Pattern of left ventricular filling in hypertrophic cardiomyopathy: Assessment by Doppler echocardiography and radionuclide angiography

Aims The left ventricle in hypertrophic cardiomyopathy is anatomicallyand functionally non-uniform. This study was undertaken to verifywhether a heterogeneity in the pattern of diastolic fillingcan be detected along the left ventricular inflow tract in hypertrophiccardiomyopathy. Methods and results Early (E) and late (A) diastolic velocitieswere recorded by Doppler echocardiography at mitral and at mid-ventricularlevel in 16 normal volunteers and 30 patients with hypertrophiccardiomyopathy. Patients with hypertrophic cardiomyopathy alsounderwent radionuclide angiography to assess left ventricularfunction. E wave decreased significantly in normal volunteers(80±15 to 60±14cm.s^–1;P<0·001),but it increased in hypertrophic cardiomyopathy (76±22to 87±28cm.s^–1;P=0·04), whereas the A wavedecreased similarly in both. By multivariate analysis, systolicasynchrony and the ejection fraction of left ventricular lateralwall were directly related to the pattern of early filling progression(r=0·656; F=9·467;P<0·002). Moreover,systolic asynchrony showed a univariate direct correlation withchanges in E velocity (r=0·42;P=0·02). Conclusion Many patients with hypertrophic cardio-myopathy havean acceleration of filling within the left ventricular inflowtract; this phenomenon is directly related to systolic asynchronyand ejection fraction of the left ventricular lateral wall,suggesting increased suction.     

Dyssynchrony of segment shortening in the anterior wall of the feline left ventricle

Non-uniformity of regional contraction may be both spatial and temporal. This study was undertaken to deal with the temporal aspects of shortening and to quantify non-uniformity with regard to timing. Nine cats were anaesthetized and artificially ventilated. Two pairs of ultrasonic crystals were situated in the anterior midwall of the left ventricle to measure regional shortening. One pair, longitudinal segment, was oriented to align with midwall fibres. The other pair, transverse segment, was placed perpendicular to the first one. Registrations in control state, during caval occlusion, and during aortic constriction were carried out with and without isoprenaline infusion. Cyclic events were analysed in terms of phase angle, 0–2π representing one heart cycle. Transverse segments showed marked shift of duration of shortening, from 1.19π± 0.06π (meanæM) in the control state to 0.40π± 0.14π during caval occlusion with isoprenaline infusion. Duration of shortening of longitudinal segments showed less prominent shift with mean values between 1.38π and 1.11π. Regional uniformity of timing, expressed as synchronization index, varied markedly with interventions (P < 0.0005). Dyssynchrony was most prominent during caval occlusion with mean values less than 0.6. A simple model of force generation for the two segments visualizes that segment shortening of the transverse segment is of shorter duration than the longitudinal segment and a common mechanism for temporal and spatial non-uniformity within a region could be elaborated. This study quantifies both the time course of shortening and temporal non-uniformity of two cross-oriented segments within the same myocardial region.     

基于手机的移动式热成像系统研究与初步应用

研究了一种基于手机的低成本热成像系统架构及其组成要素:热成像模块、手机与专属操作软件等.探讨了各种阵列热成像模块的设计理念与考虑因素,包含元器件成本与噪声等效温差等.软件中引入了场景变化侦测来改善非均匀修正算法的效率.该系统在积分时间大于16帧的情况下,其噪声等效温差(NETD)可低于150 mK.特别地,将该系统应用于人体运动健康评估中的体温监测上,试验证实了其在医学应用上的可靠性与便利性.     

Influence of Signal Intensity Non-Uniformity on Brain Volumetry Using an Atlas-Based Method

Objective

Many studies have reported pre-processing effects for brain volumetry; however, no study has investigated whether non-parametric non-uniform intensity normalization (N3) correction processing results in reduced system dependency when using an atlas-based method. To address this shortcoming, the present study assessed whether N3 correction processing provides reduced system dependency in atlas-based volumetry.

Materials and Methods

Contiguous sagittal T1-weighted images of the brain were obtained from 21 healthy participants, by using five magnetic resonance protocols. After image preprocessing using the Statistical Parametric Mapping 5 software, we measured the structural volume of the segmented images with the WFU-PickAtlas software. We applied six different bias-correction levels (Regularization 10, Regularization 0.0001, Regularization 0, Regularization 10 with N3, Regularization 0.0001 with N3, and Regularization 0 with N3) to each set of images. The structural volume change ratio (%) was defined as the change ratio (%) = (100 × [measured volume - mean volume of five magnetic resonance protocols] / mean volume of five magnetic resonance protocols) for each bias-correction level.

Results

A low change ratio was synonymous with lower system dependency. The results showed that the images with the N3 correction had a lower change ratio compared with those without the N3 correction.

Conclusion

The present study is the first atlas-based volumetry study to show that the precision of atlas-based volumetry improves when using N3-corrected images. Therefore, correction for signal intensity non-uniformity is strongly advised for multi-scanner or multi-site imaging trials.     

儿童原发免疫性血小板减少症红外热图特征初探

目的应用红外热成像技术观察儿童原发免疫性血小板减少症(immune thrombocytopenia,ITP)与健康儿童的红外热图差异,为ITP儿童的临床诊断与疗效评价提供新的可视化指标。方法采集22例ITP患儿(ITP组)与11例健康儿童(对照组)的红外热图,对躯干、四肢近段区域的非均一性进行统计学分析,并对躯干三焦、双手掌、头面区域与躯干部位相对热态差值(△t)进行统计学分析。结果 ITP组的非均一性明显大于对照组,差异具有统计学意义(t=3.432,P<0.01);ITP组的△t手掌明显大于对照组,差异具有统计学意义(t=3.438,P<0.01);ITP组的△t脊柱区小于对照组,差异具有统计学意义(t=-2.239,P<0.05);健康组三焦△t排序呈现为:△t上焦<△t中焦<△t下焦,ITP组三焦△t排序为:△t上焦>△t中焦>△t下焦。结论 ITP儿童较健康儿童躯干及四肢近段部位"均一性"差,且手掌、脊柱区域温度存在明显差异,红外热成像技术可为ITP儿童的病情评估及疗效评价提供新的方法。     

Evanescent Electromagnetics: A Novel, Super-Resolution, and Non-Intrusive, Imaging Technique for Biological Applications

Scanning tunneling and atomic force microscopes (STM and AFM) are used to study biological materials. These methods, often capable of achieving atomic resolutions, reveal fascinating information regarding the inner workings of these materials. However, both STM and AFM require physical contact to the specimen. In the case of STM, the specimen needs to be conducting as well. Here we introduce a new method for imaging biological materials through air or a suitable liquid using decaying or evanescent fields at the tip of a properly designed microwave resonator. This novel method involves the use of an evanescent microwave probe (EMP) and is capable of imaging a variety of non-uniformities in biological materials including conductivity, permittivity, and density variations. EMP is a non-contact and non-destructive sensor and it does not require conducting specimens. Its spatial resolution is currently around 0.4 m at 1 GHz. We have used this probe to map non-uniformities in a variety of materials including metals, semiconductors, insulators, and biological and botanical samples. Here we discuss applications of EMP imaging in bone, teeth, botanical, and agricultural specimens.     

Study on Fractal Characteristics of Mineral Particles in Undisturbed Loess and Lime-Treated Loess

In order to explore the fractal characteristics of particle size distribution (PSD) of various minerals in loess and lime-treated loess, the Q4 undisturbed loess and lime-treated loess were studied. From the perspective of multi-scaled microstructure, the internal characteristics of loess were observed and the regularity statistics were carried out from a macroscopic view. Fractal theory was used to quantitatively study the distribution of mineral particles in undisturbed loess and lime-treated loess. It was found that the skeleton particles of undisturbed loess were obvious and the structure of soil was loose. While that of lime-treated loess decreased, the fine particles were connected with each other, and the structure of soil changed from loose to dense. The three mineral particles in the undisturbed loess and lime-treated loess did not accord with the single fractal distribution characteristics, but the total particles had fractal characteristics. The percentage content of the mineral particles in the soil varied greatly with the particle size. In addition, the non-uniform degrees of mineral particles in the two soils from large to small were carbonate minerals of lime-treated loess, carbonate minerals of undisturbed loess, quartz minerals of lime-treated loess, feldspar mineral of lime-treated loess, feldspar mineral of the undisturbed loess, and the quartz mineral of the undisturbed loess. This paper provided a basis for the future study of the different soil mechanical properties of undisturbed loess and lime-treated loess.     

The Effects of K+ on Anisotropic Conduction in Sheets of Perfused Rabbit Ventricular Epicardium

Potassium and Anisotropy. Introduction: The purpose of this study was to investigate the effects of potassium on anisotropic conduction in rabbit ventricles. Methods and Results: In Langendorff perfused rabbit hearts, a two-dimensional epicardial layer of anisotropic myocardium was created by cryodestruction of the endocardial four fifths of the left ventricle. The heart was paced at 0.5 Hz and the epicardial spread of activation was recorded with a high-resolution mapping electrode (240 points). In ten experiments, we studied the effects of stepwise increased concentrations of extracellular potassium on epicardial conduction, longitudinal and transverse to the fiber direction. At 6.2 mM of K⁺, longitudinal conduction velocity (θ_L) was 61 ± 6.2 and transverse conduction velocity (θ_T) 25 ± 4.6 cm/sec with a ratio θ_L/θ_T of 2.6. At a high concentration of 12.5 ± 1.1 mM, conduction slowed down to 29 ± 6.0 and 11 ± 4.4 cm/sec, respectively, with a slightly increased ratio of 3.2 (NS). The amount of depression of θ_L and θ_T varied considerably from experiment to experiment and from region to region. On the average, no statistical difference in the depression of conduction velocity in relation to the fiber orientation was found. At K ⁺ concentrations of more than 12.5 ± 1.1 mM, local conduction was seriously impaired at various sites. Lines of functional conduction block appeared in longitudinal and transverse direction. Conclusion: We conclude that during slow heart rates, depression of the fast sodium channels by high extracellular K ⁺ causes no detectable differential effects on conduction velocity or on occurrence of conduction block, longitudinal or transverse to the general fiber orientation.