Particles with sizes in the order of a few micrometers can significantly enhance the capabilities of optoacoustic imaging systems by improving visualization of arbitrarily oriented vascular structures and achieving resolution beyond the acoustic diffraction barrier. Particle tracking may also be used for mapping the blood flow in two and three dimensions. However, a trade-off exists between the particle absorption properties and size, whereas large sized microparticles also tend to arrest in the capillary network. We analyzed the flow of microparticles in an intracardiac perfusion mouse model in which blood is effectively substituted by artificial cerebrospinal fluid (ACSF). This enables mitigating the strong blood absorption background in the optoacoustic images thus facilitating the visualization of microparticles. A sequence of three-dimensional optoacoustic images of the mouse brain is then acquired at a high frame rate of 100 Hz after injection of the particles in the left heart ventricle. By visualizing the flow of particles of different sizes in microvascular structures it is possible to establish optimal trade-offs between the particle size, their optoacoustic signal and perfusion properties.