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1.
目的:探讨fMRI在定性和定量评估慢性酒精中毒性脑病(CAE)患者脑白质损伤(WMLs)中的应用价值。方法:选择我院诊断的50例CAE患者作为观察组;另选择50例无饮酒史脑病患者作为对照组。采用1.5 T MRI扫描仪,行T1WI、T2WI、液体衰减反转恢复(FLAIR)、DWI、DTI及扩散峰度成像(DKI)序列。根据Fazekas方法将WMLs的脑室旁高信号(PVH)和深部白质高信号(DWMH)分为4级(0~3级)。比较2组WMLs阳性率、DTI定量参数各向异性(FA)和平均扩散率(MD),以及DKI参数平均峰度(MK),分析观察组WMLs分级与FA、MD和MK值的关系。结果:观察组50例中45例表现为脑白质脱髓鞘病变,侧脑室周围多发斑片状T1WI低信号、T2WI高信号,压水像呈高信号,边界模糊,无明显占位效应,病灶长轴垂直于侧脑室;30例表现为胼胝体变性呈不均匀T1WI低信号、T2WI高信号,T2 FLAIR高信号;26例DTI示胼胝体纤维束不同程度稀疏、断裂。观察组50例中,表现为PVH 25例,DWMH 20例,总WMLs阳性率为90.0%(45/50);对照组50例中,表现为PVH 2例,DWMH 2例,总WMLs阳性率为8.0%(4/50)。观察组WMLs阳性率显著高于对照组(P<0.05)。观察组FA值较对照组降低,MD和MK值升高,差异均有统计学意义(均P<0.05)。观察组PVH 3级患者FA值低于1~2级,MD和MK值升高(均P<0.05);DWMH 3级患者FA值低于1~2级,MD和MK值升高(均P<0.05)。结论:fMRI尤其是DTI和DKI可定性和定量评估CAE患者WMLs,有较好的诊断敏感度和准确性。  相似文献   

2.
Proliferative retinopathy: absence of white matter lesions at MR imaging   总被引:3,自引:0,他引:3  
One form of retinopathy associated with diabetes is a proliferative small vessel process thought to be mediated by biochemical, hemodynamic, and endocrinologic factors. The authors conducted a prospective study to determine whether patients with diabetes who had proliferative retinopathy had evidence of intracranial microangiopathy visible at magnetic resonance (MR) imaging. Twenty-five patients under 40 years of age with proliferative retinopathy and insulin-dependent diabetes mellitus and 10 age-matched control subjects were studied with MR imaging. Axial images were reviewed by two neuroradiologists for the presence of white matter foci of high signal intensity. No patients demonstrated evidence of these foci. There was no evidence of ischemic foci in any of the patients (all patients were neurologically asymptomatic). The vasculopathy associated with proliferative retinopathy does not appear to affect the intracranial circulation to the extent detectable with MR imaging. The presence of white matter foci of high signal intensity or ischemic changes in the brains of insulin-dependent diabetic patients under 40 years of age should not be attributed to diabetic vasculopathy. Other causes should be considered.  相似文献   

3.
MR imaging of chronic alcoholism.   总被引:3,自引:0,他引:3  
We evaluated the brain lesions of patients with chronic alcoholism (n = 34) in comparison with age- and sex-matched controls (n = 40) by MR imaging. T1-weighted sagittal and axial images and T2-weighted axial images were obtained with a 0.5 T superconducting MR unit. Various brain measurements were then performed, and the presence of regions of abnormal signal intensity was also compared between the two groups. The brain measurements revealed significant cerebral atrophy (characterized by lateral and 3rd ventricular dilatation, and widening of the interhemispheric fissure) as well as significant cerebellar atrophy (represented by 4th ventricular dilatation) in the alcoholic group. These changes were more prominent in patients in their fifties and sixties than in those aged in the thirties and forties. Focal hypointense lesions were observed in 20.6% of the alcoholics and in 5% of the controls (p less than 0.01), while focal hyperintense lesions were observed in 61.8% of the alcoholics and in 20% of the controls (p less than 0.001). The severity of these MR findings correlated well with the age of the patients. These observations suggest that alcohol is an important promoter of brain aging.  相似文献   

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Twenty-three pediatric patients with white matter abnormalities on MR images were evaluated retrospectively to assess the contribution of MR compared with CT in diagnosing these conditions. In addition, the MR findings in major categories of white matter diseases were analyzed for sensitivity in detecting the presence of an abnormality. White matter disease categories included demyelinating disease (five cases), dysmyelinating disease (eight cases), developmental white matter abnormalities (four cases), and white matter abnormalities of unknown origin (idiopathic) (six cases), as seen on long TR images. We found that MR is not more sensitive than CT in detecting disease in the demyelinating or dysmyelinating categories, although it is more sensitive than CT in detecting the degree of disease present. In cases of developmental delay, MR is distinctly more useful than CT in demonstrating abnormalities of myelination. And in the idiopathic group, MR detected the presence of focal white matter abnormalities on long TR images in children with neurologic complaints and normal CT. MR may serve to redefine and broaden the spectrum of reported imaging abnormalities in pediatric patients.  相似文献   

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MR imaging of compact white matter pathways   总被引:5,自引:0,他引:5  
A prominent decreased signal intensity can be seen in many of the heavily myelinated, compact fiber pathways of the brain on T2-weighted spin-echo MR images (TR = 2500 msec, TE = 80 msec). These areas include the anterior commissure, internal capsule, optic tract and radiations, fornix, mammillothalamic tract, superior frontooccipital fasciculus, cingulum, corpus callosum, uncinate fasciculus, and superior longitudinal fasciculus. All these pathways could be identified in normal subjects 3 years old and older when 1.5-T axial and coronal images of 50 adults and 17 children were reviewed. Correlation of the in vivo and postmortem MR appearance of two human brains with Perls and Luxol fast blue stains indicates that the short T2 reflects heavy myelination and fiber density, not iron deposition. This is in contrast to the short T2 signal seen in the subcortical U fibers and deep nuclei of the brain that result from iron deposition. These pathways also differ from areas of brain iron accumulation in that (1) they may appear as areas of short T1 on partial-saturation or inversion-recovery pulse sequences and (2) they can be seen with regularity in all patients over 3 years of age. It is important to distinguish between the effect of the myelin sheath and the effect of brain iron on the T2 relaxation values seen in the normal brain since both result in shortened T2 relaxation. The importance of the role of these fiber tracts in disease processes and in modifying the spread of vasogenic edema and tumor needs further investigation.  相似文献   

7.
大脑白质磁共振弥散张量纤维束成像研究   总被引:2,自引:1,他引:1  
大脑白质纤维(white matter fiber,WMF)是指位于两侧大脑半球皮质和基底核之间的大脑组织,又称髓质(medullary substance),是由进出大脑半球和联络两侧半球的神经纤维组成。大脑白质纤维结构复杂,功能重要,其发生病变或受到浸润均将引起严重的临床症状。在磁共振(magnetic reso  相似文献   

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PURPOSE: To determine the magnetization transfer features of progressive multifocal leukoencephalopathy (PML) and human immunodeficiency virus (HIV)-associated white matter lesions (WML) (hereafter, HIV-WML) on magnetic resonance (MR) images obtained in patients with acquired immunodeficiency syndrome (AIDS). MATERIALS AND METHODS: Conventional MR imaging and magnetization transfer MR imaging were performed in 21 AIDS patients with 42 areas of white matter hyperintensity on MR images (13 patients had 25 PML lesions, eight patients had 17 WML). The magnetization transfer ratio was calculated for each lesion. RESULTS: Compared with normal-appearing white matter (magnetization transfer ratio = 47.9%), both PML and HIV-WML showed reduced magnetization transfer ratio. The magnetization transfer ratio was significantly lower in PML lesions (magnetization transfer ratio = 26.1%) than in HIV-WML (magnetization transfer ratio = 38.0%, P < .0001), and there was no overlap in the magnetization transfer ratio between PML lesions and HIV-WML. The separation in magnetization transfer ratio between the two lesion types was valid for lesion as small as 0.5 cm2. CONCLUSION: The larger reduction in magnetization transfer ratio for PML lesions is most likely due to demyelination, whereas the reduction in HIV-WML may be associated primarily with gliosis. PML lesions appear to cause strong reductions in magnetization transfer ratio early in the course of disease. Magnetization transfer MR imaging is a noninvasive tool that improves the differentiation between PML and HIV-WML in patients with AIDS.  相似文献   

9.
Introduction  Cardiac right-to-left shunt (RLS), mainly due to patent foramen ovale (PFO), is a risk factor for paradoxical embolism and stroke. Results of studies about brain lesions in diffusion-weighted imaging (DWI) in PFO patients were controversial. DWI only detects acute ischemic lesions. We assessed the hypothesis that, in T2-weighted magnetic resonance imaging (T2WI) of stroke patients, RLS is associated with a typical distribution of small white matter lesions. Materials and methods  In this retrospective case–control study, T2WI images of 162 stroke patients were evaluated. From stroke patients admitted between 1999 and 2003, 81 stroke patients with RLS were identified with contrast-enhanced transcranial Doppler (bubble test). Controls were 81 age-matched stroke patients without RLS (negative bubble test). In T2WI images, small lesions (<2 cm) were categorized depending on their location in subcortical white matter, peritrigonal white matter, deep and paraventricular white matter, and basal ganglia. Additionally, larger territorial infarcts were rated. Results  In T2WI frontal or predominantly frontal-located subcortical small white matter, lesions are significantly associated with RLS (p < 0.0001, chi-square test). Forty-three patients with RLS (53%) and only 19 control patients (23%) showed this frontal dominance. Odds ratio is 3.7 (95% confidence interval = 1.9–7.1) for having a RLS when T2WI shows this lesion pattern in a stroke patient. No patient of the RLS group and 6% of the control group had parietal dominance. Distribution of small lesions in other locations like basal ganglia or deep white matter showed no significant difference for the groups. Conclusion  A distribution of mainly frontal subcortical small white matter lesions in T2WI is significantly associated with RLS in stroke patients.  相似文献   

10.
Childhood white matter disorders: quantitative MR imaging and spectroscopy   总被引:2,自引:0,他引:2  
PURPOSE: To prospectively investigate whether quantitative magnetic resonance (MR) parameters, including magnetization transfer ratio (MTR), apparent diffusion coefficient (ADC), fractional anisotropy (FA), and MR spectroscopic metabolite concentrations, allow for discrimination between different types of pathologic conditions that underlie signal intensity abnormalities in white matter. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Forty-one patients (19 male, 22 female; mean age, 15.4 years) and 41 control subjects (25 male, 16 female; mean age, 11.3 years) were included. Twelve patients had a hypomyelinating disorder; 14, a demyelinating disorder; five, a disorder characterized by myelin vacuolation; and 10, a disorder characterized by cystic degeneration. Regions of interest were selected within the parietal white matter and were transferred to the corresponding sections of the generated ADC, FA, and MTR maps to extract quantitative measurements. Linear discriminant analysis and univariate analysis of covariance were used for statistical evaluation. RESULTS: Linear discriminant analysis showed that 95% of patients were correctly classified by using total creatine, choline-containing compounds, myo-inositol, MTR, and ADC. In the hypomyelination group, all MR parameters were close to normal, with the exception of elevated total creatine (P = .03) and myo-inositol (P < .001) levels and decreased MTR values (P < .001). In the demyelination group, the levels of choline-containing compounds (P = .02) and myo-inositol (P < .001) were highly elevated. In the myelin vacuolation and cystic degeneration groups, high ADC values (P < .001) and variable decreases in all MR spectroscopic metabolites were seen. MTR was significantly reduced (P < .001) in the cystic degeneration group. CONCLUSION: Quantitative MR techniques can be used to discriminate between different types of white matter disorders and to classify white matter lesions of unknown origin with respect to underlying pathologic conditions.  相似文献   

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OBJECTIVE: The purpose of the study was to examine change in volume of hyperintense white matter lesions in a cohort of community-dwelling elderly subjects without neuropsychiatric disease. SUBJECTS AND METHODS. One hundred seventeen volunteers underwent brain MR imaging on a 1.5-T scanner. Demographic data and the presence of specific medical illnesses were recorded at the time of the initial scanning. Hyperintense white matter lesion volume was measured using a supervised semiautomated technique that seeded lesions and then created a segmented lesion image. Subjects underwent repeated MR imaging at a mean of 25 months. Mean change in lesion volume and mean percentage of change were determined between the two time points. Logistic regression models were used to examine the differential effects of age, sex, race, and self-reported medical morbidity. RESULTS: Mean baseline volume of cerebral hyperintense lesions was 4.91 cc, and at 2-year follow-up, it was 6.42 cm(2) (p < 0.0001), for a mean increase of 26.7%. Comparable results were seen in separate analyses of hemispheric hyperintense lesion volumes. Neither sex, race, nor baseline hyperintense lesion volume was significantly associated with an interval increase in lesion volume. Age (p = 0.0117) and presence of diabetes (p = 0.0215) were associated with greater change. CONCLUSION: Elderly subjects exhibited approximately a 27% increase in hyperintense lesion volume over a 2-year period, a finding influenced by both age and medical comorbidity rates. Because hyperintense lesions can be associated with several neuropsychiatric conditions, further research is needed to determine if interventions designed to slow hyperintense lesion disease progression may improve neuropsychiatric outcomes.  相似文献   

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Evolution of white matter lesions in neurofibromatosis type 1: MR findings.   总被引:1,自引:0,他引:1  
To characterize further the evolution of white matter lesions in neurofibromatosis type 1, we reviewed 68 MR images in 43 patients (age, 1-31 years), including 25 follow-up studies (mean interval, 27 months). Lesion number, location, morphology, signal characteristics, and contrast enhancement were assessed. Lesion characteristics and changes thereof were correlated with the patients' ages. Thirty-four patients (79%) had white matter lesions. These lesions were hyperintense on T2-weighted images, were isointense on T1-weighted images, and showed no mass effect or contrast enhancement in 31 patients; in three patients, T1-prolongation was observed (one with significant mass effect). None of the lesions evolved into a glioma. The most common locations were the cerebellum (49%), brainstem (22%), and internal capsule (19%). Nineteen patients had white matter lesions and follow-up studies. Lesions decreased in size or number in seven patients (average age, 13 years), showed no change in three (average age, 12 years), increased in size or number in four (average age, 5 years), and showed a mixed pattern (increased/decreased size/number) in four (average age, 7 years). White matter lesions in neurofibromatosis type 1 frequently increase in size or number early in childhood; this did not indicate neoplasia in our study. The lesions tend to resolve with increasing age. Lesion progression in a child more than 10 years old warrants close follow-up to rule out a neoplasm.  相似文献   

16.
He J  Inglese M  Li BS  Babb JS  Grossman RI  Gonen O 《Radiology》2005,234(1):211-217
PURPOSE: To quantify, with three-dimensional proton magnetic resonance (MR) spectroscopy, metabolic characteristics of normal-appearing white matter and nonenhancing lesions in patients with relapsing-remitting multiple sclerosis (MS). MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. Nine patients with relapsing-remitting MS (six women, three men) and nine age-matched control subjects (seven women, two men) were studied with T1- and T2-weighted MR imaging and three-dimensional proton MR spectroscopy at spatial resolution less than a cubic centimeter. Absolute N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were obtained from 171 voxels: 66 from lesions on T2-weighted MR images (43 hypointense and 23 isointense on T1-weighted MR images), 31 from normal-appearing white matter, and 74 from analogous normal white matter regions on images in control subjects. RESULTS: Mean NAA level in hypointense lesions (5.30 mmol/L +/- 2.27 [standard deviation]) was significantly lower (P < or = .05) than that in isointense lesions (7.82 mmol/L +/- 2.28), normal-appearing white matter (7.37 mmol/L +/- 1.71), and normal white matter in control subjects (8.89 mmol/L +/- 1.54). Cho (1.79 mmol/L +/- 0.65) and Cr (5.64 mmol/L +/- 1.50) levels in isointense lesions were indistinguishable from those in normal-appearing white matter (1.74 mmol/L +/- 0.46 and 4.99 mmol/L +/- 0.97, respectively) but were significantly higher (Cho, 20%; Cr, 24%) than those in normal white matter in control subjects (1.44 mmol/L +/- 0.40 and 4.30 mmol/L +/- 1.32, respectively). NAA, Cho, and Cr levels in normal-appearing white matter were significantly different than those in normal white matter in control subjects (NAA, 20% lower; Cho, 14% higher; and Cr, 17% higher). CONCLUSION: Abnormal metabolic activity persists in all MS tissue types. Increased Cr and Cho levels suggest (a) ongoing gliosis and attempted remyelination in isointense lesions on T1-weighted MR images and (b) membrane turnover (de- and remyelination), in addition to increased cellularity (gliosis, inflammation) in normal-appearing white matter.  相似文献   

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目的利用磁共振弥散张量成像(DTI)研究正常成人脑内各部位各向异性程度及正常白质纤维束构象特征.方法对25名正常志愿者进行常规MR及DTI序列检查,重建FA图及三维彩色编码张量图.分别在半卵圆中心、基底节区和大脑脚层面测量主要白质束的FA值.结果DTI显示灰质与白质区各向异性存在显著差异,不同部位的白质纤维束各向异性程度亦不相同,且左右两侧基本对称,重建FA图和三维彩色编码张量图可显示白质内大部分主要的白质纤维束.结论DTI可清晰显示脑内白质纤维束的走行及分布,为了解脑功能与白质通路间关系提供了有力研究手段.  相似文献   

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PURPOSETo validate the use of techniques of irreversible compression of images, which can be performed using a block-based discrete cosine transform technique as defined by the Joint Photographic Experts Group, before they can be used in clinical applications, by evaluating the effect of compression on the ability of observers to detect discrete white matter lesions on MR images of the brain.METHODSSixty T2- and intermediate-weighted spin-echo images were compressed with varying degrees of coefficient quantization with compression ratios from 1:1 to more than 40:1, randomized, and evaluated by three observers blinded to the degree of compression.RESULTSNo significant difference in the number of lesions detected was apparent until compression ratios reached 40:1, despite a significant subjective loss in perceived image quality at 20:1. Only small (< or = 5 mm) lesions were missed at the highest degree of compression. No significant differences were observed in the detection of confluent periventricular white matter disease at any degree of compression tested.CONCLUSIONSThe use of high degrees of irreversible compression of MR images may be acceptable for diagnostic tasks.  相似文献   

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Focal and confluent areas of periventricular hyperintensity have been reported on magnetic resonance (MR) images in 30% of patients over 60 years of age. In order to better understand the pathologic basis of these lesions, the authors studied 14 formalin-fixed brains with MR imaging. Multiple focal areas of hyperintensity were identified in the periventricular white matter in three of the 14 brains studied (21%). Subsequent gross and microscopic pathologic examination of both hyperintense and normal-intensity areas was performed on 87 tissue sections. The larger lesions were characterized centrally by necrosis, axonal loss, and demyelination and therefore represent true infarcts. Reactive astrocytes oriented along the degenerated axons were identified at distances of up to several centimeters from the central infarct. This is called isomorphic gliosis and is associated with increased intensity on T2-weighted images that increases the apparent size of the central lesion.  相似文献   

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