Modeling and selection of T1 and T2 tissue mimics for 0.0065T, 0.064T, 0.55T MRI using agarose with manganese, gadolinium, copper, or nickel

There is re-emerging interest in MRI fields ≤0.55T as well as quantitative MRI (qMRI) methods. Physiologically relevant reference objects are needed to adapt qMRI techniques to lower fields. We investigate materials as tissue mimics for brain imaging at 0.0065T, 0.064T, 0.55T, for white matter, gray matter, fat, cerebrospinal fluid, and blood. We create samples composed of agarose and paramagnetic salts and measure relaxation across field strengths. Samples suitable to mimic each tissue are presented for each field strength. This work will facilitate qMRI development for fields ≤0.55T by providing accessible mimic compositions to the community.