R₁ dispersion contrast at high field with fast field-cycling MRI

Contrast agents with a strong R₁ dispersion have been shown to be effective in generating target-specific contrast in MRI. The utilization of this R₁ field dependence requires the adaptation of an MRI scanner for fast field-cycling (FFC). Here, we present the first implementation and validation of FFC-MRI at a clinical field strength of 3 T. A field-cycling range of ±100 mT around the nominal B₀ field was realized by inserting an additional insert coil into an otherwise conventional MRI system. System validation was successfully performed with selected iron oxide magnetic nanoparticles and comparison to FFC-NMR relaxometry measurements. Furthermore, we show proof-of-principle R₁ dispersion imaging and demonstrate the capability of generating R₁ dispersion contrast at high field with suppressed background signal. With the presented ready-to-use hardware setup it is possible to investigate MRI contrast agents with a strong R₁ dispersion at a field strength of 3 T.