基于正则化方法的加权最小模估计在脑磁源成像中的应用

脑磁图 ( m agnetoencephalography,MEG)逆问题的研究 ,根据点源和分布源两种源模型 ,可分为偶极子定位和磁源成像两大类求逆方法。采用非参数的分布源模型 ,MEG逆问题转化为一个病态的欠定方程组的求解。本文系统地阐述了结合 Tikhonov正则技术的加权最小模磁源重建方法 ,着重介绍了深度归一化算法、低分辨率脑电磁断层成像技术、局部欠定系统解法、选择性最小模方法 ,此外还从广义的加权最小模估计角度对最大熵重建方法 ,融合其它脑功能成像技术的方法以及最大后验概率估计方法加以解释和分析。不同的磁源成像方法目的都是通过引入合适的约束条件 ,从算法公式本身及神经细胞活动的特性中加以修正 ,减少逆问题的不适定程度 ,因此均可认为是使用正则方法来约束解空间 ,从而获得与测量磁场数据相拟合的并具有神经生理学和解剖学意义下的最合理的解。基于正则化技术的加权最小模估计是 MEG逆问题研究中最早开展、并已被广泛应用的磁源分布图像重建方法 ,本文给出了一个较为完整的理论发展框架     

Promising Outcome of Umbilical Cord Blood Transplantation in Patients with Multiple Comorbidities

The hematopoietic cell transplantation–specific comorbidity index (HCT-CI) has been recently proposed to predict the probability of nonrelapse mortality (NRM) and overall survival (OS) in allogeneic hematopoietic stem cell transplantation (HSCT). However, the usefulness of the HCT-CI in single-unit umbilical cord blood transplantation (UCBT) remains unclear. We investigated the impact of the HCT-CI on the clinical outcomes of allogeneic HSCT in a single-center retrospective study including 53 recipients of UCBT (UCBT group) and 90 recipients of other HSCT (non-UCBT group). In the non-UCBT group 2-year OS rates for HCT-CI score <?3 and?≥3 were 67% (n?=?74; 95% confidence interval [CI], 54% to 78%) and 26% (n?=?16; 95% CI, 7% to 51%), respectively (P?=?.001). In the UCBT group these rates were 66% (n?=?39; 95% CI, 48% to 79%) and 69% (n?=?14; 95% CI, 36% to 87%), respectively (P?=?.73). In the non-UCBT group 1-year NRM rates for HCT-CI score <?3 and?≥3 were 14% (95% CI, 6.4% to 22%) and 37% (95% CI, 14% to 61%), respectively (P?=?.02). In the UCBT group these rates were 6.1% (95% CI, 3.4% to 24%) and 7.7% (95% CI, .4% to 29%), respectively (P?=?.78). Using multivariate analysis we showed that HCT-CI score ≥ 3 was significantly associated with lower OS (hazard ratio, 3.06; 95% CI, 1.47 to 6.38; P?=?.003) and higher NRM (hazard ratio, 2.87; 95% CI, 1.18 to 6.96; P?=?.02) for the non-UCBT group. UCBT showed good OS with low incidence of NRM, even in patients with high HCT-CI scores. Altogether, we propose single-unit UCB to be a promising stem cell source for improving survival in patients with multiple comorbidities.     

早期高血压激光、电刺激疗法的信号自动识别研究

目的:针对早期高血压激光、电刺激治疗中需要多种模式刺激信号以解决患者个体化差异以及适应性的问题,提出了一种刺激信号的自动识别方法,为临床选择有效的治疗信号提供了方便、快捷的筛选手段。 方法:用已被临床试验证实有疗效的数字音频信号作为原始信号,提取该类信号的MFCC特征参数建立HMM模型库;将实验用的信号分组,有效信号识别后定出判别标准;对识别信号提取特征参数,利用维特比（Viterbi）算法计算识别信号与模型匹配程度,将识别信号与模板库中的信号自动匹配,根据匹配结果判断识别信号在模板库中所属的类别。 结果和结论:待识别信号采用HMM模型能有效地分类识别,并且可从大量的待识别信号中准确、快捷地分拣出识别信号与原始信号输出概率对数的相对值小的信号,待临床验证后用作早期高血压激光、电刺激疗法的信号源。     

视听联合刺激诱发事件相关电位的时变源分析

目的 运用偶极子源分析方法分析视（V）、听（A）单独刺激和视听（VA）联合刺激早期阶段脑功能区的动态变化.方法 采用64道脑电采集系统,记录14例志愿者在视觉、听觉和视听联合刺激下诱发的事件相关电位（ERPs）,并将这3种任务的早期阶段分成不同子时间段进行偶极子源分析.结果 视觉、听觉刺激诱发的早期偶极子源定位在特定脑皮层功能区,并且偶极子的位置和强度随时间发生变化.结论 脑功能区在视听刺激的早期阶段（＜150 ms）对感觉信息存在动态的处理过程.     

Impact of new technologies on dose reduction in CT

The introduction of slip ring technology enables helical CT scanning in the late 1980's and has rejuvenated CT's role in diagnostic imaging. Helical CT scanning has made possible whole body scanning in a single breath hold and computed tomography angiography (CTA) which has replaced invasive catheter based angiography in many cases because of its easy of operation and lesser risk to patients. However, a series of recent articles and accidents have heightened the concern of radiation risk from CT scanning. Undoubtedly, the radiation dose from CT studies, in particular, CCTA studies, are among the highest dose studies in diagnostic imaging. Nevertheless, CT has remained the workhorse of diagnostic imaging in emergent and non-emergent situations because of their ubiquitous presence in medical facilities from large academic to small regional hospitals and their round the clock accessibility due to their ease of use for both staff and patients as compared to MR scanners. The legitimate concern of radiation dose has sparked discussions on the risk vs benefit of CT scanning. It is recognized that newer CT applications, like CCTA and perfusion, will be severely curtailed unless radiation dose is reduced. This paper discusses the various hardware and software techniques developed to reduce radiation dose to patients in CT scanning. The current average effective dose of a CT study is ∼10 mSv, with the implementation of dose reduction techniques discussed herein; it is realistic to expect that the average effective dose may be decreased by 2-3 fold.     

Stimulus duration influences the dipole location shift within the auditory evoked field component N100m

The equivalent source of the neuromagnetic auditory evoked field (AEF) component N100m shifts systematically within its latency range. In the current study, possible effects of stimulus duration on this shift were analysed. 15 subjects were stimulated monaurally with tones of different duration (50, 100, 200 ms) and AEFs were recorded successively over both hemispheres. Dipoles were calculated in 5-ms-steps from 15 ms before to 15 ms after the N100m peak maximum. A dipole location shift within the N100m latency from posterior to anterior and from superior to inferior was observed. The shift in anterior-posterior direction was found to be larger in the right compared to the left hemisphere. Stimulus duration significantly affected the degree of dipole shift in this direction. It was found to be shorter the shorter the stimulus.     

Removal of eye blinking artifact from the electro-encephalogram, incorporating a new constrained blind source separation algorithm

A robust constrained blind source separation (CBSS) algorithm has been developed as an effective means to remove ocular artifacts (OAs) from electroencephalograms (EEGs). Currently, clinicians reject a data segment if the patient blinked or spoke during the observation interval. The rejected data segment could contain important information masked by the artifact. In the CBSS technique, a reference signal was exploited as a constraint. The constrained problem was then converted to an unconstrained problem by means of non-linear penalty functions weighted by the penalty terms. This led to the modification of the overall cost function, which was then minimised with the natural gradient algorithm. The effectiveness of the algorithm was also examined for the removal of other interfering signals such as electrocardiograms. The CBSS algorithm was tested with ten sets of data containing OAs. The proposed algorithm yielded, on average, a 19% performance improvement over Parra's BSS algorithm for removing OAs.     

临床影像设备下的X射线相干散射成像

进行在临床影像设备条件下X射线相干散射成像的研究.通过改进影像设备的准直、聚焦设备,实现更加清晰的成像.经过后期的图像处理,获得确定的光子能量空间分布的图像和曲线,进一步深化了实验研究结果.通过对影像设备的改造,获得了更具有实验说服力的实验图像,经过对实验图像的算法分析,可以肯定临床CR影像设备上进行成像是可行的,面向临床应用的X射线相干散射成像将是进一步的研究目标.在普通X射线影像设备上的X射线相干散射成像研究,是这种成像方式向应用发展的关键步骤.通过对实验设备的优化和改造,达到了预期的成像精度.     

Identification of Rhodococcus, Gordona and Dietzia species using carbon source utilization tests (“Biotype-100” strips)

The “Biotype-100” identification system (BioMérieux, La Balme-les-Grottes, France) based on carbon source utilization was evaluated for its ability to discriminate among 10 species of Rhodococcus, 7 species of Gordona and one species of Dietzia. The type strains of three species of Tsukamurella and 8 species of Nocardia were also included in the study. Results were compared with chemotaxonomic and conventional data. Carbon source utilization was shown to be reliable, rapid and easy to use when compared with standard identification methods. The 29 species tested were unambiguously separated by carbon source utilization tests. Rhodococcus equi was found to be heterogenous.Les galeries “Biotype-100” (BioMérieux) ont été utilisées pour différencier 10 espèces du genre Rhodococcus, 7 espèces du genre Gordona et 1 espèce du genre Dietzia entre elles. Les souchestypes de 3 espèces du genre Tsukamurella et 8 espèces du genre Nocardia ont été incluses dans cette étude. Les résultats ont été comparés avec ceux des études chimiotaxonomiques et ceux obtenus avec les galeries d'identification classiques. Les galeries Biotype-100 sont sûres, rapides et faciles à utiliser par rapport aux galeries classiques. Les 29 espèces étudiées ont été identifiées sans aucune difficulté. L'espèce Rhodococcus equi s'est révélée hétérogène.     

铱源驻留步长对宫颈癌三维近距离治疗计划的影响

目的:研究宫颈癌近距离治疗计划设计中,铱源驻留步长选择对计划评估及剂量稳定性的影响。方法:选取在安徽省肿瘤医院接受治疗的15例宫颈癌患者,均接受Fletcher型施源器植入的铱源高剂量率CT引导下近距离治疗。按照驻留步长大小分别为每位患者制定4组计划(Plan₁ mm、Plan₃ mm、Plan₅ mm和Plan₇ mm),对比治疗时长,靶区D₁₀₀、D₉₀和V₁₀₀和危及器官D_{2 cc}、SF系数等参数。模拟计算施源器发生脚向3 mm移位时剂量分布,分析施源器移位对不同驻留步长近距离治疗计划剂量学的参数影响。结果:不同驻留步长治疗计划的高危靶区(HRCTV)剂量学参数差异不明显(P>0.05),而Plan₁ mm、Plan₃ mm的中危靶区(IRCTV)的D₁₀₀、D₉₀、V₁₀₀和治疗时长均大于P...