Sodium-MR-imaging of the brain: initial clinical results

Summary Twelve patients with different diseases of the brain were examined with sodium and proton MRI at 1.5 Tesla and the results of both studies compared. Due to the 1500-fold lower concentration in the body, the decreased sensitivity and the shorter relaxation times of sodium compared with hydrogen a sequence with gradient reversal and a volume imaging method was applied to achieve a short echo time (4.5 ms). As a result of the mainly extracellular distribution of sodium the CSF spaces are depicted by their high signal intensity while the normal parenchyma is not visible. Changes induced by encephalitis, ischemic infarction and tumors can also be detected by their increased sodium content. Different tumors provided different signal intensities, not always permitting a distinction between tumor, surrounding edema and CSF. The diagnostic impact of these findings is discussed.     

Role of diffusion-weighted echo-planar MRI in distinguishing between brain abscess and tumour: a preliminary report

Our purpose was to evaluate diffusion-weighted (DW) echo-planar MRI in differentiating between brain abscess and tumour. We examined two patients with surgically confirmed pyogenic brain abscess and 18 with metastatic brain tumours or high-grade glioma, using a 1.5 T system. The apparent diffusion coefficient (ADC) of each necrotic or solid contrast-enhancing lesion was measured with two different b values (20 and 1200 s/mm²). All capsule-stage brain abscesses (4 lesions) and zones of cerebritis (2 lesions) were identified on high-b-value DWI as markedly high-signal areas of decreased ADC (range, 0.58–0.70 [(10–3 mm²/s; mean, 0.63)]). All cystic or necrotic portions of brain tumours (14 lesions) were identified on high-b-value DWI as low-signal areas of increased ADC (range, 2.20–3.20 [(10–3 mm²/s; mean, 2.70)]). Solid, contrast-enhancing portions of brain tumours (19 lesions) were identified on high-b-value DWI as high-signal areas of sightly decreased or increased ADC (range, 0.77–1.29 [(10–3 mm²/s; mean, 0.94)]). Our preliminary results indicate that DW echo-planar MRI be used for distinguishing between brain abscess and tumour. Received: 23 January 1998 Accepted: 5 June 1998     

脑胶质肉瘤的MRI表现

目的：评价MRI对脑胶质肉瘤的诊断价值。方法：经病理证实的脑胶质肉瘤6例，回顾分析其MRI表现。结果：病灶基本上表现为长T1、长T2信号，边界清楚，多数形态不规则，伴有囊变和坏死，可伴瘤内出血，生长具有侵袭性；少数为结节状。周围服组织水肿，占位效应明显。增强扫描：6例均明显强化，4例呈不规则环状强化，2例呈结节状强化；2例直接侵犯邻近脑叶，2例发现脑内转移灶。结论：脑胶质肉瘤通常发生于额、顶叶，MRI能够清楚地显示病变，但信号改变易与多形胶质母细胞瘤、恶性胶质瘤、转移瘤等相混淆。确诊仍依赖于组织病理学诊断。     

MRI对成人脑体积定量分析与临床对照研究

目的：探讨共振成像对成人脑体积定量分析的方法及其价值。方法：对20例正常对照组和20例实验组行垂直于海马长轴的倾斜冠状位磁共振T1及T2加权像扫描,测量海马、颞叶、额叶体积及颅腔容积,对其比值进行定量分析。结果：海马萎缩与临床痴呆密切相关。结论：采取垂直于海马长轴的倾斜冠状位磁共振T1及T2加权像扫描,测量海马体积与颅腔体积并计算其比值的方法,对判断与临床痴呆相关的脑萎缩敏感、可靠、切实可行。     

Segmentation precision of abdominal anatomy for MRI-based radiotherapy

The limited soft tissue visualization provided by computed tomography, the standard imaging modality for radiotherapy treatment planning and daily localization, has motivated studies on the use of magnetic resonance imaging (MRI) for better characterization of treatment sites, such as the prostate and head and neck. However, no studies have been conducted on MRI-based segmentation for the abdomen, a site that could greatly benefit from enhanced soft tissue targeting. We investigated the interobserver and intraobserver precision in segmentation of abdominal organs on MR images for treatment planning and localization. Manual segmentation of 8 abdominal organs was performed by 3 independent observers on MR images acquired from 14 healthy subjects. Observers repeated segmentation 4 separate times for each image set. Interobserver and intraobserver contouring precision was assessed by computing 3-dimensional overlap (Dice coefficient [DC]) and distance to agreement (Hausdorff distance [HD]) of segmented organs. The mean and standard deviation of intraobserver and interobserver DC and HD values were DC_{intraobserver} = 0.89 ± 0.12, HD_{intraobserver} = 3.6 mm ± 1.5, DC_{interobserver} = 0.89 ± 0.15, and HD_{interobserver} = 3.2 mm ± 1.4. Overall, metrics indicated good interobserver/intraobserver precision (mean DC > 0.7, mean HD < 4 mm). Results suggest that MRI offers good segmentation precision for abdominal sites. These findings support the utility of MRI for abdominal planning and localization, as emerging MRI technologies, techniques, and onboard imaging devices are beginning to enable MRI-based radiotherapy.     

Diffusion tensor imaging of the brain: review of clinical applications

Abstract We review the theoretical background to diffusion tensor imaging (DTI) and some of its commoner clinical applications, such as cerebral ischemia, brain maturation and traumatic brain injury. We also review its potential use in diseases such as epilepsy, multiple sclerosis, and Alzheimers disease. The value of DTI in the investigation of brain tumors and metabolic disorders is assessed.     

人脑对针刺与对指反应的实时动态功能MRI的对比研究

目的　利用血氧水平依赖 (bloodoxygenleveldepended ,BOLD)实时动态功能磁共振成像技术观察针刺人体足三里和阳陵泉穴对脑运动功能区的影响 ,并对针刺机理进行初步探讨。方法17例健康志愿者 ,行实时动态功能磁共振成像。每人分别接受以下 2项任务 :(1)右手对指运动 ;(2 )被针刺右侧足三里和阳陵泉。检测感兴趣区的相关系数 ,感兴趣区包括两侧的躯体感觉运动区(SMC)、运动前区 (PMC)和副运动区 (SMA)。对被激活的感兴趣区进行计数。采用SAS软件包作精确概率法检验对两组资料进行分析。结果　对指任务除去 1例合作不好 ,其余 16例激活右侧 (SMCR)8例 ,PMCR8例 ,SMA 9例 ,左侧 (SMCL) 16例 ,PMCL9例。针刺任务 3例运动伪影明显没有获得满意图像 ,另有 2例脑功能区无明显激活 ,其余 12例次激活SMCR6例 ,PMCR10例 ,SMA 8例 ,SMCL11例 ,PMCL10例。精确概率法检验Fisher′sexacttest (2 Tail)P >0 .0 5 ,说明 2种刺激兴奋感兴趣区的差异无显著性意义。结论　脑功能磁共振成像在针刺机制和应用价值研究领域具有重要作用 ;但其实用价值尚需结合临床针刺效果进行综合评价和进一步探讨。     

颅脑MRI快速液体衰减反转回复技术探讨

目的：探讨快速液体衰减反转回复（ＦＬＡＩＲ）技术原理及其在颅脑的临床应用。材料与方法：对４０例健康志愿者及１２４例颅脑疾患患者前瞻性地进行快速ＦＬＡＩＲ及Ｔ２加权序列ＭＲ检查，并比较了快速ＦＬＡＩＲ上不同ＴＲ、ＴＩ（间隔时间）、ＴＥ组合所得图像质量。结果：ＴＲ／ＴＩ／ＴＥ为８０００／２０００／２００毫秒的组合能较好地抑制脑脊液信号。ＦＬＡＩＲ与快速自旋回波Ｔ２加权序列比较，能增加病灶的对比度，从而     

脑内原发性淋巴瘤MRI表现

目的:分析脑内原发性淋巴瘤的MRI表现。方法:回顾性分析17例经病理证实的脑内原发性淋巴瘤的MRI资料,所有病例均行MR平扫及增强扫描,其中2例行弥散加权成像。结果:17例脑内原发性淋巴瘤共34个瘤灶;其中单发8例,多发9例;幕上病灶29个,幕下病灶5个。MR平扫T1WI等信号15个病灶,略低信号19个病灶,T2WI呈等低信号23个病灶,略高信号11个病灶;增强扫描肿瘤均匀强化22个,不均匀强化12个,瘤周轻度、中度水肿各17个病灶。2例共3个瘤灶弥散受限。结论:脑内原发性淋巴瘤磁共振表现具有一定的特征性,认真分析其特点,可提高诊断的准确性。     

基于MR三维梯度回波与扩散加权成像序列的脑表面重组技术比较

目的 使用MR三维梯度回波（3D flash）序列和扩散加权成像（DWI）序列的扫描图像进行脑表面三维重组，对两种方法显示脑表面结构的能力、价值与限度及临床应用等进行比较和探讨。方法 对30名正常人行头颅3D flash和DWI检查。通过容积重组显示脑表面解剖结构。同一组医生对两种方法重组图像进行评价和评分，并比较结果。结果 基于3D flash重组的各脑表面结构清楚显示，平均得分均在2．50分以上。基于DWI的重组图像能够较好地显示中央前回、中央后回、顶上小叶、额上回、中央前沟、中央沟、中央后沟、顶间沟及额上沟等结构，平均得分2．60～2．75分，缘上回、角回、额中回、额下回、颞上回、外侧沟和额下沟等结构显示较差，平均得分1．67～2．48分，颞中回、颞下回、颞上沟及颞下沟等显示很差，平均得分仅0．88～1．27分。比较两种方法的平均得分，基于3D flash重组优于基于DWI的三维重组，差异有统计学意义，P值均〈0．01。结论 基于3D flash重组能够显示真实的脑表面主要脑沟、脑回和脑裂，对脑解剖形态的研究和定位诊断有重要意义。基于DWI的三维脑表面重组能比较满意地显示顶叶、额叶的主要表面结构，扫描和重组快速，有一定实用价值。     

A new MRI technique for demonstrating the surface of the brain together with the cortical veins

We assessed combining of surface-anatomy scanning (SAS) MRI and MR venography (MRV). We obtained SAS images with a half-Fourier single-shot fast spin-echo sequence, then MRV of the identical section with a two-dimensional phase-contrast technique. We then added the two sets of images. The combined images, which were obtained within 10 min, provided information about the surface anatomy and cortical veins. This simple technique is useful for demonstrating brain surface structures, especially in patients from whom one plans to excise a lesion. Received: 3 August 1998 Accepted: 2 November 1998     

MR扩散加权成像在评价前列腺癌内分泌治疗中的应用价值

目的探讨内分泌治疗前后前列腺外周带癌区和非癌区的表观扩散系数（ADC）值的变化情况。方法对经手术病理或穿刺活检证实的14例前列腺癌和18例内分泌治疗6个月以上的前列腺癌患者行MR扩散加权成像（DWI）。依病理结果，将前列腺6分区归类为癌区和非癌区，测量每个分区的ADC值，同时测量每例膀胱、闭孔内肌的ADC值，对2组的结果进行比较。结果未治疗组14例癌区和非癌区的ADC值分别为（1．22±0．25）×10^-3、（1．59±0．19）×10^-3mm^2／s，差异有统计学意义（t=7．03，P〈0．01）。经内分泌治疗后的18例癌区的ADC值升高至（1．46±0．30）×10^-3mm^2／s，非癌区的ADC值为（1．59±0．24）×10^-3mm^2／s，癌区和非癌区之间ADC值差异有统计学意义（t=2．46，P〈0．05）。两组癌区之间ADC值差异有统计学意义（t=4．66，P〈0．01），非癌区、膀胱、闭孔内肌的ADC值差异无统计学意义（t值分别为0．06、0．48、1．64，P值均〉0．05）。结论ADC值用于判断前列腺癌内分泌治疗效果有应用前景。     

低场磁共振T_1FLAIR序列在颅脑肿瘤诊断中的应用

目的 :通过T1FLAIR(液体反转恢复 )序列与传统SE(自旋回波 )序列T1加权图像对比分析 ,评价T1FLAIR作为T1成像序列对颅脑肿瘤的诊断价值。方法 :对 2 3例颅脑疾病患者均用两种序列检查。结果 :在 2 3例颅脑肿瘤中 ,T1FLAIR序列对病灶显示的图像清晰度比SE序列高。结论 :在相同病变检出率的情况下 ,T1FLAIR像在显示颅脑中灰白质对比度、病变和背景对比情况及病变的边界、大小、范围方面优于传统SE序列T1加权像 ,具有重要的临床诊断价值。     

DWI在脑转移瘤诊断中的临床应用

磁共振扩散成像（DWI）是目前在活体上进行水分子扩散测量与成像的唯一方法。水分子扩散运动速率与状态反映的是微米数量级的运动变化,与人体组织中细胞的大小处于同一数量级。因此,与以往的T1WI,T2WI不同,水分子扩散成像使磁共振成像对人体的研究深入到了更微观的水平,反映着人体组织的微观几何结构,以及细胞内外水分子的转移与跨膜运动、温度等变化。本文将DWI在脑转移瘤诊断中的临床应用及进展作一综述。     

Malignant evolution of presumed benign lesions in the brain in neurofibromatosis: case report

We report a patient suffering from neurofibromatosis type 1 in whom neoplasms developed from the areas of altered signal which are generally considered benign and typical of the disease. MRI, despite two previous examinations 3 and 2 years before development of the tumour, gave no clue to an unfavourable outcome. Received: 18 January 1996 Accepted: 24 October 1996     

多b值DWI在儿童脑肿瘤中的初步研究

目的:探讨多b值DWI在儿童脑肿瘤中的应用价值。方法:对31例脑肿瘤患儿行EPI-DWI扫描,采用0～4000s/mm2之间的12个b值。按照单指数模型计算低b值ADC(ADClow)(b≤200s/mm2)、高b值ADC(ADChigh,200s/mm2相似文献   

3.0T临床型MR多发性硬化大鼠颅脑成像的初步研究

目的：探索应用3.0T临床型MR设备进行多发性硬化（MS）大鼠颅脑成像的可行性。方法：用髓鞘少突胶质细胞糖蛋白多肽35-55（MOG35-55）致敏Lewis大鼠制备MS动物模型实验性自身免疫性脑脊髓炎（EAE）大鼠10只,正常对照组大鼠4只。3.0T临床型MR（Siemens Trio Tim）扫描仪配用正交腕关节线圈,行T2W、T1W和Gd-DTPA增强T1W的三维容积扫描,体素0.06mm3。结果：大鼠脑T2WI和T1WI具有较高的空间分辨率和对比度。胼胝体、小脑、新皮质和脑室等解剖结构显示清晰。MOG35-55-EAE大鼠病灶出现在脑和上段颈髓,呈斑片状,T2高信号、T1低信号,部分出现Gd-DTPA强化。结论：应用3.0T临床型MR设备可以获得高质量的大鼠颅脑MR图像,为小动物中枢神经系统疾病的实验研究提供了一种能广泛应用的无创性的活体体外监测手段。     

In vitro delineation of human brain-stem anatomy using a small resonator: correlation with macroscopic and histological findings

Our purpose was to investigate the potential of an experimental animal coil using a commercial MRI unit to delineate the anatomical structure of the human brain stem. Three formaldehyde-fixed brain-stem specimens were examined by MRI and sectioned perpendicular to their longitudinal axis. The images were compared with gross anatomy and myelin-stained histological sections. Fibre tracts and nuclei which were not evident on examination of the unstained specimen were readily identified by MRI. Due to its inherent grey/white matter contrast, MRI with a highresolution coil delineates anatomical structures in a way comparable to the myelin-stained histological sections. However, pigmented structures, readily visible on examination of the unstained specimen were discernible on neither MRI nor on myelin-stained sections. The excellent anatomical detail and grey/white matter contrast provided by these images could make MRI a useful adjunct to the pathologist investigating brain disease.     

Manganese accumulation in the brain: MR imaging

Manganese (Mn) accumulation in the brain is detected as symmetrical high signal intensity in the globus pallidi on T1-weighted MR images without an abnormal signal on T2-weighted images. In this review, we present several cases of Mn accumulation in the brain due to acquired or congenital diseases of the abdomen including hepatic cirrhosis with a portosystemic shunt, congenital biliary atresia, primary biliary cirrhosis, congenital intrahepatic portosystemic shunt without liver dysfunction, Rendu-Osler-Weber syndrome with a diffuse intrahepatic portosystemic shunt, and patent ductus venosus. Other causes of Mn accumulation in the brain are Mn overload from total parenteral nutrition and welding-related Mn intoxication.