UNC-Utah NA-MIC framework for DTI fiber tract analysis

Abstract

Diffusion tensor imaging has become an important modality in the field of neuroimaging to capture changes in micro-organization and to assess white matter integrity or development. While there exists a number of tractography toolsets, these usually lack tools for preprocessing or to analyze diffusion properties along the fiber tracts. Currently, the field is in critical need of a coherent end-to-end toolset for performing an along-fiber tract analysis, accessible to non-technical neuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents a coherent, open source, end-to-end toolset for atlas fiber tract based DTI analysis encompassing DICOM data conversion, quality control, atlas building, fiber tractography, fiber parameterization, and statistical analysis of diffusion properties. Most steps utilize graphical user interfaces (GUI) to simplify interaction and provide an extensive DTI analysis framework for non-technical researchers/investigators. We illustrate the use of our framework on a small sample, cross sectional neuroimaging study of eight healthy 1-year-old children from the Infant Brain Imaging Study (IBIS) Network. In this limited test study, we illustrate the power of our method by quantifying the diffusion properties at 1 year of age on the genu and splenium fiber tracts.

White matter fiber-based analysis of T1w/T2w ratio map

“…However, the measures are also sensitive to several brain maturation or pathological processes, such as fiber organization/wiring, axonal size and fiber density. Thus, more specific measures need to be taken to obtain information specific to myelin maturation via component analysis of T1 and T2 relaxation (2). The ratio of T1w to T2w signal intensity has been employed to show variations in myelin between cortical grey matter in (3) and thus can be used to perform myelin-based analysis of the brain.…”

“…ROI-analysis thus leads to a limited localization of findings. As shown in figure 1, quantitative tractography performs anatomically informed segmentation on volumetric data to acquire curvilinear regions that are fiber-specific, as discussed in (2). Since myelination is a process that happens along fiber bundles across the brain, a fiber-tract-based analysis via T1w/T2w ratio maps that effectively separates fiber bundles to associate effects with fiber tracts rather than large, broad region is more suited to our goal.…”

“…In a previous study (2), our lab has developed the NA-MIC framework for fiber-tract-based DTI analysis, in which labelmap based tractography has been performed via 3D Slicer (https://www.slicer.org/) to define DTI fiber bundles. (2) also shows the building of the DTI atlas and the definition of the major fiber tracts employed in our study.…”

“…(2) also shows the building of the DTI atlas and the definition of the major fiber tracts employed in our study. We then use that DTI fiber atlas as the fiber reference, as well as the deformation fields to all subject data (see below) for registering T1w/T2w ratio values into the DTI atlas space.…”

“…First, the user selects the subjects of analysis via the GUI. Then, the pipeline employs modified modules of the NA-MIC framework for fiber-tract-based DTI analysis (2) to sample T1w/T2w ratio values at all locations on the fiber tracts and then extract T1w/T2w ratio profiles along these fibers. Our submission has limited methodological novelty, and its major novelty lays in the development and open-source availability of a tool to intuitive do the proposed analysis, as well as the preliminary novel results of tract-wise of white matter content development in the infant brain.…”