Dichromate as a stain for MR microscopy

High resolution MR microscopy is normally performed at high field (≥7T) due to the increased MR signal available. At lower fields, for example, 4.7T, one way to acquire more signal is to decrease T₁ relaxation times and acquire more signal per unit time. Non-specific contrast agents may be used to shorten T₁ but contrast between tissues may remain sub-optimal. In this study, the use of diamagnetic dichromate ions as a stain for MR microscopy has been investigated. Heterogeneous tissue oxidation by dichromate creates paramagnetic chromium species that both shorten T₁ and enhance tissue contrast. This study demonstrates that increased SNR and excellent tissue contrast may be achieved by soaking fixed and freshly excised tissue in aqueous dichromate solution.