Comparison of wavefront distortion in the breast between optoacoustic imaging and ultrasonic imaging

Wavefront distortion in breast OA imaging is investigated and compared with that in conventional ultrasound. An adaptive OA imaging method is also proposed to compensate for the degradation caused by breast tissue inhomogeneities. Both OA and ultrasound wave propagation were simulated using a finite difference time-domain method. The proposed OA image correction method adaptively adjusted the sound speed at each image pixel in order to maximize an absorption-based image quality factor. As reported in in vivo and in vitro ultrasonic experiments in the literature, results showed that OA wavefronts suffer from significant time fluctuations and waveform distortion. For conventional ultrasound, the spatial coherence is limited by the van Cittert-Zernicke theorem and it decreases with the relative distance. The OA signals on the other hand, exhibit relatively higher spatial coherence under the same conditions. Results also showed that the proposed correction algorithm can greatly enhance the OA image quality around a tumor-like area.