Title: Improving imaging of the brainstem and cerebellum in autistic children: Transformation-based high-resolution diffusion MRI (TiDi-Fused) in the human brainstem
Legend: The goal of this research was to develop innovative ways of processing and combining magnetic resonance image (MRI) to better characterize the hard-to-image brainstem in children. The brainstem is an early developing part of the brain that is involved in attention, sensory gating, movement, and reflex-like responses to stressors. Our work is committed to better imaging the brainstem and its substructures because previous evidence suggests that sensorimotor and social communication features in autism may be linked to the structures of the brainstem (for a review see, Travers & Dadalko, 2018; Seif et al., 2021). The results of this study suggest that our new processing method (TiDi-Fused) led to improved spatial and age-related representations of the brainstem compared to more standard or “conventional” imaging methods. The yellow arrows indicate some of the areas that are better spatially aligned with TiDi-Fused processing.
Citation: †Guerrero-Gonzalez, J., †Surgent, O., Adluru, N., Kirk, G. R., Dean, D.C. III, Kecskemeti, S., Alexander, A. L., & Travers, B. G. (2022). Improving imaging of the brainstem and cerebellum in autistic children: Transformation-based high-resolution diffusion MRI (TiDi-Fused) in the human brainstem. Frontiers in Integrative Neuroscience, 16, 804743. doi: https://doi.org/10.3389/fnint.2022.804743. †denotes equal first-authorship contribution
Abstract: Diffusion-weighted magnetic resonance imaging (dMRI) of the brainstem is technically challenging, especially in young autistic children as nearby tissue-air interfaces and motion (voluntary and physiological) can lead to artifacts. This limits the availability of high-resolution images, which are desirable for improving the ability to study brainstem structures. Furthermore, inherently low signal-to-noise ratios, geometric distortions, and sensitivity to motion not related to molecular diffusion have resulted in limited techniques for high-resolution data acquisition compared to other modalities such as T1-weighted imaging. Here, we implement a method for achieving increased apparent spatial resolution in pediatric dMRI that hinges on accurate geometric distortion correction and on high fidelity within subject image registration between dMRI and magnetization prepared rapid acquisition gradient echo (MPnRAGE) images. We call this post-processing pipeline T1 weighted-diffusion fused, or “TiDi-Fused”. Data used in this work consists of dMRI data (2.4 mm resolution, corrected using FSL’s Topup) and T1-weighted (T1w) MPnRAGE anatomical data (1 mm resolution) acquired from 128 autistic and non-autistic children (ages 6–10 years old). Accurate correction of geometric distortion permitted for a further increase in apparent resolution of the dMRI scan via boundary-based registration to the MPnRAGE T1w. Estimation of fiber orientation distributions and further analyses were carried out in the T1w space. Data processed with the TiDi-Fused method were qualitatively and quantitatively compared to data processed with conventional dMRI processing methods. Results show the advantages of the TiDi-Fused pipeline including sharper brainstem gray-white matter tissue contrast, improved inter-subject spatial alignment for group analyses of dMRI based measures, accurate spatial alignment with histology-based imaging of the brainstem, reduced variability in brainstem-cerebellar white matter tracts, and more robust biologically plausible relationships between age and brainstem-cerebellar white matter tracts. Overall, this work identifies a promising pipeline for achieving high-resolution imaging of brainstem structures in pediatric and clinical populations who may not be able to endure long scan times. This pipeline may serve as a gateway for feasibly elucidating brainstem contributions to autism and other conditions.
About the Lab: The Motor Brain and Development Lab is dedicated to advancing knowledge about motor development, brain development, and independent living skills to support and enhance quality of life for individuals with and without developmental disorders. At the group level, we use identity-first language (i.e., “autistic individuals”) per the majority preference of the autistic community (Kenny et al., 2016), but we acknowledge that there are a variety of ways that autistic individuals prefer to be referenced. Therefore, at the individual level, we strive to use each person’s preferred language.
Investigator: Brittany Travers, PhD