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Grueneisen relaxation photoacoustic microscopy in vivo

Ma, Jun and Shi, Junhui and Hai, Pengfei and Zhou, Yong and Wang, Lihong V. (2016) Grueneisen relaxation photoacoustic microscopy in vivo. In: Photons Plus Ultrasound: Imaging and Sensing 2016. Proceedings of SPIE. No.9708. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 97082Q. ISBN 9781628419429.

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Optical-resolution photoacoustic microscopy (OR-PAM) can achieve submicron lateral resolution by tightly focusing the excitation light, while the axial resolution is still limited by the frequency bandwidth of the ultrasonic transducer. The Grueneisen relaxation effect, in which the Grueneisen parameter changes within the thermal relaxation time following a laser impulse heating, can provide excellent axial resolution due to its optical sectioning property. Based on this effect, Grueneisen relaxation photoacoustic microscopy (GR-PAM) was developed and demonstrated ex vivo. Here, we present for the first time in vivo imaging of mouse brains with improved axial resolution based on GR-PAM. An intensity-modulated continuous-wave (CW) 532 nm laser thermally heated the in-focus absorber. Another 532 nm pulsed laser, which is aligned confocally with the CW laser, generated the photoacoustic (PA) signal from the absorber. The difference between the amplitudes of the photoacoustic signals with and without heating was used for image reconstruction. The achieved axial resolution is ~12.5 µm, which is fivefold better than the acoustically determined value for a 20 MHz-bandwidth ultrasound transducer. The system was demonstrated by imaging a blood-filled tube ex vivo and blood vessels of mouse brains in vivo. The blood-filled tube diameter obtained from the PA image by GR-PAM is 105 µm, which is much closer to its actual diameter (100 µm) than the value from conventional OR-PAM (160 µm). This axial resolution improvement was further validated in imaging mouse brains in vivo, and yielded significantly narrower axial profiles of the vessels. This in vivo demonstration of imaging by GR-PAM might inspire more applications in PA biomedical imaging and sensing.

Item Type:Book Section
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Shi, Junhui0000-0002-5741-2781
Wang, Lihong V.0000-0001-9783-4383
Additional Information:© 2016 Society of Photo-Optical Instrumentation Engineers.
Series Name:Proceedings of SPIE
Issue or Number:9708
Record Number:CaltechAUTHORS:20180907-104554290
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Official Citation:Jun Ma, Jun Ma, Junhui Shi, Junhui Shi, Pengfei Hai, Pengfei Hai, Yong Zhou, Yong Zhou, Lihong V. Wang, Lihong V. Wang, } "Grueneisen relaxation photoacoustic microscopy in vivo (Conference Presentation)", Proc. SPIE 9708, Photons Plus Ultrasound: Imaging and Sensing 2016, 97082Q (27 April 2016); doi: 10.1117/12.2211196;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89465
Deposited By: Tony Diaz
Deposited On:08 Sep 2018 03:26
Last Modified:16 Nov 2021 00:35

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