Convolutional Neural Networks for Fiber Orientation Distribution Enhancement to Improve Single-Shell Diffusion MRI Tractography

Oeslle Lucena*, Sjoerd B. Vos, Vejay Vakharia, John Duncan, Sebastien Ourselin, Rachel Sparks

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

2 Citations (Scopus)

Abstract

Diffusion MRI (dMRI) tractography may help locate critical white matter (WM) tracts that should be preserved during neurosurgery. A key step in this process is estimating fiber orientation distribution (FOD), often done from a model such as constrained spherical deconvolution (CSD). Multi-shell (MS) multi-tissue CSD (M-CSD) provides a robust WM FOD by estimating the relative contribution to the dMRI signal from each tissue type (WM, grey matter, and cerebrospinal fluid), however, single-shell (SS) single tissue CSD (S-CSD) cannot independently estimate the signal contribution for each tissue type. S-CSD is therefore less accurate estimating FOD in voxels where multiple tissues are present. Due to that inaccuracy, tractography using S-CSD often generates more spurious WM streamlines compared to M-CSD. In this work, we present a framework to regress the M-CSD model coefficients from the S-CSD model coefficients using a convolutional neural network (CNN) in order to improve tractography. We construct a training dataset comprising acquired MS dMRI and paired synthetic SS dMRI, generated by selecting the outer shell from the MS dMRI. We select a High Resolution Network (HighResNet) as our choice of CNN to ensure subtle details of the CSD models are preserved during regression. The HighResNet is trained to perform patch-based regression from the S-CSD model coefficients and a co-registered T1-wieghted MR (T1) to the M-CSD model coefficients. We evaluate the method on patients with epilepsy who appeared structurally normal on T1. Four WM tracts related to language are extracted using a ROI-based probabilistic tractography. For comparison, M-CSD is as a pseudo ground truth. The original S-CSD generated tracts with Dice of 0.53–0.64, and the HighResNet regressed CSD models generated tracts with Dice of 0.73–0.77. We demonstrate HighResNet can regress M-CSD model coefficients from S-CSD model coefficients resulting in tracts more similar to the M-CSD generated tracts and with fewer spurious streamlines than S-CSD generated tracts.

Original languageEnglish
Title of host publicationMathematics and Visualization
PublisherSpringer Science and Business Media Deutschland GmbH
Pages101-112
Number of pages12
DOIs
Publication statusPublished - 2020

Publication series

NameMathematics and Visualization
ISSN (Print)1612-3786
ISSN (Electronic)2197-666X

Keywords

  • Deep learning
  • Diffusion weighted image
  • Tractography

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