Virtual wave based phasor field projection for photoacoustic imaging

Abstract

The phasor field technique has been demonstrated as a powerful tool to improve imaging performance and reduce computational complexity in time of flight imaging. In this work, we show a similar description and propose phasor field photoacoustics (PAs), a framework for forward acoustic propagation and backward source reconstruction, using phasor representations of acoustic pressure and back projection events. Based on the linear propagation mechanism, this method employs complex phasor filters to decompose the photoacoustic wave into pairs of orthogonal virtual waves, wherein each pair of orthogonal waves corresponds to the real and imaginary parts of the quasi-monochromatic phasor field contribution. By performing phasor field projection (PFP) and thereafter conjugated multiplication in the spatial domain, the complex envelope containing local amplitude and phase information can be faithfully retrieved, attaining rigorous “unipolar” photoacoustic images without ambiguous negative absorption artifacts. Theoretical and experimental results demonstrate that the orthogonal virtual wave based phasor field photoacoustic method can effectively eliminate negative artifacts and improve imaging signal-to-noise ratio (SNR) without excessively increasing computational complexity. This work may pave the way for high-fidelity quantitative imaging, e.g., multispectral and molecular imaging applications.