孤立性颈动脉粥样硬化斑块内膜长轴切面力学状态的初步超声研究

目的 超声评价孤立性颈动脉粥样硬化斑块长轴切面上中下游内膜位点力学状态.方法 经体表获取标准等长握力试验前后46例患者48个孤立性颈动脉粥样硬化斑块最大厚度长轴切面超声图像,观察颈动脉粥样硬化斑块长轴切面上中下游内膜运动速度向量变化,测取颈动脉粥样硬化斑块血管内膜分析位点应变峰值及应变峰值绝对差值.结果 二维速度向量图显示颈动脉粥样硬化斑块处内膜运动速度向量大小、方向紊乱不同步;等长握力试验前后斑块上下游内膜位点测值高端与测值低端应变峰值差异有统计学意义(P=0.000),斑块上下游内膜位点测值高端与中游内膜位点应变峰值绝对差值和斑块上下游位点间应变峰值绝对差值差异有统计学意义(P＜0.017).结论 孤立性颈动脉粥样硬化斑块长轴切面上中下游血管内膜机械运动速度向量变化方向具有不一致性,斑块内膜不同位点间应变峰值存在不一致并能够应用超声速度向量技术定性和定量评价.     

速度向量成像评价颈动脉粥样硬化斑块稳定性

目的通过测定等长握力试验前后颈动脉粥样硬化斑块超声力学参数变化,提取有效评价斑块稳定性指标,建立不稳定斑块超声评价新方法。方法采用高频超声经体表获取64例患者71个孤立性颈动脉粥样硬化斑块标准等长握力试验前后连续3个心动周期实时二维灰阶超声图像,导入二维速度向量成像工作站脱机分析。观察握力试验前后血管内膜运动速度向量大小、时相和方向变化及彩色M型二维和重建三维应变、应变率显像。测量握力试验前后斑块肩部、顶部及相同节段内膜对应点和无斑块参考段对应点血管内膜峰值应变和应变率及峰值差值,进行统计比较分析。结果颈动脉粥样硬化斑块处内膜二维速度向量图显示颈动脉内膜运动速度向量大小、方向和时相紊乱、不同步;握力前斑块顶部内膜峰值应变、应变率显著高于对应点内膜测值（P〈0.05）;握力前后斑块肩部内膜峰值应变、应变率显著高于斑块同一平面对应点内膜测值（P〈0.05）。握力前后斑块左肩部内膜峰值应变高于顶部测值（P〈0.05）,斑块内膜左肩部与顶部及顶部与右肩部的应变峰值差差异有统计学意义（P〈0.01）。结论颈动脉粥样硬化斑块段内膜运动的机械不同步和斑块两侧肩部与顶部间峰值应变和应变率差值的不对称性,有可能作为动脉粥样硬化不稳定斑块的初查和量化评价指标。     

超声速度向量成像技术评价颈动脉粥样硬化斑块内部应变

目的探讨超声速度向量成像对握力试验前后颈动脉粥样硬化斑块内部应变变化的检测价值。方法采集74例(共81个斑块,7例为双侧斑块)住院患者颈动脉粥样硬化斑块连续3个心动周期标准等长握力试验前后二维短轴灰阶图像,采用超声速度向量成像(VVI)技术检测斑块肩部、顶部和基底部峰值应变,并计算斑块肩部、顶部及基底部的峰值应变和峰值应变差(△S肩=S肩-S基底部,△S顶部=S顶部-S基底部)。结果握力试验前后,峰值应变变化趋势均为肩部>顶部>基底部(P<0.01),△S肩>△S顶部(P<0.05)。握力试验前后斑块内同一点的峰值应变比较差异无统计学意义(P>0.05)。斑块肩部峰值应变与握力试验前的收缩压存在非明显相关性(r=0.26,P=0.04)。结论颈动脉粥样硬化斑块内肩部稳定性较其他部位差,更易发生破裂;血压变化与斑块各取样点的应变之间未能建立良好相关性。     

速度向量成像评价冠心病患者颈动脉粥样斑块力学特性的临床研究

目的 探讨颈动脉正常和斑块部佗、硬斑块和软斑块及斑块的肩部和纤维帽顶部速度、应变及应变率变化规律.方法对86例冠心病伴颈动脉粥样斑块患者和50例正常人双侧颈动脉进行高频超声检查,检测颈动脉内膜-中层厚度(IMT);应用速度向量成像(VVI)斑点追踪技术检测颈动脉的运动速度、应变、应变率,并分组进行分析.结果冠心病组颈动脉IMT高于正常组,差异有统计学意义(P＜0.05);正常对照组颈动脉收缩期径向最大运动速度高于冠心病颈动脉无斑块部位的测值,差异有统计学意义(P＜0.05);软斑块收缩期最大运动速度、最大应变率高于硬斑块组,差异有统计学意义(P＜0.001或P＜0.05);颈动脉斑块肩部收缩期最大运动速度、应变率高于斑块纤维帽顶部.差异有统计学意义(P＜0.05或P＜0.001).结论 VVI技术可早期检测血管壁的弹性度,早期检测颈动脉荆样硬化及颈动脉粥样硬化斑块部位内膜运动的机械不一致性和不同部位的力学指标差别,有可能作为动脉粥样硬化不稳定斑块的初查和量化评价指标.     

颈动脉粥样斑块应变及应变率分布的初步探讨

目的 探讨超声检测颈动脉粥样硬化斑块应变及应变率的可行性，颈动脉粥样硬化斑块应变及应变率的分布情况。方法 选取26例冠心病患者的35处颈动脉斑块，运用组织速度成像(TVI)和Q-analysis软件测量斑块不同部位的位移、斑块应变及应变率的峰值，对同一处斑块分别在不同参数条件下测量斑块应变及应变率峰值。结果 斑块应变和应变率测量值在不同参数条件下差异无显著性意义；不同部位的斑块应变、应变率差异具有显著性意义；急性心肌梗死、陈旧性心肌梗死和心绞痛3组患者颈动脉斑块的受力情况存在差异。斑块肩部和纤维帽表面是应变最集中的部位，并且沿径向方向，从斑块表面至基底部，应变及应变率呈减小趋势。结论 TVI技术可以用于颈动脉斑块应变及应变率的分析。不同类型的斑块肩部及不同部位应变及应变率存在差异。     

超声二维应变技术评价动脉粥样硬化颈动脉壁弹性

目的 应用超声二维应变技术探讨颈动脉粥样硬化患者颈动脉管壁短轴方向的圆周应变及圆周应变率的分布特点,评价颈动脉粥样硬化患者颈动脉弹性的变化.方法 病例组 47 例颈动脉粥样硬化患者,根据所采集切面斑块的有无分为斑块组和无斑块组;对照组44例正常人.以超声斑点追踪二维应变技术测量各组颈总动脉管壁短轴方向整体及各节段的收缩期峰值圆周应变、峰值圆周应变率.结果 病例组中,有斑块组、无斑块组收缩期峰值整体网周应变、收缩期峰值整体圆周应变率及3～5点、5～7点的收缩期峰值圆周应变、收缩期峰值圆周应变率均较对照组明显降低(P＜0.05);有斑块组收缩期峰值整体圆周应变、收缩期峰值整体圆周应变率及3～5点、5～7点、7～9点收缩期峰值圆周应变、峰值圆周应变率较无斑块组明显降低(P＜0.05).收缩期峰值整体圆周应变率与僵硬度参数(β,r＝-0.26,P＜0.05)、压力应变弹性模量(Ep,r=-0.24,P＜0.05)呈显著负相关.结论 超声斑点追踪二维应变技术为颈动脉粥样硬化患者颈动脉管壁弹性的评价提供了新的方法,使早期血管壁病变的评价成为可能.     

速度向量成像技术评价颈总动脉粥样硬化斑块力学状态的研究

目的 应用速度向量成像(VVI) 技术评价颈总动脉壁粥样硬化斑块运动特性及斑块力学的临床价值.方法 对36例动脉粥样硬化斑块患者和对照组30例正常人双侧颈总动脉进行超声检查;并检测出颈总动脉内中膜厚度(IMT),结合同步心电图描记,取颈总动脉长轴、短轴二维图像进行动态存储,运用VVI软件进行脱机分析,计算颈动脉壁粥样斑块部位的运动速度、应变和应变率,并与正常组动脉壁运动参数进行比较.结果颈总动脉粥样斑块处运动速度、应变及应变率低于无斑块处;斑块基底部速度、应变及应变率低于斑块表面;斑块组颈动脉IMT及运动速度均高于正常对照组(P<0.5),软斑块收缩期最大运动速度、最大应变率分别高于硬斑块组,肩部运动速度、应变率高于帽顶部(P<0.5).结论 VVI 技术可用于颈总动脉管壁斑块运动速度、应变及应变率的分析,为研究颈总动脉斑块形成机理和稳定性,提供新的方法.     

速度向量成像技术早期无创性评价动脉硬化的临床研究

目的探讨冠心病组和正常对照组颈动脉运动速度、应变及应变率的变化。方法对86例冠心病患者颈动脉无斑块部位和50例健康体检者进行双侧颈动脉高频超声检查,测量颈动脉内膜．中层厚度（IMT）,应用速度向量成像（VVI）技术跟踪颈动脉的运动速度、应变、应变率,测量各项指标及肱动脉内皮依赖性舒张功能。结果冠心病组颈动脉内膜一中层厚度、弹性系数和僵硬度均高于正常对照组（P〈0．05）,冠心病组内皮依赖性舒张反应肱动脉内径变化数值低于正常对照组（P〈0．05）;冠心病组颈动脉无斑块部位长轴的收缩期径向最大运动速度、最大应变率分别低于正常对照组（P〈0．05）;冠心病组颈动脉无斑块部位短轴的径向运动速度、旋转率、周向应变及应变率均低于正常对照组（P〈0．05）。冠心病组颈动脉径向运动速度与弹性系数呈负相关（r=-0．464,P=0．002）。讨论VVI技术可检测血管壁的弹性变化,颈动脉运动的机械不一致性和不同部位的力学指标差别,有可能作为动脉硬化早期检测和定量评价指标。     

大量心包积液对左室局部收缩期峰值二维应变的影响

目的大量心包积液对左室局部收缩期峰值二维应变的影响。方法采集17例大量心包积液患者与18例正常对照者心尖位左室长轴、二腔、四腔切面以及左室短轴(二尖瓣、乳头肌、心尖水平)切面的高帧频动态二维图像。用心尖双平面Simpson法测量左室射血分数(EF)。比较大量心包积液与对照组各参数测值。结果尽管大量心包积液患者左室射血分数与正常人差异无显著性意义([69.23±7.36]%vs[72.39±6.04]%,P>0.05),但其所有短轴径向、大部分纵向、部分圆周收缩期峰值二维应变指标较正常人减小,差异有显著性意义。结论大量心包积液对收缩期峰值纵向应变和收缩期峰值径向应变存在一定的影响。     

症状性和无症状性脑梗死与颈动脉粥样硬化斑块关系的探讨

目的 探讨老年人症状性和无症状性脑梗死与颈动脉粥样硬化斑块的关系。方法 用B超显像法观察34例症状性脑梗死和35例无症状性脑梗死病人双侧颈动脉粥样硬化斑块情况。结果 症状性脑梗死在顼动脉粥样硬块检出例数,斑块数目、厚度、长度与无症状性脑梗死相比有显著性差异,两组间在颈动脉中层-内膜厚度差异无显著性。结论 对有脑梗死高危因素的老年人进行颈动脉超声检查具有预后价值。     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.     

Clinical Pharmacokinetics of Morphine

Morphine, the most widely used mu-opioid analgesic for acute and chronic pain, is the standard against which new analgesics are measured. A thorough understanding of the pharmacokinetics of morphine is required in order to safely and effectively use this analgesic in a wide variety of patients with different levels of organ function. A MEDLINE search was conducted to identify literature published between 1966 and January 2002 relevant to the pharmacokinetics of morphine. These publications were reviewed and the literature summarized regarding unique and clinically important elements of morphine disposition relative to its parenteral administration (including intravenous, intramuscular, subcutaneous, epidural and intrathecal administration), absorption profile (immediate release, controlled release, and sublingual/buccal, and rectal administration), distribution, and its metabolism/ excretion. Special populations, including infants, elderly, and those with renal/liver failure, have a unique morphine pharmacokinetic profile that must be taken into account in order to maximize analgesic efficacy and reduce the risk of adverse events.