Detailed Mapping of the Cerebellar Dentate Nucleus Using Ultra-High Field (7T) Susceptibility-Weighted Imaging.

The current study presents a novel method for imaging the cerebellar dentate nucleus, combining ultra-high field (7T) and quantitative susceptibility mapping (QSM) to enhance tissue boundary identification and segmentation. After assessing segmentation reliability, we assessed validity by evaluating volume and resting state functional connectivity (FC) of the dorsal vs. ventral dentate subregions. Neurotypical adults (n = 30, 15 females) completed 7T susceptibility-weighted imaging (SWI) and resting state fMRI. QSM maps were used to segment the dentate (whole, dorsal, ventral subregions). Reliability of the segmentation protocol was established across three raters (inter-rater) and one rater who performed the segmentations twice (intra-rater) using the Dice coefficient (d). Dorsal and ventral dentate volumes were calculated, and whole-brain seed-to-voxel FC patterns were assessed from the whole dentate, dorsal, and ventral subregions. Group-level contrasts for each subregion and between subregions were thresholded at voxel-level p <.005, with a cluster-level FDR-correction of p <.05. Segmentation reliability was high (inter-rater d = 0.89, intra-rater d = 0.93), and the dorsal subregion was significantly smaller than the ventral (p <.001). The dorsal dentate showed greater FC with regions involved in sensorimotor processing (cerebellar vermis I-V, IX-X, lobules VIII-IX, fusiform, cuneus), and the ventral dentate showed greater FC with regions involved in cognitive processing (cerebellar lobule VII, angular gyrus, middle and superior frontal gyri, middle and superior temporal gyri, temporal pole). We present an innovative, reliable, and valid method for imaging the dentate. Dentate volumes and FC were consistent with anatomical mapping from animal and human studies. Future directions include application to clinical populations with anomalous cerebellar development and injury.