Photoacoustic tomography (PAT) has demonstrated versatile biomedical applications, ranging from tracking single cells to monitoring whole-body dynamics of small animals and diagnosing human breast cancer. Currently, PAT has two major implementations: photoacoustic computed tomography (PACT) and photoacoustic microscopy (PAM). PACT uses a multi-element ultrasonic array for parallel detection, which is relatively complex and expensive. In contrast, PAM requires point-by-point scanning with a single-element detector, which has a limited imaging throughput. The trade-off between the system cost and throughput demands a new imaging method. To this end, we have developed photoacoustic topography through an ergodic relay (PATER). PATER can capture a wide-field image with only a single-element ultrasonic detector upon a single laser shot. This protocol describes the detailed procedures for PATER system construction, including component selection, equipment setup and system alignment. A step-by-step guide for in vivo imaging of a mouse brain is provided as an example application. Data acquisition, image reconstruction and troubleshooting procedures are also elaborated. It takes ~130 min to carry out this protocol, including ~60 min for both calibration and snapshot wide-field data acquisition using a laser with a 2-kHz pulse repetition rate. PATER offers low-cost snapshot wide-field imaging of fast dynamics, such as visualizing blood pulse wave propagation and tracking melanoma tumor cell circulation in mice in vivo. We envision that PATER will have wide biomedical applications and anticipate that the compact size of the setup will allow it to be further developed as a wearable device to monitor human vital signs.

光声断层扫描 (PAT) 已展示出多种生物医学应用，从跟踪单细胞到监测小动物的全身动态，再到诊断人类乳腺癌。目前，PAT 有两种主要实现方式：光声计算机断层扫描 (PACT) 和光声显微镜 (PAM)。 PACT采用多阵元超声阵列进行并行检测，相对复杂且昂贵。相比之下，PAM 需要使用单元件探测器进行逐点扫描，其成像吞吐量有限。系统成本和吞吐量之间的权衡需要一种新的成像方法。为此，我们通过遍历中继（PATER）开发了光声地形。 PATER 可以在单次激光发射时仅使用单元件超声波探测器捕获宽视场图像。该协议描述了 PATER 系统构建的详细程序，包括组件选择、设备设置和系统对准。作为示例应用，提供了小鼠大脑体内成像的分步指南。还详细阐述了数据采集、图像重建和故障排除程序。执行该协议需要大约 130 分钟，其中使用具有 2 kHz 脉冲重复率的激光器进行校准和快照宽场数据采集大约需要 60 分钟。 PATER 提供快速动态的低成本快照广域成像，例如可视化血液脉搏波传播和跟踪小鼠体内黑色素瘤肿瘤细胞循环。我们预计 PATER 将具有广泛的生物医学应用，并预计其紧凑的尺寸将使其能够进一步开发为监测人体生命体征的可穿戴设备。