Early assessment of acute kidney injury in severe acute pancreatitis with multimodal DWI: an animal model

ObjectivesTo evaluate the feasibility of multimodal diffusion-weighted imaging (DWI) for detecting the occurrence and severity of acute kidney injury (AKI) caused by severe acute pancreatitis (SAP) in rats.MethodsSAP was induced in thirty rats by the retrograde injection of 5.0% sodium taurocholate through the biliopancreatic duct. Six rats underwent MRI of the kidneys 24 h before and 2, 4, 6, and 8 h after this AKI model was generated. Conventional and functional MRI sequences were used, including intravoxel incoherent motion imaging (IVIM), diffusion tensor imaging (DTI), and diffusion kurtosis imaging (DTI). The main DWI parameters and histological results were analyzed.ResultsThe fast apparent diffusion coefficient (ADC) of the renal cortex was significantly reduced at 2 h, as was the fractional anisotropy (FA) value of the renal cortex on DTI. The mean kurtosis (MK) values for the renal cortex and medulla gradually increased after model generation. The renal histopathological score was negatively correlated with the medullary slow ADC, fast ADC, and perfusion scores for both the renal cortex and medulla, as were the ADC and FA values of the renal medulla in DTI, whereas the MK values of the cortex and medulla were positively correlated (r = 0.733, 0.812). Thus, the cortical fast ADC, medullary MK, FA(DTI), and slow ADC were optimal parameters for diagnosing AKI. Of these parameters, cortical fast ADC had the highest diagnostic efficacy (AUC = 0.950).ConclusionsThe fast ADC of the renal cortex is the core indicator of early AKI, and the medullary MK value might serve as a sensitive biomarker for grading renal injury in SAP rats.

Automated summary

This study evaluated the feasibility of using multimodal diffusion-weighted imaging for detecting the occurrence and severity of acute kidney injury caused by severe acute pancreatitis in rats. The results showed that the fast apparent diffusion coefficient of the renal cortex decreased significantly at 2 hours and the fractional anisotropy value of the renal cortex on diffusion tensor imaging also decreased. The mean kurtosis values for the renal cortex and medulla gradually increased after model generation. Therefore, the cortical fast ADC, medullary MK, FA(DTI), and slow ADC were found to be the optimal parameters for diagnosing AKI.