Diffusion kurtosis imaging and arterial spin labeling for the noninvasive evaluation of persistent post-contrast acute kidney injury.

We investigated whether diffusion kurtosis imaging (DKI) and arterial spin labeling (ASL) facilitated the assessment of serial alterations in persistent post-contrast acute kidney injury (PC-AKI). We randomly divided 24 rats into four PC-AKI groups (days 1, 3, 7, and 13, n = 6/group), with an additional six control animals. We conducted functional magnetic resonance imaging (MRI), diffusion kurtosis imaging (DKI), and arterial spin-labeling (ASL) analyses. Mean kurtosis (MK), axial kurtosis (Ka), mean diffusivity (MD), fractional anisotropy (FA), radial kurtosis (Kr), and renal blood flow (RBF) maps were normalized to baseline (prior to contrast injection) to calculate adjusted △RBF, △MK, △Ka, △MD, △FA, and △Kr values. We also investigated urinary neutrophil gelatinase associated lipocalin (NGAL), serum cystatin C (CysC), aquaporin-2 (AQP2), hypoxia-inducible factor-1 (HIF-1α), and histological indices. In the inner stripe of the outer medulla, when compared with controls, decreased △FA and △MD levels were observed on days 1, 3, and 7, and a distinct elevation in △MK and △Kr on days 1–13, and a persistent decrease in △RBF on days 1–13, and a prominent increase in △Ka on days 7 and 13 in PC-AKI animals (all p < 0.05). △Ka and △MK were positively correlated with AQP-2 (r = 0.8086, p < 0.0001 and r = 0.7314, p < 0.0001, respectively), and △RBF was highly correlated with HIF-1α (r = −0.7592, p < 0.0001). Moreover, both CysC and NGAL were significantly elevated in PC-AKI animals when compared with controls from days 1–13 (all p < 0.05). Renal histological data indicated severe tubular and glomerular injury at days 1–13 in all PC-AKI groups. ASL and DKI may be noninvasively and longitudinally used to detect PC-AKI and predict further outcomes. • Combining ASL and DKI could give one the opportunity to study PC-AKI and predict further outcomes. • Alterations of renal Mk, Ka, and RBF values after PC-AKI were useful to detect persistent renal impairment. • CysC and NGAL seems to be reliable markers for improving the identification of PC-AKI to PRD transition. [ABSTRACT FROM AUTHOR]