High-frequency (greater than 30 MHz) photoacoustic computed tomography (PACT) provides the opportunity to reveal finer details of biological tissues with high spatial resolution. To record photoacoustic signals above 30 MHz, sampling rates higher than 60 MHz are required according to the Nyquist sampling criterion. However, the highest sampling rates supported by existing PACT systems are typically within the range of 40–60 MHz. Herein, we propose a novel PACT imaging method based on sub-Nyquist sampling. The results of numerical simulation, phantom experiment, and in vivo experiment demonstrate that the proposed imaging method can achieve high-frequency PACT imaging with a relatively low sampling rate. An axial resolution of 22 μm is achieved with a 30-MHz transducer and a 41.67-MHz sampling rate. To the best of our knowledge, this is the highest axial resolution ever achieved in PACT based on a sampling rate of not greater than 60 MHz. This work is expected to provide a practical way for high-frequency PACT imaging with limited sampling rates.

中文翻译：

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基于亚奈奎斯特采样的高频光声计算机断层扫描

高频（大于 30 MHz）光声计算机断层扫描 (PACT) 提供了以高空间分辨率揭示生物组织的更精细细节的机会。为了记录30 MHz以上的光声信号，根据奈奎斯特采样标准，需要高于60 MHz的采样率。然而，现有 PACT 系统支持的最高采样率通常在 40–60 MHz 范围内。在此，我们提出了一种基于亚奈奎斯特采样的新型 PACT 成像方法。数值模拟、体模实验和活体实验的结果表明，所提出的成像方法可以以相对较低的采样率实现高频PACT成像。使用 30 MHz 传感器和 41.67 MHz 采样率可实现 22 μm 的轴向分辨率。据我们所知，这是 PACT 基于不大于 60 MHz 采样率实现的最高轴向分辨率。这项工作有望为有限采样率的高频 PACT 成像提供一种实用的方法。