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Abstract #2341

Looking at Magnetization Exchange in Human White Matter Structures in Vivo

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.