多回波采集T*2加权三维梯度回波序列在弥漫性轴索损伤出血性剪切灶检出中的应用

目的 比较多回波采集的T2*WI三维梯度回波(ESWAN)序列和常规T2*WI梯度回波序列(GRE T2*WI)对弥漫性轴索损伤(DAI)出血性剪切灶的检出效能,并结合成像参数进一步探讨ESWAN序列的原理及优势.方法 回顾性分析17例DAI患者行MR检查的影像资料,比较ESWAN序列经多回波幅度平均技术后处理后的图像与常规GRE T2*WI序列对大脑总体及分区(大脑表浅区、深部区及后颅窝区)出血灶显示数量的差异,统计学分析采用配对比较秩和检验.结果 GRE T2*WI显示的出血灶在ESWAN图像上信号更低而更明显;ESWAN序列检出出血灶的中位数(范围)分别为全脑27(1～239)个、脑表浅区13(1～89)个、脑深部区5(0～111)个及后颅窝区1(0～39)个;GRE T2*WI序列检出出血灶的中位数(范围)分别为全脑7(1～34)个、脑表浅区5(1～27)个、脑深部区2(0～25)个及后颅窝区0(0～4)个.配对比较秩和检验显示两种序列在全脑及各分区的检出数量上差异均有统计学意义(Z值分别为-3.519、-3.182、-3.185、-2.677,P值均＜0.05).结论 ESWAN序列的多回波采集优势保障了足够的磁敏感效应,较GRE T2*WI序列检出小出血灶更敏感,为DAI的诊断及病情的评估提供了更多有价值的影像信息.

Abstract：

Objective To compare the efficiency of enhanced T2* weighted angiography (ESWAN) sequence with that of a conventional T2*-weighted gradient-recalled-echo (GRE T2*WI) sequence for the detection of hemorrhagic shearing lesions in patients with diffuse axonal injury (DAI). And combined with MRI parameters, to further discuss the principles and virtues of ESWAN sequence. Methods Seventeen patients with DAI were enrolled in this study. The raw data acquired from ESWAN scan were postprocessed by using the mean square root of multi-echoes. Then, the postprocessed images were compared with the conventional GRE T2* weighted images. The global and regional (superficial, deep and posterior fossa) lesion numbers determined by both sequences were compared by using Wilcoxon signed ranks test (two-tailed). Differences were considered to be significant at P≤0.05. Results Hemorrhagic lesions were more obvious on ESWAN images than those on conventional GRE T2* weighted images. The median and range value of the detected lesion numbers on ESWAN images were 27 and (1-239) in whole brain, 13 and (1-89) in cerebral superficial region, 5 and (0-111) in cerebral deep region and 1 and (0-39) in posterior fossa region, respectively; whereas, on GRE T2* weighted images, they were 7 and (1-34) in whole brain, 5 and (1-27) in cerebral superficial region, 2 and (0-25) in cerebral deep region and 0 and (0-4) in posterior fossa region, respectively. There were significant statistical differences between the two sequences in revealing the lesions in all the four regions (Z=-3.519,-3.182,-3.185,-2.677,P＜0.05). Conclusion In ESWAN sequence, multi-echo acquisition ensured sufficient magnetic susceptibility for detecting small hemorrhagic lesions. So, ESWAN is more sensitive to small hemorrhage, which revealed more hemorrhagic lesions than conventional GRE T2*WI and presented more valuable information for the diagnosis of DAI.

Application and technical analysis of enhanced T*2 star weighted angiography sequence in the detection of hemorrhagic shearing lesions associated with diffuse axonal injury

Objective To compare the efficiency of enhanced T2* weighted angiography (ESWAN) sequence with that of a conventional T2*-weighted gradient-recalled-echo (GRE T2*WI) sequence for the detection of hemorrhagic shearing lesions in patients with diffuse axonal injury (DAI). And combined with MRI parameters, to further discuss the principles and virtues of ESWAN sequence. Methods Seventeen patients with DAI were enrolled in this study. The raw data acquired from ESWAN scan were postprocessed by using the mean square root of multi-echoes. Then, the postprocessed images were compared with the conventional GRE T2* weighted images. The global and regional (superficial, deep and posterior fossa) lesion numbers determined by both sequences were compared by using Wilcoxon signed ranks test (two-tailed). Differences were considered to be significant at P≤0.05. Results Hemorrhagic lesions were more obvious on ESWAN images than those on conventional GRE T2* weighted images. The median and range value of the detected lesion numbers on ESWAN images were 27 and (1-239) in whole brain, 13 and (1-89) in cerebral superficial region, 5 and (0-111) in cerebral deep region and 1 and (0-39) in posterior fossa region, respectively; whereas, on GRE T2* weighted images, they were 7 and (1-34) in whole brain, 5 and (1-27) in cerebral superficial region, 2 and (0-25) in cerebral deep region and 0 and (0-4) in posterior fossa region, respectively. There were significant statistical differences between the two sequences in revealing the lesions in all the four regions (Z=-3.519,-3.182,-3.185,-2.677,P＜0.05). Conclusion In ESWAN sequence, multi-echo acquisition ensured sufficient magnetic susceptibility for detecting small hemorrhagic lesions. So, ESWAN is more sensitive to small hemorrhage, which revealed more hemorrhagic lesions than conventional GRE T2*WI and presented more valuable information for the diagnosis of DAI.