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Biomedical Photoacoustic Imaging

Biomedical Photoacoustic Imaging. Dene Ringuette ECE1457H Dec. 6, 2011. Photoacoustic Effect. Material emitting sound when exposed light More Generally: Physical Vibrations induced from EM radiation absorption Discovered by Alexander Graham Bell in 1880 Used in gas composition spectroscopy

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Biomedical Photoacoustic Imaging

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  1. Biomedical Photoacoustic Imaging DeneRinguette ECE1457H Dec. 6, 2011

  2. Photoacoustic Effect • Material emitting sound when exposed light • More Generally: Physical Vibrations induced from EM radiation absorption • Discovered by Alexander Graham Bell in 1880 • Used in gas composition spectroscopy • Used in new biomedical imaging technique • Short EM pulse • Rapid millikelvin temperature changes • Record ultrasonic pulse

  3. Example Microscope Zhang et al., 2006

  4. Photoacoustic Physics • Pressure wave due to changing heat delivery • Valid for short laser pulse • Thermal and stress confinement • Forward Solution: H(r, t) --> p(r, t) • Inverse Problem: pd(r, t) --> p0(r) • Solution based on architecture

  5. Advantages of PAI • Higher absorption contrast than ultrasound • Optical absorption • Lower scattering than optical techniques • Not reliant on quasi-ballistic • Ultrasound weekly scattered • RF weekly scattered • Spectroscopic absorption (NIR)

  6. Attenuation Optical Acoustic bme240.eng.uci.edu Treebyet al., 2011

  7. Architectures Wu et al., 2006 Wu et al., 2006

  8. Single Vessel Discrimination and Oxygen Saturation Example Microscope Group Zhang et al., 2007

  9. Transparent Fabry–Perot Polymer Film Sensing Interferometer Excitation: 590 nm Repeat: 637/800 nm and 889 nm Scanning: 1550nm • depths up to 3.7 mm Lauferet al., 2009

  10. Continued ... Zhang et al., 2011

  11. Frequency-domain (Continuous Wave) 785 nm 50 MHz Amplitude Phase • reduce peak power • reduce system size • analog to digital holography Zhu et al., 2011

  12. Gold Nanocages as Contrast Agents • Compact • Inert • Wavelength tunable Li et al., 2011 Diameter < 50 nm

  13. Continued ... sentinel lymph node Li et al., 2011

  14. Pulsed Fibre Laser • Compact • Efficient • 1060 nm • 600-1200nm • spatial <10 µm See Zhang et al., 2011 Allen et al., 2011

  15. Correction forAcoustic Speed Variations Large differential density element Jin et al., 2006

  16. Roumeliotiset al., 2011 • SVD • 3D at 0.7 Hz • 10 Hz achievable

  17. Fluorescent Proteins Razanskyet al., 2007 Burgholzeret al., 2009

  18. Photoacoustic Doppler Brunkeret al., 2010 See also Chen et al .,2011 measurement from single red blood cells.

  19. Full-body “Baby Mouse” Full-ring • Excitation 532 nm • Full-ring array • Axial 0.1 mm and Elevation 1 mm • Deconvolution reduces to 0.2 mm Xia et al., 2011

  20. Through Skull • Radial < 1 mm • FOV = 6 cm • Depth 4 mm • 606 and 678 nm Nie et al., 2011

  21. Future Work • Improved Algorithms and System Interaction • Increased Portability • System Flexibility Conclusion • Numerous Measurable Quantities • Faster Fibre Lasers • Through skull and small animal whole-body

  22. THE ENDQuestions?

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