Apreliminary Study Of The Fractional Kidney Hypoxia For The Assessment Of Chronic Kidney Disease

Objective:To explore the clinical application of the fractional kidney hypoxia measured by usingblood-oxygen-level-dependent MRI for the assessment of chronic kidney disease.Methods:32cases of chronic kidney disease patients who were treated in the hospital fromMarch2013to February2014, were selected and divided into two groups (CKD1,2periodof mild group of16cases, CKD3-5period of medium-severe group a total of16cases).And13cases of healthy volunteers as a control group. Regular T1WI and T2WI sequenceand mGRE BOLD sequence were performed in Siemens Verio3.0T MR. Two experiencedradiologists analyzed the renal BOLD-MRI data by using two different methods.MethodOne is the conventional method, manually placed the region of interest (ROI), measuredand calculated renal cortex and medulla of R2*values by using Siemens Syngo software.Another Method is to estimate the fractional kidney hypoxia (percentage of entire sectionwith R2*above35sec-1), by selecting the entire kidney as a whole ROI, which measuredand calculated R2*values of each voxel by using spin software. Statistical analysis（t test,One-way ANOVA,ROC curve et al） were performed to compare the advantages anddisadvantages of the two methods.Results:1. Conventional method, medullary R2*values were higher than that of cortex in bothcontrol group and CKD group. There was a significant difference of cortical and medullaryR2*in each group (medullary F=13.634,P<0.05; cortical F=7.961, P=0.001)except that there weren’t remarkable differences of cortical R2*between control group and CKD mildgroup (P>0.05).2. Fractional kidney hypoxia methods: there were significantly differences (F=60.144, P <0.05), the medium-severe group> mild group> control group.3. Using ROC curve, compared two methods, fractional kidney hypoxia had highersensitivity and specificity.4. Two methods of reliability analysis, fractional kidney hypoxia (Cronbach’s Alpha=0.918) was significantly greater than medulla R2*(Cronbach’s Alpha=0.549).Conclusion:Fractional kidney hypoxia had higher sensitivity and specificity, and betterrepeatability than the conventional method(manual selection of ROI). Fractional kidneyhypoxia were more suitable for BOLD-MRI to detect changes of CKD renal oxygenationcontent, suggesting that it can be used as a noninvasive modality in the assessment of renalfunction.