磁共振扩散张量成像在中枢神经系统的应用

DTI在中枢神经系统中的应用 扩散成像利用脑实质中水扩散的各向异性，是一种真正意义的定量成像方法，DTI为准确反映包括脑白质纤维在内的中枢神经系统研究提供可能。DTI相关概念，扩散系数(diffusion coefficien，DC)；表示单位时间内分子自由扩散的范围；扩散敏感因子b值(b value)是反映MRI各成像序列(如SE、FE、EPI)对扩散运动表现的敏感程度，体现成像序列检测扩散的能力；     

扩散张量MR成像

扩散张量成像(DTI)是在分子水平上研究组织中水分子随机运动的一种无创性的功能性磁共振成像技术。在人体生理条件下，水分子在各个方向上的扩散率不同，即扩散异向性，DTI能够测量到水分子在三维空间扩散的方向和扩散程度，描述组织的各向异性特点，精确地研究纤维走行方向。     

扩散张量成像在腹部的应用

扩散张量成像是在扩散加权成像(DWI)技术基础上改进和发展的一项新技术,突出强调水分子扩散的各向异性,可以从细胞及分子水平研究疾病病理改变情况。腹部DTI的研究尚属起步阶段,对近年国内外关于腹部脏器的DTI研究予以综述,主要关注DTI在肝脏、肾脏及前列腺的研究进展情况。     

正常前列腺的磁共振扩散张量成像研究

目的探讨前列腺磁共振扩散张量成像(DTI)的可行性及正常外周带和中央腺区DTI特征。方法研究对象为20例健康男性志愿者,DTI都采用Siemens Sonata1.5T超导成像仪和腹部相控阵线圈,应用西门子Leonardo工作站相应的软件进行数据处理。DTI记录感兴趣区各向异性(FA)比值和平均ADC值,并绘制相应参数图和纤维示踪影像。对比不同感兴趣区的相应成像指标的差异。结果正常外周带(PZ)和中央区(CZ)的FA值分别为0.16±0.03和0.23±0.04,两者差异具有统计学意义(P0.05)。PZ和CZ的平均ADC值分别为(1.85±0.34)×10-3mm2/s和(1.37±0.27)×10-3mm2/s,两者差异具有统计学意义(P0.05)。结论正常前列腺DTI具有可行性,中央腺区与外周带DTI指标存在明显差异。     

扩散张量MR成像

扩散张量成像(DTI)是在分子水平上研究组织中水分子随机运动的一种无创性的功能性磁共振成像技术.在人体生理条件下,水分子在各个方向上的扩散率不同,即扩散异向性,DTI能够测量到水分子在三维空间扩散的方向和扩散程度,描述组织的各向异性特点,精确地研究纤维走行方向.     

正常肾脏扩散张量成像的初步研究

目的 探讨正常成人肾脏扩散张量成像(DTI)的特性及其临床意义.方法 21例志愿者行肾脏DTI检查.分析肾脏皮质、髓质的表观扩散系数(ADC)、分数各向异性(FA值),并行髓质纤维束成像.结果 肾皮质和肾髓质ADC值分别为(2.34±0.16)×10-3 mm2/s和(2.10±0.17)×10-3 mm2/s,两者间具有显著性差异(t=2.45,P<0.05).髓质扩散张量示踪图显示肾髓质内放射状指向皮质的放射束.结论 DTI 可显示正常肾脏超微结构变化.肾髓质中水分子扩散具有高各向异性,肾皮质各向异性较弱.肾髓质的高FA值与肾小管、集合管的放射性走行有关.     

扩散张量成像技术及在脑白质病变中的应用

扩散张量成像(DTI)是一种崭新的MRI技术,它对组织内水的扩散在三维空间进行考察,比常规扩散加权成像能更好地反映生物组织扩散的各向异性.叙述了DTI的成像技术、数据处理及其衍生的量化信息、DTI对一些脑白质病变检查和评价的作用.     

扩散峰度成像(DKI)在中枢神经系统的应用

在磁共振成像领域中,扩散张量成像(diffusion tensor imaging,DTI)作为一项磁共振功能成像技术,可以从微观领域评估组织结构的完整性,目前最主要应用于脑组织各方向白质纤维及纤维束的评价。扩散加权成像(DWI)及DTI的理论前提为水分子扩散呈正态分布[2];而扩散峰度成像(diffusion kurtosis imaging,DKI)是基于DTI技术上的延伸,为描绘组织内非正态分布水分子扩散的一种新的磁共振成像方法,较传统的DTI技术,DKI更适合把握组织微观结构的变化[3]。笔者旨在简要综述DKI在中枢神经系统的有关应用及DKI与DTI在相关方面作一定的比较。     

磁共振扩散张量成像在多发性硬化中的研究进展

磁共振扩散张量成像(diffusion tensor imaging,DTI)是在扩散加权成像(diffusion weighted imaging,DWI)基础上发展起来的一项新技术,主要用于中枢神经系统的组织形态学改变与病理学的细微分析研究。多发性硬化(multiple sclero-sis,MS)是中枢神经系统最常见的脱髓鞘性疾病,DTI     

DTI在正常前列腺的应用研究

目的探讨1.5 T MR扩散张量成像(diffusion tensor imaging,DTI)在正常前列腺的参数特点及纤维示踪图像(fiber tracking,FT)表现,为DTI在前列腺癌的应用提供研究基础。资料与方法 21名健康男性志愿者[(24.7±3.59)岁]行前列腺常规MRI及DTI扫描,将DTI扫描数据行后处理分析,测量中央叶和外围叶感兴趣区的表观扩散系数(ADC)和各向异性分数(FA),比较两者的ADC、FA值差异有无统计学意义,并重建前列腺的FT图像。结果 (1)健康男性前列腺DTI左右两侧中央叶和外围叶的ADC、FA值差异均无统计学意义(P>0.05);(2)中央叶和外围叶的ADC、FA值差异有统计学意义,中央叶的ADC值低于外围叶,中央叶的FA值高于外围叶(P<0.05);(3)FT图显示不同颜色的纤维对应不同走行方向,且中央叶的纤维排列比外围叶紧密。结论 1.5 TMR DTI在正常前列腺研究中具有可行性,有助于DTI在前列腺癌中的应用研究。     

Optimization of the system of medical service of students of Cadet Schools of the Ministry of Defense of the Russian Federation

One of the factors of the successful military career guidance Cadet schools students is preserving and promoting their health. Medical support of children and adolescents aged 10-17 years should include the full range of medical and preventive measures defined for this group. The state of providing outpatient care for pupils at the Cadet School in St. Petersburg was studied. These results show that full medical care in accordance with the standards can be based only on children's health clinics. It is important that the organization of medical support pupils cadet schools should be cooperate with civilian health care.     

带状疱疹83例误诊原因分析

带状疱疹是由水痘—带状疱疾病毒引起的皮肤科常见疾病。其主要的病理损害,一是受累神经的严重炎症性浸润,继而导致受侵犯神经节内神经细胞变性、坏死;二是皮肤的水泡。迅速抑制神经节和相应的感觉神经纤维的充血、水肿和坏死,防止粘连形成,达到迅速镇痛、改善皮损,缩短病程及防止后遗症的发生是治疗的关键。因而,尽早明确诊断,     

Estimation of accumulated dose of radiation by method of ESR-spectrometry of dental enamel of mammals

ESR-spectrometry was used to investigate radiation-induced paramagnetic centers in enamel of mammals: carnivores (polar bear and fox), ungulates (reindeer, European bison, moose), and man. Values at half the microwave power saturation of the radiation signal, P_1/2, evaluated at room temperature, was found to range from 16 to 26 mW for animals and man. A new approach to discrimination of the radiation induced signal from the total ESR spectrum of reindeer enamel is proposed. ‘Dose-response’ dependencies of enamel of different species mammals were measured within the dose range from 0.48 up to 10.08 Gy. Estimations of ‘radiosensitivity’ enamel of carnivores and ungulates showed good agreement with radiosensitivity enamel of man by ESR method.     

Analysis of the results of the international comparison of activity measurements of a solution of Fe

The results of an international comparison of activity measurements of a solution of ⁵⁵Fe organized by the BIPM in 2005 are reported and analysed. This exercise, which follows the procedures of the CIPM mutual recognition arrangement to update older comparisons, is a renewal of the comparison organized by the BIPM that took place in 1978. A EUROMET comparison was organized in 1996 specifically to compare activity measurements of a ⁵⁵Fe solution by means of liquid-scintillation techniques. Results of these three comparisons are presented and discussed in this paper.

The radionuclide solution was provided by the NPL, which also distributed the samples to the participants. The activity of the ampoules was measured by 16 laboratories using 12 methods producing 25 results. Some general considerations on uncertainty assessments pertaining to the different techniques used are drawn. The outcome of four different estimators is compared from which the presence of at least one outlier can be confirmed. Further measurements should be made to try to reduce the discrepancy between the results. To date the outcome of the present comparison does not show an improvement to that of the 1996 comparison.     

Evaluation of the results of various technics of non-surgical therapy of varicocele

A new method of non-surgical treatment of varicocele syndrome is described: it consists in sclerotherapy of spermatic vein by trans-femoral percutaneous catheterization with balloon-catheters. In 8 cases venous thrombosis has been induced by direct electric clotting. The techniques and a 6 months follow-up are discussed. It is pointed out that this procedure should be considered as the method of choice for tubular lesions and sub-fertility prophylaxis in young people and in childhood.     

延迟性脾破裂误漏诊原因分析

目的探讨延迟性脾破裂误漏诊原因和预防措施.方法回顾性分析总结12例延迟性脾破裂中的诊断和误漏诊的经验与教训.结果本组延迟性脾破裂的误漏诊5例(41.66%).对多发伤与脾破裂并存可能认识不足,外伤史轻微或伤员隐瞒外伤史,缺乏腹痛-缓解-突然再腹痛的典型病史,缺乏“对冲性脾破裂”力学分析和整体化诊断思路等为其误漏诊的主要原因.结论详细的外伤史和全面系统检查,重视腹以外多发伤掩盖腹内脏器伤及延迟性脾破裂可能.确立外伤-腹内脏器伤-脾破裂整体化诊断思路.不间断地辅以B超检查脾形态学变化和腹内有无积液,腹腔穿刺确定有无血腹、X线胸腹部检查观察左侧胸肋角和膈肌运动情况、必要时CT检查以尽早发现脾包膜下血肿,降低延迟性脾破裂误漏诊率.