急性胆红素脑病常规MRI及~1H-MR波谱表现

目的 探讨急性胆红素脑病(acute bilirubin encephalopathy,ABE)患儿MRI特征及脑内代谢物含量与胆红素水平相关性.方法 对28例临床确诊为ABE新生儿(病例组)和15名正常新生儿(对照组)行T_1WI、T_2WI、DWI及~1H-MRS检查.~1H-MRS检查采用定点分辨率波谱序列,病例组28例均行基底节区多体素扫描,其中15例另行苍白球区单体素扫描.对照组15名新生儿均进行多体素及单体素~1H-MRS检查,测定代谢产物包括N-乙酰天冬氨酸(NAA)、肌酸复合物(Cr)、胆碱复合物(Cho)、肌醇(mI)、乳酸(Lac)、谷氨酸及谷氨酰胺复合物(Glx)浓度.并计算NAA/Cr、Cho/Cr、Lac/Cr、Glx/Cr、mI/Cr比值,应用独立两样本t检验分析两组间各代谢物浓度差异.病例组按照血清总胆红素(TSB)水平分为342.0 μmol/L513.0 μmol/L 11例共3组,对3组患儿脑内代谢物浓度进行方差分析.结果 病例组中有23例在常规MRI表现为T_1WI苍白球高信号,其余5例常规MRI表现无异常.对照组15名均无异常信号出现.~1H-MRS检查病例组15例单体素成像患儿中,7例mI峰增高,mI/Cr比值为0.74±0.23,对照组为0.57±0.20,两组差异有统计学意义(t=2.13,P=0.04);13例ABE患儿Glx波峰明显增高,Glx/Cr比值单体素为1.45±0.37,多体素为0.51±0.36,对照组为0.95±0.23、0.29±0.18,两组间比较差异具有统计学意义(t值分别为4.40、2.17,P值分别为0.00、0.03).结论 双侧苍白球对称性T_1WI高信号为ABE特征性表现,~1H-MRS可见Glx/Cr、mI/Cr升高,提示相应病理生理变化.

Preliminary study of conventional MRI and ~1H-MR spectroscopy in diagnosis of acute bilirubin encephalopathy

Objective To investigate the characterized imaging in conventional MRI, get information about the metabolites in basal ganglia from proton MR Spectroscopy(~1H-MRS) of acute bilirubin encephalopathy(ABE) and find out the relationship between those changes and bilirubin levels. Methods Twenty-eight patients with acute bilirubin encephalopathy and 15 normal neonates underwent MR and ~1H-MRS examinations T_1 WI, T_2WI and DWI were collected via conventional MRI scanning of all neonates. All patients underwent multi-voxels scanning and 15 of them had single voxel scanning. ~1H-MRS used point resolved spectroscopy (PRESS) both in multi-voxels and single voxel scanning. The data of them were acquired from the ROIs placed in basal ganglia and globus pallidus, respectively. The metabolites including NAA choline, Lactate, glutamate and glutamine, myoinositol and creatine were quantitatively analyzed to compare them between the control group and the case group. Equality of variance between patient data and normal values were tested by using the two-tailed t test. The case group was divided into three groups of 342.0 μmol/L < TSB ≤ 427. 5 μmol/L,427.5 μmol/L < TSB ≤ 513.0 μmol/L, TSB > 513.0 μmol/L including 8,9,11 patients, respectively. Analysis of variance was used for statistics. Results Conventional magnetic resonance imaging showed symmetrical high signal of T_1WI in globus pallidus of 23 patients. The case group and the control group were significantly different. Single voxel ~1H-MRS revealed that the relative concentrations of Glx/Gr and mI/Cr in the control group were 0.95±0.23, 0.57±0.20, respectively, While those in case group were 1.45±0.37, 0.74±0.23, respectively. There were significant differences between two groups (t =2. 13,4. 40,P =0.04,0.00 respectively). Multi-voxels scanning 1H-MRS revealed that Glx / Cr were 0.51±0.36 in case group and 0.29±0.18 in control group. There was also a significant difference between two groups (t =2.17,P =0.03). And the values of Cho/Cr, NAA/Cr and Lac/Cr were not significantly different. The results were same in multi-voxels ~1H-MRS. Total bilirubin level and the concentration of metabolites in the brain do not have obvious correlation. Conclusions ABE has a characteristic signature which is symmetrical high signal of T_1 WI in globus pallidus on conventional MBI; The values of mI/Cr and Glx/Cr remarkably increase as detected by ~1H-MRS, which is generally in agreement with what has been known about bilirubin pathology.