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Visible-light photon migration through myocardium in vivo.
Am J Physiol 1999; 277(2):H698-704AJ

Abstract

Empirical data between 510 and 590 nm of diffuse reflected light from the pig heart in vivo have shown that myoglobin and cytochrome c absorption peaks with little apparent contribution of red blood cell (RBC) Hb. Monte Carlo simulations of photon migration in tissue were performed to compare the effects of myoglobin and cytochromes with those of blood Hb on photon pathlengths and diffuse reflectance of visible wavelengths (450-600 nm) from the pig heart in vivo. Wavelength dependence of the input parameters, including the transport-corrected scattering coefficients (1.1-1.2 mm(-1)) and the absorption coefficients of blood-free solubilized heart tissue (0.43-1.47 mm(-1)), as well as the absorption coefficients of Hb, were determined by an integrating sphere method and standard spectrophotometry, respectively. The Monte Carlo simulations indicate that in the 510- to 590-nm range the mean path length within the myocardium for diffusely reflected light varies from 1.4 to 1.2 mm, whereas their mean penetration depth within the epicardium is only 330-400 micrometer for blood-free heart tissue. Analysis shows that the blood Hb absorption extrema are only observable between 510 and 590 nm when RBC concentration in tissue is >0.5%. Blood within vessels much larger than capillaries does not contribute significantly to the spectral features, because virtually all light in this spectral range is absorbed during transit through large vessels (>100 micrometer). This analysis suggests that diffuse reflected light in the 510- to 590-nm region will show spectral features uniquely associated with myoglobin and cytochrome c oxygenation states within 400 micrometer of the surface of the heart in situ as long as the capillary RBC concentration remains <0.5%.

Authors+Show Affiliations

Laboratory of Integrative and Medical Biophysics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

10444496

Citation

Gandjbakhche, A H., et al. "Visible-light Photon Migration Through Myocardium in Vivo." The American Journal of Physiology, vol. 277, no. 2, 1999, pp. H698-704.
Gandjbakhche AH, Bonner RF, Arai AE, et al. Visible-light photon migration through myocardium in vivo. Am J Physiol. 1999;277(2):H698-704.
Gandjbakhche, A. H., Bonner, R. F., Arai, A. E., & Balaban, R. S. (1999). Visible-light photon migration through myocardium in vivo. The American Journal of Physiology, 277(2), pp. H698-704. doi:10.1152/ajpheart.1999.277.2.H698.
Gandjbakhche AH, et al. Visible-light Photon Migration Through Myocardium in Vivo. Am J Physiol. 1999;277(2):H698-704. PubMed PMID: 10444496.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Visible-light photon migration through myocardium in vivo. AU - Gandjbakhche,A H, AU - Bonner,R F, AU - Arai,A E, AU - Balaban,R S, PY - 1999/8/13/pubmed PY - 1999/8/13/medline PY - 1999/8/13/entrez SP - H698 EP - 704 JF - The American journal of physiology JO - Am. J. Physiol. VL - 277 IS - 2 N2 - Empirical data between 510 and 590 nm of diffuse reflected light from the pig heart in vivo have shown that myoglobin and cytochrome c absorption peaks with little apparent contribution of red blood cell (RBC) Hb. Monte Carlo simulations of photon migration in tissue were performed to compare the effects of myoglobin and cytochromes with those of blood Hb on photon pathlengths and diffuse reflectance of visible wavelengths (450-600 nm) from the pig heart in vivo. Wavelength dependence of the input parameters, including the transport-corrected scattering coefficients (1.1-1.2 mm(-1)) and the absorption coefficients of blood-free solubilized heart tissue (0.43-1.47 mm(-1)), as well as the absorption coefficients of Hb, were determined by an integrating sphere method and standard spectrophotometry, respectively. The Monte Carlo simulations indicate that in the 510- to 590-nm range the mean path length within the myocardium for diffusely reflected light varies from 1.4 to 1.2 mm, whereas their mean penetration depth within the epicardium is only 330-400 micrometer for blood-free heart tissue. Analysis shows that the blood Hb absorption extrema are only observable between 510 and 590 nm when RBC concentration in tissue is >0.5%. Blood within vessels much larger than capillaries does not contribute significantly to the spectral features, because virtually all light in this spectral range is absorbed during transit through large vessels (>100 micrometer). This analysis suggests that diffuse reflected light in the 510- to 590-nm region will show spectral features uniquely associated with myoglobin and cytochrome c oxygenation states within 400 micrometer of the surface of the heart in situ as long as the capillary RBC concentration remains <0.5%. SN - 0002-9513 UR - https://www.unboundmedicine.com/medline/citation/10444496/Visible_light_photon_migration_through_myocardium_in_vivo_ L2 - http://www.physiology.org/doi/full/10.1152/ajpheart.1999.277.2.H698?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -