A feasibility study of using noninvasive renal oxygenation imaging for the early assessment of ischemic acute kidney injury in an embolization model

Purpose: To investigate the feasibility of using MRI based oxygenation imaging for early assessment of ischemic acute kidney injury (AKI) in an embolization model. Methods: Ischemic AKI model was induced in 40 rabbits by injection of microspheres into the right renal arteries. Animals were grouped according to the dose of microspheres: Severe AKI group, 2.0 mg (N = 10); Moderate AKI group, 1.0 mg (N = 10); Mild AKI group, 0.5 mg (N = 10); Control group, saline without microspheres (N = 10). A serial MRI examination was performed at intervals of 1 h, 1 day, 1 week and 4 weeks to evaluate the deterioration of renal function. A multi-echo ASE sequence was implemented for renal oxygenation measurement 1 h after surgery. Pathological examinations were performed 4 weeks after the surgery. Results: In renal cortex, renal oxygen extraction fraction (OEF) raised significantly after embolization procedures in all experimental groups (severe AKI: 0.39 +/- 0.05, P < 0.05; moderate AKI: 0.36 +/- 0.03, P < 0.05; mild AKI: 0.34 +/- 0.02, P < 0.05) compared to the control group (0.29 +/- 0.02). In outer medulla, significant difference was observed between control group (0.29 +/- 0.03) and severe AKI group (0.35 +/- 0.03, P < 0.05), and between control group and moderate AKI group (0.34 +/- 0.04, P < 0.05). Corresponding lesions were found in pathological examinations 4 weeks after the procedure. Conclusion: This study demonstrates the feasibility of using oxygenation imaging to assess the embolization induced ischemic AKI at an early stage.