title: Comparison of mouse brain DTI maps using K-space average, image-space average, or no average approach.
abstract: Diffusion tensor imaging (DTI) is achieved by collecting a series of diffusion-weighted images (DWIs). Signal averaging of multiple repetitions can be performed in the k-space (k-avg) or in the image space (m-avg) to improve the image quality. Alternatively, one can treat each acquisition as an independent image and use all of the data to reconstruct the DTI without doing any signal averaging (no-avg). To compare these three approaches, in this study, in vivo DTI data were collected from five normal mice. Noisy data with signal-to-noise ratios (SNR) that varied between five and 30 (before averaging) were then simulated. The DTI indices, including relative anisotropy (RA), trace of diffusion tensor (TR), axial diffusivity (λ║), and radial diffusivity (λ⊥), derived from the k-avg, m-avg, and no-avg, were then compared in the corpus callosum white matter, cortex gray matter, and the ventricles. We found that k-avg and m-avg enhanced the SNR of DWI with no significant differences. However, k-avg produced lower RA in the white matter and higher RA in the gray matter, compared to the m-avg and no-avg, regardless of SNR. The latter two produced similar DTI quantifications. We concluded that k-avg is less preferred for DTI brain imaging.
authors.affiliation: Basic Science, School of Medicine, Loma Linda University, CA; Radiation Medicine, School of Medicine, Loma Linda University, CA; Pharmaceutical Science, School of Pharmacy, Loma Linda University, CA; Bioengineering, University of California, Riverside, CA. Electronic address: rsun@llu.edu.
authors.forename: Shu-Wei
authors.initials: SW
authors.lastname: Sun
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mei
authors.forename: Keelan
authors.initials: K
authors.lastname: Tuel
mesh_terms: D000465:Algorithms; D000818:Animals; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D004058:Diffusion; D056324:Diffusion Tensor Imaging; D005260:Female; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D051379:Mice; D008810:Mice, Inbred C57BL; D016011:Normal Distribution; D059629:Signal-To-Noise Ratio
keywords: DTI reconstruction; Image-space average; In vivo DTI; Mouse brain; k-space average