Optimization of in vivo spectroscopic photoacoustic imaging by smart optical wavelength selection.

Spectroscopic photoacoustic (sPA) imaging is an emerging biomedical imaging modality which can be used to simultaneously identify multiple optical absorbers in tissue. With current technology, the image acquisition time is limited primarily by the laser repetition rate, and sPA image acquisition can take seconds to minutes, depending on the system and imaging volume. We have developed an algorithm that can be used to eliminate extraneous wavelengths and decrease image acquisition time while maintaining image quality. Here, we show the effect the wavelength selection has on in vivo sPA imaging. As an example, dye draining to the lymph node of a mouse was imaged. We demonstrate that sPA image quality is more accurately preserved when wavelengths are chosen based on the spectral features of the absorbers compared to often-used selection of evenly spaced wavelengths. In fact, only three wavelengths are needed to accurately spectrally unmix the dye from oxygenated and deoxygenated hemoglobin.