title: Super-resolution track-density imaging studies of mouse brain: comparison to histology.
abstract: The recently proposed track-density imaging (TDI) technique was introduced as a means to achieve super-resolution using diffusion MRI. This technique is able to increase the spatial resolution of the reconstructed images beyond the acquired MRI resolution by incorporating information from whole-brain fibre-tracking results. It not only achieves super-resolution, but also provides very high anatomical contrast with a new MRI contrast mechanism. However, the anatomical information-content of this novel contrast mechanism has not yet been assessed. In this work, we perform such a study using diffusion MRI of ex vivo mouse brains acquired at 16.4 T, to compare the results of the super-resolution TDI technique with histological staining (myelin and Nissl stains) in the same brains. Furthermore, a modified version of the directionally-encoded colour TDI map using short-tracks is introduced, which reduces the TDI intensity dynamic range, and therefore enhances the directionality colour-contrast. Good agreement was observed between structures visualised in the super-resolution TDI maps and in the histological sections, supporting the anatomical information-content of the images generated using the TDI technique. The results therefore show that the TDI methodology does provide meaningful and rich anatomical contrast, in addition to achieving super-resolution. Furthermore, this study is the first to show the application of TDI to mouse brain imaging: the high-resolution, high-quality images demonstrate the useful complementary information that can be achieved using super-resolution TDI.
authors.affiliation: Brain Research Institute, Florey Neuroscience Institutes, Heidelberg, Victoria, Australia. fercala@brain.org.au
authors.forename: Fernando
authors.initials: F
authors.lastname: Calamante
authors.forename: Jacques-Donald
authors.initials: JD
authors.lastname: Tournier
authors.forename: Nyoman D
authors.initials: ND
authors.lastname: Kurniawan
authors.forename: Zhengyi
authors.initials: Z
authors.lastname: Yang
authors.forename: Erika
authors.initials: E
authors.lastname: Gyengesi
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Galloway
authors.forename: David C
authors.initials: DC
authors.lastname: Reutens
authors.forename: Alan
authors.initials: A
authors.lastname: Connelly
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007150:Immunohistochemistry; D051379:Mice; D009434:Neural Pathways / Q000033:anatomy & histology*