title: Calibration-free quantification of absolute oxygen saturation based on the dynamics of photoacoustic signals.
abstract: Photoacoustic tomography (PAT) is a hybrid imaging technique that has broad preclinical and clinical applications. Based on the photoacoustic effect, PAT directly measures specific optical absorption, which is the product of the tissue-intrinsic optical absorption coefficient and the local optical fluence. Therefore, quantitative PAT, such as absolute oxygen saturation (sO₂) quantification, requires knowledge of the local optical fluence, which can only be estimated through invasive measurements or sophisticated modeling of light transportation. In this Letter, we circumvent this requirement by taking advantage of the dynamics in sO₂. The new method works when the sO₂ transition can be simultaneously monitored with multiple wavelengths. For each wavelength, the ratio of photoacoustic amplitudes measured at different sO₂ states is utilized. Using the ratio cancels the contribution from optical fluence and allows calibration-free quantification of absolute sO₂. The new method was validated through both phantom and in vivo experiments.
authors.affiliation: Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, Missouri 63130, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Xia
authors.forename: Amos
authors.initials: A
authors.lastname: Danielli
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Lidai
authors.initials: L
authors.lastname: Wang
authors.forename: Konstantin
authors.initials: K
authors.lastname: Maslov
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
mesh_terms: D000818:Animals; D002138:Calibration; D002540:Cerebral Cortex / Q000098:blood supply; D051379:Mice; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D019047:Phantoms, Imaging; D061088:Photoacoustic Techniques / Q000379:methods*; D014057:Tomography, X-Ray Computed
chemical_list: D010100:Oxygen
references.citation: Proc Natl Acad Sci U S A. 2003 Oct 14;100(21):12349-54
references.pmid: 14514888
references.citation: J Biomed Opt. 2011 Sep;16(9):096016
references.pmid: 21950930
references.citation: J Biomed Opt. 2011 Sep;16(9):090505
references.pmid: 21950908
references.citation: Science. 2012 Mar 23;335(6075):1458-62
references.pmid: 22442475
references.citation: Phys Med Biol. 2007 Jan 7;52(1):141-68
references.pmid: 17183133
references.citation: Opt Lett. 2010 Jun 15;35(12):2067-9
references.pmid: 20548388
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Jan;71(1 Pt 2):016706
references.pmid: 15697763
references.citation: Comput Methods Programs Biomed. 1995 Jul;47(2):131-46
references.pmid: 7587160
references.citation: J Clin Oncol. 2006 May 1;24(13):2098-104
references.pmid: 16648512
references.citation: J Biomed Opt. 2012 May;17(5):050506
references.pmid: 22612121
references.citation: J Natl Cancer Inst. 2001 Feb 21;93(4):266-76
references.pmid: 11181773
references.citation: Opt Express. 2009 Jun 22;17(13):10489-98
references.pmid: 19550444
references.citation: J Biomed Opt. 2012 Jul;17(7):076012
references.pmid: 22894495
references.citation: J Biomed Opt. 2012 Jun;17(6):061202
references.pmid: 22734732
references.citation: Expert Rev Neurother. 2012 Aug;12(8):915-28
references.pmid: 23002936