10.5 Tesla High-Resolution Macaque Brain MRI for Connectivity Studies

Mapping brain connectivity in primates remains a major challenge due to difficulties in resolving microscopic white matter architecture, while maintaining whole-brain coverage. Increasing imaging spatial resolution is key for disambiguating fiber configurations within smaller anatomical volumes. Here, we present developments that allow high-resolution diffusion MRI of the macaque brain, both in vivo and ex vivo, using one of the world's highest-field human MRI scanners operating at 10.5 Tesla. Our approach achieves data of highest reported resolutions for this field strength and scanner type, (750 μm)3 in vivo and (400 μm)3 ex vivo, with diffusion weighting up to b = 6000 s/mm2. We detail methodological advances in data acquisition, image reconstruction, processing and whole-brain tractography that overcome critical challenges associated with ultra-high-field imaging. This work establishes a new benchmark for high-resolution neuroimaging at 10.5T, paving the way for comparable human studies and enabling analyses of brain connectivity across species and tissue states at unprecedented detail. The dataset, along with all processing pipelines, containerised workflows, and reusable web services, is openly shared to support reproducibility and future integration with microscopy for studying white matter microstructure and connections at the mesoscale. ### Competing Interest Statement The authors have declared no competing interest. NIH Common Fund, UM1NS132207 European Research Council, 101000969 Sir Henry