Assessing intrarenal nonperfusion and vascular leakage in acute kidney injury with multinuclear ¹H/¹⁹F MRI and perfluorocarbon nanoparticles

Purpose: We sought to develop a unique sensor-reporter approach for functional kidney imaging that employs circulating perfluorocarbon nanoparticles and multinuclear ¹H/¹⁹F MRI. Methods: ¹⁹F spin density weighted and T1 weighted images were used to generate quantitative functional mappings of both healthy and ischemia-reperfusion (acute kidney injury) injured mouse kidneys. ¹H blood-oxygenation-level-dependent (BOLD) MRI was also employed as a supplementary approach to facilitate the comprehensive analysis of renal circulation and its pathological changes in acute kidney injury. Results: Heterogeneous blood volume distributions and intrarenal oxygenation gradients were confirmed in healthy kidneys by ¹⁹F MRI. In a mouse model of acute kidney injury, ¹⁹F MRI, in conjunction with blood-oxygenation-level-dependent MRI, sensitively delineated renal vascular damage and recovery. In the cortico-medullary junction region, we observed 25% lower ¹⁹F signal (P<0.05) and 70% longer ¹H T2* (P<0.01) in injured kidneys compared with contralateral kidneys at 24 h after initial ischemia-reperfusion injury. We also detected 71% higher ¹⁹F signal (P<0.01) and 40% lower ¹H T2* (P<0.05) in the renal medulla region of injured kidneys compared with contralateral uninjured kidneys. Conclusion: Integrated ¹H/¹⁹F MRI using perfluorocarbon nanoparticles provides a multiparametric readout of regional perfusion defects in acutely injured kidneys.