Abstract
BackgroundBlood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) and diffusion tensor imaging (DTI) are useful methods for investigating the morphology and function of the kidneys, including revealing unilateral renal damage. Nevertheless, these techniques have not yet been applied for bilateral renal function. The aim of this study was to investigate whether the combination of DTI and BOLD could be used to examine different degrees of contrast-induced acute kidney injury (CI-AKI) in bilateral kidneys compared to standard methods such as serum creatinine (SCr) detection.MethodsForty-Two New Zealand white rabbits were divided into two groups: the experimental group and the control group. Physiological saline and iodine contrast agent (iohexol, 1.0 g iodine/kg, 1.0 ml/sec) were injected via the right renal artery. DTI and BOLD-MR data were acquired longitudinally at the baseline and 1, 24, 48, and 72 h after high-pressure syringe injection to measure the apparent diffusion coefficient (ADC), fractional anisotropy (FA) and relative transverse relaxation rate (R2*). After the MR scan at each time point, three rabbits in each group were sacrificed, and changes in SCr and hypoxia-inducible factor-1α (HIF-1α) were analyzed using histopathology and immunochemistry.ResultsTwenty-four hours after iohexol administration, the values of ADC and FA decreased significantly (P < 0.05), while R2* values increased (P < 0.05) in the renal cortex (CO), outer medulla (OM) and inner medulla (IM). Besides, significant negative correlations were observed among ADC, FA, and R2* in CO, OM, and IM (all P < 0.001, r = − 0.654–0.828).ConclusionsDTI and BOLD can simultaneously and non-invasively assess different degrees of CI-AKI in bilateral kidneys.
Highlights
Blood oxygenation level-dependent magnetic resonance imaging (BOLD-Magnetic resonance imaging (MRI)) and diffusion tensor imaging (DTI) are useful methods for investigating the morphology and function of the kidneys, including revealing unilateral renal damage
Contrast-induced acute kidney injury (CI-AKI) is the third leading cause of hospital-acquired acute kidney injury. It is defined as a sudden deterioration of renal function 1–3 days after exposure to contrast agents [1, 2]
The CO, outer medulla (OM), and inner medulla (IM) of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values at 1, 24, and 48 h after iohexol injection were low, while R2* values were elevated; at 72 h R2* values decreased to a level that was near to the baseline
Summary
Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) and diffusion tensor imaging (DTI) are useful methods for investigating the morphology and function of the kidneys, including revealing unilateral renal damage. These techniques have not yet been applied for bilateral renal function. Contrast-induced acute kidney injury (CI-AKI) is the third leading cause of hospital-acquired acute kidney injury It is defined as a sudden deterioration of renal function 1–3 days after exposure to contrast agents (serum creatinine level increased by 25% or the absolute value of serum creatinine increased by 0.5 mg/dL) [1, 2]. An advanced approach to the separation of bilateral renal function is of urgent importance
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