A volume birdcage coil with an adjustable sliding tuner ring for neuroimaging in high field vertical magnets: Ex and in vivo applications at 21.1Â T

► In vivo vertical bore rat MRI probe for high field 21.1 T magnet is presented. ► Volume coil uses sliding tuner ring to accommodate diverse biological specimens. ► Volume coil homogeneity remains good across diverse sample loads. ► Variety of practical in vivo and ex vivo applications are demonstrated at 21.1 T.