Light excitation methods for five dimensional optoacoustic imaging

Multispectral optoacoustic tomography offers unprecedented capabilities in biological research and newly-developed systems prompt the clinical translation of this modality. By exciting tissues at multiple optical wavelengths, the distribution of spectrally-distinctive absorbers can be resolved with high resolution in deep tissues, thus enabling reading important biological parameters such as blood oxygenation or the biodistribution of photo-absorbing agents. Multispectral three-dimensional optoacoustic imaging generally comes at the expense of slow acquisition times, which limits the dynamic imaging capabilities of this modality. Recently, the feasibility of multispectral three-dimensional imaging in real time (five dimensional imaging) has been showcased. Two different illumination strategies can be used for this purpose. The first approach is based on tuning the wavelength of the laser on a per-pulse basis, which enables acquisition of large multispectral datasets on a very short time. The second approach is based on properly synchronizing the light beams from two (or more) laser sources. The performances of these two approaches are compared and discussed herein based on experiments with mice and human volunteers.