Brain magnetic resonance in the diagnostic evaluation of mitochondrial encephalopathies
Brain magnetic resonance in the diagnostic evaluation of mitochondrial encephalopathies
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DOI：
10.1007/s10540-007-9046-z
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发表时间：
2007-06-01
影响因子：
4
通讯作者：
Cioni, Giovanni
中科院分区：
文献类型：
--
作者：
Bianchi, Maria Cristina;Sgandurra, Giuseppina;Cioni, Giovanni
脑磁共振成像技术是诊断疑似线粒体脑病的重要辅助测试，因为它们提供了有关脑结构和代谢异常的详细信息。尤其是在儿童中，非特定的神经症状很常见，生化结果可能是边缘的，遗传缺陷可能没有被发现。磁共振成像包括常规或结构成像(MRI)和功能或超微结构成像(光谱学，MRS；弥散成像，DWI-ADC；灌注，DSCI-ASL)。其中MRI和MRS是诊断和评估MD的主要工具，本文将重点介绍这两种检查方法。MD的MRI表现非常不同，因为它们取决于代谢性脑缺陷、患者的年龄、疾病的分期和严重程度。尚未发现遗传缺陷与神经影像图像之间的相关性，但MR表现与临床表型之间可能存在一定的联系。常见的MRI信号异常有不同的组合，但最常见的表现可概括为三种主要的MR类型：(I)非特异性；(Ii)特异性；(Iii)脑白质营养不良样。就功能性磁共振技术而言，只有质子磁共振在显示大脑氧化代谢损伤方面发挥重要作用，因为它可以显示乳酸的积累，在1.33ppm呈现双峰。乳酸的评估应始终在脑组织和脑室脑脊液上进行。至于MRI，代谢MRS异常可以有不同的类型，可以识别两种不同的模式：非特异性和特异性。特殊的代谢特征虽然不常见，但却是MD的高度病因学特征。非特定的代谢图谱增加了结构图像的价值，使其能够定义病变负荷并监控对治疗试验的反应。
Brain MR imaging techniques are important ancillary tests in the diagnosis of a suspected mitochondrial encephalopathy since they provide details on brain structural and metabolic abnormalities. This is particularly true in children where non-specific neurologic symptoms are common, biochemical findings can be marginal and genetic defects may be not discovered. MR imaging modalities include conventional, or structural, imaging (MRI) and functional, or ultrastructural, imaging (spectroscopy, MRS; diffusion, DWI-ADC; perfusion, DSCI - ASL). Among them MRI and MRS are the main tools for diagnosis and work up of MD, and this review will focus mainly on them. The MRI findings of MD are very heterogeneous, as they depend on the metabolic brain defects, age of the patient, stage and severity of the disease. No correlation has been found between genetic defects and neuroimaging picture; however, some relationships between MR findings and clinical phenotypes may be identified. Different combinations of MRI signal abnormalities are often encountered but the most common findings may be summarized into three main MR patterns: (i) non-specific; (ii) specific; (iii) leukodystrophic-like. Regarding the functional MR techniques, only proton MRS plays an important role in demonstrating an oxidative metabolism impairment in the brain since it can show the accumulation of lactate, present as a doublet peak at 1.33 ppm. Assessment of lactate should be always performed on brain tissue and on the ventricular cerebral spinal fluid. As for MRI, metabolic MRS abnormalities can be of different types, and two distinct patterns can be recognized: non-specific and specific. The specific metabolic profiles, although not frequent to find, are highly pathognomonic of MD. The un-specific metabolic profiles add value to structural images in allowing to define the lesion load and to monitor the response to therapy trials.