Multiparametric Evaluation of Drug-Induced Acute Kidney Injury Using Preclinical 7T Magnetic Resonance Imaging in Rat Models

Objectives: Acute kidney injury (AKI), characterized by a rapid decline in renal function, affects approximately 13 million new patients annually. Adverse drug reactions have increasingly contributed to renal injury, underscoring the need for methods to directly and quantitatively evaluate renal injury. Methods: We utilized a drug-induced AKI model using gentamicin overdose, combining 7T magnetic resonance imaging (MRI) relaxation time measurements and blood tests to evaluate pathophysiological changes from multiple perspectives. Ten-week-old Wistar rats received intraperitoneal administration of gentamicin (80 mg/kg) for 7 days. Under respiratory synchronization, T1, T1rho, T2, and T2* maps were obtained in six control and five disease model rats. Relaxation times in the cortex and medulla were measured separately and compared between groups. Results: Blood tests evaluated Na, K, Cl, blood urea nitrogen, creatinine, and hematocrit levels. Renal tissue damage was evaluated via hematoxylin and eosin (HE) staining. Relaxation time showed significant changes in the cortex, especially in the T1 (control: 1156.7 ± 140.0, gentamicin: 1550.4 ± 162.1, p < 0.05) and T2 (control: 42.9 ± 3.4, gentamicin: 53.4 ± 4.8, p < 0.05) maps. Blood tests revealed significant increases in Na, blood urea nitrogen, creatinine, and hematocrit levels in the disease model. A correlation was observed between the T1 map of the renal cortex and each substance. HE staining revealed tissue damage due to renal injury. Conclusions: Multiparametric MRI facilitates quantitative and multidimensional evaluation of renal pathological changes caused by drug-induced AKI.