Dynamic dextran-enhanced CEST MRI reveals the size effect of BBB disruption associated with neuroinflammation

Prevailing imaging methods primarily focus on detecting blood-brain barrier (BBB) dysfunction utilising tracers of small molecular weight. Robust imaging methods suitable for assessing BBB permeability in the macro-molecular size range are still lacking. Our study aimed to develop and optimize a dextran-based MRI approach for detecting size-dependent BBB permeability. Demonstrated in an EAE MS mouse model, we established a dextran-based CEST MRI protocol for measuring the intracerebral distribution of non-labeled dextrans, validated the results using immunohistochemistry, and compared the CEST MRI results with conventional Gd-enhanced MRI.