ABSTRACT
Objective: To explore the impact of non-ionic dimeric isotonic iodine contrast agent on rabbit kidneys using intravoxel incoherent motion (IVIM)-DWI and blood oxygen level-dependent (BOLD) imaging. Methods: Totally 25 male New Zealand rabbits were randomly equally divided into 5 groups (each n=5). IVIM-DWI and BOLD scanning and blood collection were performed in four experimental groups (1, 24, 48, 72 h group) 1, 24, 48,72 h after injection of iodixanol, respectively, also in base-line group after injection of equal amount of saline. The rabbits were killed immediately after MRI,and the kidneys were taken for histopathological analysis. Results: Compared with base-line group, both cortex and medulla of kidneys showed decreased ADC, D and f values and the lowest D* value, as well as increased R2* in 1 h group. The lowest ADC, D and f values, the highest R2* and increased D* value of both cortex and medulla were observed in 24 h group. In 72 h group, R2* value of both cortex and medulla were still lower than baseline (all P<0.05), and D* value basically returned to baseline, while f and D values of medulla were still statistically different with respect to baseline (all P<0.05). Meanwhile, different degrees of glomerular and tubular damage were observed in the pathological sections. The serum creatinine and blood urea nitrogen in 48 h group and 72 h group were higher than those in base-line group (all P<0.05). The expression of hypoxia inducible factor-1α and heme oxygenase-1 increased in 1 h group and up to peak in 24 h group. Conclusion: Combining IVIM-DWI with BOLD can effectively evaluate rabbit renal pathophysiologic changes associated with contrast-induced acute kidney injury.
ABSTRACT
OBJECTIVE: To examine the potential of intravoxel incoherent motion (IVIM) and blood oxygen level-dependent (BOLD) magnetic resonance imaging for detecting renal changes after iodinated contrast-induced acute kidney injury (CI-AKI) development in a diabetic rabbit model. MATERIALS AND METHODS: Sixty-two rabbits were randomized into 2 groups: diabetic rabbits with the contrast agent (DCA) and healthy rabbits with the contrast agent (NCA). In each group, 6 rabbits underwent IVIM and BOLD imaging at 1 hour, 1 day, 2 days, 3 days, and 4 days after an iohexol injection while 5 rabbits were selected to undergo blood and histological examinations at these specific time points. Iohexol was administrated at a dose of 2.5 g I/kg of body weight. Further, the apparent transverse relaxation rate (R2*), average pure molecular diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were calculated. RESULTS: The D and f values of the renal cortex (CO) and outer medulla (OM) were significantly decreased compared to baseline values in the 2 groups 1 day after the iohexol injection (p < 0.05). A marked reduction in the D* values for both the CO and OM was also observed after 1 hour in each group (p < 0.05). In the OM, a persistent elevation of the R2* was detected for 4 days in the DCA group (p < 0.05). Histopathological changes were prominent, and the pathological features of CI-AKI aggravated in the DCA group until day 4. The D, f, and R2* values significantly correlated with the histological damage scores, hypoxia-inducible transcription factor-1α expression scores, and serum creatinine levels. CONCLUSION: A combination of IVIM and BOLD imaging may serve as a noninvasive method for detecting and monitoring CI-AKI in the early stages in the diabetic kidney.