研究目的
To improve the imaging characteristics of a compact acoustic-resolution photoacoustic (PA) imaging system by addressing blurring in the out-of-focus region of the ultrasound sensor and degraded resolution due to low-frequency components in the PA signals.
研究成果
The present PA signal processing methods, based on combined practical SAFT and bandpass ?ltering, were effective for enhancing the quality of PA vasculature imaging in both ex vivo and in vivo settings. These methods improved both the spatial resolution and SNRs at all depths examined and enhanced the contrast of both larger-diameter and smaller-diameter blood vessels.
研究不足
The study was limited by the motion artifact in in vivo imaging, which can cause a PA signal phase shift and hence degrade the correction effect of the SAFT+CF weighting. Additionally, the imaging depth range was limited, especially for higher frequency imaging.
1：Experimental Design and Method Selection:
The study introduced signal processing methods based on the synthetic-aperture focusing technique (SAFT) and digital acoustic signal ?ltering with three speci?c frequency bands.
2：Sample Selection and Data Sources:
Ex vivo and in vivo PA imaging of blood vessels in the rat skin and subcutaneous tissue.
3：List of Experimental Equipment and Materials:
A compact acoustic-resolution PA imaging system with optical ?ber-based illumination, a commercial 50-MHz ultrasound sensor (Olympus V214-BB-RM), and an optical parametric oscillator (OPO) as a light source.
4：Experimental Procedures and Operational Workflow:
The sensor was scanned over the sample with a step size of 5 μm for phantom study and 40 μm or 60 μm for ex vivo and in vivo imaging, respectively. PA signals were processed with SAFT and digital bandpass ?ltering.
5：Data Analysis Methods:
The temporal waveforms of PA signals of each frequency component were converted into depth pro?les by using an assumed sound velocity of tissue, producing PA images of each frequency component.
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