Unraveling pathology in juvenile Alexander disease: serial quantitative MR imaging and spectroscopy of white matter
Unraveling pathology in juvenile Alexander disease: serial quantitative MR imaging and spectroscopy of white matter
复制标题
揭示青少年亚历山大病的病理学：白质的连续定量磁共振成像和光谱学
作者：
J. P. van der Voorn;P. Pouwels;G. Salomons;F. Barkhof;M. S. van der Knaap
亚历山大病是一种罕见的中枢神经系统疾病，其特征性的对称性白色物质异常，在磁共振（MR）图像上以额叶为主。组织学检查显示受累的白色组织缺乏髓鞘，可解释为髓鞘形成不足或脱髓鞘。为了增加我们的洞察力的病理性质导致的MR成像结果在亚历山大病，我们应用系列MR成像，光谱，磁化传递（MT）成像（MTI），和扩散张量成像（DTI）在6例青少年亚历山大diseases.MethodsThe MR成像协议包括T1和T2加权自旋回波图像和液体衰减反转恢复图像。分数各向异性（FA），表观扩散系数（ADC），MT比（MTR）的地图，和MR波谱浓度进行了定量为几个metabolish.ResultsMR成像显示类似的脑白色物质异常的所有患者，只有轻微增加长期随访，尽管有时严重的临床进展。磁共振波谱显示肌醇，乳酸和胆碱含化合物的水平高度升高，总N-乙酰-天冬氨酸和N-乙酰-N-乙酰基-谷氨酸水平降低，在异常的白色物质。ADC值高，观察到，FA和MTR衰减。ConclusionThe序列的MR成像结果在亚历山大病提供了强有力的证据，对活动性脱髓鞘作为唯一的解释为基础的病理。对于我们的光谱、DTI和MTI结果的另一种解释可能是脱髓鞘，星形胶质细胞增生和肥大，如在低级别胶质瘤中所见。
IntroductionAlexander disease is a rare disorder of the central nervous system with characteristic symmetric white matter abnormalities with frontal predominance on magnetic resonance (MR) images. Histopathology shows a lack of myelin in the affected white matter, variably interpreted as hypomyelination or demyelination. To increase our insight into the nature of the pathology leading to the MR imaging findings in Alexander disease, we applied serial MR imaging, spectroscopy, magnetization transfer (MT) imaging (MTI), and diffusion tensor imaging (DTI) in six patients with juvenile Alexander disease.MethodsThe MR imaging protocol comprised T1- and T2-weighted spin echo images and fluid-attenuated inversion recovery images. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), and MT ratio (MTR) maps were generated, and MR spectroscopy concentrations were quantified for several metabolites.ResultsMR imaging showed similar cerebral white matter abnormalities in all patients, with only minor increase on prolonged follow-up, despite sometimes serious clinical progression. MR spectroscopy showed highly elevated levels of myo-inositol, lactate, and choline-containing compounds and decreased total N-acetyl-aspartate and N-acetyl-aspartyl-glutamate levels in the abnormal white matter. High values of ADC were observed, and both FA and MTR were attenuated.ConclusionThe sequential MR imaging findings in Alexander disease provide strong evidence against active demyelination as sole explanation for the underlying pathology. An alternative explanation for our spectroscopic, DTI, and MTI findings—which would suggest demyelination—could be hyperplasia and hypertrophy of astrocytes, as seen in low grade gliomas.