Abstract #1943

Combination of MT and R2* measurements to distinguish between contributions of semisolids and iron to R1

Xu Jiang¹, Erika Raven^1,2, Peter van Gelderen¹, and Jeff H. Duyn¹

¹Advanced MRI Section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States, ²Center for Functional and Molecular Imaging, Georgetown University Medical Center, Washington, DC, United States

In human brain, the apparent longitudinal relaxation rate (R₁) primarily originates from magnetization transfer (MT) effects associated with the macromolecular ¹H-proton fraction (f), although in some regions the iron concentration may contribute as well (Rooney, 2007). To quantify their relative contributions at 7 T, we measured f and R₁ of water protons (R_1,WP) corrected for MT effects using a pulsed, transient MT approach (van Gelderen, 2016). The iron concentration was taken from literature and correlated with R₂^*. The results indicate that the combination of R₂^* and MT measurements may provide a sensitive means to quantify R_1,WP, f and iron concentration.

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