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Journal of Biomedical Optics • Open Access

Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

Paper Abstract

Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra ( ~ 0.3 dB / MHz). The experimental midband fit increased by ~ 5 dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was > 20% greater than the nonaggregated sample. The results provide a framework for using PA signals' spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

Paper Details

Date Published: 12 December 2012
PDF: 10 pages
J. Biomed. Opt. 17(12) 125006 doi: 10.1117/1.JBO.17.12.125006
Published in: Journal of Biomedical Optics Volume 17, Issue 12
Show Author Affiliations
Eno Hysi, Ryerson Univ. (Canada)
Ratan K. Saha, Saha Institute of Nuclear Physics (India)
Michael C. Kolios, Ryerson Univ. (Canada)

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