文件名称：Photoacoustic Tomography.pdf
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更新时间：2022-12-27 05:58:30
光声成像 photoacoustic
Photoacoustic tomography (PAT) is an emerging biomedical imaging modality that combines the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging in a single modality. By listening to light, PAT detects tissue-absorbed photons ultrasonically through the photoacoustic effect. Since ultrasonic scattering is two to three orders of magnitude weaker than optical scattering in tissue, PAT breaks the 2–4 mm spatial resolution limit associated with pure optical tomography such as diffuse optical tomography (DOT) for deep tissue imaging, or the ~1 mm depth limit associated with confocal and multiphoton microscopy and optical coherent tomography (OCT). In PAT, tissue is excited with a short (typically a few nanoseconds) laser pulse (focused or unfocused); the subsequent laser-induced transient photoacoustic waves in the range of 1–100 MHz, due to the transient thermoelastic expansion of light-absorbing components in tissue, are detected by wideband unfocused or focused ultrasound transducer(s). Unique advantages of PAT are that functional or biochemical parameters such as deoxy-hemoglobin (HbR), oxy-hemoglobin (HbO2), water (H2O), lipids, and so forth along with vasculature and blood flow can be imaged in high resolution. In addition, highly specific molecular PAT can be realized through the use of molecular contrast agents. Finally, PAT can be made portable for bedside applications, is economical, and uses non-ionization radiation.