  Acoustic impedance mismatches between soft tissues and bones are known to
result in strong aberrations in optoacoustic and ultrasound images. Of
particular importance are the severe distortions introduced by the human skull,
impeding transcranial brain imaging with these modalities. While modelling of
ultrasound propagation through the skull may in principle help correcting for
some of the skull-induced aberrations, these approaches are commonly challenged
by the highly heterogeneous and dispersive acoustic properties of the skull and
lack of exact knowledge on its geometry and internal structure. Here we
demonstrate that the spatio-temporal properties of the acoustic distortions
induced by the skull are preserved for signal sources generated at neighboring
intracranial locations by means of optoacoustic excitation. This optoacoustic
memory effect is exploited for building a three-dimensional model accurately
describing the generation, propagation and detection of time-resolved broadband
optoacoustic waveforms traversing the skull. The memory-based model-based
inversion is then shown to accurately recover the optical absorption
distribution inside the skull with spatial resolution and image quality
comparable to those attained in skull-free medium.
