MRI T1、T2相对比值对新生儿高胆红素脑损害的定量诊断

Quantitative diagnosis of hyperbilirubin-induced neonatal brain damage by relative ratios of T1 and T2 intensity

目的探讨苍白球(globus pallidum,GP)与额叶白质(frontal white matter,FWM)T1、T2比值在足月新生儿胆红素脑病早期诊断中的价值。方法收集75例临床确诊高胆红素血症(hyperbilirubinemia,HB)的新生儿,根据苍白球T1WI信号分为46例信号正常组(HBn组)和29例信号升高组(HBh组);同期收集44例健康新生儿作为健康对照组(healthy control,HC组)。测量双侧GP与FWM的信号强度并计算GP/FWM的T1、T2信号强度比值(简称T1比值、T2比值)。比较3组间各比值差异并绘制ROC曲线评估诊断效能,AUCs比较采用Delong检验。分析各比值与血清总胆红素(total serum bilirubin,TSB)的相关性。结果 3组间T1比值存在显著性差异(H=112.254,P<0.001),HC、HBn、HBh组T1比值中位值依次增高,为2.14(1.87,2.52)、2.41(2.10,2.60)、3.08(2.81,3.43)。ROC曲线分析显示,当T1比值分别以2.675、2.655、2.155作为阈值时,HC-HBh组、HBn-HBh组、HC-HBn组之间曲线下面积(AUC)最大(0.973、0.926、0.633),敏感性和特异性分别为0.948、0.898;0.983、0.795;0.707、0.528。此外,HBh组T2比值[0.66(0.65,0.68)]显著低于HBn组[0.69(0.66,0.72)]和HC组[0.70(0.68,0.73)],调整后P<0.001,ROC曲线分析表明,T2比值具有一定鉴别诊断能力(AUC=0.726、0.798)。HB组T1、T2比值与TSB水平均无相关性(P>0.05)。结论 T1和T2相对比值可用于新生儿胆红素脑病的早期诊断,其中T1比值诊断效能最佳,尤其能够提高对肉眼不可见的早期病变的检出率。

Objective To investigate the value of globus pallidum(GP)versus frontal white matter(FWM)T1 and T2 ratios in early diagnosis of neonatal bilirubin encephalopathy in full-term neonates.Methods Seventy-five cases of neonates with clinically confirmed hyperbilirubinemia were collected.All patients were divided into two groups based on T1 WI signal intensity in GP,including 46 case of normal signal intensity group(HBn group)and 29 cases of high signal intensity group(HBh group).In the meantime,44 healthy neonates were enrolled in healthy control group(HC group).The signal intensities of bilateral GPs and FWMs were measured and the GP/FWM ratios of T1 and T2 signal intensity were calculated(referred to as T1 ratio and T2 ratio).The ratio differences were compared among three groups and ROC curves were created to evaluate the diagnostic performance,the area under the curves(AUCs)were compared using Delong test.The correlation between each signal intensity ratio and total serum bilirubin(TSB)was analyzed.Results There was significant difference in T1 ratios among three groups(H=112.254,P<0.001);the median value of T1 ratios in HC,HBn,and HBh groups were 2.14(1.87,2.52),2.41(2.10,2.60)and 3.08(2.81,3.43),which increased sequentially.ROC curve analysis revealed that AUCs of HC-HBh group,HBn-HBh group,and HC-HBn group were the largest(0.973,0.926,0.633)when the T1 ratios were 2.675,2.655,2.155 as threshold,respectively.The sensitivities and specificities were 0.948 and 0.898,0.983 and 0.795,0.707 and 0.528,respectively.Furthermore,the T2 ratio of HBh group[0.66(0.65,0.68)]was significantly lower than that of HBn group[0.69(0.66,0.72)]and HC group[0.70(0.68,0.73)](P<0.001 after adjustment).ROC analysis showed that T2 ratio had certain differential diagnostic ability(AUC=0.726,0.798).The T1,T2 ratio of HB group was not correlated with the TSB level(P>0.05).Conclusion The relative ratios of T1 and T2 can be used in early diagnosis of neonatal bilirubin encephalopathy.T1 ratio has the best diagnostic performance and can be especially useful for the detection of early lesions that are invisible to the naked eyes.