title: NODDI reproducibility and variability with magnetic field strength: A comparison between 1.5 T and 3 T.
abstract: Diffusion models are advantageous for examining brain microstructure non-invasively and their validation is important for transference into the clinical domain. Neurite Orientation Dispersion and Density Imaging (NODDI) is a promising model for estimating multiple diffusion compartments from MRI data acquired in a clinically feasible time. As a relatively new model, it is necessary to examine NODDI under certain experimental conditions, such as change in magnetic field-strength, and assess it in relation to diffusion tensor imaging (DTI), an established model that is largely understood by the neuroimaging community. NODDI measures (intracellular volume fraction, νic, and orientation distribution, OD) were compared with DTI at 1.5 and 3 T data in healthy adults in whole-brain tissue masks and regions of white- and deep grey-matter. Within-session reproducibility and between-subject differences of NODDI with field-strength were also investigated. Field-strength had a significant effect on NODDI measures, suggesting careful interpretation of results from data acquired at 1.5 and 3 T. It was demonstrated that NODDI is feasible at 1.5 T, but with lower νicin white-matter regions compared with 3 T. Furthermore, the advantages of NODDI over DTI in a region of complex microstructure were shown. Specifically, in the centrum-semiovale where FA is typically as low as in grey-matter, νicwas comparable to other white-matter regions yet accompanied by an OD similar to deep grey-matter. In terms of reproducibility, NODDI measures varied more than DTI. It may be that NODDI is more susceptible to noisier parameter estimates when compared with DTI, conversely it may have greater sensitivity to true within- and between-subject heterogeneity. Hum Brain Mapp 37:4550-4565, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Developmental Imaging & Biophysics, UCL Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom.
authors.forename: Ai Wern
authors.initials: AW
authors.lastname: Chung
authors.affiliation: Developmental Imaging & Biophysics, UCL Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom.
authors.forename: Kiran K
authors.initials: KK
authors.lastname: Seunarine
authors.affiliation: Developmental Imaging & Biophysics, UCL Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom.
authors.forename: Chris A
authors.initials: CA
authors.lastname: Clark
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D004058:Diffusion; D056324:Diffusion Tensor Imaging; D005240:Feasibility Studies; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D066127:White Matter / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: diffusion tensor; magnetic field strength; neurite density; orientation dispersion; reproducibility