Metabolic heterogeneity at the level of the anterior and posterior commissures.

Multislice, 2D proton spectroscopic imaging was performed in six healthy volunteers at long echo time (TE = 280 msec). The center of the most inferior of three slices was placed directly at the level of the line connecting the anterior and posterior commissures. Significant regional variations in metabolite levels were observed. In particular, based on statistical analysis, levels of choline were significantly high in insular cortex, thalamus, and centrum semiovale compared to other brain regions such as parietal or occipital gray and white matter. NAA levels were highest in the centrum semiovale white matter, while creatine levels were relatively constant. Globus pallidus exhibited lower signal intensities and increased linewidths for all metabolites. No spectra could be obtained from the inferior frontal lobe because of field inhomogeneity. These data show that the metabolism, and perhaps the underlying cellular composition, of thalamus and insular cortex appears to be different from other neocortical gray matter. Normal regional variations in the brain spectra should be considered when evaluating pathological conditions.     

儿童异染性脑白质营养不良的MRI表现

目的 观察异染性脑白质营养不良（MLD）的特征性表现。方法 回顾分析我院经生化检查证实的MLD共11例,观察MRI上脑内白质病变的部位和特殊结构（白质纤维束、丘脑、胼胝体）受累的情况。结果 11例均表现为双侧脑室周围白质T2WI对称高信号,10例双侧半卵圆中心T2WI对称高信号;4例累及皮层下白质。8例累及胼胝体膝部,9例累及压部,两者同时受累为8例;7例累及内囊后肢,4例累及外囊,4例累及脑干皮质脊髓束（3例中脑,1例桥脑）。1例累及小脑白质,8例半卵圆中心T2WI有虎纹征,8例T2WI丘脑呈低信号;5例侧脑室扩大,1例全脑萎缩。结论 MLD的典型表现为双侧半卵圆中心和侧脑室周围白质T2WI对称高信号,早期皮层下白质不受累,胼胝体膝部和压部受累为重要征象;另外征象包括脑干皮质脊髓束和内、外囊受累及虎纹征。     

Quantitative proton magnetic resonance spectroscopic imaging: regional variations in the corpus callosum and cortical gray matter

PURPOSE: To evaluate regional variations of metabolite concentrations in normal adult brain cortical gray matter regions, and the genu and splenium of the corpus callosum, using proton magnetic resonance spectroscopic imaging (MRSI). MATERIALS AND METHODS: Quantitative, multislice proton MRSI (TR/TE = 2000/280 msec) was performed in 12 normal human volunteers (age = 39 +/- 6 years, 7 male). Metabolite concentrations in selected cortical gray matter regions and the corpus callosum were estimated using the phantom replacement methodology. RESULTS: Frontal and parietal gray matter (PGM) showed strong differences in choline-containing compound (Cho) concentrations; in particular, Cho was higher in mesial frontal gray matter than in both dorsolateral prefrontal cortex (P < 0.0005) and PGM (P < 0.004). In contrast, both N-acetylaspartate (NAA) and creatine (Cr) were relatively uniformly distributed in the cortical gray matter regions evaluated. Significant metabolic differences were found between the genu and splenium of the corpus callosum. Cho concentrations were significantly higher in genu than splenium (P < 0.005), while Cr was lower (P < 0.004). NAA showed a trend to be higher in the splenium than the genu (P = 0.05). CONCLUSION: Metabolite concentrations, particularly Cho, showed strong regional variations both within cortical gray matter regions and between the genu and splenium of the corpus callosum. Mesial frontal regions showed the highest Cho signals. Differences in spectra presumably reflect underlying changes in structure and cellular composition. Normal spectral variations should always be considered when evaluating pathology within those brain regions.     

液体衰减反转恢复脉冲对DWI图像信噪比及ADC值的影响

目的:探讨液体衰减反转恢复(FLAIR)脉冲序列对扩散加权图像(DWI)信噪比及ADC值的影响.方法:17名健康志愿者在3.0T MRI上行常规轴位DWI和FIAIR-DWI扫描,分别测量两侧半卵圆区、扣带回、丘脑及胼胝体膝部和压部的ADC值及DWI信号强度,同时测量基底节层面的DWI信号强度作为噪声,计算以上5个部位DWI图像的信噪比.结果:扣带回和胼胝体压部的ADC值在施加FLAIR脉冲后显著下降,而半卵圆区、丘脑及胼胝体膝部在施加FLAIR脉冲前后无明显变化;5个部位的DWI图像信噪比在施加FLAIR脉冲后均显著下降(P＜0.01).结论:FLAIR显著提高了脑组织和脑脊液ADC值测量的准确性,但是也明显降低了DWI图像的信嗓比.     

The corpus callosum, a unique white-matter tract: anatomic features that may explain sparing in Binswanger disease and resistance to flow of fluid masses

The corpus callosum exhibits several unusual features: arteriole-venule pairs, perivascular fibrous alae, and recurrent companion arterioles. These and other anatomic aspects are compared and contrasted with those of the centrum semiovale. Vascular changes occurring with aging or hypertension, commonly seen in the centrum semiovale, rarely develop in the corpus callosum. The vascular supply to the central zone of the genu and body of the corpus callosum, via short penetrating arterioles, is similar to that of the cerebral cortex, whereas the vascular supply to the extreme lateral corpus callosum, centrum semiovale, and basal ganglia is substantially carried by long end-arteries. When observed critically, the anatomic features of the corpus callosum may explain such clinically observed phenomena as its relative resistance to flow of fluid masses, radiation injury, Binswanger disease, lacunar infarction, hypoxia, and hypoperfusion.     

MR of childhood metachromatic leukodystrophy.

PURPOSETo investigate the MR findings of childhood metachromatic leukodystrophy (MLD).METHODSNine MR imaging studies in seven children (five girls and two boys, 10 to 32 months old) with MLD were evaluated retrospectively for the extent and progression of white matter abnormalities and the presence of contrast enhancement.RESULTSAll seven cases showed symmetric, confluent high signal intensity on T2-weighted images in the periventricular white matter and centrum semiovale. A posterior predominance of white matter abnormalities was noted in all cases. Although initially spared from demyelination in all cases, in one case, the subcortical U fibers were later involved in demyelination of follow-up MR studies. Other sites of involvement were the genu (n = 5) and splenium (n = 6) of the corpus callosum, the posterior limbs of the internal capsule (n = 5), the descending pyramidal tracts (n = 4), the claustrum (n = 4), and the cerebral white matter (n = 2); diffuse brain atrophy was seen in two cases. No enhancement of the lesion was seen on any of the five postcontrast examinations. A "tigroid" pattern, previously described in cases of Pelizaeus-Merzbacher disease, was noted in the centrum semiovale in six cases.CONCLUSIONIn late-infantile MLD, demyelination is more prominent in the occipital region. In addition to demyelination of the periventricular white matter, common manifestations include a "tigroid" pattern and involvement of the corpus callosum, the internal capsule, and the corticospinal tract.     

3.0T MR弥散梯度编码方向对脑组织FA值测量的影响

目的:探讨超高场强MR下弥散张量成像中弥散梯度编码方向对脑组织弥散各向异性分数(FA)的影响。方法:使用3种不同的弥散梯度编码方向(6、13和21个)在3.0T MRI上对14名健康志愿者进行头颅弥散张量成像(DTI)。在FA图上分别测量两侧半卵圆中心、胼胝体膝部、胼胝体压部、两侧内囊、丘脑及桥脑FA值,并进行统计学分析。结果:胼胝体压部FA值最高,其次为胼胝体膝部、内囊和桥脑,丘脑FA值最低。随着弥散梯度编码方向的增加,FA图质量提高,对白质纤维束细节的显示也更清楚,尤其是对脑干结构的分辨,但成像时间延长;3种不同弥散梯度编码方向的DTI扫描方案所观察到的半卵圆中心、胼胝体膝部、胼胝体压部、内囊、丘脑及桥脑的FA值不存在统计学显著性差异。结论:超高场MRI弥散梯度编码方向数目对脑组织FA值的测量无显著性影响,在临床运用中可根据患者状况选择弥散梯度编码方向,以提高DTI检查的成功率。     

Evaluation of brain metabolism in steno-occlusive carotid artery disease by proton MR spectroscopy: a correlative study with oxygen metabolism by PET.

Carotid occlusive diseases may cause ischemic changes in both the gray matter and the white matter as a result of hemodynamic compromise. To validate the use of proton magnetic resonance spectroscopy (MRS) in evaluating the carotid occlusive diseases, we compared changes in peaks of choline, in the sum of creatine and phosphocreatine, and in N-acetyl-aspartate (NAA) of the white matter with cortical oxygen metabolism measured by PET. METHODS: Eleven patients with unilateral steno-occlusive carotid artery disease underwent PET and MRS. Ten age-matched healthy volunteers underwent MRS. No subjects had cortical infarction. MRS was performed bilaterally in the centrum semiovale. Regional blood flow, regional metabolic rate of oxygen (rCMRO2), and regional oxygen extraction fraction (rOEF) of the cerebral cortex were measured by the steady-state method with 15O gas. RESULTS: The asymmetry index of the ratio of NAA to the sum of creatine and phosphocreatine (NAA/Cr) correlated positively with the asymmetry index of rCMRO2 (r = 0.77; P < 0.01). Because rCMRO2 is a marker of tissue viability, the NAA/Cr of the centrum semiovale may reflect viable neuronal cells. The asymmetry index of the ratio of choline to the sum of creatine and phosphocreatine (Cho/Cr) showed a significant positive correlation with the asymmetry index of rOEF (r = 0.65; P < 0.05). All but 1 patient with an increased Cho/Cr (>1.03) showed an increase in rOEF of the ipsilateral cortex (>0.56). This finding may indicate membrane damage caused by ischemia, because the centrum semiovale is the deep watershed zone. CONCLUSION: The metabolic changes in the centrum semiovale detected by proton MRS reflect a hemodynamically compromised state and are useful in evaluating tissue viability.     

急性一氧化碳中毒脑损伤的磁共振扩散张量成像

目的：利用磁共振扩散张量成像(DTI )评估急性一氧化碳(CO)中毒患者的脑结构损伤情况。方法25例急性(5.0 d±1.44 d) CO 中毒患者和37例性别、年龄、利手、受教育程度匹配的健康志愿者进行 DTI 扫描,获得扩散张量纤维束成像(DTT)图像,并分别测量双侧小脑半球(齿状核)、黑质、海马、额叶白质(侧脑室前角前下方、侧脑室体部上方)、尾状核头、苍白球、丘脑、内囊前肢、内囊后肢、枕叶白质(视中枢)、顶叶白质(侧脑室体部上方)及胼胝体膝部、压部共26个感兴趣(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值,进行组间配对 t 检验。结果病患组双侧苍白球、双侧内囊前肢、双侧黑质、右侧小脑、左侧额叶下部白质、右额叶上下部白质、胼胝体膝部的 FA 值显著低于对照组(P <0.05)。病患组右侧黑质、左侧苍白球的 ADC 值显著降低(P <0.05),病患组右额叶上下部白质及双侧枕叶白质 ADC 值显著升高(P <0.05)。结论急性 CO 中毒患者广泛脑微结构受损,提示脑微结构的原发损伤可能是 CO 中毒迟发性脑病潜在的病理生理基础。     

遗传性弥漫性脑白质病变合并轴索球样变的磁共振特征附2例报告

目的探讨遗传性弥漫性脑白质病变合并球状轴索(HDLS)的磁共振特点,以加深对该病的理解和认识。方法报道2例确诊为集落刺激因子1受体基因突变的HDLS患者的临床诊疗经过,结合文献对其磁共振不同序列的影像学特征进行讨论及分析。结果2例均为青年,慢性起病,亚急性进展,临床表现为体重减轻,口齿不清,反应迟钝,近记忆力减退及肢体运动功能障碍。头颅MRI表现为双侧侧脑室旁、半卵圆中心对称性白质病变、DWI显示弥散受限,MRS提示病变区域NAA峰减低,Cho峰增高,2例均有不同程度脑萎缩,以顶叶及胼胝体体部较明显。结论HDLS为罕见疾病,临床表现多样,容易误诊,双侧侧脑室体旁、半卵圆中心区多发持续性DWI高信号伴有Cho峰增高为本病较特异性的影像学表现,有助于HDLS的早期诊断。     

Acute and chronic brain infarcts on MR imaging in a 20-year-old woman with acute posterior multifocal placoid pigment epitheliopathy

A 20-year-old woman recently diagnosed with acute posterior multifocal placoid pigment epitheliopathy developed headaches, weakness, and paresthesias. MR imaging of the brain revealed an acute infarct (demonstrated by diffusion-weighted images) in the head of the right caudate nucleus, a chronic infarct with encephalomalacia in the body of the corpus callosum, and multiple foci of abnormal signal intensity in the white matter of the centrum semiovale.     

Delayed encephalopathy after acute carbon monoxide intoxication: MR imaging features and distribution of cerebral white matter lesions.

Magnetic resonance (MR) images obtained in 15 patients with delayed encephalopathy after acute carbon monoxide (CO) intoxication were reviewed. Images had been obtained 4-9 weeks after exposure to CO, during the relapse of neuropsychiatric symptoms after initial recovery. Bilateral symmetric confluent high signal intensity in the periventricular white matter and centrum semiovale was seen on long-repetition-time images (n = 15). The high intensity extended into the corpus callosum (n = 11), subcortical U fibers (n = 12), and external (n = 9) and internal (n = 7) capsules. Bilateral diffuse low-intensity signal in the thalamus and putamen on T2-weighted images, suggesting iron deposition, was demonstrated in 10 patients. Bilateral ischemia or necrosis of the globus pallidus was seen in nine patients. In three of four patients with follow-up MR imaging studies, a decrease in extent and signal intensity of white matter lesions accompanied lessening of clinical symptoms. These results suggest that the main pathologic feature of delayed encephalopathy associated with CO intoxication is a reversible demyelinating process of the cerebral white matter.     

Subcortical gray matter N-acetylaspartate reduction in two cases of vascular dementia

Many of the previous studies of vascular dementia using proton magnetic resonance (MR) spectroscopy had been carried out on white matter. However, no proton spectroscopic data of the subcortical gray matter are available in such disease. We report two cases suffering from vascular dementia, with an unilateral N-acetylaspartate (NAA) decrease on subcortical gray matter. This significant reduction in NAA ratios was associated with an increase of choline on the ipsilateral centrum semiovale. We discuss the pathophysiology of these cases.     

Normal brain maturation during childhood: developmental trends characterized with diffusion-tensor MR imaging.

PURPOSE: To characterize the maturational changes in water diffusion within central gray matter nuclei and central white matter pathways of the human brain by using diffusion-tensor magnetic resonance (MR) imaging. MATERIALS AND METHODS: Retrospective analysis of normal MR examination findings in 153 subjects (age range, 1 day to 11 years) referred for clinical neuroimaging was performed. All studies included diffusion tensor-encoded echo-planar MR imaging. Isotropic diffusion coefficient (D) and diffusion anisotropy (A(sigma)) were measured in the corpus callosum, internal capsule, caudate nucleus, lentiform nucleus, and thalamus. RESULTS: exhibited biexponential decay with age in gray and white matter regions, except for monoexponential decay in the genu of the corpus callosum. There was a steep nonlinear increase of A(sigma) in white matter tracts that paralleled the time course of the decline in D. In basal ganglia, only a small linear increase in A(sigma) was observed in patients. A(sigma) changes in the thalamus were intermediate between basal ganglia and white matter structures. CONCLUSION: Changes in magnitude and anisotropy of water diffusion follow stereotypical time courses during brain development that can be empirically described with multiexponential regression models, which suggests that quantitative scalar parameters derived from diffusion-tensor MR imaging may provide clinically useful developmental milestones for brain maturity.     

Unusual pattern of leukoencephalopathy after morphine sulphate intoxication

We report a 14-year-old girl with an unusual pattern of leukoencephalopathy after intentional intoxication with morphine sulphate tablets. Toxicological analysis showed exceedingly high levels of morphine and its metabolites. MRI disclosed a leukoencephalopathy with high signal from the centrum semiovale, corpus callosum and cerebellar white matter on T2-weighted images. These findings could be only partially explained by a hypoxic-ischaemic event; neurotoxic effects must be considered in this atypical leukoencephalopathy. Received: 3 August 1999 Accepted: 3 April 2000     

常染色体显性遗传性脑动脉病伴皮层下梗死和白质脑病患者的MR定量指标及其与临床的关系

目的 对常染色体显性遗传性脑动脉病伴皮层下梗死和白质脑病(CADASIL)患者的白质高信号和脑体积进行定量分析,并探讨其与临床的关系.方法 15例通过病理检查确诊为CADASIL的患者进行常规MR扫描,统计脑半卵圆中心、内囊后肢、外囊、胼胝体和颞极白质受病变累及情况.利用计算机后处理软件计算标准化颅脑体积和白质高信号占颅脑体积的百分比,并与年龄、美国国立卫生研究院卒中量表(NIHSS)和简易精神状态检查(MMSE)量表评分进行Spearman相关性分析.结果 CADASIL患者的白质病变累及部位依次为:半卵圆中心(13/15)、颞极白质(10/15)、外囊(8/15)、内囊后肢(5/15)、胼胝体(4/15).白质高信号占颅脑体积的百分比为(5.7±1.4)%,标准化颅脑体积为(1602±58)×103mm3.年龄与标准化颅脑体积呈负相关(r=-0.555,P＜0.05);白质高信号百分比与NIHSS、MMSE量表评分分别呈正、负相关(r=0.522,P＜0.05;r=-0.679,P＜0.01);标准化颅脑体积与NIHSS评分呈负相关(r=-0.624,P＜0.05).结论 CADASIL患者的白质高信号和脑体积可以定量测量,这两种影像学指标可以在一定程度上反映患者的病情.白质高信号的发展可能预示患者认知功能的下降.     

Gray matter and white matter abnormalities in online game addiction

Online game addiction (OGA) has attracted greater attention as a serious public mental health issue. However, there are only a few brain magnetic resonance imaging studies on brain structure about OGA. In the current study, we used voxel-based morphometry (VBM) analysis and tract-based spatial statistics (TBSS) to investigate the microstructural changes in OGA and assessed the relationship between these morphology changes and the Young's Internet Addiction Scale (YIAS) scores within the OGA group. Compared with healthy subjects, OGA individuals showed significant gray matter atrophy in the right orbitofrontal cortex, bilateral insula, and right supplementary motor area. According to TBSS analysis, OGA subjects had significantly reduced FA in the right genu of corpus callosum, bilateral frontal lobe white matter, and right external capsule. Gray matter volumes (GMV) of the right orbitofrontal cortex, bilateral insula and FA values of the right external capsule were significantly positively correlated with the YIAS scores in the OGA subjects. Our findings suggested that microstructure abnormalities of gray and white matter were present in OGA subjects. This finding may provide more insights into the understanding of the underlying neural mechanisms of OGA.     

Reproducibility over a 1-month period of 1H-MR spectroscopic imaging NAA/Cr ratios in clinically stable multiple sclerosis patients

N-acetylaspartate/creatine (NAA/Cr) ratios, assessed with proton magnetic resonance spectroscopy, are increasingly used as a surrogate marker for axonal dysfunction and degeneration in multiple sclerosis (MS). The purpose of this study was to test short-time reproducibility of NAA/Cr ratios in patients with clinically stable MS. In 35 MS patients we analysed NAA/Cr ratios obtained with (1)H-MR spectroscopic imaging at the centrum semiovale either with lateral ventricles partially included (group 1; n=15) or more cranially with no ventricles included (group 2; n=20). To test short-term reproducibility of the NAA/Cr measurements, patients were scanned twice 4 weeks apart. We determined mean NAA/Cr and Cho/Cr ratios of 12 grey matter and 24 white matter voxels. Mean NAA/Cr ratios of both the white and grey matter did not change after 4 weeks. Overall 4-week reproducibility of the NAA/Cr ratio, expressed as coefficient of variation, was 4.8% for grey matter and 3.5% for white matter. Reproducibility of cranial scanning of the ventricles was slightly better than with cerebrospinal fluid included. Our study shows good short-term reproducibility of NAA/Cr ratio measurements in the centrum semiovale, which supports the reliability of this technique for longitudinal studies.     

佩梅病的头颅MRI表现及其与临床、基因分型的关系

目的 探讨佩梅病( PMD)患儿的头颅MRI特点,以及与临床及基因分型的关系.方法 回顾性分析16例经临床诊断为佩梅病患儿的临床和影像资料.患儿均为男性,年龄5个月至9岁8个月.由儿科神经医师对患儿的症状和体征进行检查,将其按照临床症状进行临床分型.由影像科医师对头颅MRI图像的特点进行分析,病灶的位置包括苍白球、锥体束、胼胝体、小脑白质、半卵圆中心,判断大、小脑是否萎缩、是否有“豹纹征”.结果 临床诊断经典型佩梅病8例,中间型7例,先天型1例.16例佩梅病患儿MRI均以广泛的脑白质髓鞘化延迟为特点,病灶累及苍白球13例、锥体束7例、胼胝体11例、小脑白质7例、半卵圆中心12例、脑萎缩5例、小脑萎缩1例,5例有“豹纹征”.锥体束和小脑白质受累在点突变患儿中多见;临床症状较重的中间型及先天型患儿出现小脑白质病变频率较高;“豹纹征”多见于经典型患儿,提示患儿的髓鞘化程度相对较高.结论 佩梅病患儿的头颅MRI具有典型的影像特点,其影像学表现与临床分型和基因突变类型有一定的相关性.     

枫糖尿病的临床和脑磁共振成像特点

目的：探讨枫糖尿病(MSUD)脑 MRI 表现及其诊断价值。方法经气相色谱、串联质谱、基因确诊9例 MSUD 患儿,通过 MRI 了解脑损伤特点,结合临床表现、生化特点进行分析,重点分析影像学表现。结果9例患儿于生后3 d~6岁发病,临床表现缺乏特异性,主要是喂养困难、昏睡、反应差、抽搐发作、智力下降。患者血亮氨酸、异亮氨酸、缬氨酸显著增高。9例均行 MRI 检查,2例同时行氢质子磁共振波谱(1 H-MRS)检查。脑 MRI 显示小脑半球、小脑脚、大脑脚、脑干、苍白球各有5例受累,4例累及丘脑、内囊后肢,3例累及半卵圆中心,2例同时合并胼胝体、枕部、颞叶深部、额叶、顶叶信号异常。受累的区域均表现为 T1稍低、T2稍高信号,而在扩散加权成像(DWI)上表现为明显高信号。1例影像正常。2例1 H-MRS 于0.9 ppm 处均未见甲基峰。结论MSUD 临床表现缺乏特异性,MRI 特点主要是生后已经开始髓鞘化的脑白质区域如小脑半球、内囊后肢、脑干内、小脑脚、大脑脚等在 DWI 上表现为明显高信号。