1Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, United States; 2Biomedical Engineering, Duke University, Durham, NC, United States; 3Brain Imaging & Analysis Center, Duke University Medical Center, Durham, NC, United States; 4Radiology, Duke University Medical Center, Durham, NC, United States
Characterizing the effect of paramagnetic contrast agents and field strength on magnetic susceptibility image contrast aids in the effective use, comparability, and consistency of susceptibility mapping to quantify myelination using MR histology. In this study, we generate field-normalized magnetic susceptibility maps of the adult mouse brain perfused with six different concentrations of paramagnetic contrast agent and at three magnetic field strengths. We verify that the susceptibility-field strength relationship is linear and quantify the linear effect of gadolinium contrast agent on improving the apparent susceptibility contrast between white and gray matter. We propose that this contrast arises due to the decaying signal contributions of a complex white matter water pool structure.