动脉自旋标记及体素内不相干运动成像对大鼠肾损伤及肾纤维化程度评估的价值OA

Objective To investigate the value of arterial spin labeling(ASL)and intravoxel incoherent motion(IVIM)MRI in assessing renal injury and fibrosis in a rat model of adriamycin-induced nephropathy.Methods Forty-two rats were randomly divided into a continuous-scanning group(n=6)and an intermittent-scanning group(n=36).Magnetic resonance imaging(T2-weighted imaging,ASL,and IVIM)was performed at baseline and at 2,3,4,5,and 6 weeks after adriamycin injection.Rats in the continuous-scanning group underwent repeated MRI examinations at all time points.In the intermittent-scanning group,six rats were randomly selected at each time point and sacrificed after MRI for laboratory and pathological analyses.Laboratory tests included serum creatinine(Scr)and tumor necrosis factor-α.Renal pathology was evaluated using hematoxylin-eosin and Masson staining to assess renal injury and fibrosis,and immunohistochemistry was performed to semi-quantitatively analyze α-smooth muscle actin(α-SMA)expression.A hematoxylin-eosin score>2 was used to differentiate mild from moderate-to-severe renal injury.Renal fibrosis severity was classified into mild,moderate,and severe groups using K-means clustering.Renal blood flow(RBF),true diffusion coefficient(D),pseudo-diffusion coefficient(Dp),and perfusion fraction(f)were measured.One-way analysis of variance was used to compare imaging parameters,laboratory indices,and pathological findings among different time points in the intermittent-scanning group.Repeated-measures ANOVA was applied to assess longitudinal changes in imaging parameters in the continuous-scanning group.Spearman correlation analysis was performed to evaluate correlations between imaging parameters,laboratory indices,and pathological findings.Receiver operating characteristic(ROC)curve analysis and the area under the curve(AUC)were used to assess the diagnostic performance of imaging parameters and Scr in differentiating renal injury and fibrosis severity,with AUCs compared using the DeLong test.Results In the intermittent-scanning group,Scr levels showed a progressive increase,with significant differences observed at weeks 5 and 6 compared with baseline(P<0.05).Cortical RBF values and cortical and medullary D and f values exhibited a decreasing trend over time.Cortical RBF,D,and f values,as well as medullary f values,were significantly correlated with hematoxylin-eosin scores,fibrosis area,and α-SMA expression(|r|=0.411-0.868,all P<0.05).Cortical RBF demonstrated the highest diagnostic performance for distinguishing mild from moderate-to-severe renal injury and fibrosis(AUC=0.968 and 0.888,respectively;P<0.05).The AUCs of cortical RBF,D,and f values,as well as medullary f values,for differentiating mild from moderate-to-severe renal fibrosis were significantly higher than those of Scr.Similarly,cortical RBF and medullary f values showed significantly better diagnostic performance than Scr in distinguishing mild from moderate-to-severe renal injury(P<0.05).Conclusion ASL and IVIM imaging can dynamically characterize alterations in renal cortical and medullary perfusion and diffusion in an adriamycin nephropathy model.These imaging parameters demonstrate superior performance over conventional serological markers in differentiating the severity of renal injury and fibrosis,providing strong imaging support for early intervention and therapeutic decision-making.