下肢动脉闭塞性病变的多普勒血流频谱形态观察

目的：观察下肢动脉闭塞性病变的多普勒血流频谱。方法：选择32例下肢动脉栓塞患者作为研究对象并行彩色多普勒超声检查,观察血流频谱及血流频谱指标,并与健侧做比较。结果：32例下肢动脉闭塞患者,闭塞长度最长28cm,最短4.8cm,平均长度17.4±4.9cm;闭塞前段血流频谱形态失常,频窗消失,频带增宽,舒张期反向血流消失,出现静脉样血流频谱或者舒张期正向血流频谱,闭塞后段频谱多普勒呈单向且血流速度减低或无血流频谱。下肢动脉血流频谱各项指标显示,患侧PSV明显低于健侧,AT、RI、PI明显高于患侧（p＜0.05）。结论：多普勒超声血流频谱异常改变是下肢动脉闭塞性疾病一项重要的检查方式,有较高的临床价值。     

椎-基底动脉狭窄诊断中采用经颅多普勒超声的效果和价值

目的:探讨椎-基底动脉狭窄诊断中采用经颅多普勒超声的效果和价值。方法:选择我院于2014年04月-2017年04月间收治的30例椎-基底动脉狭窄患者,作为本次研究样本,全部患者均采用经颅多普勒超声诊断,进一步探析TCD频谱刑天与血流速度。结果:椎-基底动脉狭窄30例患者,大致上有两种,一种是基底动脉临界值低于血流速度,检查结果提示声频、频谱均嘈杂、杂乱;另一种为椎动脉存在明显过快的血流速度,TCD频谱形态呈涡流,基底动脉临界值高于血流速度。结论:经颅多普勒超声诊断椎-基底动脉狭窄,具有较高的诊断价值,值得临床进一步应用推广。     

胎儿大脑中动脉与子宫动脉血流参数对胎儿宫内窘迫的预测

目的:了解应用彩色多普勒超声测定胎儿大脑中动脉(MCA)与子宫动脉(UtA)血流参数对胎儿宫内窘迫的预测价值。方法:选择使用彩色多普勒超声进行检查的539例孕晚期胎儿作为观察对象。将其中缺氧高危的72例作为研究组,另467例非高危胎儿作为对照组。比较两组胎儿的MCA和UtA的搏动指数(PI)、阻力指数(RI)、心室收缩期峰值速度/心室舒张期末血流速度(S/D),并计算MCA/UtA血流参数的比值。结果:两组中研究组UtA的PI、RI、S/D较高,且和MCA/UtA血流参数的比值也较高,MAC的PI较低,其余指标差别不明显。预测胎儿缺氧的灵敏度为65.79%,特异度为93.21%。结论:应用彩色多普勒超声测定胎儿MCA与UtA血流参数能较好的对胎儿宫内窘迫进行预测。     

G7 二维/脉冲多普勒对青光眼眼血流动力学研究

本文首次应用二维和脉冲波多普勒超声技术对57例正常人(平均年龄46.6岁)共114只眼 球后的视网膜中央动脉(CRA)、睫状动脉(CA)和眼动脉(OA)进行血流动力学定量研究。结 果表明:CRA、CA和OA血流检出率分别为100%、96.5%和98.3%。频谱均呈典型的脉动 血流特征。CRA、CA和OA的峰值血流速度分别为10.03±1.98cm/see,23.27±5.72cm/ see,29.95±6.09cm/sec。并提出舒张期和平均血流速度及速度一时相等指标的测量方法和 意义。该技术是一种简便、可靠的无创性诊断方法,为临床眼血流动力学的研究和客观评价 提供了一种有价值的手段。正常人…     

应用无创性影像学方法探讨冠状动脉和颅脑动脉粥样硬化相关性及临床价值

目的：探讨冠状动脉和颅脑动脉粥样硬化相关性及其临床应用价值。方法：选取疑似冠心病患者90例,分别进行CT血管造影、颈动脉超声、经颅多普勒超声检查,统计对比相关指标。结果：经CCTA评估轻度狭窄31例、中度狭窄32例、重度狭窄27例;冠状动脉狭窄程度不同患者颈动脉超声检查IMT、斑块数目差异、TCD颅内血管PI、RI指标差异具有统计学意义（P＜0.05）。结论：冠状动脉与颅脑动脉粥样硬化具有一致性,因此冠心病患者应积极诊断、治疗脑血管疾病。     

糖尿病人眼球后动脉血流的二维/脉冲多普勒超声研究

本文首次应用二维脉冲多普勒超声技术(2DE-PDE)对23例正常人和25例糖尿病患者 的视网膜中央动脉(CRA)与眼动脉(OA)进行血流动力学定量研究。证实了糖尿病患者的血 流频谱特征。其血流峰值,峰时和血流时相等测值与正常人有显著差异(P(0.05-0.01),并 与糖尿病性视网膜病变关系极为密切。平均血流速度(Vm),脉动指数(PI)和阻力指数(RI) 与血糖测值呈明显负相关关系(t值分别为-0.68,-0.51、-0.64)。2DE-PDE是一种简 便,可靠的无创性诊断技术,为糖尿病视网膜病变患者的眼血流动力学研究和动态评价提供 了一种极有价值的定量检测方法。糖…     

头颈部CTA和颈部血管彩超在脑梗死患者颈动脉狭窄检测中的应用价值分析

目的:探讨头颈部CT血管成像技术(CTA)在脑梗死患者颈动脉狭窄检测中的临床应用价值。方法:选择我院2011年8月至2014年7月期间收治的经病理检查确诊为脑梗死颈动脉狭窄的患者共58例作为研究对象,并按数字表法随机分为两组。其中观察组患者(n=30)采用头颈部CT血管成像技术进行检查,而对照组患者(n=28)则采用颈部血管彩超技术进行检查。观察并比较两种检测方法对脑梗死患者颈动脉狭窄的检出情况。结果:观察组检出颈动脉轻度狭窄9例,中度狭窄14例,重度狭窄或闭塞5例,总检出率为93.33%(28/30),而对照组检出颈动脉轻度狭窄6例,中度狭窄10例,重度狭窄或闭塞4例,总检出率为71.43%(20/28),两组间差异比较具有统计学意义(P0.05)。结论:头颈部CT血管联合造影技术可准确评估脑梗死患者的颈动脉狭窄情况,其检出率显著优于颈部血管彩超技术,是一种较好的诊断方法,值得在临床推广使用。     

DSA冠状动脉造影分析

目的:分析453例冠状动脉造影诊断结果,探讨冠心病的冠状动脉造影结果及其临床应用价值。方法:应用DSA选择性冠状动脉造影证实的病变直径狭窄≥50%病例365例,依病变狭窄程度,累及冠状动脉部位、数目、形态,冠状动脉优势状况,侧支循环及心肌梗死病例左室壁运动情况进行分析。结果:≥50%狭窄或闭塞365例,冠状动脉右优势型311例,左优势型57例,均衡型85例,单支病变121例,2支病变135例。结论:本组住院患者病例,冠状动脉病变多累及前降支(LAD)44.1%,其次为左回旋支(LCX)及右冠状动脉(RCA);侧支循环形成良好者对左心室功能有保护作用,高质量的DSA设备是开展冠心病介入治疗的重要基础[1]。     

180例卵巢肿瘤患者经阴道彩色多普勒超声诊断结果分析

目的:探讨超声诊断卵巢肿瘤的诊断经验,进一步提高诊断水平。方法:收集我院2012年9月-2013年8月经手术或病理检查确诊的180例卵巢肿瘤患者对其超声检查情况进行回顾性分析。结果:本组180例患者,良性肿瘤162例,占90.0%,恶性肿瘤18例,占10.0%,良性肿瘤图像表现肿块包膜完整,边界清楚,形态规则,肿块内回声规则,阻力指数(RI)为(0.67±0.13)大于0.4,搏动指数(PI)均大于1.0,最大血流速度(PSV)均小于15cm/s。恶性肿瘤的超声图像表现为肿瘤边缘不整,欠清晰,结构紊乱,隔增厚不整齐,多呈乳头状突起,边界形态不规则,内部回声不均。阻力指数(RI)为(0.38±0.02),均小于0.4,搏动指数(PI)小于1.0,最大血流速度(PSV)均大于15cm/s。结论:超声是诊断卵巢肿瘤具有无痛、可重复性强等优点,值得临床推广。     

64位螺旋CT在冠状动脉供血不足临床诊断价值

目的:探讨分析应用64位螺旋CT冠状动脉成像(64SCTCA)在冠状动脉供血不足中的临床诊断价值。方法:对在2009年8月-2011年8月间我院治疗的65例疑似冠心病患者进行64位螺旋CT冠状动脉成像并将此结果与作为诊断冠心病的金标准冠状动脉造影(CAG)进行比较分析。结果:由于冠状动脉供血不足主要由患者冠状动脉狭窄引起,因此对可评估的262支冠状动脉,64SCTCA显示的冠状动脉狭窄为181支,其中有176支得到CAG证实。64SCTCA诊断狭窄的敏感性可以达到97.2%,特异性可以达到91.2%,阳性预测值可以达到94.9%,阴性预测值可以达到95.1%。结论:64SCTCA具有很高的敏感性和特异性以及阴阳性预测值,在应用64SCTCA诊断患者冠状动脉狭窄程度等病变时具有较高临床价值。     

64排CT在糖尿病下肢动脉硬化闭塞症中的应用

目的:探讨64排CT在糖尿病下肢动脉硬化闭塞症中的应用.方法:选择我院收治的糖尿病下肢动脉硬化闭塞症患者86例,先进行64排CT扫描(CTA),后再进行数字减影检查(DSA),比较两种方法诊断的准确性和血管病变检查情况.结果:CTA对下肢血管病变准确范围、部位等显示清晰.其检测的敏感性显著高于DSA,P<0.05.且前...     

Acoustic droplet vaporization for temporal and spatial control of tissue occlusion: a kidney study

Acoustic droplet vaporization (ADV) has been introduced with the potential application of tumor treatment via occlusion and subsequent necrosis. New Zealand White rabbits were anesthetized, and their left kidney was externalized. An imaging array and single-element transducer were positioned in a tank with direct access to the kidney's vasculature and renal artery. Filtered droplet emulsions (diameter <6 microm) were injected intra-arterially (IA) into the left heart during insonification of the renal artery, and the extent of blood flow reduction by ADV was compared to the untreated right kidney. Flow cytometry (using colored microspheres) of kidney tissue samples and reference blood from the femoral artery allowed the quantitative estimation of regional blood flow. A maximum regional blood flow reduction in the treated region of >90% and an average organ perfusion reduction of >70% was achieved using ADV. After treatment of the left kidney, the control kidney on the contralateral side showed a maximum decrease in regional blood flow of 18% relative to the pre-ADV baseline. Image-based hyper-echogenicity from ADV of IA injections was monitored for approximately 90 minutes, and cortex perfusion was reduced by >60% of its original value for more than 1 hour. This could be enough time for the onset of cell death and possible tumor treatment via ischemic necrosis. Moreover, currently used radiofrequency tissue ablation-based tumor treatment could benefit from ADV due to the decreased heat loss via vascular cooling.     

Superposition of Two Dynamic Speckle Patterns

Abstract

A model is proposed to explain the influence of blood flow and moving surrounding tissue on laser light scattering. Blood and tissue are represented by two sets of scatterers which are moving in arbitrary directions with different velocities. The real dynamic speckle pattern is thought to be composed of the coherent superposition of the two speckle patterns due to the scattering on these two sets of scatterers. The model describes the spectrum of the speckle intensity in an arbitrary observation point. No special assumptions must be made concerning the geometry of illumination and the position of the observation point. A measuring value B for the determination of the blood flow is derived from the speckle intensity. The model also provides the dependence of B on density and mean velocity of each set of scatterers. It has been shown that the main contribution of the tissue movement on B can be compensated by a control measurement and that the sensitivity of B due to blood velocity variations depends on the density of both sets of scatterers and on the tissue velocity.     

The theory of critical distances

The aim of this review article is to introduce the theory of critical distances, to which this special issue of the journal is devoted. The theory of critical distances (TCD) is the name which I have given to a group of theories used for predicting the effects of notches and other stress concentration features. The basic methodology is described, along with a number of variants which have developed over the years. After a brief history of the TCD, the predictive power of this group of theories is demonstrated, showing that they are capable of predicting experimental data on fracture and fatigue in a wide variety of circumstances. After some discussion regarding the fundamental scientific basis of the TCD, areas for future work in this field are suggested.     

空频域结合的多尺度扩张卷积注意力数字水印

目的 将深度学习应用于数字水印,在隐藏信息的同时,不断提高图像的不可见性和鲁棒性,提出一种结合空间域和频率域的多尺度扩张卷积注意力数字水印算法(SF-ACA)。方法 SF-ACA算法的网络框架包含由ACA和SFE构成的生成器、解码器2个部分组成。其中,ACA网络中的MCA模块将3个不同扩张率的扩张卷积对载体图像以多尺度融合的方式进行特征提取,使载体图像能更有效地隐藏水印信息;SFE结合快速傅里叶卷积块,在空域和频域中通过不同大小的感受野捕获互补信息,更精准地获取水印的特征信息,增强了秘密信息的不可见性和鲁棒性。结果 本文提出的水印方法在隐藏与载体图像尺寸相等的三通道彩色图像时,PSNR值为38.81 dB,较UDH方法的PSNR值提高了7.78%。水印图像的隐藏容量是4 096比特,该算法与UDH方法在Dropout、Gaussian噪声、JPEG攻击下,提取精度分别提升了5.38%、10.5%、1.65%,满足不可见性要求的同时实现了强鲁棒性。结论 本文方法在隐藏容量较大时,不可见性和鲁棒性都达到了较好的性能。     

Experimental and numerical investigation on crack initiation of fretting fatigue of dovetail

The present study investigated the fretting fatigue crack initiation of dovetail structure based on experimental observation and multiple axial criteria. Two typical critical plane approaches of the Smith‐Watson‐Topper (SWT) and the Fatemi and Socie (FS) model were used to predict the crack initiation location, orientation angle, and fatigue life. The results indicate that both SWT and FS models predict consistent results with the experiment in crack initiation location. Regarding the crack initiation angle, FS model shows good agreement with the experimental observation, but SWT model exhibits a large difference. The two models give conservative results in fretting fatigue life. In view of this, the theory of critical distance (TCD) was incorporated into the SWT and the FS models. It shows that both the TCD‐SWT and the TCD‐FS predict fatigue lives within a scatter band of 2. It suggests that introducing the TCD into the critical plane model can greatly reduce the conservatism of the prediction. Furthermore, the prediction has less dependence on specific models.     

Nitric oxide transport in an axisymmetric stenosis

To test the hypothesis that disturbed flow can impede the transport of nitric oxide (NO) in the artery and hence induce atherogenesis, we used a lumen–wall model of an idealized arterial stenosis with NO produced at the blood vessel–wall interface to study the transport of NO in the stenosis. Blood flows in the lumen and through the arterial wall were simulated by Navier–Stokes equations and Darcy''s Law, respectively. Meanwhile, the transport of NO in the lumen and the transport of NO within the arterial wall were modelled by advection–diffusion reaction equations. Coupling of fluid dynamics at the endothelium was achieved by the Kedem–Katchalsky equations. The results showed that both the hydraulic conductivity of the endothelium and the non-Newtonian viscous behaviour of blood had little effect on the distribution of NO. However, the blood flow rate, stenosis severity, red blood cells (RBCs), RBC-free layer and NO production rate at the blood vessel–wall interface could significantly affect the transport of NO. The theoretical study revealed that the transport of NO was significantly hindered in the disturbed flow region distal to the stenosis. The reduced NO concentration in the disturbed flow region might play an important role in the localized genesis and development of atherosclerosis.     

Development of Decay Energy Spectroscopy for Radionuclide Analysis Using Cryogenic 4π Measurements

We report the recent progress in the development of decay energy spectroscopy for radionuclide analysis using a metallic magnetic calorimeter. In the present analysis, sample radionuclides were completely enclosed by a 4π steradian absorber. The use of a 4π absorber composed of gold foil guarantees that the total energy associated with radioactive decay is converted into thermal energy in the absorber. A paramagnetic temperature sensor was attached to the absorber to accurately measure the temperature change due to radioactive decay. The plutonium isotopes ²³⁸Pu, ²³⁹Pu, and ²⁴⁰Pu were readily identified in the decay energy spectrum because each isotope creates a single peak at its characteristic Q value. Two clear peaks were observed for ²³⁹Pu and ²⁴⁰Pu, and a 6.3?keV FWHM was obtained. The energy resolution of the method was affected by the low-energy tail of the spectrum at the left-hand side of the peaks. A 4.1?keV FWHM of a Gaussian fit was obtained for the right-hand side of the peak. Slow heat release to the absorber due to heat flow mechanisms is discussed to explain the low-energy tailing effect.