MRI-Compatible Rigid Head Holders for Artifact-Free Multimodal Imaging in Mice

PurposeHigh-resolution intravital microscopy allows cellular-scale analysis of the brain in vivo but is greatly sensitive to physiological motion. Combining optical microscopy with magnetic resonance imaging (MRI) in the same animal could relate cellular and mesoscale functional readout to whole-brain structural information, but this requires head holders that are both mechanically rigid and MRI compatible. Conventional metallic head holders introduce MRI artifacts, whereas many nonmetallic alternatives lack sufficient stability for chronic microscopy. Thus, we developed rigid, MRI-compatible head holders engineered from 3D-printed zirconia ceramics to reduce motion during microscopy while preserving MRI image quality. MethodsHead holders were designed for mouse cranial fixation and fabricated from zirconia ceramics using additive manufacturing. We quantified motion artifacts during two-photon and multimodal widefield imaging of the mouse cortex and assessed their impact on neuronal calcium activity, functional connectivity, and hemodynamic readouts. MRI compatibility was evaluated by measuring image quality in the presence of the head holder. ResultsThe ceramic head holders provided mechanical stability to reduce motion artifacts to micrometer levels during intravital imaging. The head holders produced no detectable susceptibility artifacts in MRI, and image contrast was comparable to control acquisitions performed without head holder. Sequential optical and MRI imaging of the same brain regions established artifact-minimized multimodal data acquisition within the same animal. ConclusionsNon-metallic ceramic head holders support longitudinal multimodal studies that combine high-resolution optical microscopy with whole-brain MRI measurements in the same animal.