心脏磁共振特征追踪技术定量评价肥厚型心肌病患者心肌形变

目的 探讨心脏磁共振（CMR）特征追踪（CMR-FT）技术定量评价肥厚型心肌病（HCM）患者心肌形变的价值。方法 对16例HCM患者（HCM组）及18名健康志愿者（正常对照组）采用CMR-FT技术行CMR检查。比较两组间左心室舒张末期容积（LVEDV）、收缩末期容积（LVESV）、左心室射血分数（LVEF）、左心室质量（LVMASS）及左心室心肌整体径向应变（RS）、环向应变（CS）的差异。并分析HCM患者各节段室壁厚度与节段性RS、CS的相关性及整体RS、CS与LVEDV、LVESV、LVEF、LVMASS间的相关性。结果 HCM组的LVMASS高于正常对照组[（133.74±79.13）g vs（76.87±14.15）g,P=0.01]。两组间LVEDV、LVESV、LVEF差异均无统计学意义（P均>0.05）。HCM组心肌整体RS、CS值均明显低于正常对照组[RS：（27.05±13.35）% vs（40.62±4.92）%,P<0.01;CS：（-8.68±5.56）% vs（-20.73±1.56）%,P<0.01]。HCM患者各节段室壁厚度与节段性RS（r=-0.41,P<0.01）、CS（r=0.28,P<0.01）间无相关性;心肌整体RS（r=-0.36、-0.41、0.22、-0.36）、CS（r=0.34、0.10、0.22、0.42）与LVEDV、LVESV、LVEF、LVMASS间无相关性（P均>0.05）。结论 CMR-FT有助于定量评估HCM患者心肌形变情况。     

Left atrial deformation analysis as a predictor of severity of coronary artery disease

Background

Two-dimensional (2D) speckle-tracking strain imaging is a novel method for assessment of regional myocardial deformation that uses tracking of acoustic speckles or kernels rather than Doppler myocardial velocities. It has been suggested that Left atrial (LA) strain as measured by 2D speckle tracking can be used to evaluate dynamic LA function.

Ultrasonographic study of mechanosensory properties in human esophagus during mechanical distension

AIM: To study the esophageal geometry and mechano-sensation using endoscopic ultrasonography during volume-controlled ramp distensions in the distal esophagus. METHODS: Twelve healthy volunteers underwent distension of a bag. During distension up to moderate pain the sensory intensity was assessed on a visual analogue scale (VAS). The esophageal deformation in terms of multidimensional stretch ratios and strains was calculated at different volumes and VAS levels. Distensions were done before and during administration of the anti-cholinergic drug butylscopolamine. RESULTS: The stimulus-response (volume-VAS) curve did not differ without or with the administration of butylscopolamine. Analysis of stretch ratios demonstrated tensile stretch in circumferential direction, compression in radial direction and a small tensile stretch in longitudinal direction. A strain gradient existed throughout the esophageal wall with the largest circumferential deformation at the mucosal surface. The sensation intensity increased exponentially as function of the strains. CONCLUSION: The method provides information of esophageal deformation gradients that correlate to the sensation intensity. Hence, it can be used to study mech-anosensation in the human esophagus. Further studies are needed to determine the exact deformation stimulus for the esophageal mechanoreceptors.     

Self-joining of zirconia/hydroxyapatite composites using plastic deformation process

A plastic deformation process was demonstrated to self-join 3 mol.% yttria partially stabilized zirconia (3Y-TZP)/hydroxyapatite (HA) composites. The 3Y-TZP/40 vol.% HA composites were fabricated by conventional ceramic processing by cold pressing premixed 3Y-TZP and HA powders into pellets. Densification (≈90%) of composites was achieved by sintering composite powder compacts at 1450 °C for 5 h. Optimum self-joining of 3Y-TZP/40 vol.% HA composites was obtained at 1300 °C for a strain rate of 5 × 10⁻⁵/s. The flow stress during joining was 40 MPa. Microstructural and mechanical characterizations of the joint interface demonstrated that there were no discernible differences between the joint and the composite material away from the interface.     

An in vitro model of traumatic brain injury utilising two-dimensional stretch of organotypic hippocampal slice cultures

Traumatic brain injury (TBI) is caused by rapid deformation of the brain, resulting in a cascade of pathological events and ultimately neurodegeneration. Understanding how the biomechanics of brain deformation leads to tissue damage remains a considerable challenge. We have developed an in vitro model of TBI utilising organotypic hippocampal slice cultures on deformable silicone membranes, and an injury device, which generates tissue deformation through stretching the silicone substrate. Our injury device controls the biomechanical parameters of the stretch via feedback control, resulting in a reproducible and equi-biaxial deformation stimulus. Organotypic cultures remain well adhered to the membrane during deformation, so that tissue strain is 93 and 86% of the membrane strain in the x- and y-axis, respectively. Cell damage following injury is positively correlated with strain. In conclusion, we have developed a unique in vitro model to study the effects of mechanical stimuli within a complex cellular environment that mimics the in vivo environment. We believe this model could be a powerful tool to study the acute phases of TBI and the induced cell degeneration could provide a good platform for the development of potential therapeutic approaches and may be a useful in vitro alternative to animal models of TBI.     

Erratum to Decomposition cross-correlation for analysis of collagen matrix deformation by single smooth muscle cells

Microvascular remodeling is known to depend on cellular interactions with matrix tissue. However, it is difficult to study the role of specific cells or matrix elements in an in vivo setting. The aim of this study is to develop an automated technique that can be employed to obtain and analyze local collagen matrix remodeling by single smooth muscle cells. We combined a motorized microscopic setup and time-lapse video microscopy with a new cross-correlation based image analysis algorithm to enable automated recording of cell-induced matrix reorganization. This method rendered 60–90 single cell studies per experiment, for which collagen deformation over time could be automatically derived. Thus, the current setup offers a tool to systematically study different components active in matrix remodeling.     

Reality about migration of the nucleus pulposus within the intervertebral disc with changing postures

Background

Previous studies reported that, in non-degenerate discs, the nucleus pulposus migrates posteriorly during flexion and anteriorly during extension within the intervertebral disc. However, in these studies the differences between anterior and posterior distances have been regarded as an indicator of nucleus pulposus migration. This study investigated the reality of migration of the nucleus pulposus within the intervertebral disc with changing postures.

Method

Magnetic resonance images were obtained of the lumbar spines of 25 asymptomatic volunteers in sitting, standing and supine postures. The anterior and posterior height of the intervertebral disc, the anterior -posterior length of the intervertebral disc and nucleus pulposus, and the positions of the anterior and posterior margins of the nucleus were measured from mid-line sagittal images.

Findings

Changing postures altered the anterior and posterior height of the disc and three types of morphological changes, including changes in the anterior -posterior lengths of the intervertebral disc and nucleus pulposus, together with the position of the nucleus in the disc were found. The length of the intervertebral disc and nucleus pulposus changed under the variations in spinal loading caused by posture.

Interpretation

The results of this study indicated that the apparent nucleus pulposus migration within intervertebral disc is actually deformation of the nucleus pulposus length which depends on posture and the magnitude of the load. In other words, adopting different postures deforms the nucleus pulposus and therefore, changes the position of the nucleus pulposus but there is no apparent nucleus pulposus migration within the intervertebral disc.     

Recognition of finger flexion motion from ultrasound image: a feasibility study

Muscle contraction results in structural and morphologic changes of the related muscle. Therefore, finger flexion can be monitored from measurements of these morphologic changes. We used ultrasound imaging to record muscle activities during finger flexion and extracted features to discriminate different fingers' flexions using a support vector machine (SVM). Registration of ultrasound images before and after finger flexion was performed to generate a deformation field, from which angle features and wavelet-based features were extracted. The SVM was then used to classify the motions of different fingers. The experimental results showed that the overall mean recognition accuracy was 94.05% ± 4.10%, with the highest for the thumb (97%) and the lowest for the ring finger (92%) and the mean F value was 0.94 ± 0.02, indicating high accuracy and reliability of this method. The results suggest that the proposed method has the potential to be used as an alternative method of surface electromyography in differentiating the motions of different fingers.