A Preliminary Study Of Blood-oxygen-level-dependent MRI For The Assessment Of Diabetic Nephropathy

Objective:To evaluate the clinical application of blood-oxygen-level-dependent MRI for the assessment of diabetic nephropathy.Methods:BOLD-MRI of kidneys was performed in11normal healthy volunteers,19patients with early diabetic nephropathy (eGFR>60ml/min/1.73m2with micro-or macro-albumin) and15patients with moderate to severe diabetic nephropathy (eGFR≤60ml/min/1.73m2with macro-albumin). Siemens Magnetom Verio3.0T was employed. Bilateral renal cortical R2*(CR2*) and medullary R2*(MR2*) values were quantified, then R2*ratio between medulla and cortex (MCR) was calculated. CR2*, MR2*and MCR were compared between groups by ANOVA, and their diagnostic efficiencies were determined by ROC curve. The relationships between R2*values and clinical indexes (eGFR and HbA1c) were analyzed by Peason.Results:1. On T2*pseudo-color map, the cortex of normal group showed striped blue, while that of DN group showed diffuse blue dot, which was63.2%in early DN(12/19) and66.7%in moderate to severe DN(10/15).2. There was a significant difference of MR2*between health group and early DN (P<0.01). Its diagnostic efficiency was great (P<0.01) at the cutoff point of33.88s-1with sensitivity and specificity of94.74%and90.91%separately.3. There were significant statistical differences of CR2*and MCR between early DN and moderate to severe DN (P<0.01). The difference between two groups could be better detected by CR2*at the cutoff point of17.63s-1with sensitivity and specificity of80%and84.21%separately.4. There were significant statistical differences of CR2*and MCR between healthy individuals and moderate to severe DN (P<0.01). The difference between two groups could be determined by CR2*at the cutoff point of16.86s-1with sensitivity and specificity of93.33%and100%separately. Whereas, there was no diagnostic efficiency in MCR (P>0.05).5. CR2*correlated inversely with eGFR (r=-0.492, P<0.01), while MCR correlated positively with eGFR (r=0.423, P<0.05). There were no correlations between HbA1c and CR2*, MR2*, MCR.Conclusion:1. On T2*pseudo-color map, the cortex of DN showed diffuse blue dot, which might be characteristic.2. BOLD-MRI could be used for the diagnosis and stages of diabetic nephropathy. In this study, MR2*could be used to identify normal and early DN group. CR2*could be used to identify early DN and moderate to severe DN group, normal and moderate to severe DN group.3. CR2*correlated inversely with eGFR, while MCR correlated positively with eGFR. Both of CR2*and MCR could be used to detect the progress of diabetic nephropathy.