磁共振成像在肾上腺脑白质营养不良诊断中的应用

目的 探讨氢质子磁共振波谱成像(1H-MRSI)和弥散张量成像(DTI)在肾上腺脑白质营养不良(ALD)诊断中的价值,并应用弥散张量白质纤维束追踪成像(DTT)技术显示ALD纤维束受累情况.方法 对6例ALD患者行1H-MRSI、DTI和常规影像学检查,比较不同病变区域N-乙酰天冬氨酸(NAA)、胆碱复合物(Cho)、肌酐(cr)、表观扩散系数(ADC)和各向异性分量(FA)的变化及相关性,选择胼胝体和锥体束进行白质纤维束成像.结果 病变起始区域NAA/Cr比值(0.55±0.19),NAA/Cho比值(0.22±0.11)降低(F=7.693、7.751),Cho/Cr比值(2.54±0.37)升高(F=6.348),ADC值最高(1.49±0.36,F=5.226),FA值最低(0.21±0.08,F=5.139,均P＜0.05);病变区域近周NAA/Cr比值(1.16±0.03)和NAA/Cho比值(0.45±0.17)降低较远周明显(t=1.769、1.842,P＜0.05);病变发展区域ADC值(0.89±0.03)低,FA值(0.45±0.07)最高;NAA/Cho与ADC负相关(r=-0.71,P＜0.05),与FA正相关(r=0.31,P＜0.05);DTT结果 显示病变区域胼胝体和锥体束均受累,走行中断或呈不连续碎片样.结论 1H-MRSI和DTI为ALD提供了更多的早期诊断依据,并且可动态监测脑白质病变进展,DTT可直接显示ALD患者纤维束受累情况.     

RETRACTED ARTICLE: The sequential magnetic resonance images of tri-methyl tin leukoencephalopathy

Organotin compounds are commonly used in industrial and agriculture. It causes toxic effects on skin, eyes, respiratory system, gastrointestinal system, and nervous system. After cleaning a di-methyl tin tank, 43-year-old man showed a dizziness, disorientation, visual hallucination, and agitation. Through a measurement by liquid chromatography and inductively coupled plasma-mass spectrometry, di-methyl tin and tri-methyl tin was detected. Although magnetic resonance (MR) image 3 days after exposure showed no abnormal signal intensity, follow-up MR images 15 days after exposure revealed abnormal extensive signal intensities in the white matter that was not ever coincident with previous reports. It was hardly explainable that previous abnormal signal intensities of MR image nearly disappeared 4 months later. We present a case of a patient who developed acute toxic leukoencephalopathy from an acute inhalational exposure to methyl tin with sequential MR images showing an involvement of white matter that was not ever reported.     

多模式MRI对线粒体脑肌病的诊断价值

目的探讨线粒体脑肌病多模式MRI影像学特点。方法对21例线粒体脑肌病患者的脑MRI、MRA、MRS影像资料进行分析。结果 MRI：线粒体脑肌病病灶多位于颞、枕、顶叶,病灶具有不符合脑动脉分布及游走性的特点;4例患者病灶对称性累及豆状核、丘脑和（或）尾状核;2例患者大脑、小脑、脑干萎缩,脑室增大,脑沟增宽。病灶均呈T1低信号、T2高信号,陈旧性病灶T2信号稍高;MRA：10例新发病灶处脑动脉及其远端分支较对侧相应脑动脉增粗,信号增强;MRS：14例新鲜病灶可检出倒置的乳酸双峰波及NAA/Cr降低。结论线粒体脑肌病的多模式MR影像学特点有一定的特异性,对线粒体脑肌病的诊断有一定价值。     

磁共振成像对肾上腺脑白质营养不良的诊断价值

报告４例肾上腺脑白质营养不良（ＡＬＤ）患者的磁共振成像（ＭＲＩ）表现。ＭＲＩ表现为双侧对称的白质异常信号，主要位于枕、顶、颞叶，视放射和胼胝体压部，Ｔ１加权为低信号，Ｔ２加权为高信号，有增强效应。多维成像和高对比强度使ＭＲＩ比ＣＴ有更强的敏感性，能明确病变的部位及其严重程度，故ＭＲＩ是诊断ＡＬＤ的有效手段。     

脑静脉窦血栓形成患者磁共振成像与磁共振静脉血管成像联合诊断的价值

目的：探讨脑静脉窦血栓（cerebral venous sinus thrombosis ,CVST ）形成患者磁共振成像与磁共振静脉血管成像联合诊断的价值。方法选取脑静脉窦血栓患者40例进行分析。诊断过程中,全体患者均接受磁共振（magnetic resonance venography ,MR）平扫,数字减影血管造影（digital subtraction angiography ,DSA）检查12例,MRV检测6例,增强扫描22例。结果单一横窦受累6例,上矢状窦、乙状窦及横窦受累8例,单一乙状窦受累16例,横窦和上矢状窦联合受累10例。所有患者磁共振成像（magnetic resonance venography ,MRI）及磁共振静脉成像（magnetic resonance venography ,MRV）均表现出信号改变。22例患者增强扫描显示脑静脉非正常强化,但静脉窦内部血栓未强化。M RV检查6例患者及DSA 12例患者的结果显示其受累静脉窦不明显、狭小、不规则,且出现侧支血管形成现象。结论 M RI与M RV联合诊断对于脑静脉窦血栓形成的诊断具有较好效果。     

磁共振脑部侧支循环的灌注成像

目的 研究血管编码的动脉自旋标记(VE-ASL)灌注方法对于脑部侧支循环灌注的显示能力.方法 56例超声检查显示颈内动脉狭窄的患者入组.使用VE-ASL测量侧支循环的存在及功能.Willis环侧支循环的存在通过定义A1段和后交通动脉的血流状态确定.远端侧支循环灌注功能通过测量不同脑区脑血流量来区分:脑血流量≥10 ml·min-1100g-1为供血功能可以接受,脑血流量<10 ml·min-1·100g-1为供血不足.使用交叉表将VE-ASL得到的结果与MRA、DSA的结果进行比较.计算Kappa值比较不同方法之间的一致性.比较颈动脉支架患者在治疗前后VE-ASL结果的差异.结果 比较MRA和VE-ASL确定A1段和后交通血流状态的一致性,Kappa值分别为0.746及0.700.对于侧支循环灌注功能的区分,DSA与VE-ASL比较的Kappa值是0.914.除基于Willis环的侧支循环,VE-ASL还显示了通过软脑膜的侧支血供.颈动脉支架治疗前后VE-ASL结果有明显差异.结论 在颈内动脉狭窄、闭塞的患者,VE-ASL可以无创地显示侧支循环的存在、来源及远端功能,可用于评价颈动脉支架植入后的治疗效果.     

Differentiating between glioblastomas with and without isocitrate dehydrogenase gene mutation by findings on conventional magnetic resonance images

Various studies using advanced techniques have estimated the isocitrate dehydrogenase (IDH) gene mutation status in glioblastoma (GBM) from preoperative images. However, it is important to be able to predict mutation status using conventional MRI, which is more widely used in clinical practice. In this study, we examined the features of GBM with and without IDH gene mutation on conventional MRI. Twenty-three patients with GBM in whom IDH gene mutation status had been pathologically and molecularly confirmed in tumor specimens were included. The cases were divided into an IDH-wildtype group (n = 17) and an IDH-mutant group (n = 6). We retrospectively compared the following imaging parameters between the two groups: tumor location (superficial or deep), borders on T2-weighted images (regular or irregular), borders of enhancing lesions (regular or irregular), number of lesions showing contrast enhancement (solitary or multiple), presence or absence of intralesional bleeding, and presence or absence of a low-grade glioma in the background around the enhancing lesion. IDH-wildtype tumors were significantly more likely to be superficial than were IDH-mutant tumors (p < 0.05). Enhancing lesions in the IDH-wildtype group were less likely to have an irregular border (p = 0.059). Low-grade glioma was a background lesion in 5 patients (83.3%) in the IDH-mutant group and 9 (52.9%) in the IDH-wildtype group. The IDH mutation status is likely to be wildtype in patients with superficial GBM in which the enhancing lesion has a regular border and when low-grade glioma is not found as a background lesion on MRI.     

T2 hyperintense foci on magnetic resonance images of schizophrenic patients and controls

High resolution magnetic resonance imaging (MRI) of the brain was performed on 18 male schizophrenic patients and 15 male normal control subjects using an identical imaging protocol. The number and size of T₂ hyperintense foci were clinically quantified by an academic radiologist. Large foci ( 3 mm in diameter) were observed more frequently on patient images ( ) than on control images ( ). The imaging protocol detected high rates of focal hyperintensities, but no differences between patients and controls were noted in the total affected brain area (sum of focal areas) or in the presence or absence of foci.     

Evaluation index for asymmetric ventricular size on brain magnetic resonance images in very low birth weight infants

Objective

Asymmetric ventriculomegaly is often evident on brain magnetic resonance imaging (MRI) in very low birth weight infants (VLBWI) and is interpreted as white matter injury. However, no evaluation index for asymmetric left-right and anterior-posterior ventricular sizes has been established.

多发性硬化患者的脑部磁共振成像表现

目的　寻找多发性硬化(multiplesclerosis,MS)患者有诊断及鉴别诊断意义的脑部磁共振成像(MRI)征象。方法　分析41例临床确诊MS患者的常规脑部MRI表现,内容包括病灶数目、分布、大小、形态、信号特征及增强表现等。结果　脑部的MS灶可以单发和多发,单发者幕下多见,多发者以4~15个病灶者最多。少数病例的病灶弥漫分布,无法计数,呈现“白质变脏征”。斑块分布以两侧脑室旁最多见,其次为额顶叶皮层下、胼胝体、脑干,伴发小脑内病灶仅2例。斑块直径约几个毫米至2cm不等,约占75%; 2cm以上病灶者少见,最大病灶约6~7cm。根据形态和信号,病灶可以分为急性和慢性。急性病灶呈卵圆形或圆形,有明显膨胀感,T1WI呈低或略低信号,周围可见等或略高信号;T2WI呈高信号,但增高程度不同,表现为中央呈“核心”而周围呈“晕环”。此类病灶均表现强化,最典型为环形强化、强化环完整或呈不完整弓形,即使病灶较大仍具有上述特点。慢性病灶也可分为两种,一种为大体对称性的病灶,分布于两侧脑室旁,另一种病灶分布较分散,额、顶叶,侧脑室旁及脑干等处都有,病灶呈小条、片状,部分融合成较大片状。慢性病灶有收缩感,边缘较锐利,信号较均匀,周围无晕环征象,增强后无强化。结论　脑部MS有多种MRI表现,部分征象具有特征性。     

书写痉挛脑功能磁共振成像研究

目的 应用脑功能磁共振成像（fMRI）技术,观察书写痉挛患者痉挛性书写脑功能区激活特点,探讨书写痉挛可能发病机制.方法 采用fMRI组块设计,分别获得10例书写痉挛患者和10名年龄、性别匹配健康对照组执行默写、手写、笔写任务时的平均脑功能激活图,同时通过一般线性分析法产生“笔写减手写”及“笔写减默写”的差异脑功能图.结果 书写痉挛患者进行书写任务时,受累手对侧基底节区,特别是壳核（激活体素个数864）,较健康对照组（激活体素个数54）显著激活;运动皮质（第一运动区、辅助运动区、运动前区）及同侧小脑较健康对照亦有明显激活;而进行手指写和默写任务时两组间差异并不明显;＂笔写减手写＂及＂笔写减默写＂差异脑功能图发现书写痉挛患者在除去手指写运动及语言处理相关影响后上述脑区仍有明显激活,健康对照组则皮质下结构激活消失,运动相关皮质激活亦明显减少.结论 书写痉挛患者执行笔写任务时上述脑区尤其皮质下结构异常激活与书写痉挛发生存在一定关联,基底节区及相应皮质-皮质下环路功能紊乱,可能在书写痉挛发病机制中起到重要作用.     

肌萎缩侧索硬化38例弥散张量成像及磁共振波谱表现

目的 研究肌萎缩侧索硬化(ALS)的弥散张量成像(DTI)和磁共振波谱(MRS)特点,并对ALs的病理生理机制进行初步探讨.方法 ALS患者38例,单纯下运动神经元受累疾病患者8例,混合型颈椎病5例和健康对照34名,行常规头颅MRI、DTI和1H-MRS测定.结果 21%(8/38)的ALS患者可见T2 FLAIR序列双侧锥体束走行异常高信号,强度高于皮质灰质.ALS组和健康对照组相比,中央前回(ALS组0.492±0.059,健康对照组0.552 4-0.045,F=17.150,P<0.01)、内囊后肢(分别为0.679 ±0.048、0.727±0.031,F=19.481,P<0.01)、大脑脚(左侧0.740±0.038、0.761±0.024,F=4.290;右侧0.720±0.044、0.746±0.034,F=3.264,均P<0.01)的部分各向异性(FA值)显著降低;ALS组上述部位的N-乙酰大冬氨酸/肌酸(NAA/Cr)值和健康对照组相比亦存在显著降低.AKS组各部位FA值降低百分率分别为10.9%、6.6%、2.8%～3.5%,以中央前回处最为显著;内囊前肢、枕叶处的FA值亦有不同程度降低.结论 DTI和MRS枪测不仪有助于ALS患者:运动神经元高位受累的确认和ALS的诊断和鉴别诊断,而且还可促进对ALS病理机制和病损分布的了解.     

Quantitative magnetic resonance analysis in vascular dementia

The potential role of magnetic resonance imaging (MRI) in differentiating between specific causes of cognitive decline in patients with vascular dementia (VD) has not yet been fully established. We therefore decided to assess the supratentorial cerebral contents in 24 patients with a diagnosis of probable VD and in 24 normal subjects, matched for age and education level, using MRI volumetric parameters obtained by means of a quantitative method. The volumes of subarachnoid and ventricular spaces, cerebral tissue, and hyperintense areas on T2-weighted images were calculated. In order to reduce interindividual variability caused by differences in intracranial size, each absolute measurement was normalized to the relative size of the intracranial volume. In addition, we calculated the ratio between the areas of the corpus callosum (CC) and supratentorial brain at the same level on the T1-weighted image midsagittal plane. The MRI data were correlated with the deterioration of cognitive functions. Patients with VD showed significantly lower cerebral tissue volume and CC area, and higher ventricular space volume than normal subjects. Furthermore, the total volume of the T2 signal alterations was higher in VD patients than in normal subjects. In VD patients, this volume was found to be proportional to the increase in the volume of the ventricular space. On the other hand, no correlation was found between the volume of the T2 signal alterations and the area of the CC. The degree of global cognitive dysfunction and the score of each neuropsychological test did not show any correlation with the MRI data. Our results suggest that ventricular enlargement in VD patients is correlated with the increase in volume of the T2 signal abnormalities, but that the degree of global cognitive dysfunction is not influenced by the volume of these T2 signal abnormalities. Furthermore, the CC atrophy does not influence the score of any neuropsychological test or the degree of global cognitive dysfunction. Received: 22 Februar 1996 Received in revised form: 14 October 1996 Accepted: 30 December 1996     

Short echo time 1 H magnetic resonance spectroscopy of childhood brain tumours

Aims To explore short echo time (30 ms) 1 H magnetic resonance spectroscopy (MRS) in children with brain tumours and determine the contributions to the characterization of these tumours of the metabolites inositol/myoinositol and glutamate/glutamine, which are not visible at long echo times (135 or 270 ms). Methods Over a 12-month period 86 single-voxel MRS investigations were performed on 59 children with various brain tumours on a Siemens Symphony 1.5-T Magnetom using point-resolved spectroscopy and echo time of 30 ms. Results The procedure was well tolerated, and good-quality data were obtained. N-Acetyl aspartate (NAA)/Choline (Cho) and creatine (Cr)/Cho concentration ratios were significantly (p<0.001) lower in tumour (0.95 and 1.63, respectively) compared with non-involved brain (3.68 and 3.98, respectively) in all histological types. Inositol/Myoinositol (Inos)/Cho ratios were significantly (p<0.05) lower in untreated tumours (1.91) than in treated tumours (3.93) and in non-involved brain (3.32). Inos/Cho ratios were high in diffuse pontine gliomas and low in medulloblastomas and supratentorial primitive neuroectodermal tumours (p<0.01). Glutamate/Glutamine (Glut)/Cho ratios were high in grade 1 astrocytomas (6.4) and unbiopsied optic gliomas (9.84) but low in diffuse pontine gliomas (2.44). Lipids and macromolecules were present in most tumours but in low quantities in non-involved brain. Conclusion Good-quality short echo time MRS data can be collected routinely on children with brain tumours. Inos and Glut levels show greater variability between tumour types than NAA, Cho and Cr present at long echo times, providing improved tumour characterization. Inos/Cho levels differ between untreated and treated tumours and may be useful for treatment monitoring.     

A cellular neural network based method for classification of magnetic resonance images: towards an automated detection of hippocampal sclerosis

We present a cellular neuronal network (CNN) based approach to classify magnetic resonance images with and without hippocampal or Ammon’s horn sclerosis (AHS) in the medial temporal lobe. A CNN combines the architecture of cellular automata and artificial neural networks and is an array of locally coupled nonlinear electrical circuits or cells, which is capable of processing a large amount of information in parallel and in real time. Using an exemplary database that consists of a large number of volumes of interest extracted from T1-weighted magnetic resonance images from 144 subjects we here demonstrate that the network allows to classify brain tissue with respect to the presence or absence of mesial temporal sclerosis. Results indicate the general feasibility of CNN-based computer-aided systems for diagnosis and classification of images generated by medical imaging systems.     

Automated morphometric magnetic resonance imaging analysis for the detection of periventricular nodular heterotopia

Purpose: To describe a novel magnetic resonance imaging (MRI) postprocessing technique for the detection of periventricular nodular heterotopia (PNH) and to evaluate its diagnostic value. The method is a further development of voxel‐based morphometric analysis with focus on a region of interest around the lateral ventricles to increase the sensitivity and specificity for automated detection of abnormally located gray matter in this area. Methods: T₁‐weighted MRI volume data sets were normalized and segmented in statistical parametric mapping (SPM 5 software), and the distribution of gray matter was compared to a normal database. As a new approach, individual masks derived from segmentation of the lateral ventricles were used to restrict the search for ectopic gray matter to the periventricular area. PNH were automatically detected by localizing the maximum deviation from the normal database in this area, provided that the z‐score exceeded a certain threshold. The optimal z‐score threshold for maximum sensitivity and specificity was determined by a receiver operating characteristic (ROC) curve analysis. The method was applied in 40 patients with PNH and 400 controls. Key Findings: PNH were detected in 37 of 40 patients, and false positives were found in 34 of 400 controls, amounting to 92.5% sensitivity and 91.5% specificity. In 17 of the patients in whom PNH could be identified, these lesions had been overlooked in the past, and in 8 patients even in the high‐resolution MRI subsequently used for postprocessing. Significance: The results suggest that automated morphometric MRI analysis with focus on ectopic gray matter in the periventricular areas facilitates the evaluation of MRI data and increases the sensitivity for the detection of PNH.     

磁共振多体素波谱技术对颞叶癫痫的定位研究

目的评价磁共振多体素波谱扫描技术对颞叶癫痫的定位诊断价值。方法选择具有明显颞叶癫痫表现,并经脑电图检查定位诊断明确的单侧颞叶癫痫患者30例作为研究对象;排除M R I检查存在颅脑肿瘤、脑血管畸形等症状性癫痫患者。患者均行常规M RI及双侧海马区多体素波谱扫描,完成检查后将以代谢物峰值含量为灰阶的伪彩图与倾斜冠状重度T2W I图像进行融合,测量双侧海马区N-乙酰天冬氨酸、胆碱峰值含量和胆碱/N-酰天冬氨酸比值,并直观分析双侧海马区两代谢物的分布情乙况。结果患侧N-乙酰天冬氨酸峰值含量为(13587.61±3913.99)M R units,健侧为(17683.10±5610.61)M R units,患侧低于健侧差异有显著性意义(t=6.728,P<0.001);患侧胆碱/N-乙酰天冬氨酸比值为(1.26±0.11),健侧比值为(1.01±0.14),患侧高于健侧差异亦有显著性意义(t=7.883,P<0.001)。将两代谢物含量及比值伪彩图与常规M RI图像进行融合,可直观发现双侧海马区N-乙酰天冬氨酸峰值含量及胆碱/N-酰天冬氨酸比值存在明显差异。结论磁共振多体素波谱技术不仅可以通过对某些代谢物含量乙的定量分析进行癫痫灶的定位、定侧诊断,还可通过常规M RI图像与多体素磁共振波谱图像的融合图像直观评价代谢物分布状态,描记癫痫灶的大致轮廓,为制定手术方案提供依据。     

The use of magnetic resonance imaging for the diagnosis of fetal intracranial anomalies

While fetal cranial sonography has been used for the sensitive detection of ventriculomegaly, ancillary imaging techniques may be needed for precise delineation of structural abnormalities. This report outlines the radiologic and clinical results using maternal magnetic resonance imaging (MRI) in ten patients with suspected fetal intracranial anomalies. Imaging was accomplished at 17–39 weeks gestational age, using spin-echo, a multislice technique with intramuscular morphine sulfate for sedation. In four cases, MRI significantly clarified the sonographic diagnosis, while in two cases the scan agreed with the sonographic findings. In one patient, MRI failed to image a lumbar meningomyelocele associated with the Chiari II malformation. In two patients with the Chiari II malformation, both sonography and MRI failed to delineate the anatomic pathology completely. Optimal imaging resolution was achieved in the third trimester. Four patients died in the perinatal period. All the surviving patients required shunting to treat intracranial hypertension; only two patients were meeting cognitive milestones. We conclude that due to the high incidence of multiple anomalies in the fetus with ventriculomegaly, precision in neuroradiological diagnosis is essential. MRI can be a useful adjunct to cranial sonography for the specific delineation of abnormalities of the fetal central nervous system.     

Single voxel proton magnetic resonance spectroscopy in post-stroke depression

Mood disorders are associated with structural, metabolic and spectroscopic changes in prefrontal regions. In the case of depression associated with stroke, there is little information about the biochemical profile of these regions, as assessed by proton magnetic resonance spectroscopy (¹H-MRS). In a group of first-ever stroke patients, we studied the association between post-stroke depression and ¹H-MRS measurements in unaffected frontal lobes. Twenty-six patients with a first ischemic stroke located outside the frontal lobes were included in the study. Single voxel proton magnetic resonance spectroscopy (¹H-MRS) was performed to assess N-acetylaspartate/creatine (NAA)/Cr, glutamate + glutamine (Glx)/Cr, choline (Cho)/Cr and myo-inositol (mI)/Cr ratios. Patients were assessed within the first 10 days after stroke and again four months later. The diagnosis of depression was made on the basis of clinical observation, interview and Hamilton Depression Rating Scale scores. In a group of 26 patients, eight (31%) met criteria for depression at the first assessment, and nine (35%) met criteria for depression at follow-up. Patients with depression in the immediate post-stroke phase had significantly higher Glx/Cr ratios in the contralesional hemisphere than non-depressive patients. No biochemical differences were found between the groups at 4-month follow-up. These findings suggest that post-stroke depression is accompanied by changes in frontal lobe glutamate/glutamine levels, perhaps reflecting abnormalities in glutamatergic transmission in the immediate post-stroke period.