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Proceedings Paper

Lifetime-weighted photoacoustic imaging
Author(s): A. Forbrich; P. Shao; Wei Shi; Roger J. Zemp
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Paper Abstract

It has previously been shown that photoacoustic imaging can interrogate lifetimes of exogenous agents by a sequence of pulses with varying pump-probe delay intervals. Rather than attempt to unmix molecules based on their composite lifetime profile, we introduce a technique called lifetime weighted imaging, which preferentially weights signals from chromophores with long lifetimes (including exogenous contrast agents such as methylene blue and porphyrins with microsecond-scale lifetimes) while nulling chromophores with short lifetimes (including hemoglobin with ps-ns-scale lifetimes). A probe beam is used to interrogate samples with or without a pump beam. By subtracting probe-beam photoacoustic signals with pump- from those without a pump excitation, we effectively eliminate probe signals from chromophores with short lifetimes while preserving excited-state photoacoustic signals from long-lifetimes. This differential signal will be weighted by a decaying exponential function of the pump-probe delay divided by the exogenous agent lifetime. This technique enabled the imaging of both triplet excited state lifetime and ground-state recovery lifetime. We demonstrate the oxygen-dependent lifetime of both methylene blue and porphyrins. Lifetimeweighted imaging could be used for photodynamic therapy dosimetry guidance, oxygen sensing, or other molecular imaging applications.

Paper Details

Date Published: 11 March 2015
PDF: 6 pages
Proc. SPIE 9323, Photons Plus Ultrasound: Imaging and Sensing 2015, 93231H (11 March 2015); doi: 10.1117/12.2079815
Show Author Affiliations
A. Forbrich, Univ. of Alberta (Canada)
P. Shao, Univ. of Alberta (Canada)
Wei Shi, Univ. of Alberta (Canada)
Roger J. Zemp, Univ. of Alberta (Canada)

Published in SPIE Proceedings Vol. 9323:
Photons Plus Ultrasound: Imaging and Sensing 2015
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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