardiac arrest, and the cytochrome aa3 oxidation was restored. The estimated tissue chromophore fractions, saturation and oxidation, were in agreement with other studies.
Place, publisher, year, edition, pages
Wiley , 2011. Vol. 4, no 4, 268-276 p.
IdentifiersURN: urn:nbn:se:liu:diva-25583DOI: 10.1002/jbio.201000048ISI: 000289716000007OAI: oai:DiVA.org:liu-25583DiVA: diva2:246009