The dose makes the poison - Studying toxicity in MEMRI applications

Introduction Manganese-enhanced MRI (MEMRI) is an increasingly used imaging method in animal research, which allows improved T1-weighted tissue contrast, thus enabling in vivo visualization of neuronal activity . At higher concentrations, however, manganese (Mn) exhibits toxic effects that interfere with the animals’ behaviour and well-being. While CD1 mice tolerate single doses of ~100mg/kg MnCl2 well, C57BL/6N show severe distress. Therefore, a trade-off has to be made between minimizing side effects and gaining high image contrast when optimizing MEMRI protocols. Recently, a low concentrated fractionated Mn application scheme has been proposed for rats as a promising alternative. Here, we investigate the potential of such a fractionated application protocol for the widely used mouse strain C57BL/6N.