title: Wavelength-Modulated Differential Photoacoustic Spectroscopy (WM-DPAS) for noninvasive early cancer detection and tissue hypoxia monitoring.
abstract: This study introduces a novel noninvasive differential photoacoustic method, Wavelength Modulated Differential Photoacoustic Spectroscopy (WM-DPAS), for noninvasive early cancer detection and continuous hypoxia monitoring through ultrasensitive measurements of hemoglobin oxygenation levels (StO2 ). Unlike conventional photoacoustic spectroscopy, WM-DPAS measures simultaneously two signals induced from square-wave modulated laser beams at two different wavelengths where the absorption difference between maximum deoxy- and oxy-hemoglobin is 680 nm, and minimum (zero) 808 nm (the isosbestic point). The two-wavelength measurement efficiently suppresses background, greatly enhances the signal to noise ratio and thus enables WM-DPAS to detect very small changes in total hemoglobin concentration (CHb ) and oxygenation levels, thereby identifying pre-malignant tumors before they are anatomically apparent. The non-invasive nature also makes WM-DPAS the best candidate for ICU bedside hypoxia monitoring in stroke patients. Sensitivity tunability is another special feature of the technology: WM-DPAS can be tuned for different applications such as quick cancer screening and accurate StO2 quantification by selecting a pair of parameters, signal amplitude ratio and phase shift. The WM-DPAS theory has been validated with sheep blood phantom measurements. Sensitivity comparison between conventional single-ended signal and differential signal.
authors.affiliation: Center for Advanced Diffusion-Wave Technologies, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.
authors.forename: Sung Soo Sean
authors.initials: SS
authors.lastname: Choi
authors.affiliation: Center for Advanced Diffusion-Wave Technologies, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada. mandelis@mie.utoronto.ca.|Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany. mandelis@mie.utoronto.ca.
authors.forename: Andreas
authors.initials: A
authors.lastname: Mandelis
authors.affiliation: Center for Advanced Diffusion-Wave Technologies, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Guo
authors.affiliation: Center for Advanced Diffusion-Wave Technologies, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.
authors.forename: Bahman
authors.initials: B
authors.lastname: Lashkari
authors.affiliation: Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kellnberger
authors.affiliation: Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ntziachristos
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis / Q000473:pathology; D015687:Cell Hypoxia; D055088:Early Detection of Cancer / Q000379:methods*; D006801:Humans; D008403:Mass Screening; D061088:Photoacoustic Techniques / Q000379:methods*; D012756:Sheep; D059629:Signal-To-Noise Ratio
keywords: biosensor; differential photoacoustic; hypoxia; noninvasive; premalignant