Time-intensity based optoacoustic flow measurements with gold nanoparticles

Pai Chi Li, Chen Wei Wei, Chao Kang Liao, Hsiao Chien Tseng, Yen Ping Lin, Chia Chun Chen

Research output: Contribution to journalConference article

7 Citations (Scopus)

Abstract

The indicator-dilution theory has been used for flow rate measurements in various imaging modalities, including magnetic resonance imaging, computed tomography and ultrasound. The experimental procedure generally involves the injection of a dose of indicator (i.e., the contrast agent), after which the concentration of the agent is monitored as a function of time; it is therefore also known as the time-intensity method. Although the time-intensity method has been widely applied to other imaging modalities, it has not been demonstrated with optoacoustic imaging. In this study, we experimentally test the hypothesis that quantitative blood flow measurements are feasible with the time-intensity based method in optoacoustic imaging. Gold nanospheres (broad band absorption spectrum peaks at 520 nm) were used as the optoacoustic contrast agent. The imaging system consisted of a frequency-doubled Nd:YAG laser operating at 532 nm for optical illumination, and an ultrasonic single crystal transducer with a center frequency of 3.5 MHz and a focal depth of 7 cm for detection. The volumetric flow rate ranged from 0.23 to 4.29 ml/sec, and the volume of the mixing chamber was from 30 to 80 ml. Results show good agreement between the measured mean transit times and the predicted time constants (correlation coefficient higher than 0.88), thus demonstrating the feasibility of the time-intensity based flow measurement technique. In addition to describing the method and experimental results, issues regarding the system sensitivity and estimation of the dilution transfer function are also discussed.

Original languageEnglish
Article number14
Pages (from-to)63-72
Number of pages10
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume5697
DOIs
Publication statusPublished - 2005 Aug 16
EventSixth Conference on Biomedical Thermosacoustics, Optoacoustics, and Acousto-Optics - Photons Plus Ultrasound: Imaging and Sensing 2005 - San Jose, CA, United States
Duration: 2005 Jan 232005 Jan 25

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Keywords

  • Contrast agent
  • Flow rate
  • Gold nanospheres
  • Indicator-dilution theory
  • Nd:YAG laser
  • Optoacoustic imaging
  • Time-intensity method

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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