| First Author | Jensen JH | Year | 2023 |
| Journal | NMR Biomed | Volume | 36 |
| Issue | 1 | Pages | e4816 |
| PubMed ID | 35994169 | Mgi Jnum | J:348516 |
| Mgi Id | MGI:7642118 | Doi | 10.1002/nbm.4816 |
| Citation | Jensen JH, et al. (2023) Comparison of two types of microscopic diffusion anisotropy in mouse brain. NMR Biomed 36(1):e4816 |
| abstractText | Two distinct types of microscopic diffusion anisotropy (MA) are compared in brain for both normal control and transgenic (3xTg-AD) mice, which develop Alzheimer's disease pathology. The first type of MA is the commonly used microscopic fractional anisotropy (muFA), and the second is a new MA measure referred to as muFA'. These two MA parameters have different symmetry properties that are central to their physical interpretations. Specifically, muFA is invariant with respect to local rotations of compartmental diffusion tensors while muFA' is invariant with respect to global diffusion tensor deformations. A key distinction between muFA and muFA' is that muFA is affected by the same type of orientationally coherent diffusion anisotropy as the conventional fractional anisotropy (FA) while muFA' is not. Furthermore, muFA can be viewed as having independent contributions from FA and muFA', as is quantified by an equation relating all three anisotropies. The normal control and transgenic mice are studied at ages ranging from 2 to 15 months, with double diffusion encoding MRI being used to estimate muFA and muFA'. muFA and muFA' are nearly identical in low FA brain regions, but they show notable differences when FA is large. In particular, muFA and FA are found to be strongly correlated in the fimbria, but muFA' and FA are not. In addition, both muFA and muFA' are seen to increase with age in the corpus callosum and external capsule, and modest differences between normal control and transgenic mice are observed for muFA and muFA' in the corpus callosum and for muFA in the fimbria. The triad of FA, muFA, and muFA' is proposed as a useful combination of parameters for assessing diffusion anisotropy in brain. |
