Correlation of diffusion tensor imaging parameters in the canine brain.
The goal of this study was to determine the degree to which ex vivo diffusion tensor imaging (DTI) parameters correlate to one another in white matter regions on very high resolution MR scans. Specifically, we hypothesized that radial diffusivity (RD) and apparent diffusion coefficient (ADC) would correlate more closely than either would correlate with fractional anisotropy (FA). We performed post mortem DTI imaging on three canine brains on a 7 T MR scanner (TR = 100 ms, NEX = 1, gradient amplitude = 600 mT/m, b = 1492-1,565 s/mm²) and generated maps of FA, RD, and ADC. We measured RD, FA and ADC within 14 regions of interest representative of various portions of white matter. We compared the three combinations of values, i.e., FA vs ADC, FA vs RD and ADC vs RD, using linear regression models. Linear regression demonstrated that RD was significantly correlated with FA (p << 0.01; R² = 0.3053) and also with ADC (p << 0.01; R² = 0.6755), but to a much greater degree. However, ADC was not significantly correlated with FA (p = 0.526; R² = 0.101). Our findings suggest that both RD and ADC reflect similar cytoarchitectural features, most likely that of myelination, whereas FA values likely reflect both myelination and additional microstructural features that constrain the diffusion of water in white matter.
Duke-NUS School of Medicine; Singapore.
Dalun
D
Leong
Duke University School of Medicine; Durham, North Carolina, USA.
Evan
E
Calabrese
Department of Orthopedic Surgery, Duke University School of Medicine, Durham NC 27710.
Leonard E
LE
White
Duke University School of Medicine; Durham, North Carolina, USA.
Peter
P
Wei
Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
Steven
S
Chen
University of Georgia College of Veterinary Medicine; Athens, Georgia, USA.
Simon R
SR
Platt
Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA james.provenzale@dm.duke.edu.
James M
JM
Provenzale
D000818:Animals; D016880:Anisotropy; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging; D004285:Dogs; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D066127:White Matter / Q000033:anatomy & histology*
canine brain; diffusion tensor imaging