Sodium signal evolution in kidney imaging at 7T after water intake applying an interleaved sequence scheme for 23Na/1H(pTx) imaging

Motivation: The sodium medulla-to-cortex ratio (MCR) has previously been shown to be an indicator for kidney function. Goal(s): Quantification of MCR using an interleaved 23Na/1H(pTx) sequence at 7T. Approach: Using an interleaved 23Na/1H(pTx) sequence, time-resolved renal 23Na and 1H images were obtained. Segmentation of cortex and medulla was performed on first 1H image after drinking to which all other images were co-registered. After applying B1-/+ corrections for 23Na MRI, the MCR of left and right kidney was calculated for six subjects before and after water intake. Results: The MCR decreased significantly for both kidneys after water intake, indicating reproducible changes in the MCR. Impact: This study demonstrates the feasibility of interleaved 23Na/1H(pTx) MRI at 7T to assess renal sodium dynamics non-invasively, allowing exploration of hydration effects on renal sodium balance. Improved B1-correction and respiratory motion correction could enhance early detection of kidney function changes.