Using Functional MRI To Evaluate Renal Functional Alternation After Iodinated Contrast Angiography

Part 1 Intravoxel Incoherent Motion Diffusion Weighted Imaging AndDiffusion Tensor Imaging Study of Normal KidneyObjective:To assess characteristic of diffusion tensor imaging（DTI）,intravoxel incoherent motion-diffusion weighted imaging（IVIM-DWI）and blood oxygen level dependent（BOLD）parameters in healthy kidneys.Methods:35 healthy adult volunteers underwent DTI,IVIM-DWI and BOLD examination of kidneys.Two radiologists determined fractional anisotropy（FA）,pure diffusion coefficient（D）,pseudo diffusion coefficient（D*）,perfusion fraction（f）and Apparent relaxation rate（R₂*）in upper pole,middle part and lower pole of the bilateral renal cortex and medulla.Intraclass correlation coefficient（ICC）test was used to verify repeatability.We applied variance（ANOVA）to analysis differences of upper,middle and lower poles.The differences between left and right kidneys,between the cortex and medulla were compared with matched pairs test.Result:There were no statistically significant difference of any parameter between DTI,IVIM-DWI and BOLD for bilateral kidneys,same results as in upper pole,middle part and lower pole of solitary kidney.FA and R₂*values obtained in the medulla were significantly higher than in the cortex（P<0.01）,While D values obtained in the cortex were significantly higher than those in the medulla（t=2.914 P<0.05）.There were no statistically significant difference between the values of cortex and medulla in D*and f（P>0.05）.Among the values of the same measure at different time,FA,D,R₂*showed good measuring consistency,while D*and f showed moderate measuring consistency.Conclusion:FA,D and R₂*show dramatically difference between renal cortex and medulla,and these parameters have high consistency,which can accurate reflect kidney function well.D*and f are less stable that there still need further studies to verify their value.Part 2 Using Blood Oxygen Level Dependent,Diffusion Tensor Imaging and Intravoxel Incoherent Motion Diffusion Weighted MR Imaging to Evaluate Renal Functional Alternation After Iodinated Contrast AngiographyObjective: To demonstrate that blood oxygen level dependent（BOLD）,diffusion tensor imaging（DTI）and intravoxel incoherent motion-diffusion weighted imaging（IVIM-DWI）can evaluate early renal functional alternation after iodinated contrast angiography.Methods: 29 volunteers who planned to underwent CT coronary angiograph were arranged undergoing BOLD,DTI and IVIM-DWI MRI examination of kidneys and creatinine collected: one at 24 h prior to and another twice at 1h,16 h after angiography.Two radiologists determined apparent relaxation rate（R₂*）,fractional anisotropy（FA）,pure diffusion coefficient（D）,pseudo diffusion coefficient（D*）,perfusion fraction（f）in upper pole,middle part and lower pole of the renal cortex and medulla.We applied two ways repeated measures（ANOVA）for statistics analysis.Result: at 1h after the angiography,R₂* in medulla raised remarkably（P<0.01）.D* and f decreased with statistically significant differences in both medulla and cortex（P<0.05）.At 16 h after the angiography,R₂* fell but was still higher than before angiography（P<0.01）.D* and f decreased progressively in both medulla and cortex（P<0.05）.There were no statistically significant difference among R₂*in cortex at the three parameter collection,same result as FA and D in medulla and cortex and Cr.Conclusion: BOLD and IVIM-DWI were effective to demonstrate early renal functional alternation after iodinated contrast angiography.