Comparison of skin tone and target detectability in simulated, tissue-mimicking phantom, and clinical photoacoustic breast images

Photoacoustic imaging is promising for noninvasive breast cancer detection. However, previous simulation studies demonstrate diminished photoacoustic image quality with greater melanin content, depending on the use of delay-and-sum (DAS) or short-lag spatial coherence (SLSC) beamformers. Herein, we investigate the applicability of these findings to experimental data, including tissue-mimicking phantom data and in vivo breast data acquired from 20 patients with skin tone individual typology angles (ITAs) ranging from -78° (dark) to 71° (very light). Raw photoacoustic channel data were acquired with 757 nm and 1064 nm wavelengths and beamformed with DAS and SLSC. With brown and dark skin tones (i.e., ITA ≤ 0°) and targets ≥5 mm deep, the mean signal-to-noise ratios of simulated, phantom, and in vivo targets were 2.07, 12.67, and 19.41, respectively, with SLSC beamforming, relative to 1.97, 7.84, and 10.12 with DAS beamforming. Therefore, SLSC beamforming has the potential to advance equity across skin tones in photoacoustic breast imaging, relative to the skin tone bias observed with amplitude-based beamforming.