On the Importance of Low-Frequency Signals in Functional and Molecular Photoacoustic Computed Tomography
On the Importance of Low-Frequency Signals in Functional and Molecular Photoacoustic Computed Tomography
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DOI：
10.1109/tmi.2023.3320668
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发表时间：
2024-02-01
影响因子：
10.6
通讯作者：
Yao，Junjie
中科院分区：
文献类型：
--
作者：
Vu，Tri;Klippel，Paul;Yao，Junjie
在短脉冲激光激励的光声计算机层析成像(PACT)中，生物组织中产生的宽带声信号的频率与光吸收目标的有效形状和大小有关。低频光声信号分量对应于缓慢变化的空间特征，并且通常在成像期间由于超声换能器的有限检测带宽而被省略，或者在作为降低图像对比度的不希望的背景的图像重建期间被省略。在这里，我们证明，低频光声信号实际上包含功能和分子信息，可以用来增强结构可见性，提高定量精度，并减少多余的采样伪影。我们对PACT中的低频信号进行了深入的理论分析，并从实验上评估了它们对几种典型的PACT应用的影响，例如光热治疗中的测温，低氧挑战中的血氧含量测量，以及在深部器官中检测可光开关的分子探针。我们的结果有力地表明，低频信号对于功能和分子PACT是重要的。
In photoacoustic computed tomography (PACT) with short-pulsed laser excitation, wideband acoustic signals are generated in biological tissues with frequencies related to the effective shapes and sizes of the optically absorbing targets. Low-frequency photoacoustic signal components correspond to slowly varying spatial features and are often omitted during imaging due to the limited detection bandwidth of the ultrasound transducer, or during image reconstruction as undesired background that degrades image contrast. Here we demonstrate that low-frequency photoacoustic signals, in fact, contain functional and molecular information, and can be used to enhance structural visibility, improve quantitative accuracy, and reduce spare-sampling artifacts. We provide an in-depth theoretical analysis of low-frequency signals in PACT, and experimentally evaluate their impact on several representative PACT applications, such as mapping temperature in photothermal treatment, measuring blood oxygenation in a hypoxia challenge, and detecting photoswitchable molecular probes in deep organs. Our results strongly suggest that low-frequency signals are important for functional and molecular PACT.