A method to estimate the spatial coherence of photoacoustic channel data without access to channel data

Channel signal-to-noise ratio (SNR) is a metric to assess photoacoustic image quality based on the raw photoacoustic channel data. Current methods for measuring channel SNR require access to raw data or delay data prior to summation (e.g., prior to DAS beamforming) in addition to knowledge of the noise profile to differentiate signal from noise. However, access to pre-beamformed data is not always feasible with clinical ultrasound scanners, and knowledge of noise profiles are typically not available. This paper introduces a new method for calculating channel SNR based on the probability density functions (PDFs) of beamformed data and shows how this method is related to not only channel SNR, but also other properties of channel data and image data for photoacoustic images.