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Observation of angular dependence of T1 in the human white matter at 3T

Knight, Michael J.; Damion, Robin A.; Kauppinen, Risto A.


Michael J. Knight

Risto A. Kauppinen



Background and Objective: Multiple factors including chemical composition and microstructure influence relaxivity of tissue water in vivo. We have quantified T1 in the human white mater (WM) together with diffusion tensor imaging to study a possible relationship between water T1, diffusional fractional anisotropy (FA) and fibre-to-field angle.

Methods: An inversion recovery (IR) pulse sequence with 6 inversion times for T1 and a multi-band diffusion tensor sequence with 60 diffusion sensitizing gradient directions for FA and the fibre-to-field angle θ (between the principal direction of diffusion and B0) were used at 3 Tesla in 40 healthy subjects. T1 was assessed using the method previously applied to anisotropy of coherence lifetime to provide a heuristic demonstration as a surface plot of T1 as a function of FA and the angle θ.

Results: Our data show that in the WM voxels with FA > 0.3 T1 becomes longer (i.e. 1/T1 = R1 slower) when fibre-to-field angle is 50–60°, approximating the magic angle of 54.7°. The longer T1 around the magic angle was found in a number of WM tracts independent of anatomy. S0 signal intensity, computed from IR fits, mirrored that of T1 being greater in the WM voxels when the fibre-to-field angle was 50–60°.

Conclusions: The current data point to fibre-to-field-angle dependent T1 relaxation in WM as an indication of effects of microstructure on the longitudinal relaxation of water.


Knight, M., Damion, R., & Kauppinen, R. (2019). Observation of angular dependence of T1 in the human white matter at 3T. Biomedical Spectroscopy and Imaging, 7(3-4), 125-133.

Journal Article Type Article
Online Publication Date Jan 24, 2019
Publication Date Jan 24, 2019
Deposit Date Dec 14, 2022
Print ISSN 2212-8794
Electronic ISSN 2212-8794
Publisher IOS Press
Peer Reviewed Peer Reviewed
Volume 7
Issue 3-4
Pages 125-133
Keywords Radiology, Nuclear Medicine and imaging
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