The Impact of Gadolinium on Quantitative Myelin Metrics in Ex Vivo Spinal Cord

The goal of this work was to evaluate the impact of gadolinium on quantitative myelin MRI metrics in ex vivo tissue. Ex vivo ferret spinal cords were imaged with and without gadolinium. Mean metrics were calculated across white and gray matter. T₁ of the free proton pool and T₂ of water other than myelin showed the largest differences between gadolinium and without gadolinium samples. Myelin water fraction, bound pool fraction, and myelin water T₂ showed a 2%-12% change between gadolinium and no gadolinium data. The relationships between the myelin water fraction, bound pool fraction, and myelin water T₂ and a recently established axon diameter surrogate were not affected by gadolinium; however, the trends observed between T₁ of the free proton pool and other water T₂ and the axon diameter surrogate without gadolinium were flattened in the samples with gadolinium. Overall, the impacts of gadolinium were primarily observed in the relaxation parameters of the non-myelin proton pools.