伴有皮层下囊肿的巨脑性脑白质病二例

例1 男,8岁.2009年1月10日以步态不稳、不能独立行走就诊.家长诉患儿出生时正常,1岁后头围明显增大,现头围60 cm,余体格检查未见异常.颅脑MRI示双侧大脑半球弥漫脑白质水肿,伴双侧颞叶前部皮质下大小不等囊肿样改变.     

Megalencephalic leukoencephalopathy with subcortical cysts: report of 4 new cases

Megalencephalic leukoencephalopathy with subcortical cysts or Van der Knapp disease is a rare entity that has recently been identified. It is characterized by the presence of macrocephaly, epilepsy and a slowly progressive spastic cerebellar syndrome. The culprit MLC1 gene is located on chromosome 22. MRI provides valuable data for diagnosis characterized by diffuse white matter lesions with subcortical cysts. We report four cases of megalencephalic leukoencephalopathy with subcortical cysts from two different families.     

Astroblastoma: diffusion MRI, and proton MR spectroscopy.

A patient with grade II astroblastoma is reported. The tumor revealed an inhomogenous enhancement pattern on T1-weighted images after contrast medium. It contained cyst-like structures with high signal in FLAIR images, consistent with presence of viscous material. In spectroscopy, NAA was decreased, and Cho was increased. Peaks belonging to lipids and a combined broad peak belonging to myoinositol and glycine were noticed. In diffusion MRI, the mean apparent diffusion coefficient (ADC) value of intratumoral cyst-like structures was 2.12 x 10(-3)mm(2)/s less than that of CSF. The matrix of the tumor had lower ADC values ranging from 1.19 to 1.25 x 10(-3)mm(2)/s, higher than that of normal cerebral parenchyma.     

Vacuolating megalencephalic leukoencephalopathy with mild clinical course validated by diffusion tensor imaging and MR spectroscopy

We report a case of presumed vacuolating megalencephalic leukoencephalopathy (VML) in a 5-year-old boy that was diagnosed when the patient was 34 months old. The patient presented clinically with megalencephaly and delayed onset of slowly progressive neurologic dysfunction. Serial MR imaging and biochemical analysis were performed to differentiate VML from other disease entities with megalencephaly and leukoencephalopathy of infantile onset. Information obtained with diffusion tensor MR imaging revealed nearly intact white matter anisotropy and vectors in parietal and posterior temporal lobes in which hyperintense abnormality was shown on conventional T2-weighted images, and proton MR spectra showed a significant decrease in n-acetylaspartate-creatine + phosphocreatine ratio.     

Longstanding tectal tumors: proton MR spectroscopy and diffusion MRI findings.

Four patients with longstanding tectal tumors are included in this study. The tectal lesion in a neurofibromatosis type 1 (NF1) patient was due to a hamartoma, while others represented gliomas. On spectroscopy, decreased NAA peaks with resultant decreases in the NAA/Cho, and NAA/Cr ratios were observed in two patients. In three patients, on diffusion MRI the tectal tumors were hyperintense on b=1000 s/mm(2) (heavily diffusion-weighted) images. On apparent diffusion coefficient (ADC) maps, they had high signal, and high ADC values (mean=1.20 x 10(-3)mm(2)/s), compared to normal cerebral parenchyma. Diffusion MRI findings suggested that tectal tumors had a relatively high nuclear to cytoplasmic ratio (high-signal on b=1000 s/mm(2) images) in association with a relatively loose intercellular matrix (high ADC values).     

Neuro-Behcet''s disease: diffusion MR imaging and proton MR spectroscopy

We herein report the case of a 53-year-old woman with Behcet's disease and an acute T2-hyperintense lesion in left side of the pons. Echo-planar "trace" diffusion MR imaging revealed high signal intensity changes at the lesion site on b = 1000 s/mm(2) images, initially suggesting restricted diffusion. On corresponding apparent diffusion coefficient maps, however, the lesion had high signal intensity and high apparent diffusion coefficient values (1.22 x 10(-3) mm(2)/s), compared with the contralateral normal side of the pons (0.86 x 10(-3) mm(2)/s) and compared with the normal temporal white matter (0.80 x 10(-3) mm(2)/s). This was consistent with the presence of increased diffusion, hence vasogenic edema. Proton MR spectroscopy excluded acute infarction. This particular pattern (high signal intensity on b = 1000 s/mm(2) images in association with high apparent diffusion coefficient values) likely represented the acute inflammatory process associated with disrupted brain-blood barrier in the fulminant form of neuro-Behcet's disease. Follow-up examinations 相似文献   

Maple syrup urine disease: diffusion MRI, and proton MR spectroscopy findings.

A 7-month-old boy is reported with acute metabolic crisis of maple syrup urine disease. A reversible intramyelinic type of edema was noted by diffusion MRI which completely resolved in 3 months in accordance with good clinical outcome. Proton MR spectroscopy revealed decreased NAA, and presence of methyl resonances of branched chain amino acids at 0.9 ppm, and lactic acid in the initial examination. After 3 months, NAA returned to normal, and lactic acid disappeared. The methyl resonance of branched chain amino acids, however, remained.     

阿尔茨海默病患者扣带回后部的扩散张量成像与MR波谱的相关性研究

目的 探讨导致阿尔茨海默病(AD)患者DTI改变的生化代谢基础.方法 选取15例轻度AD患者、20例中重度AD患者以及20名年龄相匹配的正常老年志愿者进行DTI和1H-MRS检查.测最双侧扣带回后部皮质区N-乙酰大冬氨酸(NAA)/肌酸(Cr)、胆碱(Cho)/Cr、肌醇(mI)/Cr的相对值.DTI采用EPI序列,生成平均扩散系数(MD)、部分各向异性(FA)参数图.选择与MRS同一层面的DTI参数图将R01分别置于双侧扣带束后部区域,测量MD及FA值.组间比较采用Mann-Whitney U非参数法分析,相关分析采用偏相关分析法控制年龄因素的差异.结果 正常组、轻度及中重度AD组间NAA呈逐步降低的趋势;mI/Cr升高,在轻度AD组(0.68±0.12)与对照组(0.61±0.07)差异有统计学意义(Z=2.911,P<0.01).轻度AD患者左侧扣带束FA值(0.517±0.058)较对照绀(0.549±0.0567)明显降低(Z=2.014,P<0.05),中重度组较轻度AD组右侧扣带束FA值下降,同时MD值增高[轻度组:FA 0.517±0.059,MD(0.726±0.041)×10-3 mm2/s;中重度组:FA 0.432±0.073,MD(0.761±0.057)×10-3 mm2/s,Z值分别为3.216、1.970,P值均<0.05].轻度AD组左侧扣带束FA值与mI/Cr值呈正相关(r=0.586,P<0.05).中重度组右侧扣带束MD值与NAA/Cr中负相关性(r=-0.505,P<0.05).结论 AD患者扣带束后部的白质纤维束完整性降低存在区域件和时域性差异,提示AD患者的白质损害在不同阶段存在不同的主导因素.联合应用MRS和DTI的方法有助于了解AD患者病理进程改变.     

MR imaging and proton MR spectroscopy in adult Krabbe disease

We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical presentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2-weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother. Proton MR spectroscopy showed increased choline and myo-inositol in the affected white matter. In the second family, the clinical presentation differed in that the signs of pyramidal tract involvement were asymmetrical, with concomitant asymmetry on MR images in one. In adults, Krabbe disease may present on MR imaging with selective pyramidal fiber involvement.     

Proton MR spectroscopy demonstration of taurine peaks in megalencephalic leukoencephalopathy with cysts.

Taurine is an amino acid. It has roles in neurotransmitter activities, facilitates synaptic connections, and possesses cyto-protective properties. Normally, it is invisible on proton MR spectroscopy acquired at low field strengths (i.e. 1.5T). In a patient with megalencephalic leukoencephalopathy with cysts (MLC), distinct taurine peaks centered at 3.35ppm were found on hybrid-CSI spectroscopy obtained at 1.5T with a long TE value (i.e. TE=135ms). This suggested increased concentrations of this metabolite in MLC. In this leukoencephalopathy taurine may be linked to a metabolic disturbance related with neurotransmitters associated with a disturbance in synaptic connections, and cyto-protective mechanisms. Further spectroscopic and clinical studies are required to evaluate this observation.     

Prognostic value of brain proton MR spectroscopy and diffusion tensor imaging in newborns with hypoxic-ischemic encephalopathy treated by brain cooling

Introduction

MRI, proton magnetic resonance spectroscopy (¹H-MRS), and diffusion tensor imaging (DTI) have been shown to be of great prognostic value in term newborns with moderate–severe hypoxic-ischemic encephalopathy (HIE). Currently, no data are available on ¹H-MRS and DTI performed in the subacute phase after hypothermic treatment. The aim of the present study was to assess their prognostic value in newborns affected by moderate–severe HIE and treated with selective brain cooling (BC).

Methods

Twenty infants treated with BC underwent conventional MRI and ¹H-MRS at a mean (SD) age of 8.3 (2.8) days; 15 also underwent DTI. Peak area ratios of metabolites and DTI variables, namely mean diffusivity (MD), axial and radial diffusivity, and fractional anisotropy (FA), were calculated. Clinical outcome was monitored until 2 years of age.

Results

Adverse outcome was observed in 6/20 newborns. Both ¹H-MRS and DTI variables showed higher prognostic accuracy than conventional MRI. N-acetylaspartate/creatine at a basal ganglia localisation showed 100 % PPV and 93 % NPV for outcome. MD showed significantly decreased values in many regions of white and gray matter, axial diffusivity showed the best predictive value (PPV and NPV) in the genu of corpus callosum (100 and 91 %, respectively), and radial diffusivity was significantly decreased in fronto white matter (FWM) and fronto parietal (FP) WM. The decrement of FA showed the best AUC (0.94) in the FPWM.

Conclusion

Selective BC in HIE neonates does not affect the early and accurate prognostic value of ¹H-MRS and DTI, which outperform conventional MRI.     

Pantothenate kinase-associated neurodegeneration: MR imaging,proton MR spectroscopy,and diffusion MR imaging findings

We herein report the case of a 15-year-old male patient with pantothenate kinase-associated neurodegeneration. The classic "eye-of-the-tiger" appearance was initially present on the globus pallidi on T2-weighted MR images and had disappeared by the time of the 10-month follow-up examination. Fluid-attenuated inversion recovery images revealed marked hypointensity in the globus pallidi and dentate nuclei and high signal intensity changes in the deep cerebral white matter. Proton MR spectroscopy revealed markedly decreased N-acetylaspartate in the globus pallidi, associated with decreased N-acetylaspartate and increased myoinositol in the deep cerebral white matter. Diffusion MR images (b=1000 s/mm(2)) were negative (normal appearing) for deep cerebral white matter lesions, whereas apparent diffusion coefficient values were slightly increased (1.08-1.12 x 10(-3) mm(2)/s), compared with the apparent diffusion coefficient values from the normal white matter regions. Apparent diffusion coefficient values in the globus pallidi were lower than those in the unaffected thalamus.     

Inflammatory CNS demyelination: histopathologic correlation with in vivo quantitative proton MR spectroscopy.

BACKGROUND AND PURPOSE: The mechanisms behind the demyelination that is characteristic of multiple sclerosis (MS) are still poorly understood. The purpose of this study was to compare immunopathologic findings in demyelinating lesions of three patients with in vivo assessments obtained by quantitative proton MR spectroscopy (MRS). METHODS: Between four and seven stereotactic needle brain biopsies were performed in three young adults with diagnostically equivocal findings for MS. Axonal density, gliosis, blood brain-barrier breakdown, and demyelinating activity of lesions were determined. Combined MR/MRS studies were performed (T1-weighted fast low-angle shot and single-voxel stimulated-echo acquisition mode), and absolute metabolite levels were obtained with a user-independent fitting routine. Metabolite control values were obtained from a group of age-matched healthy volunteers (n = 40, age range, 20-25 years old). Alterations of metabolite levels of control subjects were considered significant when exceeding two standard deviations. RESULTS: There were parallel decreases of N-acetylaspartate (21%-82%) and reductions of axonal density (44%-74%) in demyelinating plaques. Concomitant increases of choline (75%-152%) and myo-inositol (84%-160%) corresponded to glial proliferation. Elevated lactate was associated with inflammation. CONCLUSION: The present data suggest that in vivo MRS indicates key pathologic features of demyelinating lesions.     

Dysembryoplastic neuroepithelial tumors: proton MR spectroscopy,diffusion and perfusion characteristics

Introduction We describe the magnetic resonance (MR) imaging characteristics of dysembryoplastic neuroepithelial tumors (DNT) and discuss their differential diagnosis. Material and methods Proton MR spectroscopy (TE 30 and 136 ms), diffusion-weighted and perfusion images were retrospectively evaluated in 22 patients with pathologically proven DNT (17 male and 5 female, mean age 18.7 years) and 14 control subjects (10 male and 4 female, mean age 16.9 years). The results from the DNT patients and from the control subjects were compared using an independent sample t-test and the degree of correlation was tested by Pearson’s correlation. Results All DNTs were solitary and in a supratentorial cortical or subcortical location (ten temporal, eight frontal and four parietal). They had low-signal on T1-weighted images and high-signal on T2-weighted images without a prominent mass effect. Additionally a cystic appearance (six patients, 27.3%), cortical dysplasia (six patients, 27.3%) and contrast enhancement (four patients, 18.2%) were also noted. No significant differences were detected in NAA/Cho, NAA/Cr, NAA/Cho+Cr or Cho/Cr ratios between DNT and normal brain. DNTs had a significantly higher mI/Cr ratio and apparent diffusion coefficient (ADC) values and lower cerebral blood values than normal parenchyma (P < 0.001). ADC had the highest correlation with the diagnosis of DNT (r = 0.996) followed by relative cerebral blood volume (rCBV) (r = −0.883) and mI/Cr ratio (r = 0.663). Conclusion Proton MR spectroscopy, diffusion-weighted and perfusion imaging characteristics of DNTs provide additional information to their MR imaging findings. The MR spectrum showing a slight increase in mI/Cr ratio, and higher ADC and lower rCBV values than normal parenchyma help to differentiate DNTs from other cortical tumors, which had higher rCBV and lower ADC values than DNTs. This work was presented at the ASNR 45th Annual Meeting 2007.     

3T MR with diffusion tensor imaging and single-voxel spectroscopy in giant axonal neuropathy

Magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), and MR spectroscopy (MRS) data were obtained in a patient with giant axonal neuropathy (GAN) and compared to a control group. Fractional anisotropy (FA) and apparent coefficient diffusion (ADC) data were obtained from specific white matter tracts including the corticospinal tracts (CST), corpus callosum (CC), optic radiations (OR), and middle cerebellar peduncle (MCP). Analysis of the MRS was performed. DTI parameters and MRS results were correlated with the neuropathological findings described for GAN. No significant difference between the FA of the CC of the patient and the control group was found. However, there was a significant difference between the FA of the CST, OR, and MCP of the patient and the control group. The ADC values for all tracts of the patient were significantly increased. N-acetylaspartate to creatine (NAA/Cr) and N-acetylaspartate to choline (NAA-Cho) (choline) metabolite ratios were slightly decreased and choline to creatine (Cho/Cr) and myo-inositol to creatine (Ins/Cr) metabolite ratios were increased in the parietal gray and white matter of the patient as compared to the control group. Cerebellar involvement was less evident. The DTI and MRS findings suggest myelin and axonal damage.     

MR imaging, MR spectroscopy, and diffusion tensor imaging of sequential studies in neonates with encephalopathy

BACKGROUND: Although the imaging, spectroscopic, and diffusion characteristics of brains of infants with neonatal encephalopathy have been described, the time course during which these changes evolve is not clear. The results of sequential MR imaging studies--including anatomic MR imaging, proton MR spectroscopy, and diffusion tensor imaging (DTI)--of 10 patients enrolled prospectively in a study of neonatal encephalopathy are reported to help to clarify the time course of changes in different brain regions during the first 2 weeks of life. METHODS: Ten neonates were prospectively enrolled in a study of the evolution of MR findings in neonatal encephalopathy and were studied 2 (8 patients) or 3 (2 patients) times within the first 2 weeks of life. The MR examination included spin-echo T1 and T2-weighted images, DTI, and long echo time (288 milliseconds) proton MR spectroscopy. Diffusion parameters (diffusivity [D(av)], fractional anisotropy [FA], and individual eigenvalues) were calculated for 10 1-cm2 regions of interest in each hemisphere that were placed based on anatomic landmarks. D(av) and FA were then measured manually in the same areas on a workstation. Metabolite ratios (NAA/Ch, Cr/Ch, Cr/NAA, Lac/Ch, and Lac/NAA) were calculated in 7 regions of interest. Imaging appearance, diffusion parameters, and metabolite ratios were then evaluated longitudinally (comparing with other studies on the same patient at different times) and cross-sectionally (comparing all studies performed on the same postnatal day). RESULTS: In most of the patients a characteristic evolution of DTI and MR spectroscopy parameters was seen during the first 2 weeks after birth. Although the anatomic images were normal or nearly normal on the first 2 days after birth in most patients, abnormalities were detected on DTI (both visually and by quantitative interrogation of D(av) maps) and proton MR spectroscopy (abnormal metabolite ratios). These parameters tended to worsen until about day 5 and then normalize, though in several patients abnormal metabolite ratios persisted. Of interest, as areas of abnormal diffusivity pseudonormalized within one region of the brain they would develop in other areas. Therefore, the pattern of injury looked very different when imaging was performed at different times during this evolution. CONCLUSION: Patterns of injury detected by standard anatomic imaging sequences, DTI sequences, and proton MR spectroscopy varied considerably during the first 2 weeks after injury. The appearance of new areas of reduced diffusion simultaneous with the pseudonormalization of areas that had reduced diffusion at earlier times can result in an entirely different pattern of injury on diffusivity maps acquired at different time points. Awareness of these evolving patterns is essential if studies are performed and interpreted during this critical period of time.     

正常人颈髓不同节段磁共振扩散张量成像分析

目的 定量分析正常人颈髓不同节段弥散张量成像(diffusion tensor imaging,DTI)的参数值及其相关性.方法 使用单次激发自旋回波平面回波(single-shot spin echo echo-planar image,SS-SE-EPI)序列、12个扩散敏感梯度磁场方向、b值为0 s/mm2和500 s/mm2,对20例健康志愿者行颈髓DTI检查,测量颈髓各节段各向异性分数(fractional anisotropy,FA)值与表观扩散系数( apparent diffusion coefficient,ADC)值,同时感兴趣区(ROI)分别选择16 mm2和26 mm2.结果 纤维示踪图显示颈髓纤维束连续,粗细均匀;颈髓各节段FA值之间存在差异,C2/3椎间盘及C3椎体平面颈髓FA较余节段高(P<0.05);而各节段颈髓ADC值之间差异无统计学意义(P>0.05).ROI面积取值不同,所测得的颈髓DTI参数值差异无统计学意义(P>0.05).颈髓FA值与ADC值之间呈负相关(P<0.05).结论 正常人颈髓不同节段FA值存在差异,ADC值无明显差异;ROI面积不同,所测得参数值无明显差异;颈髓FA值与ADC值呈负相关.