目的 总结儿童线粒体脑肌病（ME）急性发病期的临床特点及MRI表现，以提高对该疾病的认识。方法 回顾性分析2018年3月至2021年12月确诊ME的12例患儿的临床及影像学资料。结果 纳入ME 12例，男5例、女7例，中位年龄8岁6个月。主要症状包括卒中样发作（8例，66.7%）和头痛（7例，58.3%）。实验室检查显示血清乳酸增高10例（83.3%），基因检测阳性9例（75%）。11例颅脑MRI平扫发现病变，病变区均表现大片状T1WI低信号、T2WI/T2-FLAIR高信号，其中9例累及皮质及皮质下区域，颞顶枕叶为最易受累区，另2例分别对称性累及基底节/脑干及小脑半球/脑干，6例合并脑萎缩；7例扩散加权成像（DWI）显示6例弥散受限；4例磁共振血管造影（MRA）均表现患侧大脑中动脉分支增多；3例动脉自旋标记（ASL）均显示病变区高灌注；6例磁共振波谱（MRS）提示病变区均可探测到升高的乳酸峰。结论 儿童ME临床症状以卒中样发作最为多见，基因检测少数可为阴性，血清乳酸增高多见但不具特异性；MRI表现具一定特征性，包括单侧颞顶枕叶皮质和皮质下片状T2-FLAIR高信号，急性期病灶弥散受限并高灌注，病变脑组织乳酸峰增高，患侧大脑中动脉分支增多。

Objective To summarize the clinical features and MRI manifestations of the acute onset of mitochondrial encephalomyopathy (ME) in children, so as to improve the understanding of the disease. Methods The clinical and imaging data of 12 children with confirmed ME from March 2018 to December 2021 were retrospectively analyzed. Results Twelve cases of ME were included, 5 males and 7 females, with a median age of 8 years and 6 months. The main symptoms included stroke-like episodes (8 cases, 66.7%) and headache (7 cases, 58.3%); laboratory tests showed increased serum lactate in 10 cases (83.3%), and genetic testing was positive in 9 cases (75%). 11 cases of cranial MRI scanning detected the lesion, and the lesion areas all showed large patchy T1WI low signal, T2WI/T2-FLAIR high signal, of which nine cases involved cortical and subcortical regions, with the temporoparieto-occipital lobe being the most susceptible area, and the other two cases symmetrically involved the basal ganglia/brainstem and cerebellar hemispheres/brainstem, and six cases were combined with cerebral atrophy; diffusion-weighted imaging (DWI) in seven cases showed that the diffusion of the disease was limited in six cases; magnetic resonance angiography (MRA) in four cases showed that there was an increase in the number of branches of the middle cerebral artery of the affected side; arterial spin labelling (ASL) in three cases showed that the lesion area was highly perfused; and MRS in six cases suggested that the lesion area was highly perfused; and spectroscopy (MRS) suggested that elevated lactate peaks were detected in the lesion area in six cases. Conclusions The most common clinical symptoms of ME in children are stroke-like episodes. Genetic testing may be negative in a few cases, and increased serum lactate is common but not specific; MRI has some characteristic features, including unilateral temporoparieto-occipital cortex and subcortical patchy T2-FLAIR high signals, restricted dispersion and hyperperfusion of the lesion in the acute phase, and increased peaks of lactate in the brain tissue of the lesion, with an increase in the branches of the middle cerebral artery on the affected side.