MR扩散张量成像在慢性肾病分期诊断中的价值

Primary study of chronic kidney disease with MR diffusion tensor imaging

目的 探讨MR扩散张量成像（DTI）在慢性肾病（CKD）分期诊断中的价值.方法 前瞻性收集26例符合临床CKD诊断标准,MR图像质量达到诊断要求,并行99m锝-二乙三胺五乙酸肾动态显像测定肾功能的患者,将患者按照CKD分期标准分为轻度肾损害组（12例）和中重度肾损害组（14例）.收集同期20名志愿者作为对照组.所有受试者均行双肾MRI常规扫描和DTI检查,测量皮、髓质ADC及FA值.所有受试者肾皮、髓质间ADC值和FA值的比较采用配对样本t检验.3组受试者肾皮、髓质ADC值和FA值的比较采用单因素方差分析,两两比较采用LSD法.CKD患者肾脏皮、髓质ADC值及FA值与肾小球滤过率的相关性采用Pearson相关性分析.结果 46例受试者皮、髓质的ADC值分别为（2.25±0.25）×10-3和（2.10±0.20） ×103mm2/s,FA值分别为3.48±0.61和4.27±0.75,皮质和髓质的测量值差异均有统计学意义（t值分别为6.754和10.043,P值均＜0.01）.对照组、CKD轻度肾损害组、CKD中重度肾损害组肾皮质的ADC值分别为（2.25±0.22） ×10-3、（2.31±0.19） ×103和（2.18±0.32）×103mm2/s,肾髓质ADC值分别为（2.09±0.19）×10-3、（2.17±0.17）×10-3和（2.06±0.24）×10-3mm2/s,差异均无统计学意义（F值分别为0.968和0.882,P值均＞0.05）.上述3组肾皮质FA值分别为3.85±0.47、3.18±0.62和3.20±0.52,肾髓质分别为4.92±0.38、3.93±0.57和3.62±0.53,差异均有统计学意义（F值分别为8.725和33.705,P值均＜0.01）,两两比较对照组FA值均高于CKD两组（P值均＜0.01）.CKD患者皮、髓质ADC值及皮质的FA值与肾小球滤过率[（30.14±15.79） ml· min-1· 1.73 m-2]无相关性（r值分别为0.243、0.197及0.196,P值分别为0.231、0.334及0.337）,仅髓质FA值与GFR呈正相关（r=0.556,P=0.003）.结论 DTI能为CKD的分期诊断提供有价值的信息,肾髓质FA值测量可用于评价肾功能状态.

Objective To study the value of MR diffusion tensor imaging（DTI） in the staging of chronic kidney disease（CKD）.Method MR diffusion tensor imaging was used on 26 CKD patients.All patients were diagnosed as CKD according to the criteria of clinical diagnostic.All MR images achieved diagnostic requirements.Diethylenetriamine pentaacetic acid（99mTc-DTPA） renal dynamic imaging was used to determine the unilateral renal function.CKD patients were determined as mildly renal impairment group and moderately to severely renal impairment group based on the glomerular filtration rate（GFR）.Twenty healthy volunteers underwent DTI at the same time.The cortical and medullary ADC value and FA value were measured in all subjects who underwent conventional MRI and DTI.The paired Student＇s t test was used to compare the cortico-medullary difference of the mean ADC and FA values in all subjects.The oneway analysis of variance（ANOVA） was carried out to assess the difference among the medullary and cortical diffusion parameters（ADC,FA） of all the three groups,and LSD was used to assess multiple comparisons.The correlation of GFR and ADC value of the patients,and FA value of the patients were tested by Pearson correlation analysis.Results The cortical and medullary ADC values of 46 subjects were（2.25±0.25） × 10-3 and（2.10±0.20） × 10-3 mm2/s respectively,FA of them were（3.48±0.61） and（4.27±0.75） respectively（t =6.754,10.043 respectively; P＜0.01）.The cortical ADC values of volunteers,mild renal impairment group,severely renal impairment group were（2.25±0.22） ×10-3,（2.31±0.19） ×103,（2.18±0.32） ×10-3mm2/s respectively.The medullary ADC value of the three groups were（2.09±0.19） × 10-3,（2.17±0.17） × 10-3,（2.06±0.24） × 10-3mm2/s respectively（F=0.968,0.882 respectively; P＞0.05）.The cortical FA values of the three groups were 3.85± 0.47,3.18±0.62,3.20±0.52 respectively.The medullary FA of the three groups were 4.92±0.38,3.93±0.57,3.62 ± 0.53（F=8.725,33.705 respectively; P＜0.01）.There was no correlation between cortical ADC,medullary ADC,cortical FA of the patients and GFR [（30.14±15.79） ml· min-1 · 1.73 m-2]（r =0.243,0.197,0.196 respectively; P＞0.05）.There was a positive correlation between medullary FA of the patients and GFR （r=0.556,P=0.003）.Conclusion FA value has certain value in evaluating CKD early diagnosis and renal function.