Contrast-to-noise ratio analysis of microscopic diffusion anisotropy indices in q-space trajectory imaging.
Z Med Phys
; 30(1): 4-16, 2020 Feb.
Article
em En
| MEDLINE
| ID: mdl-30853147
ABSTRACT
Diffusion anisotropy in diffusion tensor imaging (DTI) is commonly quantified with normalized diffusion anisotropy indices (DAIs). Most often, the fractional anisotropy (FA) is used, but several alternative DAIs have been introduced in attempts to maximize the contrast-to-noise ratio (CNR) in diffusion anisotropy maps. Examples include the scaled relative anisotropy (sRA), the gamma variate anisotropy index (GV), the surface anisotropy (UAsurf), and the lattice index (LI). With the advent of multidimensional diffusion encoding it became possible to determine the presence of microscopic diffusion anisotropy in a voxel, which is theoretically independent of orientation coherence. In accordance with DTI, the microscopic anisotropy is typically quantified by the microscopic fractional anisotropy (µFA). In this work, in addition to the µFA, the four microscopic diffusion anisotropy indices (µDAIs) µsRA, µGV, µUAsurf, and µLI are defined in analogy to the respective DAIs by means of the average diffusion tensor and the covariance tensor. Simulations with three representative distributions of microscopic diffusion tensors revealed distinct CNR differences when differentiating between isotropic and microscopically anisotropic diffusion. q-Space trajectory imaging (QTI) was employed to acquire brain in-vivo maps of all indices. For this purpose, a 15min protocol featuring linear, planar, and spherical tensor encoding was used. The resulting maps were of good quality and exhibited different contrasts, e.g. between gray and white matter. This indicates that it may be beneficial to use more than one µDAI in future investigational studies.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Processamento de Imagem Assistida por Computador
/
Mapeamento Encefálico
/
Imagem de Tensor de Difusão
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Z Med Phys
Assunto da revista:
RADIOTERAPIA
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Alemanha