韧带样纤维瘤的影像学表现

目的：探讨韧带样纤维瘤的影像学表现。方法：结合文献分析4例经术后病理证实的韧带样纤维瘤的病理、临床及影像学表现。结果：本组4例发病部位分别为腹腔、腹壁、胸壁及腋窝和股骨下段。典型的韧带样纤维瘤表现为较均质的单发病灶,CT平扫比相邻软组织密度稍高或相等,在MRI上可因肿瘤内成分不同而引起T2WI信号的变化。增强后有轻度、...     

PET/MRI新技术应用研究进展

PET/CT的广泛应用有力地促进了核医学的发展。MRI与CT相比有更高的软组织对比度和空间分辨率,且无电磁辐射,因此PET/MRI的研究成为近些年的热点,并已取得了初步的进展,虽然目前PET/MRI离广泛应用还存在一定距离,但已有的研究成果表明,PET/MRI具有广阔的发展空间,有望将分子影像技术的发展带入一个新的时代...     

骨巨细胞瘤的CT、MRI诊断

目的文中分析了X线平片、CT及MRI征象并与手术病理对照,总结骨巨细胞瘤的CT、MRI表现及其特点.材料与方法收集经病理或活检证实的16例骨巨细胞瘤.结果显示CT、MRI可以提供比X线平片更全面的影像学信息.结论综合运用以上检查方法将大大提高骨巨细胞瘤诊断的准确性,并且能够为临床提供更全面的影像学信息.     

Magnetic resonance imaging of the Lake Agassiz–Lake Winnipeg transition

As part of the Geologic Survey of Canada (GSC) Lake Winnipeg Study, we have successfully imaged the Lake Agassiz to Lake Winnipeg transition in Section 4 of Core Namao 94-900-122a (i.e., from 313 cm to 465 cm), using a newly-developed magnetic resonance imaging (MRI) technique called SPRITE (Single-Point, Ramped Imaging with T₁ Enhancement). Whole core, gamma-ray attenuation measurements have been used to calculate the bulk porosity of the sediment at 1 cm intervals for comparison with the SPRITE images. Image contrast and image intensities observed in the SPRITE images of Section 4 are related to local porosity and magnetic susceptibility variations. In general, regions of the core with low signal intensity contain high porosity and low magnetic susceptibility. The best contrast between sediment layers is observed from regions of the core with high magnetic susceptibility. High signal intensity is observed from regions with low porosity and/or high magnetic susceptibility.     

神经诊断性检查在诊断儿童自身免疫性脑炎中的应用

目的 本研究收集确诊和疑诊为自身免疫性脑炎（autoimmune encephalitis,AE）的儿童患者,并进行磁共振（MRI）和脑电图（EEG）检查。回顾性的识别儿童AE患者的特异性MRI和脑电图改变,为以后快速诊断该疾病提供临床证据。方法 本研究收集从2009~2013年在笔者医院就诊为自身免疫性脑炎的儿童患者。通过指南进行筛选,汇总患者相关信息,并把患者分为确诊组和疑诊组。同时收集患者头部MRI和EEG结果,观察AE患者MRI的主要病变部位和EEG的异常波形,并进行共性分析。结果 本研究最终纳入18例符合纳入标准的AE患者,其中9例为确诊患者,9例为疑诊患者。18例纳入患者中有17例患者至少做过1次头部MRI。其中13例患者MRI结果有异常。笔者在9例确诊患者中发现7例患者有边缘系统的病变,且多累积双侧但不对称。5例疑诊患者具有异常的MRI显影,这些病变累积到额外的皮质（包括颞叶、顶叶和枕叶）,且同样是累积双侧但不对称。18例纳入研究的患者中有16例患者进行了EEG检查。其中主要的改变有非特异性的背景波形改变,常规慢波和局灶性慢波。且在5例患者的EEG中发现了睡眠时纺锤样改变。结论 本研究发现大部分AE患者都存在头部MRI和EEG异常。确诊为自身免疫性脑炎的儿童患者接受头部MRI检查后发现病变主要集中在边缘系统,且大部分患者的EEG呈现癫痫样放电,少数患者中发现EEG呈纺锤样改变。     

Effects of entrapped residual air bubbles on tracer transport in heterogeneous soil: Magnetic resonance imaging study

Magnetic resonance imaging (MRI) was used to study the process of infiltration and solute transport in an undisturbed soil sample of coarse sandy loam. The sample was subjected to the recurrent ponded infiltration (RPI) experiment, which was carried out in order to assess the changes in the entrapped air volume and its impact on steady state flow rates and solute breakthrough. The main stages of the first and second experimental RPI runs were monitored using an MRI sequence that follows both water density and magnetic relaxation. In a steady state stage of each experimental run a nickel nitrate pulse was injected in order to visualize the solute breakthrough. Effluent from the sample was collected for chemical analysis and a breakthrough curve of the nickel was constructed. To obtain information about the soil structure and to reveal potential preferential pathways, the soil sample was scanned using computed tomography. The local nickel ion transport breakthrough was evaluated from MR images in a series of local observation points distributed along the selected preferential pathways.The preferential flow instability phenomenon with the emphasis on air bubble formation was shown by detecting a 60% decrease of the steady state infiltration rate. The detailed analyses of MRI measurements at observation points revealed air bubble formation, producing a flow rate decrease accompanied by redirection of nickel ion transport trajectories. By analyzing M0 maps it was found that the volumetric water content decrease was 2.2%.     

Void distributions in samples of Ottawa sand

The void distribution of saturated specimens of Ottawa sand is presented. The presence of water inside the sand specimen is detected using the magnetic resonance imaging (MRI) technique. The void distribution of the sample was determined from the image. The specimen was prepared in a non-metallic triaxial cell and was put insie a MRI apparatus to obtain the image. Two sample preparation methods (wet tamping and dry pluviation) were used to illustrate the uniformity of the samples in the initial state. The void distribution along the height of the sample and the three-dimensional orientational void distribution at different locations inside the sample were analysed. The results indicate that the sample generated by the dry-pluviation method is more uniform than the sample generated by the wet-tamping method. When the wet-tamping sample preparation technique is used, the dense sample is more uniform than the loose sample. The development of voids was investigated by a sample loaded inside the MRI device under drained compression condition. The void distribution along the height of the sample at different stages was observed. This work has demonstrated the feasibility of using the MRI technique to examine void distribution in granular material.     

Measurement of fluid flow in pipe and porous media by high-resolution magnetic resonance imaging

The objective of this study is to understand the process of fluid flow in pipe and porous media with different pore structures.High-resolution Magnetic Resonance Imaging(MRI)technique was used to visualize the pore structure and measure fluid flow.The porous media was formed by packed bed of glass beads.Flow measurement was carried out by a modified spin echo sequence.The results show that the velocity distribution in pipe is annular and the linear relation between MRI velocity and actual velocity is found in pipe flow measurement.The flow distribution in porous media is rather heterogeneous,and it is consistent with heterogeneous pore structure.The flow through pores with the high volume flow rate is determined largely by geometrical effects such as pore size and cross-sectional area.     

多模态影像技术在临床中的应用进展

自人类进入20世纪后,知识结构呈现信息爆炸征象,各项技术迅速发展。PET、PET/CT、PET/MRI、SPECT、SPECT/CT等仪器、技术得以广泛应用,并在疾病诊治等方面取得重大进展。因疾病发生机制较为复杂,各种模态信息量相对单一及片面,存在其自身局限性,使得即使拥有如此多模态的影像技术,仍无法完全实现对复杂疾病的精确评估。故此不同模态图像的信息融合使得信息互补及交叉验证成为可能。该文主要介绍多模态影像技术的发展及应用进展。