Rapid functional optoacoustic micro-angiography in a burst mode

Optoacoustic microscopy (OAM) can image intrinsic optical absorption contrast at depths of several millimeters where state-of-the-art optical microscopy techniques fail due to intense light scattering in living tissues. Yet, wide adoption of OAM in biology and medicine is hindered by the slow image acquisition speed, small field-of-view (FOV), and/or lack of spectral differentiation capacity of common system implementations. We report on a rapid acquisition functional optoacoustic micro-angiography (FOMA) approach that employs burst-mode laser triggering scheme to simultaneously acquire multi-wavelength 3D images over an extended FOV covering 50 mm by 50 mm in a single mechanical overfly scan, attaining 28 μm and 14 μm resolution in lateral and axial dimensions, respectively. Owing to an ultrawideband low-noise design featuring a spherically-focused olyvinylidene difluoride (PVDF) transducer, we demonstrate imaging of human skin and underlying vasculature at up to 3.8 mm depth when using per-pulse laser energies of only 25 μJ without employing signal averaging. Over- all, the developed system greatly enhances the performance and usability of OAM for dermatologic and micro-angiographic studies.