Saeed Kalantari1, Cornelia Laule2,
Thorarin Bjarnason3, Alex MacKay1,2
1Department of Physics and Astronomy,
University of British Columbia Hospital, Vancouver, BC, Canada; 2Department
of Radiology, University of British Columbia Hospital, Vancouver, BC, Canada;
3Department of Electrical and Computer Engineering, University of
Calgary
The
objective of this study was to measure the cross relaxation exchange time
between the myelin water and intra/extracellular water pools in healthy human
white matter in vivo. Five different white matter structures were
investigated. Bloch equations were solved analytically and cross relaxation
exchange times were extracted. Due to the ambiguity in the literature on
spin-lattice relaxation times in white matter, three T1 scenarios were
developed. The extracted cross relaxation times were then used to estimate
the exchange corrections for myelin water fraction (MWF) measurements. The choice of T1 scenario had a significant effect on cross
relaxation times and consequently on MWF corrections.