研究目的
To introduce a technique called lifetime-weighted imaging for photoacoustic (PA) imaging that uses only three laser pulses to preferentially weight signals from chromophores with long lifetimes while nulling chromophores with short lifetimes, aiming to reduce acquisition times and sensitivity to motion, absorption, or photobleaching.
研究成果
The lifetime-weighted imaging technique effectively differentiates chromophores based on their lifetimes, providing a method to visualize long-lifetime agents while nulling short-lifetime background signals. This has potential applications in photodynamic therapy dosimetry guidance, oxygen sensing, and other molecular imaging applications.
研究不足
The technique may be affected by factors such as temperature changes due to the pump laser, pulse-to-pulse stability of the pump laser, and the presence of multiple decay pathways. The high concentration of contrast agents used in phantom experiments may be difficult to achieve with intravenous injections in vivo.
1：Experimental Design and Method Selection:
The study employs a pump-probe approach to investigate the lifetime profile of exogenous agents in PA imaging. The technique involves using three laser pulses to generate lifetime-weighted images.
2：Sample Selection and Data Sources:
Samples include methylene blue and porphyrin-lipids, with their oxygen-dependent lifetimes measured. A pO2 electrode was used to estimate the partial pressure of oxygen in the samples.
3：List of Experimental Equipment and Materials:
Two Nd:YAG lasers, a dye laser, an OPO, a pulse-delay generator, a 50 MHz ultrasound transducer, and a custom-designed user interface for data acquisition were used.
4：Experimental Procedures and Operational Workflow:
The pump and probe light paths were combined and co-aligned into a multimode fiber, focused through a prism, and detected by an ultrasound transducer. The samples were prepared and deoxygenated, then imaged under the prism.
5：Data Analysis Methods:
MATLAB was used to process the data, including curve-fitting to estimate lifetimes and generating lifetime-weighted images.
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