血管内超声在冠脉复杂病变介入诊疗中的临床价值

目的:研究血管内超声在冠脉复杂病变介入诊疗中的临床价值。方法:30例确诊为冠心病的患者,其中男性23例,女性7例,先采用冠脉造影(CAG),选择美国心脏病学会和美国心脏病协会(ACC/AHA)推荐的冠脉分型C型中弥漫性病变(>20mm)、近端血管过度扭曲病变,然后行IVUS检查,PCI术后再行IVUS检查,比较两者及PCI前后IVUS结果的差异。结果:CAG示支架贴壁良好,再行IVUS检查示支架贴壁不良率达78.4%,IVUS观察均达到支架置入理想标准。结论:IVUS在评价支架贴壁情况、选择高压球囊后扩张时,有着更明显的优势。     

冠状动脉内放射抑制球囊扩张术后ERK1/2活性及c-fos基因表达

本文旨在观察血管内放射对冠状动脉球囊扩张术后细胞外信号调节激酶１／２（ＥＲＫ１／２）及ｃ－ｆｏｓ基因表达的影响。实验对猪的左冠状动脉前降支或回旋支行球囊行过度扩张术,术后即刻能过血管内放射治疗系统对猪冠状动脉损伤局部给予２０Ｇｙ的放射剂量,分别是在术后３ｄ和３０ｄ处死动物,留取目标血管组织。通过反转录－聚合酶链反应定量检测血管内入射对球囊扩张术后血管组织ｃ－ｆｏｓ ｍＲＮＡ的表达,采用生化方法测定     

基于光谱编码的血管内光声组分成像

光声成像突破了传统的光学成像和超声成像在生物组织成像领域的困境,该技术基于光声(Photoacoustic,PA)效应,脉冲激光激励下的生物组织产生超声信号,超声信号被接收后,通过反投影算法将其携带的时间信息和强度信息转化为能够反映生物组织吸收结构和分布的可视化图像。基于不同生物组织的光吸收差异,当激发光强度均匀且稳定时,光声成像反映的就是该物质对于该波长光的吸收特性。本文中,我们基于导管式的血管内光声断层扫描平台结合多波长激发的光声成像算法开发了基于光谱编码的血管内光声组分成像系统,实现了在离体血管斑块中脂质组分的定量成像,高分辨获得了脂质核心的大小形态和边界信息,表征了斑块内的脂质相对含量。     

超声弹性成像技术及其应用

超声弹性成像作为一种新的超声成像方法,它通过获取有关组织弹性信息进行成像,弥补了X射线、超声成像(US)、磁共振成像(MRI)、计算机断层扫描(CT)等传统医学成像模态不能直接提供组织弹性的不足,具有无创、简单、便宜、容易应用等优点,被广泛应用于临床,成为目前医学弹性成像的一个研究热点。本文介绍了弹性成像基本的原理,详细阐述了血管内超声弹性成像、超声振动声成像、超声剪切波弹性成像、瞬时弹性成像、心肌弹性成像等不同激励方式下的几种超声弹性成像的基本原理、成像方法、国内外目前的研究现状、成像优缺点等,叙述了超声弹性成像在乳腺检测、前列腺癌的检测、射频消融监测和检测、冠状动脉粥样硬化的治疗等临床应用,并总结了超声弹性成像的发展趋势。     

三段移床法Smart——Prep CeMRA在下肢动脉血管病变中的应用

探讨三段移床法智能跟踪对比增强磁共振血管造影(Smart-prep contrast enhanced magnetic resonance angiography,简称Smart-Prep CeMRA)在检查下肢血管性病变的方法和效果。材料和方法采用GESignatwin exciteⅡ型1,5T磁共振扫描仪对46例临床怀疑下肢动脉及其分支血管疾病进行三段移床法Smart-PrepCeMRA检查。结果 全部病例均获得清晰的下肢动脉及其主要分支血管造影图像。结论 采用Smart-PrepCeMRA能清晰显示下肢动脉及其分支血管图像,具有很好的临床应用价值。     

高血压前期患者颈动脉血管弹性超声参数与左室舒张功能的关系研究

摘要 目的：研究高血压前期患者颈动脉血管弹性超声参数与左室舒张功能的关系。方法：选取2019年12月-2020年12月因血压异常于河北北方学院附属第一医院接受诊断与治疗的161例患者,根据血压水平分为高血压前期组（82例）与高血压组（79例）;另选取同期于我院体检的80例健康志愿者作为对照组。收集三组临床资料,检测生化指标与血压;通过超声诊断仪中超声射频信号血管内中膜定量分析（QIMT）与动脉僵硬度定量分析（QAS）软件测量颈动脉血管弹性超声参数[颈动脉内中膜厚度（IMT）、顺应性系数（CC）、扩张性系数（DC）、血管弹性指数（α、β）、脉搏波传导速度（PWV）];超声心动图检查左室功能指标[左室射血分数（LVEF）、左室质量指数（LVMI）、舒张早期血流速度峰值（E）/舒张晚期血流速度峰值（A）、等容舒张时间（IVRT）、舒张期减速时间（DT）];采用Pearson相关性法分析颈动脉血管弹性超声参数与心室指标的相关性。结果：三组收缩压与舒张压水平存在统计学意义（P＜0.05）。高血压前期组与高血压组IMT、α、β、PWV高于对照组,DC、CC低于对照组（P＜0.05）,且高血压前期组IMT、α、β、PWV低于高血压组,DC、CC高于高血压组（P＜0.05）。高血压前期与高血压组E/A低于对照组,IVRT、DT高于对照组（P＜0.05）,且高血压前期组E/A高于高血压组,IVRT、DT低于高血压组（P＜0.05）。经Peason相关性分析显示,IMT、α、β、PWV与E/A呈负相关,与IVRT、DT呈正相关（P＜0.05）;DC、CC与E/A呈正相关,与IVRT、DT呈负相关（P＜0.05）。结论：高血压前期患者颈动脉血管弹性功能下降,且伴有左室舒张功能受损,颈动脉血管弹性超声参数与左室舒张功能密切相关。     

氢氧化钠瘤内注射通过抗血管生成作用抑制肝癌生长的机制研究

目的：研究氢氧化钠溶液瘤内注射对肝癌的生长抑制作用并探索其机制。方法：对SMMU-LTNM肝癌裸鼠皮下模型进行2%浓度的氢氧化钠溶液瘤内注射,检测肿瘤组织微血管密度、HIF-1α和VEGF的表达情况。结果：与生理盐水瘤内注射组相比,氢氧化钠显著抑制肿瘤生长（P〈0.01）、降低肿瘤微血管密度（P=0.01）、抑制肿瘤组织HIF-1α和VEGF的表达（P=0.02和P=0.01）。结论：氢氧化钠瘤内注射可有效抑制肝癌生长,主要机制可能是抗血管生成作用。     

药物涂层球囊概述及其在外周动脉疾病治疗中的应用进展

经皮经腔血管成形术(PTA)已广泛用于外周动脉疾病(PAD)的治疗。然而,该技术存在血管壁弹性回缩和内膜增生等不足。PTA术后植入金属裸支架(BMS)虽然可以减少血管壁弹性回缩,但由此引起的支架内再狭窄(ISR)又成为治疗中的一个突出问题。药物洗脱支架(DES)被用来解决狭窄问题,但晚期支架内血栓形成(LST)、内皮化延迟和必须长期抗血小板治疗等问题也随之而来。在这样的背景下,药物涂层球囊(DCB)获得了快速发展。DCB作为非支架方案,可将所携载的活性药物转移至病变段血管壁,对ISR或原发病变均有较好的治疗效果。本文简要介绍了DCB的发展历史,并通过实验室研究、动物实验和临床试验,从机制上阐述涂层技术、涂层药物、赋形剂等对DCB功效和安全性的影响以及DCB在PAD治疗中的应用进展。     

64层螺旋CTA容积重建结合轴位图像对明确颈部包块与血管关系的价值

目的:探讨64层螺旋CT血管成像(CTA)对明确颈部包块与周围血管关系的价值。方法:采用GE LightSpeed6 4层螺旋CT对25例颈部包块患者行颈部平扫及增强扫描,将获得的原始数据传入ADW4.3后处理工作站,血管重建技术选择容积重建(VR),诊断采用VR与轴位图像相结合的方式。结果:淋巴性病变10例,包括淋巴结结核2例、淋巴结转移4例、淋巴瘤4例,非淋巴性病变15例,包括淋巴管瘤1例、腮腺混合瘤2例、甲状腺癌4例、甲状腺腺瘤3例、孤立性纤维瘤1例、蔓状血管瘤2例、表皮样囊肿1例、咽旁脓肿1例。包块位于气管两侧6例,左侧15例,右侧4例;位于甲状腺内7例,腮腺内2例,颈动脉间隙11例,1例位于咽旁,其余4例位于颈部表浅组织内;颈部包块致毗邻血管移位、变形9例,其中动脉7例、静脉2例;颈部包块侵袭及包绕血管3例,包括动脉1例、静脉2例,其中1例静脉内血栓形成;颈部包块与血管关系密切2例;颈动脉发出分支供应颈部包块1例;其余10例与颈部血管无明显关系。结论:64层螺旋CTA容积重建结合轴位图像,可较准确地明确颈部包块与血管之间的关系。     

血管内支架和支架内皮化

简要介绍了血管内支架产生的背景、发展进程及其应用于临床后出现的再狭窄问题,着重综述了十几年来内皮细胞种植血管内支架预防术后再狭窄的相关研究成果。血管内支架内皮化的最终实现可以使现行的血管支架具有正常血管内皮的生物相容性及生理功能,是控制支架植入术后再狭窄问题的很有前途的支架改进方法。     

Simulation of a Single Red Blood Cell Flowing Through a Microvessel Stenosis Using Dissipative Particle Dynamics

The motion and deformation of a single red blood cell flowing through a microvessel stenosis was investigated employing dissipative particle dynamics (DPD) method. The numerical model considers plasma, cytoplasm, the RBC membrane and the microvessel walls, in which a three dimensional coarse-grained spring network model of RBC’s membrane was used to simulate the deformation of the RBC. The suspending plasma was modelled as an incompressible Newtonian fluid and the vessel walls were regarded as rigid body. The body force exerted on the free DPD particles was used to drive the flow. A modified bounce-back boundary condition was enforced on the membrane to guarantee the impenetrability. Adhesion of the cell to the stenosis vessel surface was mediated by the interactions between receptors and ligands. Firstly, the motion of a single RBC in a microfluidic channel was simulated and the results were found in agreement with the experimental data cited by [1]. Then the mechanical behavior of the RBC in the microvessel stenosis was studied. The effects of the bending rigidity of membrane, the size of the stenosis and the driven body force on the deformation and motion of red blood cell were discussed.     

Effects of vessel compliance on flow pattern in porcine epicardial right coronary arterial tree

The compliance of the vessel wall affects hemodynamic parameters which may alter the permeability of the vessel wall. Based on experimental measurements, the present study established a finite element (FE) model in the proximal elastic vessel segments of epicardial right coronary arterial (RCA) tree obtained from computed tomography. The motion of elastic vessel wall was measured by an impedance catheter and the inlet boundary condition was measured by an ultrasound flow probe. The Galerkin FE method was used to solve the Navier–Stokes and Continuity equations, where the convective term in the Navier–Stokes equation was changed in the arbitrary Lagrangian–Eulerian (ALE) framework to incorporate the motion due to vessel compliance. Various hemodynamic parameters (e.g., wall shear stress—WSS, WSS spatial gradient—WSSG, oscillatory shear index—OSI) were analyzed in the model. The motion due to vessel compliance affects the time-averaged WSSG more strongly than WSS at bifurcations. The decrease of WSSG at flow divider in elastic bifurcations, as compared to rigid bifurcations, implies that the vessel compliance decreases the permeability of vessel wall and may be atheroprotective. The model can be used to predict coronary flow pattern in subject-specific anatomy as determined by noninvasive imaging.     

First-in-human imaging using a MR-compatible e4D ultrasound probe for motion management of radiotherapy

PurposeRespiration-induced tumor or organ positional changes can impact the accuracy of external beam radiotherapy. Motion management strategies are used to account for these changes during treatment. The authors report on the development, testing, and first-in-human evaluation of an electronic 4D (e4D) MR-compatible ultrasound probe that was designed for hands-free operation in a MR and linear accelerator (LINAC) environment.MethodsUltrasound components were evaluated for MR compatibility. Electromagnetic interference (EMI) shielding was used to enclose the entire probe and a factory-fabricated cable shielded with copper braids was integrated into the probe. A series of simultaneous ultrasound and MR scans were acquired and analyzed in five healthy volunteers.ResultsThe ultrasound probe led to minor susceptibility artifacts in the MR images immediately proximal to the ultrasound probe at a depth of <10 mm. Ultrasound and MR-based motion traces that were derived by tracking the salient motion of endogenous target structures in the superior-inferior (SI) direction demonstrated good concordance (Pearson correlation coefficients of 0.95–0.98) between the ultrasound and MRI datasets.ConclusionWe have demonstrated that our hands-free, e4D probe can acquire ultrasound images during a MR acquisition at frame rates of approximately 4 frames per second (fps) without impacting either the MR or ultrasound image quality. This use of this technology for interventional procedures (e.g. biopsies and drug delivery) and motion compensation during imaging are also being explored.     

Real-time detection of vessel diameters with ultrasound.

Transcutaneous vessel imaging is a frequently used ultrasound imaging modality in medicine. The measurement of vessel diameters can be done with conventional B-mode imaging systems, which work at frame rates up to 100 Hz. Furthermore, there are special systems available, which can track vessel walls very precisely using the phase of signals that are sent at frame rates up to several thousand Hz. Though, such systems are usually not able to provide the examiner with 2D images of the object. With respect to brachial artery flow-mediated vasodilatation (FMD), which is frequently used as a measure of endothelial function, it is necessary to observe diameter changes of small arterial vessels noninvasively for several minutes at a high resolution. In the past, the diameter had to be measured manually in tedious postprocessing of ECG-gated image sequences. We developed a system composed of a Siemens Omnia ultrasound system with a VF13-5 transducer (9 MHz center frequency) and a personal computer, that is capable of calculating vessel diameter changes with an accuracy below the wavelength of the ultrasound system in real-time at a frame rate of 27 Hz. We implemented a two-dimensional active contour model using the Viter-bi-algorithm and a phase-sensitive vessel wall tracking algorithm, in order to guarantee both, geometric information and accuracy. Results from carotid and brachial arteries show that arterial pulsations below 0.1 mm can be visualized reliably over several minutes. With this system we want to find out, if FMD is suitable for an individual assessment of the risk for cardiovascular diseases.     

Noninvasive ultrasonic measurement of arterial wall motion in mice

Despite the extensive use of genetically altered mice to study cardiovascular physiology and pathology, it remains difficult to quantify arterial function noninvasively in vivo. We have developed a noninvasive Doppler method for quantifying vessel wall motion in anesthetized mice. A 20-MHz probe was held by an alligator clip and positioned over the carotid arteries of 16 mice, including six 3- to 5-mo-old wild-type (WT), four 30-mo-old senescent (old), two apolipoprotein E null (ApoE), and four alpha-smooth muscle actin null (alpha-SMA) mice. Doppler signals were obtained simultaneously from both vessel walls and from blood flow. The calculated displacement signals from the near and far walls were subtracted to generate a diameter signal from which the excursion and an augmentation index were calculated. The excursion ranged between 13 microm (in ApoE) and 95 microm (in alpha-SMA). The augmentation index was lowest in the WT mice (0.06) and highest in the old mice (0.29). We conclude that Doppler signal processing may be used to measure vessel wall motion in mice with high spatial and temporal resolution and that diameter signals can replace pressure signals for calculating the augmentation index. This noninvasive method is able to identify and confirm characteristic changes in arterial properties previously associated with age, atherosclerosis, and the absence of vascular tone.     

Ultrasound-driven cardiac MRI

PurposeOne of the challenges of cardiac MR imaging is the compensation of respiratory motion, which causes the heart and the surrounding tissues to move. Commonly-used methods to overcome this effect, breath-holding and MR navigation, present shortcomings in terms of available acquisition time or need to periodically interrupt the acquisition, respectively. In this work, an implementation of respiratory motion compensation that obtains information from abdominal ultrasound and continuously adapts the imaged slice position in real time is presented.MethodsA custom workflow was developed, comprising an MR-compatible ultrasound acquisition system, a feature-motion-tracking system with polynomial predictive capability, and a custom MR sequence that continuously adapts the position of the acquired slice according to the tracked position. The system was evaluated on a moving phantom by comparing sharpness and image blurring between static and moving conditions, and in vivo by tracking the motion of the blood vessels of the liver to estimate the cardiac motion. Cine images of the heart were acquired during free breathing.ResultsIn vitro, the predictive motion correction yielded significantly better results than non-predictive or non-corrected acquisitions (p ≪ 0.01). In vivo, the predictive correction resulted in an image quality very similar to the breath-hold acquisition, whereas the uncorrected images show noticeable blurring artifacts.ConclusionIn this work, the possibility of using ultrasound navigation with tracking for the real-time adaptation of MR imaging slices was demonstrated. The implemented technique enabled efficient imaging of the heart with resolutions that would not be feasible in a single breath-hold.     

Rheological factors in platelet - vessel wall interactions

Rheological aspects of platelet-vessel wall interactions involve cell-cell encounters, platelet - vessel wall encounters and platelet-thrombus interactions. The cell-cell encounters are usually caused by convection of cells in shear flows rather than by Brownian motion; this is important in aggregation and in the enhancement of the diffusion of platelets by red cell motion. Platelet - vessel wall interactions can involve transient adhesion (lasting from a fraction of a second to a few minutes) as well as more permanent adhesion. Reaction rates between platelets and walls are generally very small except on damaged vessels and some artificial surfaces. Ultra-filtration through the vessel wall affects cell-wall interactions. Rheological analyses of thrombus formation have been made and shown interesting relations to experimental observations. Some experimental results have indicated that platelets are capable of reacting within a small fraction of a second. Red cells may act as mechanoreceptors for increases in shear rate and facilitate the speed of response of platelets. Surface geometrical forms such as bumps and cavities tend to prolong residence times and facilitate thrombus formation.     

Quantitative Analysis of Coronary Vessels with Optimized Intracoronary CT Number

Background

Variability in intracoronary computed tomography (CT) number may influence vessel quantification. We confirmed the feasibility of a novel method for measuring vessel diameter and area using coronary CT angiography (CCTA) with an optimized intracoronary CT number, 350 HU.

Methods

We performed intravascular ultrasound (IVUS) imaging in 52 patients with significant stenosis detected by coronary CT angiography targeting 350 HU using a CT number-controlling system. We measured 0-to-0 HU distances in the cross-sectional coronary images of 32 patients. We analyzed the ratio of 0-to-0 HU distances in CT images to media-to-media distances in IVUS images (C:I ratio). The area of ≥0 HU for 103 representative points in the remaining 20 patients was compared to the area of the traced external elastic membrane (EEM) in IVUS images.

Results

There was a strong correlation between 0-to-0 HU distance in CT images and media-to-media diameter in IVUS images (r = 0.97, p<0.001). The C:I ratio was 1.1. EEM area was estimated by dividing the area of ≥0 HU by the square of C:I. There was also a strong correlation between the estimated EEM area and the EEM area in IVUS images (r = 0.95, p<0.001).

Conclusions

Media-to-media diameter and EEM area can be estimated by CCTA targeting the optimized intracoronary CT number when blood vessel borders are defined at 0 HU.     

Tissue Doppler imaging of carotid plaque wall motion: a pilot study

Background

Studies suggest the physical and mechanical properties of vessel walls and plaque may be of clinical value in the diagnosis and treatment of cardiovascular atherosclerotic disease. The purpose of this pilot study was to investigate the potential clinical application of ultrasound Tissue Doppler Imaging (TDI) of Arterial Wall Motion (AWM) and to quantify simple wall motion indices in normal and diseased carotid arteries.

Methods

224 normal and diseased carotid arteries (0–100% stenoses) were imaged in 126 patients (age 25–88 years, mean 68 ± 11). Longitudinal sections of the carotid bifurcation were imaged using a Philips HDI5000 scanner and L12-5 probe under optimized TDI settings. Temporal and spatial AWMs were analyzed to evaluate the vessel wall displacements and spatial gradients at peak systole averaged over 5 cardiac cycles.

Results

AWM data were successfully extracted in 91% of cases. Within the carotid bifurcation/plaque region, the maximum wall dilation at peak systole ranged from -100 to 750 microns, mean 335 ± 138 microns. Maximum wall dilation spatial gradients ranged 0–0.49, mean 0.14 ± 0.08. The AWM parameters showed a wide variation and had poor correlation with stenoses severity. Case studies illustrated a variety of pertinent qualitative and quantitative wall motion features related to the biophysics of arterial disease.

Conclusion

Our clinical experience, using a challenging but realistic imaging protocol, suggests the use of simple quantitative AWM measures may have limitations due to high variability. Despite this, pertinent features of AWM in normal and diseased arteries demonstrate the potential clinical benefit of the biomechanical information provided by TDI.     

A Feasibility Study of an Intravascular Imaging Antenna to Image Atherosclerotic Plaques in Swine Using 3.0 T MRI

Purpose

To investigate the feasibility of an intravascular imaging antenna to image abdominal aorta atherosclerotic plaque in swine using 3.0T magnetic resonance imaging (MRI).

Methods

Atherosclerotic model was established in 6 swine. After 8 months, swine underwent an MR examination, which was performed using an intravascular imaging guide-wire, and images of the common iliac artery and the abdominal aorta were acquired. Intravascular ultrasound (IVUS) was performed in the right femoral artery; images at the same position as for the MR examination were obtained. The luminal border and external elastic membrane of the targeted arteries were individually drawn in the MR and IVUS images. After co-registering these images, the vessel, lumen, and vessel wall areas and the plaque burden in the same lesions imaged using different modalities were calculated and compared. The diagnostic accuracy of intravascular MR examination in delineating the vessel wall and detecting plaques were analyzed and compared using IVUS.

Results

Compared with IVUS, good agreement was found between MRI and IVUS for delineating vessel, lumen, and vessel wall areas and plaque burden (r value: 0.98, 0.95, 0.96 and 0.91, respectively; P<0.001).

Conclusion

Compared with IVUS, using an intravascular imaging guide-wire to image deep seated arteries allowed determination of the vessel, lumen and vessel wall areas and plaque size and burden. This may provide an alternative method for detecting atherosclerotic plaques in the future.