California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Pasadena, California, United States.
J Biomed Opt. 2023 Apr;28(4):046004. doi: 10.1117/1.JBO.28.4.046004. Epub 2023 Apr 13.
Current photoacoustic (PA) imaging modalities typically require either serial detection with a single-element transducer or parallel detections with an ultrasonic array, indicating a dilemma between system cost and imaging throughput. PA topography through ergodic relay (PATER) was recently developed to address this bottleneck. However, PATER requires object-specific calibration due to varied boundary condition and must be recalibrated through pointwise scanning for each object before measurements, which is time-consuming and severely limits practical application.
We aim to develop a new single-shot PA imaging technique that only requires a one-time calibration for imaging different objects using a single-element transducer.
We develop an imaging method, PA imaging through a spatiotemporal encoder (PAISE), to address the above issue. The spatial information is effectively coded into unique temporal features by the spatiotemporal encoder, which allows for compressive image reconstruction. An ultrasonic waveguide is proposed as a critical element to guide the PA waves from the object into the prism, which effectively accounts for the varied boundary condition of different objects. We further add irregular-shaped edges on the prism to introduce randomized internal reflections and further facilitate the scrambling of acoustic waves.
The proposed technique is validated through comprehensive numerical simulations and experiments, and it is demonstrated that PAISE can successfully overcome the changed boundary condition and can image different samples given a single calibration.
The proposed PAISE technique is capable of single-shot widefield PA imaging with a single-element transducer and does not require sample-specific calibration, which successfully overcomes the major limitation of previous PATER technology.
目前的光声（PA）成像模式通常需要使用单个元件换能器进行串行检测，或者使用超声阵列进行并行检测，这表明在系统成本和成像吞吐量之间存在两难选择。最近开发的遍历式光声层析成像（PATER）技术旨在解决这一瓶颈问题。然而，由于边界条件的变化，PATER 要求针对特定对象进行校准，并且必须在每次测量之前通过逐点扫描对每个对象进行重新校准，这既耗时又严重限制了实际应用。
我们旨在开发一种新的单次激发 PA 成像技术，该技术仅使用单个元件换能器即可对不同物体进行成像，且仅需一次校准。
我们开发了一种成像方法，即通过时空编码器的光声成像（PAISE），以解决上述问题。时空编码器将空间信息有效地编码为独特的时间特征，从而实现压缩图像重建。提出了一种超声导波作为关键元件，将 PA 波从物体引导到棱镜中，这有效地考虑了不同物体的不同边界条件。我们还在棱镜上添加了不规则形状的边缘，以引入随机内部反射，进一步促进声波的混乱。
通过全面的数值模拟和实验验证了所提出的技术，结果表明 PAISE 可以成功克服变化的边界条件，并在单次校准的情况下对不同的样本进行成像。
所提出的 PAISE 技术能够使用单个元件换能器进行单次激发宽场 PA 成像，并且不需要针对特定样本进行校准，成功克服了先前 PATER 技术的主要限制。
