Three-dimensional microangiography of the mouse brain using super-resolution ultrasound and optoacoustic imaging with a spherical array transducer

High-resolution visualization of the mouse brain microvasculature is essential for advancing neurovascular research and understanding neurological disorders. Recent advances in pulse-echo ultrasound (US) and optoacoustic (OA) imaging enable angiographic imaging beyond the acoustic diffraction limit through localization of microbubbles in ultrasound localization microscopy (ULM) and light-absorbing microparticles in localization optoacoustic tomography (LOT). Despite their distinct contrast mechanisms, a direct comparison has been lacking. Here, we evaluate three-dimensional motion-contrast US and OA imaging, including their super-resolved variants ULM and LOT, using the same ultrasound array, localization and tracking algorithms, and frame rates. Studies in mice of different ages reveal complementary strengths: OA/LOT offers higher-SNR for cortical imaging, especially in older animals with thicker skulls, while the lower attenuation of ultrasound enables US/ULM to achieve substantially greater penetration depth and whole-brain coverage. This comparison provides practical guidance for choosing optimal localization-based strategies for cerebrovascular studies.