动态心脏体模在心脏计算机断层扫描成像质量控制中的应用

论述了动态心脏体模作为计算机断层扫描（CT）设备心脏成像质量评价与质量保证工具的重要性;介绍了当前几类动态心脏体模在心脏CT成像质量控制中的应用进展,包括运动型、功能型和仿真型动态心脏体模。分析了现有动态心脏体模在解剖结构、组织材料和运动特性的不足,并提出利用等效材料制作四腔室心脏体模和基于容积-时间曲线控制模拟心脏全周期运动的可行性,以探究研制一种“结构仿生、运动仿真”动态心脏体模的可行性,从而为建立心脏CT成像质量定量评价标准提供理论依据和技术支撑。     

构建基于正常人心脏解剖及影像数据的动态心脏模型

目的　构建基于正常心脏数据的三维动态心脏模型。 方法　采集正常成人心脏数据,通过Microsoft Visual C++和3DMax软件重建生成心脏三维模型,并将正常心电图与之整合,同步显示心脏运动。 结果　建立了数字化心脏可视动态模型,能够反映心脏三维形状和内腔结构,并可与心电图同步运动。 结论　动态心脏模型能够为心脏结构与运动的教学及疾病分析提供可视化的数值仿真平台。     

心率变异性慢性实验研究

心率变异性指标在心脏状态上作用已经有很多研究，除了反映心脏自身健康状况外，它尚对机体其他系统对心脏的调控能力有的映。我们利用动物模型设计了一系列特定的心脏状态，检测这一系列心脏状态下的心率变异性指标变化规律，发现心率变异性指标在实验过程中的动态变化规律，说明变异参数适用需要一定的限制，并且动态检测的方式明显优于静态检测。     

基于动态心脏模型的体表心电图仿真研究

以往的电生理心脏模型大多是静态的,而非动态模型.这样在用准静电场理论求解体表电位时,整个心动周期中等效心电偶极子（源点）与体表（场点）之间的距离假设为恒定不变,从而会引入较大的系统误差.因此,为了更准确仿真心电图,有必要采用动态或跳动的心脏模型.基于原来静态心脏模型,构造了一个动态心脏模型,并对体表12导联心电图进行仿真比较研究.在动态心脏模型中考虑了心肌电兴奋引起的心脏机械力学收缩,通过计算心动周期中心室壁的位移,从而将心脏与体表之间的相对距离变化考虑进体表电位计算过程.仿真结果表明,对于正常心电图,基于动态心脏模型的仿真结果比基于静态心脏模型的仿真结果更符合临床记录心电图,特别是V1-V6胸导联的ST段和T波.对于前壁轻微缺血情况,在动态心脏模型的仿真心电图中能明显看出ST段和T波的变化,而在静态心脏模型的仿真心电图中与正常心电图相比看不出什么变化.本研究的仿真研究证实了动态心脏模型的确能更准确地仿真体表心电图.     

心脏超声图像的运动分析研究进展

心脏腔室的运动特征与心功能的健全与否是密切相关的。临床上常根据超声心动图像来观察目标的运动，并结合其它方法对心脏状况做出判断，但往往定量分析的准确程度不够，本文介绍了目前心脏超声技术的发展情况，以及国内外基于超声心动图进行心脏运动分析的主要研究内容，包括图像的运动跟踪，动态分割，超声成像过程仿真等，同时就一些研究方向和思路进行了探讨。     

组织多普勒超声心脏图像的动态三维重建

传统的超声心脏图像三维重建技术只限于描述三维及动态三维解剖结构,不能对心脏动态功能做出准确有效的评价。本研究将建立组织多普勒超声心脏图像的动态三维重建方法,通过超声医学图像三维重建技术和组织多普勒超声成像技术的结合,重建心脏运动的动态三维加速度场,为心脏功能的准确评价提供一条新的途径。论文解决了加速度矢量场重建过程中关键的矢量插值和融合显像的问题,从组织多普勒加速度图像中分别重建心肌运动三维加速度场和三维解剖结构,并进行融合显像。试验结果证明了二者之间相对空间位置正确,该方法可以为心脏疾病的诊断和心脏功能的评价提供更多信息,在心脏靶点起搏和心内消融等领域有潜在的应用价值。     

依帕司他治疗糖尿病心脏自主神经病变疗效分析

目的评价依帕司他治疗糖尿痛心脏自主神经病变疗效。方法糖尿痛心脏痛心脏自主神经病变患者接受依帕司他50mg，每日3次治疗，服用4周，运用24小时动态心电图检测患者在服用依帕司他前后心率变异性指标的变化，明确依帕司他治疗糖尿病心脏自主神经病变的疗效。结果心率变异性各项指标治疗4周后较治疗前有显著提高。自主神经症状明显好转。结论依帕司他治疗糖尿病心脏自主神经病变的疗效显著，可以改善患者心率变异性。     

评价心率变异性的一种新方法

本文提出了一种基于动态系统模型以研究心率变异性的新方法。该方法是将心脏视为一个近似的线性动态系统，并将心率视为系统的输出，而系统动态模型的参数则表征了神经的调节能力。文中，我们先由各心搏的ＲＲ间期数据建立离散的动态系统模型，再由所求得的模型计算出表征动态系统的特征的各参数，并将参数的变化描绘成各种趋势图，用以研究各种趋势与疾病的关系     

评价心率变异性一种新方法

本文提出了一种基于动态系统模型以研究心率变异性的新方法。该方法是将心脏视为一个挖的线性动态系统，并将心率视力系统的输出，而系统动态模型的参数则表征了神经的调节能力，文中，我们先由各心搏的ＲＲ间期数据建立离散的动态系统模型，再由所求得的模型计算出表征动态系统的特征的各参数，并将参数的变化描绘成各种趋势图，用以研究各种趋势与疾病的关系。     

国内外最新医学动态

国内外最新医学动态西京医院研究生物心脏瓣膜钙化获突破一直为医学界所关注的生物心脏瓣膜钙化机理及减轻钙化的重要课题，经第四军医大学西京医院心外科青年专家易定华教授等十几年研究获得突破．他们从分子水平上阐明了生物辩钙化机制，并在国际上首先筛选出化学改性方...     

Time to reconfigure balancing behaviour in man: changing visual condition while riding a continuously moving platform

While balancing on a continuously antero-posterior (A-P) translating platform (10 cm, 0.5 Hz), the head normally oscillates with the platform without vision but is stabilized in space with vision. We estimated the time to shift from one to the other balancing behaviour when visual condition changed at some stage during the balancing trials. Ten subjects performed randomly 50 balancing trials (each lasting 18 s): 10 trials with eyes open (EO), 10 with eyes closed (EC), 15 in which participants started with EO and closed their eyes (condition EO → EC) in response to an acoustic signal delivered during the trial, and 15 starting with EC and closing their eyes (EC → EO) in response to the same signal. No other specific instruction was given. Displacements of malleolus, hip and head, and EMG from leg and axial muscles were recorded. Indexes of amplitude of A-P head and hip oscillation and of amplitude of EMG activity were computed. All variables were larger with EC than EO. On changing visual condition during the trial, the pattern of head and hip movement and of muscle activity turned into that appropriate for the new visual condition in a time-interval ranging from about 1 to 2.5 s. For each subject, the mean latency of the change in the balancing behaviour was assessed by statistical methods. On average, the latencies of kinematics and EMG changes proved to be longer for the EO → EC condition than viceversa. Further, the latencies of the changes were also measured across all EO → EC and EC → EO individual trials. These values were clustered around particular epochs of the first few oscillation cycles following the shift in visual condition. The results show that subjects can rapidly adapt their balancing behaviour to the new visual condition. However, they appear to refrain from releasing the new behaviour were this unfit, and unfastened it at appropriate time in the next platform translation cycle. These findings reveal the temporal and spatial features of the automatic release of the new balancing strategy in response to a shift in the ongoing sensory set, and emphasize the swiftness in the change in balancing behaviour when subjects pass from a non-visual to a visual reference frame.     

New estimation methods that directly use the time accumulated counts in the input function in quantitative dynamic PET studies

In cardiac dynamic PET studies, the input function can be obtained directly from the reconstructed images. Therefore, there is a need to convert the time accumulated count to the time-activity curve (TAC). Conventionally, this is done by dividing the total counts in a localized region on the reconstructed image obtained during each scan frame period by its frame duration. This conversion, however, can significantly bias the estimates of rate constants of a compartmental model describing the dynamics of a PET tracer. Three new methods are formulated in this study. These new methods either use the accumulated counts in the input function directly or convert the accumulated counts to the input function more accurately. Computer simulation results show, for C-11 acetate and F-18 fluoro-2-deoxy-D-glucose (FDG), that the three new methods proposed can improve significantly the parameter estimates over the ones obtained by the conventional method.     

Measuring clinical pathway adherence

As clinical pathway adoption continues worldwide, it is necessary to establish adherence measurement methods in order to understand the difficulties and results of implementation. Adherence measurement literature mostly provides binary measurements of adherence to guidelines regarding individual medical activities over patient groups. The resulting measurements are of limited value in view of the pathways actually followed by individual patients. We develop and test dynamic programming formulations for adherence measurement in clinical pathways – based on partially ordered data in medical records and pathway definitions. With these new methods at hand, we analyze clinical pathway adherence at the Cardiovascular Center of Maastricht University Medical Center.     

A field-programmable gate array based system for high frame rate laser Doppler blood flow imaging

This paper presents a general embedded processing system implemented in a field-programmable gate array providing high frame rate and high accuracy for a laser Doppler blood flow imaging system. The proposed system can achieve a basic frame rate of flow images at 1 frame/second for 256×256 images with 1024 fast Fourier transform (FFT) points used in the processing algorithm. Mixed fixed-floating point calculations are utilized to achieve high accuracy but with a reasonable resource usage. The implementation has a root mean square deviation of the relative difference in flow values below 0.1% when compared with a double-precision floating point implementation. The system can contain from one or more processing units to obtain the required frame rate and accuracy. The performance of the system is significantly higher than other methods reported to date. Furthermore, a dedicated field-programmable gate array (FPGA) board has been designed to test the proposed processing system. The board is linked with a laser line scanning system, which uses a 64×1 photodetector array. Test results with various operating parameters show that the performance of the new system is better, in terms of noise and imaging speed, than has been previously achieved.     

Latency as a region contrast: Measuring ERP latency differences with Dynamic Time Warping

Methods for measuring onset latency contrasts are evaluated against a new method utilizing the dynamic time warping (DTW) algorithm. This new method allows latency to be measured across a region instead of single point. We use computer simulations to compare the methods’ power and Type I error rates under different scenarios. We perform per‐participant analysis for different signal‐to‐noise ratios and two sizes of window (broad vs. narrow). In addition, the methods are tested in combination with single‐participant and jackknife average waveforms for different effect sizes, at the group level. DTW performs better than the other methods, being less sensitive to noise as well as to placement and width of the window selected.     

A novel surgical technique for a rat subcutaneous implantation of a tissue engineered scaffold

Objectives

Subcutaneous implantations in small animal models are currently required for preclinical studies of acellular tissue to evaluate biocompatibility, including host recellularization and immunogenic reactivity.

The use of ultrasound in automated prostatectomy

A new way of applying transurethral ultrasound scanning in the common surgical procedure of the transurethral resection of the prostate is described. The scanning is incorporated as part of a robotic procedure for surgery, so that the overall time spent in an operation can be further shortened, and a safe and accurate operation can be achieved. The prostate dimensions obtained pre-operatively by the transrectal method and those obtained operatively are compared. A robotic system, which was developed specifically to remove prostatic adenoma automatically, is discussed. The system, called a motorised frame, is briefly described, together with its predecessor, a manual frame, in relation to ultrasound measurements. Sizing of the prostate pre-operatively using transrectal ultrasound methods is discussed, using both the manual and the motorised frame. The shortcomins of transrectal ultrasound for use in a robotic procedure are highlighted.     

Dysfunctional beliefs in the process of change of cognitive treatment in obsessive compulsive checkers

Cognitive behaviour therapy (CBT) is considered to be effective in the reduction of obsessive compulsive symptoms. However, questions remain as to how CBT works. Cognitive-behavioural models postulate that negative appraisals of intrusive thoughts and dysfunctional beliefs that give rise to them underlie the development and maintenance of obsessive-compulsive disorder (OCD). The current study aimed to study this hypothesis by investigating the processes of change over the course of cognitive treatment for OCD. Furthermore, a new theoretical approach and method for studying processes of change was presented. The participants were seven patients suffering from OCD with predominantly checking symptoms. Process variables (beliefs, anxiety and compulsions) were measured using idiosyncratic diaries and were analysed on an intra- and inter-individual level using dynamic systems methods. Results showed significant decreases in credibility of dysfunctional beliefs in six out of the seven participants, which is in line with the cognitive-behavioural model. Associations between process variables were in general medium to high. However, the actual patterns of change showed important intra- and interpersonal differences. Results indicated that different paths can lead to clinical recovery, and it was concluded that process studies that focus on individual trajectories of change can contribute to our understanding of OCD and its treatment. Furthermore, dynamic systems methods provide insight into intra-individual processes and shed a new light on variability.     

Quantitative rotating frame relaxometry methods in MRI

Macromolecular degeneration and biochemical changes in tissue can be quantified using rotating frame relaxometry in MRI. It has been shown in several studies that the rotating frame longitudinal relaxation rate constant (R_1ρ) and the rotating frame transverse relaxation rate constant (R_2ρ) are sensitive biomarkers of phenomena at the cellular level. In this comprehensive review, existing MRI methods for probing the biophysical mechanisms that affect the rotating frame relaxation rates of the tissue (i.e. R_1ρ and R_2ρ) are presented. Long acquisition times and high radiofrequency (RF) energy deposition into tissue during the process of spin‐locking in rotating frame relaxometry are the major barriers to the establishment of these relaxation contrasts at high magnetic fields. Therefore, clinical applications of R_1ρ and R_2ρ MRI using on‐ or off‐resonance RF excitation methods remain challenging. Accordingly, this review describes the theoretical and experimental approaches to the design of hard RF pulse cluster‐ and adiabatic RF pulse‐based excitation schemes for accurate and precise measurements of R_1ρ and R_2ρ. The merits and drawbacks of different MRI acquisition strategies for quantitative relaxation rate measurement in the rotating frame regime are reviewed. In addition, this review summarizes current clinical applications of rotating frame MRI sequences. Copyright © 2016 John Wiley & Sons, Ltd.