6 April 2000 Optoacoustic monitoring of freezing and hypothermia of tissue and tissue phantoms
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Abstract
Monitoring of tissue freezing and hypothermia during cryotherapy in real time is in the great demand for precise selective destruction of tumors. Ultrasound imaging, magnetic resonance imaging, and computer tomography techniques proposed for cryotherapy monitoring have problems associated with long acquisition time, high cost, low contrast, and poor resolution. In this paper we propose to use optoacoustic technique for monitoring of tissue freezing and hypothermia. Optoacoustic imaging is based on time-resolved detection of laser-induced acoustic waves. We studied influence of cooling and freezing on amplitude and profile of laser induced optoacoustic signals recorded from tissue phantoms (aqueous solution of potassium chromate) and canine liver. We used liquid nitrogen as a coolant of our samples. Q-switched Nd:YAG laser pulses were used to induce optoacoustic pulses. Our studies demonstrated that (1) amplitude of optoacoustic signals recorded from native tissues and aqueous solutions decreases with cooling down to the temperatures of -2 °C and 0 °C, respectively; and (2) freezing of tissues and aqueous solutions results in dramatic change in the optoacoustic signal profiles and amplitude. Our results indicate that the laser optoacoustic technique can potentially be used for real-time monitoring of freezing front in tissue with 0.5-mm spatial resolution.
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Irina V. Larina, Irina V. Larina, Kirill V. Larin, Kirill V. Larin, Massoud Motamedi, Massoud Motamedi, Rinat O. Esenaliev, Rinat O. Esenaliev, } "Optoacoustic monitoring of freezing and hypothermia of tissue and tissue phantoms", Proc. SPIE 4001, Saratov Fall Meeting '99: Optical Technologies in Biophysics and Medicine, (6 April 2000); doi: 10.1117/12.381528; https://doi.org/10.1117/12.381528
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