生物感应式磁声成像的研究现状

生物感应式磁声(MAT-MI)成像是一种新型功能成像技术,融合电磁技术、超声技术和多物理场探测与成像技术,具有电阻抗成像的高对比度以及超声扫描成像的高空间分辨率的特点,能够反映生物组织的电导率变化信息,达到对病变组织进行早期诊断的目的。将MAT-MI与内窥检测技术相结合,则可直接检测生物腔体组织(如鼻腔、消化道以及血管等)病变的情况,为腔体组织疾病的诊断和治疗提供更及时可靠的依据。在分析MAT-MI的成像原理的基础上,对其正/逆问题的研究现状进行综述,并探讨内窥感应式磁声成像的可行性以及所面临的技术难点。     

基于Golay互补序列的20 MHz眼科超声成像方法

目的研究一种新型20 MHz眼科超声扫描成像方法,可在满足临床成像分辨力和声能安全性要求的前提下,显著提高图像的探测深度,拓展20 MHz超声频段的临床应用范围。方法通过8位Golay互补序列,激励超声换能器产生超声波。回波信息经高速采集与匹配滤波后,采用相邻正、反编码扫描线数据复用的方法交替相加,完成解码运算。在保证图像扫描线数和扫描帧频的前提下,实现实时显像。最后通过钨丝靶线和仿组织超声体模实验,验证了新的成像方法在保持原有分辨能力与扫描帧频不变的前提下,提高了图像的探测深度。结果与传统单脉冲模式相比,Golay互补编码模式成像中轴向分辨率与侧向分辨率分别达到80μm和150μm,小信号探测深度增加约0.5 cm,图像信噪比也得到显著改善。结论基于Golay互补序列实现20 MHz眼部组织超声成像,相对于传统成像方式可极大改善图像质量,具有很好的临床应用前景。     

光声技术在癌症检测和非侵犯性诊断中的应用（英文）

目的：探讨光声技术的原理、优势及癌症临床应用前景。方法：根据肿瘤发展过程,相继介绍光声技术在肿瘤检测过程中的应用。结果：光声技术对光散射生物组织-肿瘤,能够进行无损深层探测及成像,具有其他成像技术所无法比拟的优势。结论：光声技术是一种新的发展中的成像模式,应用于生物医药并获得解剖和功能信息。它对于了解肿瘤生长、转移,癌症诊断和评测治疗功效都有着潜在的重大用途。     

声致荧光成像的初步研究

目的：本文对一种改进型快速的声致荧光成像方法进行了初步研究，即探索在体荧光增强剂和灵敏的ICCD阵列结合成像的可行性。方法：该方法利用聚焦超声对样品内的一层进行逐点扫描，超声焦区将发出声致荧光，借助用于灵敏的弱光接受ICCD阵列,大范围快速收集该超声焦区的声致荧光。结果：实验结果给出聚焦超声场的分布，并利用扫描各点的差异导致的声荧光强度的不同进行模拟样品的图像重建。结论：该研究证明了该技术实现声致荧光成像的可行性．而且其图像的横向分辨率主要受超声聚焦区的形状影响，本实验中接近2mm。     

高频超声中血流散射信号的实验研究

目的分析高频条件下红细胞对超声的背向散射情况,探索高频血流成像的条件。方法在现有理论的基础上,利用瑞利散射公式推导红细胞背向散射回声强度与超声频率的关系,并采用10、20、50 MHz超声进行成像,观察血流散射情况。结果实验对同一人体样本的手臂不同深度浅表静脉成像,实验结果在一定程度上验证了理论推导的结论,表明在1~4 mm的深度范围内高频超声成像可获得较强的血流散射回声。结论在高频超声条件下探测浅表血管,即使采用单脉冲探测,依然可获得较丰富的血流回声信号,采用20 MHz的超声频率,可获得较理想的血流散射信息,为高频血流成像提供了条件。     

模拟微血管的光声成像技术研究

目的：为了实现较深层组织内微血管的光声成像。方法：采用波长532nm、重复频率10Hz的脉冲激光作为激励源,宽带非聚焦针状探头以圆周扫描的方式采集时域光声信号,二维光学吸收分布图像由时域后向投影算法重建,以线扩展函数为依据测量系统的成像空间分辨率。结果：成像空间分辨率0．1mm,模拟微血管网络的光声图像与原始样品完全吻合。结论：对组织内癌症病灶的早期诊断具有较大的意义。     

提高光声成像质量的Renyi熵方法

针对光声成像数据采集系统中获得的超声数据存在杂波问题,提出一种先基于Renyi熵分离超声信号和杂波,再利用分离后的超声数据进行光声成像的方法。光声成像平台实验表明,通过Renyi熵的直方图来选择超声信号和杂波分离的阈值,可以有效地滤除超声信号中的大部分杂波。成像重构的评估结果也验证了该结论。可见,该文提出的方法能有效滤除超声采集数据中的杂波,从而提高光声成像的质量。     

Barker编码激励在眼科高频超声成像中的应用研究

为了平衡医学高频超声成像中纵向分辨率和探测深度这两项指标之间的矛盾,本研究提出了在眼科超声成像中,采用13位Barker数字编码激励并结合失配滤波解码压缩方法替代传统的单脉冲激励的方法。在对比各种编解码方式的优缺点的基础上,构建了眼科超声成像平台。仿真和实验结果表明,失配滤波解码技术的输出信号主副比是匹配滤波的9.7倍。与传统的单脉冲成像在安全性、分辨率、探测深度等方面比较,编码激励技术能有效地改善眼部组织超声成像的效果,具有较强的实际应用价值和市场前景。     

基于时域后向投影的光声谱成像系统研究

光声谱成像是一种新的生物组织成像方法,它结合光学成像和超声成像的特点,可提供高分辨率和对比度的图像。采用波长532nm、重复频率10Hz的脉冲激光作为激励源,宽带PVDF非聚焦超声探测器频率响应范围为200kHz～15MHz,探测器以圆周扫描的方式采集样品的时域光声信号,并采用时域后向投影算法重建样品内部的二维光学吸收分布图像。实验表明,系统成像的空间分辨率小于1mm,重建的图像与原始样品完全吻合。     

生物组织非接触光声层析成像EI北大核心CSCD

在光声成像中,超声信号通常需要采用接触传感器探测,这使其在很多应用中受到很大的限制,如脑功能成像。为了替代接触探测器实现非接触的光声层析成像(NCPAT),激光干涉技术被用于远程获取超声信号。本文搭建了非接触光声层析成像系统,系统采用波长为532 nm、能量17.5 m J/cm^2的激光作为光声激发源,激光外差干涉仪作为光声信号的远程探测系统,对实际生物组织模型进行了旋转几何的光声信号探测。利用激光外差干涉仪探测到的光声信号,进行反投影算法的图像重建。实验结果表明在具有组织散射特性的模型中,激光外差干涉仪在2.25 MHz带宽(峰值下15 d B强度的信号宽带)下,NCPAT成像系统可以识别500μm直径的黑色微球,并实现了在强散射介质中多层结构的光学对比成像。这将扩展光声和超声在体成像在生物医学领域的应用范围。     

Ambivalence resolution in brief psychotherapy for depression

Ambivalence in the process of psychotherapeutic change should be addressed and resolved if we are to avoid psychotherapeutic failure and promote sustained change. In this context, ambivalence can be defined as the cyclical conflictual relation between two opposed positions of the self: one expressed as an innovation, and a subsequent one expressed in a trivialization or rejection of the innovation (problematic position). This conflict may be resolved in two different ways: (a) the dominance of the innovative position and the consequent inhibition of the problematic one and (b) the negotiation between the innovative and the problematic positions. In this study, we sought to study the evolution of the dominance and the negotiation processes in recovered and unchanged cases; to analyse if different therapeutic models produce different results on the evolution of the dominance and negotiation processes, and finally, to study if these processes are predictive of ambivalence resolution. The complete sessions of 22 clinical cases of depression (6 cognitive‐behavioural therapy, 10 narrative therapy, and 6 emotion‐focused therapy cases) were independently coded for innovative moments, ambivalence, and ambivalence resolution. Results revealed that recovered cases had a progressively higher proportion of negotiation along treatment, whereas in unchanged cases, negotiation was virtually absent throughout treatment. Both dominance and negotiation were significant predictors of ambivalence reduction, however, negotiation had a higher impact than dominance. Overall, these results did not significantly differ for the 3 therapeutic models. The theoretical implications of these findings are discussed, and theoretical derived suggestions for clinicians are presented.     

CT空间分辨率的自动检测

目的：采用Matlab6．1编写的自动检测程序来测量CT的空间分辨率。方法：用美国生产的Catphan500体模、对两台螺旋CT及一台常规CT的空间分辨率进行检测，并将目测结果与随机程序检测结果进行对比。结果：该方法方便省时，人工干预少，客观性程度高，可取代人工检测。     

CT低对比度分辨力性能检测体模分析

目的：探索新型体模设计方案，材料与方法：对比分析和实验验证目前国内普遍使用的Catphan和AAPM两种体模的优缺点。结果：两种体模在定义，材料与几何结构等方面存在显著差别，实际检测结果也不一致。结论：设计一种新型体模是有意义而且是必要的，并得出初步设计方案。     

Higher resolution banding techniques in the clinical routine

Experience with higher resolution banding techniques is described. Cell synchronization and different chemicals which delay the mitotic condensation process were tried. None of these agents alone was able to induce undercondensation in a sufficient way in any of the patients investigated. Of the banding techniques, GTG banding proved preferable, but in some special cases RBA banding will be more informative.     

SPECT的数据采集条件对其断层分辨率的影响实验探讨

目的：探讨采集条件的选择对ＳＰＥＣＴ断层分辨率的影响。方法：来用 Ｊａｓｚｃｚａｋ模型。设定不同条件对模型进行 ３６０°采集,并对所采集的４８组原始资料进行重建处理,观察重建图像。结果：配置高能准直器,１２８×１２８矩阵,２００Ｋ以上计数,重建结果可分辨出直径 １１ ｍｍ柱型模型及直径 １２ ｍｍ球形模型,其余采集方式所重建的结果均达不到此分辨效果。讨论;就矩阵大小而言,１２８×１２８矩阵采集分辨能力优于６４×６４矩阵。采集信息量的大小亦是影响分辨率好坏的重要因素之一,采集信息量大,分辨率则高;反之,则分辨率下降。     

The surface laplacian,high resolution EEG and controversies

Summary The surface Laplacian estimate (i.e., current source density) as obtained with spline functions is evaluated in the context of some recent controversies concerning high resolution EEG and source localization. In simulation studies, the spline-Laplacian provides much better estimates of cortical surface potential than is obtained from raw scalp potential, provided dense electrode arrays (e.g., 64 or more electrodes) are used. Spline-Laplacians (which are relatively independent of volume conductor model) provide estimates of cortical potential distribution which are quite similar to those obtained with a cortical imaging algorithm based on a four sphere model.     

翼腭窝区的高分辨力CT三维重建

目的:探讨高分辨力CT(HRCT)三维重建技术在翼腭窝区的应用价值,为临床该区疾病诊断及手术方案设计提供影像解剖学资料。方法:对10例健康志愿者行HRCT扫描后,利用多平面重组(MPR)和遮盖表面显示法(SSD)三维重建技术显示翼腭窝区骨性结构。结果:HRCT扫描及MPR重建图像清晰显示翼腭窝及其通道在横断面、冠状面及矢状面上的形态特征,SSD重建图像能满意显示翼腭窝区骨性结构的立体解剖及与周围结构的空间位置关系。结论:HRCT轴位扫描与MPR、SSD相结合可直观、立体、清晰地显示翼腭窝区结构。     

Laser tomography of heterogeneous scattering media using spatial and temporal resolution

Time-resolved tomography is performed in transillumination by using 527 nm picosecond pulses from a passively mode-locked doubled Nd/glass laser and a streak camera to select photons according to their flight time. This work reports on the increase in contrast of a time-resolved profile of a 2 mm radius opaque object embedded in a scattering medium, constituted of diluted milk in a 30 mm thick cell. For spatial analysis, the emerging photons are detected through a 6 mm slit at the outlet face of the cell. Transmission profiles obtained as a function of time show that the contrast is enhanced for the shortest flight times, while the ‘shadow’ of the object is no longer detected after about 100 ps. Moreover, improvements in contrast are studied for different configurations of the model, to analyse separately the role of collimated and scattered photons. It is expected that such a tomographic method based on time-resolved absorption could be applied to imaging for more complex biological structures in the red and near-infra-red range.     

Chronic inflammation in asthma: a contest of persistence vs resolution

Recent investigations have highlighted that endogenous anti-inflammatory mediators and immune regulating mechanisms are important for the resolution of inflammatory processes. A disruption of these mechanisms can be causally related not only to the initiation of unnecessary inflammation, but also to the persistence of several chronic inflammatory diseases. In asthma, chronic Th-2 driven eosinophilic inflammation of the airways is one of the central abnormalities. To date, elucidating the role of the different pro-inflammatory mediators involved in orchestrating the inflammatory processes in asthma has been the subject of intense research in both humans and animal models. However, the counter-regulatory mechanisms that co-determine the outcome in the contest of resolution vs persistence of the eosinophilic airway inflammation remain poorly understood. These are currently being investigated in animal models of chronic asthma. Elucidating these mechanisms is of relevance, since it can give rise to a new therapeutic approach in the treatment of chronic airway inflammation in asthmatics. This novel concept of treatment involves the stimulation of endogenous anti-inflammatory pathways, rather than solely antagonising the various pro-inflammatory mediators. Here, we review and discuss the current knowledge about these endogenous anti-inflammatory mediators in clinical and experimental asthma.     

A categorical analysis of coreference resolution errors in biomedical texts

BackgroundCoreference resolution is an essential task in information extraction from the published biomedical literature. It supports the discovery of complex information by linking referring expressions such as pronouns and appositives to their referents, which are typically entities that play a central role in biomedical events. Correctly establishing these links allows detailed understanding of all the participants in events, and connecting events together through their shared participants.ResultsAs an initial step towards the development of a novel coreference resolution system for the biomedical domain, we have categorised the characteristics of coreference relations by type of anaphor as well as broader syntactic and semantic characteristics, and have compared the performance of a domain adaptation of a state-of-the-art general system to published results from domain-specific systems in terms of this categorisation. We also develop a rule-based system for anaphoric coreference resolution in the biomedical domain with simple modules derived from available systems. Our results show that the domain-specific systems outperform the general system overall. Whilst this result is unsurprising, our proposed categorisation enables a detailed quantitative analysis of the system performance. We identify limitations of each system and find that there remain important gaps in the state-of-the-art systems, which are clearly identifiable with respect to the categorisation.ConclusionWe have analysed in detail the performance of existing coreference resolution systems for the biomedical literature and have demonstrated that there clear gaps in their coverage. The approach developed in the general domain needs to be tailored for portability to the biomedical domain. The specific framework for class-based error analysis of existing systems that we propose has benefits for identifying specific limitations of those systems. This in turn provides insights for further system development.