Probing Tissue Microarchitecture of the Baby Brain via Spherical Mean Spectrum Imaging

Khoi Minh Huynh, Tiantian Xu, Ye Wu, Xifeng Wang, Geng Chen, Haiyong Wu, Kim Han Thung, Weili Lin, Dinggang Shen, Pew Thian Yap

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

— During the first years of life, the human brain undergoes dynamic spatially-heterogeneous changes, involving differentiation of neuronal types, dendritic arborization, axonal ingrowth, outgrowth and retraction, synaptogenesis, and myelination. To better quantify these changes, this article presents a method for probing tissue microarchitecture by characterizing water diffusion in a spectrum of length scales, factoring out the effects of intra-voxel orientation heterogeneity. Our method is based on the spherical means of the diffusion signal, computed over gradient directions for a set of diffusion weightings (i.e., b-values). We decompose the spherical mean profile at each voxel into a spherical mean spectrum (SMS), which essentially encodes the fractions of spin packets undergoing fine- to coarse-scale diffusion processes, characterizing restricted and hindered diffusion stemming respectively from intra- and extra-cellular water compartments. From the SMS, multiple orientation distribution invariant indices can be computed, allowing for example the quantification of neurite density, microscopic fractional anisotropy (µFA), per-axon axial/radial diffusivity, and free/restricted isotropic diffusivity. We show that these indices can be computed for the developing brain for greater sensitivity and specificity to development related changes in tissue microstructure. Also, we demonstrate that our method, called spherical mean spectrum imaging (SMSI), is fast, accurate, and can overcome the biases associated with other state-of-the-art microstructure models.

Original languageEnglish
Pages (from-to)3607-3618
Number of pages12
JournalIEEE Transactions on Medical Imaging
Volume39
Issue number11
DOIs
StatePublished - Nov 2020
Externally publishedYes

Keywords

  • Brain Tissue Microstructure
  • Diffusion Magnetic Resonance Imaging (dMRI)
  • Pediatric Imaging
  • Spherical Mean Spectrum Imaging (SMSI)

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