McKinney Alexander M, Teksam Mehmet, Felice Ross, Casey Sean O, Cranford Ronald, Truwit Charles L, Kieffer Stephen
University of Minnesota Medical School, Department of Radiology, Box 292, 420 Delware St SE, Minneapolis, MN 55455, USA.
AJNR Am J Neuroradiol. 2004 Nov-Dec;25(10):1659-65.
As is the case for CT scans, MR images may occasionally appear deceptively normal unless proper windowing is used. We sought to illustrate the necessity for proper windowing and for assessing the gray-white matter differentiation on diffusion-weighted (DW) images in the setting of hypoxic-ischemic encephalopathy.
Six comatose patients (age range, 34-56 years) underwent MR imaging in the early phase (range, 1-5 days) after severe anoxic insult. T2-weighted, turbo fluid-attenuated inversion-recovery, and DW images were obtained in all six patients, with contrast-enhanced T1-weighted images obtained in four and apparent diffusion coefficient (ADC) maps in five of the six patients.
At presentation, each of the six patients had symmetric, uniform hyperintensity in the cortex (mean ADC, 0.35 x 10(-3) mm(2)/s) relative to the white matter (mean ADC, 0.91 x 10(-3) mm(2)/s) on DW images. Each also had a poor outcome: brain death in four patients and a permanent vegetative state in two patients.
The appearance of the MR images in the setting of diffuse cortical laminar necrosis can be deceptive to the unwary radiologist. The key to correct interpretation is proper windowing and the marked gray-white matter differentiation on spin-echo images but best seen on properly windowed DW images in the early subacute phase. This appearance also implies an extremely poor outcome, either a permanent vegetative state or brain death.
如同CT扫描一样，除非采用合适的窗宽，否则磁共振成像（MR）图像偶尔可能看似正常。我们试图说明在缺氧缺血性脑病情况下，采用合适窗宽以及评估扩散加权（DW）图像上灰白质区分的必要性。
6名昏迷患者（年龄范围34 - 56岁）在严重缺氧损伤后的早期阶段（范围1 - 5天）接受了MR成像检查。所有6名患者均获得了T2加权、快速液体衰减反转恢复序列以及DW图像，其中4名患者获得了对比增强T1加权图像，6名患者中的5名获得了表观扩散系数（ADC）图。
就诊时，6名患者在DW图像上相对于白质（平均ADC，0.91×10⁻³mm²/s），皮质均呈现对称、均匀的高信号（平均ADC，0.35×10⁻³mm²/s）。所有患者预后均较差：4名患者脑死亡，2名患者处于永久性植物状态。
弥漫性皮质层状坏死情况下的MR图像表现可能会误导粗心的放射科医生。正确解读的关键在于合适的窗宽以及自旋回波图像上明显的灰白质区分，但在亚急性期早期通过合适窗宽的DW图像能最佳显示。这种表现还意味着预后极差，要么是永久性植物状态，要么是脑死亡。
