Coherent‐Excitation PACT With Frequency‐Compensated Reconstruction for High‐Contrast Deep‐Tissue Imaging

Photoacoustic computed tomography (PACT) synergizes optical absorption contrast with ultrasonic resolution for noninvasive biomedical imaging yet faces limitations in signal‐to‐noise ratio (SNR), resolution, and contrast. This study introduces a coherent‐excitation PACT system integrating interferometric optical excitation and Frequency‐Compensated Filtered Back Projection (FC‐FBP) reconstruction. The proposed method utilizes phase‐locked dual‐pulse interferometric excitation to amplify photoacoustic emissions; for the isolated chicken heart, the resolution is improved by 7.9% compared to the single‐pulse protocol. The FC‐FBP algorithm compensates for frequency‐dependent acoustic attenuation via depth‐adaptive Gaussian filtering, enhancing the projected signal in the target area while suppressing speckle artifacts. Through experimental validation, we confirm that the coherent‐excitation scheme enables simultaneous optimization of optical fluence distribution and acoustic coherence; hence, it can be used to resolve previously indistinguishable hemoglobin oxygenation gradients in murine tumor models. This advancement establishes a high‐sensitivity PACT framework, showing potential for real‐time intraoperative imaging and dynamic metabolic monitoring in clinical applications.