Research Papers: Sensing

Dual-wavelength photoacoustic technique for monitoring tissue status during thermal treatments

[+] Author Affiliations
Yi-Sing Hsiao, Cheri X. Deng

University of Michigan, Department of Biomedical Engineering, Ann Arbor, Michigan 48109

Xueding Wang

University of Michigan, Department of Radiology, Ann Arbor, Michigan 48109

J. Biomed. Opt. 18(6), 067003 (Jun 03, 2013). doi:10.1117/1.JBO.18.6.067003
History: Received December 5, 2012; Revised May 4, 2013; Accepted May 10, 2013
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Abstract.  Photoacoustic (PA) techniques have been exploited for monitoring thermal treatments. However, PA signals depend not only on tissue temperature but also on tissue optical properties which indicate tissue status (e.g., native or coagulated). The changes in temperature and tissue status often occur simultaneously during thermal treatments, so both effects cause changes to PA signals. A new dual-wavelength PA technique to monitor tissue status independent of temperature is performed. By dividing the PA signal intensities obtained at two wavelengths at the same temperature, a ratio, which only depends on tissue optical properties, is obtained. Experiments were performed with two experimental groups, one with untreated tissue samples and the other with high-intensity focused ultrasound treated tissue samples including thermal coagulated lesion, using ex vivo porcine myocardium specimens to test the technique. The ratio of PA signal intensities obtained at 700 and 800 nm was constant for both groups from 25 to 43°C, but with distinct values for the two groups. Tissue alteration during thermal treatment was then studied using water bath heating of tissue samples from 35 to 60°C. We found that the ratio stayed constant before it exhibited a marked increase at around 55°C, indicating tissue changes at this temperature.

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© 2013 Society of Photo-Optical Instrumentation Engineers

Topics

Tissues ; Water

Citation

Yi-Sing Hsiao ; Xueding Wang and Cheri X. Deng
"Dual-wavelength photoacoustic technique for monitoring tissue status during thermal treatments", J. Biomed. Opt. 18(6), 067003 (Jun 03, 2013). ; http://dx.doi.org/10.1117/1.JBO.18.6.067003


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