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 pulse repetition rate within safe exposure limits. Studies in mice of different ages reveal complementary strengths: OA/LOT offers higher-SNR 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.