早期皮质缺血时的皮质下低信号强度。
Subcortical low intensity in early cortical ischemia.
作者信息
Ida M, Mizunuma K, Hata Y, Tada S
机构信息
Department of Radiology, Jikei University School of Medicine, Tokyo, Japan.
出版信息
AJNR Am J Neuroradiol. 1994 Aug;15(7):1387-93.
PURPOSE
To describe subcortical low intensity on T2- and proton density-weighted MR images in early cortical ischemia and to discuss a cause of these findings.
METHODS
Nine patients with early cortical ischemia were studied with proton density- and T2-weighted images, and T1-weighted images at 1.5 T. Gadolinium enhancement was added in six cases.
RESULTS
In all cases there was high to intermediate intensity in the cortex and low intensity in the subcortical white matter (subcortex) on the proton density- and T2-weighted images. No significant signal abnormalities were shown on T1-weighted images in the subcortex; gyriform enhancement was seen in the affected cortex in all of the six patients studied with gadolinium. Of the four patients with follow-up MRs, the subcortical low intensity changed to high intensity in two and remained low in two patients in the chronic stage. Neither hemorrhage nor calcification was seen on CT.
CONCLUSION
Iron accumulation in the subcortex caused by disruption of the axonal transportation and continuous production of free radicals caused by the hypoxic-ischemic state most likely reduces the signal intensity of the subcortex on the proton density- and T2-weighted images. The subcortical low intensity on the proton density- and T2-weighted images is an important diagnostic sign of early cortical ischemia.
目的
描述早期皮质缺血时T2加权和质子密度加权磁共振图像上的皮质下低信号强度，并探讨这些表现的原因。
方法
对9例早期皮质缺血患者进行了质子密度加权、T2加权成像以及1.5T的T1加权成像检查。6例患者加做了钆增强检查。
结果
在质子密度加权和T2加权图像上，所有病例的皮质均呈高到中等信号强度，皮质下白质（皮质下）呈低信号强度。皮质下在T1加权图像上未见明显信号异常；在6例接受钆增强检查的患者中，所有患者的患侧皮质均可见脑回样强化。在4例接受随访磁共振成像检查的患者中，慢性期有2例患者皮质下低信号强度变为高信号强度，2例患者仍为低信号强度。CT检查未见出血或钙化。
结论
轴突运输中断导致皮质下铁沉积，以及缺氧缺血状态持续产生自由基，很可能降低了质子密度加权和T2加权图像上皮质下的信号强度。质子密度加权和T2加权图像上的皮质下低信号强度是早期皮质缺血的重要诊断征象。
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