弥散张量磁共振成像方法概述

弥散张量成像(diffusion tensor imaging,DTI)是一种根据组织内水分子的弥散特性来探测有机体的微观结构和病理改变的核磁共振成像方法,目前已经成为临床评估和生命科学研究重要的工具。本文结合近年来的文献综述了弥散张量成像的基本原理,列举了目前常用的成像方法,分析了它们的优缺点以及用途,并对弥散张量成像的发展方向作了一些展望。     

女性控尿解剖学机制的MRI研究

目的探讨女性控尿的解剖学机制在MRI（磁共振成像）的表现和观察方法。方法对20例正常控尿的成年女性进行MRI扫描，采用八通道体部线圈、快束自旋回波（FSE）扫描序列进行扫描，采集静息时盆腔横断面、矢状面和冠状面影像。结果MRI显示，女性的尿道分三层结构，与病理学对照，由内向外依次为黏膜及黏膜下组织、肌肉、外膜组织，但无法区分平滑肌与括约肌；与控尿有关的盆底肌肉也能够清楚显示。结论MRI能够清楚观察到女性控尿的有关解剖结构，是观察女性控尿解剖结构的较理想影像方法。     

腮腺间隙良性肿瘤的MRI诊断

目的探讨腮腺间隙常见良性肿瘤的影像特征及其诊断与鉴别诊断。方法良性肿瘤20例，包括多形性腺瘤13例、乳头状淋巴囊腺瘤3例、淋巴管瘤2例、血管瘤1例、脂肪瘤1例。经手术病理证实15例，穿刺活检证实4例，典型MR特征结合病史确诊1例。结果13例多形性腺瘤中有11例位于腮腺浅叶，2例位于深叶；9例表现为均匀等T1长T2信号．4例在T2WI上信号明显不均匀；静脉注射Gd—UIPA后3例瘤实质均匀强化，4例增强后明显不均匀强化。3例Warthin瘤中2例发生于一侧，1例累及双侧腮腺，在T1WI上呈低信号，T2WI上信号等于或低于正常腺实质，增强后无明显强化。2例淋巴管瘤呈明显长T1长T2信号，并有多房现象。1例血管瘤信号不均质，呈明显长T1长T2信号，静1脉注射Gd—DTPA后病变往往显著异常强化。1例脂肪瘤在T1WI及T2WI上均表现为明显高信号强度。结论运用MR成像研究腮腺间隙的良性肿瘤，有利于疾病的定位，有助于病变的诊断与鉴别诊断。     

33例肝占位性病变MRI误诊的分析

我院１９８８年以来４０００余例腹部ＭＲＩ中，发现肝占位性病变误诊３３例。所用机型为美国Ｄｉｓｏｎｉｃｓ公司０．５Ｔ超导ＭＲＩ，自旋回波序列（ＳＥ序列）、常规Ｔ１加权（Ｔ１ＷＩ）、质子加权（ＰＤＷＩ）、Ｔ２加权（Ｔ２ＷＩ），覆盖全肝。其中，ＰＨＣ误诊为ＭＨＣ５例、ＭＨＣ误诊为ＰＨＣ６例、ＰＨＣ误为ＨＨＥ５例、ＭＨＣ误诊为ＨＨＥ２例、ＨＨＥ误诊为ＰＨＣ６例、肝硬化结节误诊为ＰＨＣ２例、炎性假瘤误诊为ＰＨＣ３例、肝结核误诊为ＰＨＣ１例、ＨＣＹ误诊为ＨＨＥ３例。本文从病变的影像学特征和扫描技术方面详细探讨了误诊的原因和鉴别诊断要点。     

后颅凹成血管细胞瘤的影像学特点及其诊断

目的：探讨成血管细胞瘤的影像学特点。材料与方法：报道１４例成血管细胞瘤的ＣＴ和ＭＲＩ所见，分析肿瘤的特点。结果：囊性肿瘤，在ＭＲＩ上表现为囊性病灶和附壁肿瘤结节；在ＣＴ上表现为该典型征象占８１．８％。混合性肿瘤３例，在ＣＴ和ＭＲＩ上表现实质性肿块、偏心性囊变和均一显著强化；后者还可见肿瘤旁和肿瘤内血管流空。结论：ＣＴ和ＭＲＩ均是诊断成血管细胞瘤的有效检查方法。成血管细胞瘤的特征性影像学表现是囊肿和突入囊内的壁结节，以及肿瘤的异常显著增强     

彩色多普勒超声对肝癌肝动脉化疗栓塞的疗效评价

目的 :探讨彩色多普勒超声 (CDFI)在评价肝癌肝动脉化疗栓塞 (TAE)疗效中的应用价值。方法 :对 4 8例原发性肝癌TAE术前、后行CDFI检查 ,观察肿瘤大小、血供及肝动脉、门静脉血流动力学改变。结果 :TAE术后大多数肿瘤均有不同程度缩小 ;肿瘤内部及周边血供明显减少 (P <0 0 5 ) ,以肿瘤内血流减少更明显 ,其血供减少程度与肿瘤缩小程度呈正相关 (r =0 75 ,P <0 0 0 1) ,肝动脉峰值流速明显下降 ,门静脉血流速度增快 (P <0 0 0 1)。结论 :CDFI能客观判断肿瘤大小及血流灌注状态 ,是目前检验肝癌TAE效果较理想的影像学检查方法     

Copper radionuclides and radiopharmaceuticals in nuclear medicine

The chemistry, radiochemistry, radiobiology, and radiopharmacology of radiopharmaceuticals containing copper radionuclides are reviewed. Copper radionuclides offer application in positron emission tomography, targeted radiotherapy, and single photon imaging. The chemistry of copper is relatively simple and well-suited to radiopharmaceutical application. Current radiopharmaceuticals include biomolecules labelled via bifunctional chelators primarily based on cyclic polyaminocarboxylates and polyamines, and pyruvaldehyde-bis(N⁴-methylthiosemicarbazone) (PTSM) and its analogues. The chemistry of copper, of which only a fraction has yet been exploited, is likely to be applied more fully in the future.     

A rare case of nasopharyngeal angiofibroma in an elderly female

Nasopharyngeal angiofibromas occur predominantly in males in their puberty and adolescence; the incidence in other age groups and in women is exceptional. This report describes a case of a 57-year-old woman with nasopharyngeal angiofibroma presenting typical radiological findings in computed tomography, MR imaging and angiography. The tumour was successfully removed and histopathological examination confirmed the diagnosis. In 6 years follow-up the patient is free of symptoms.     

Transcranial magnetic stimulation: new insights into representational cortical plasticity

In the last decade, transcranial magnetic stimulation (TMS) has been used increasingly as a tool to explore the mechanisms and consequences of cortical plasticity in the intact human cortex. Because the spatial accuracy of the technique is limited, we refer to this as plasticity at a regional level. Currently, TMS is used to explore regional reorganization in three different ways. First, it can map changes in the pattern of connectivity within and between different cortical areas or their spinal projections. Important examples of this approach can be found in the work on motor cortex representations following a variety of interventions such as immobilization, skill acquisition, or stroke. Second, TMS can be used to investigate the behavioural relevance of these changes. By applying TMS in its "virtual lesion" mode, it is possible to interfere with cortical function and ask whether plastic reorganization within a distinct cortical area improves function. Third, TMS can be used to promote changes in cortical function. This is achieved by using repetitive TMS (rTMS) to induce short-term functional reorganization in the human cortex. The magnitude and the direction of rTMS-induced plasticity depend on extrinsic factors (i.e. the variables of stimulation such as intensity, frequency, and total number of stimuli) and intrinsic factors (i.e. the functional state of the cortex targeted by rTMS). Since conditioning effects of rTMS are not limited to the stimulated cortex but give rise to functional changes in interconnected cortical areas, rTMS is a suitable tool to investigate plasticity within a distributed functional network. Indeed, the lasting effects of rTMS offer new possibilities to study dynamic aspects of the pathophysiology of a variety of diseases and may have therapeutic potential in some neuropsychiatric disorders. Electronic Publication