鼻咽癌放疗后局部纤维化与肿瘤复发的MRI灌注成像研究

目的探讨MRI灌注成像对鼻咽癌放疗后局部纤维化与肿瘤复发的诊断价值。方法将放射治疗后鼻咽癌局部纤维化(31例)及肿瘤复发病例(25例)共56例分为2组,采用FLASH序列进行动态增强及灌注成像扫描,获得动态增强时间-信号强度曲线类型,统计分析动态增强及灌注成像参数:达峰时间(TTP)、最大斜率(Slope_(max))、曲线下面积(AUC),并获取伪彩图,及进行统计学处理。结果放疗后复发组动态增强时间-信号曲线类型均呈速升型,出现明显上升期,随后转为平台期或缓升缓降期;放疗后纤维化组时间-信号曲线呈缓升型,出现缓慢上升期,随后转为平台期或缓升缓降期。2组病例MRI动态增强参数TTP、Slope_(max)、AUC的均值行组间两两比较,复发组和纤维化组的Slope_(max)、TTP均值存在统计学差异,t值分别为67.18、-21.04(P0.05)。灌注参数伪彩图可直观的显示肿瘤或放疗后纤维化组织相应的血流灌注情况,发现AUC灌注伪彩图显示肿瘤组织较为清晰,分辨率较好。结论应用MR动态增强及灌注成像有助于鉴别鼻咽癌复发和纤维化。     

鼻咽癌放疗后局部复发MRI动态增强灌注成像23例分析

目的:探讨鼻咽癌放疗后局部复发的MRI动态增强灌注成像的时间-信号变化特征。方法:回顾性分析总结经病理及临床证实的鼻咽癌放疗后局部复发23例,测量动态增强不同时间病灶区相对信号强度,分析复发病灶的时间-信号强度变化的曲线特征。结果:鼻咽癌放疗后复发病灶在动态增强灌注成像延时后100～140s达到强化峰值,时间一相对信号强度变化曲线特征表现为速升-缓升-缓降。结论:动态增强MRI灌注成像对鼻咽癌放疗后复发的诊断具有重要的临床价值。     

超声造影评价大鼠肝纤维化分期与肾血流灌注的相关性

目的 分析CEUS技术评价大鼠肝纤维化分期与肾血流灌注的相关性。方法 健康雄性Wistor大鼠50只,随机选取44只,经硫代乙酰胺诱导为肝纤维化模型(肝纤维化组),6只作为对照组。于造模后第4、8、12周分别选取12只肝纤维化组大鼠及2只对照组大鼠行CEUS检查。比较各期(S0~S4)肝纤维化大鼠肾血流灌注情况及时间-强度曲线检测指标变化,并进行统计学分析。结果 与其他各期和对照组比较,S4期大鼠肾皮质血流时间-强度曲线峰值强度减低、达峰时间延长、曲线下面积减小(P均<0.05)。峰值强度、曲线下面积与肝纤维化分期呈负相关(P均<0.01);达峰时间与肝纤维化分期呈正相关(P<0.01)。结论 CEUS结合时间-强度曲线可定量分析不同程度肝纤维化大鼠肾血流灌注情况。肾皮质CEUS参数变化与大鼠肝纤维化分期密切相关。     

相位对比磁共振成像观察颅内基底动脉、上矢状窦和中脑导水管的生理流动模式

目的 相位对比磁共振成像(PC MRI)观察颅内基底动脉(BA)、上矢状窦(SSS)和中脑导水管(AM)的生理流动模式。方法 选取健康志愿者37名,采用PC MRI测量BA、SSS和AM流体的流动模式。观察时相-流速曲线特征,记录舒张期和收缩期的峰值流速及达峰时相点,并计算两峰值时相差率,记录心动周期内每搏流量、净流量。结果 BA呈单向高幅流动,时相-流速曲线为"缓降-速升-缓降"型;SSS呈单向低幅流动,曲线为"缓降-缓升-缓降"型,两波峰时相差率最小;AM脑脊液呈双向振动式流动,呈"缓升-缓降-缓升型",时相差率最大,绝对每搏流量(74.03±33.22)×10^-3 ml,向4脑室净流量为(3.70±2.78)×10^-3 ml。BA心动周期内两流速波峰间时相差率小于SSS、AM(F=26.63,P<0.01)。结论 BA、SSS及AM的生理流动模式不同。脑室系统、脑组织容积在心动周期内发生动态变化。PC MRI时相-流速曲线可直观、准确地观察脑血管、脑脊液的流动模式。     

MRI动态增强技术对鼻咽癌放疗后局部纤维化与复发的诊断研究

目的:探讨磁共振成像(MRI)动态增强技术对鼻咽癌放疗后局部纤维化与复发的诊断价值。方法:选取在我院鼻咽癌放疗后患者70例,根据患者复查结果分为局部纤维化组(40例)和复发组(30例),均先后进行MRI动态增强和常规增强T1WI扫描,分析两组动态增强时间-信号增强曲线(TIC)的达峰时间、最大斜率及图像。结果:复发组最大斜率较局部纤维化组明显升高,差异有统计学意义(P0.05);两组患者达峰时间比较,差异无统计学意义(P0.05)。结论:MRI动态增强技术可有效鉴别鼻咽癌放疗后局部纤维化和复发。     

血水混合物浓度及留存时间对模拟木质异物CT表现的影响:体外实验观察

目的 通过体外实验观察不同浓度血水混合物及留存时间对模拟木质异物CT表现的影响。方法 将20根杉木条置入含全血比例为0%、25%、50%、75%与生理盐水（血水）混合物及100%全血试管中,分别对应阴性对照（NC）组、T25组、T50组、T75组及T100组,每组4个样本。将试管置于恒温水浴锅中采集CT图像,每6 h重复一次,共采集300 h;比较相同时间点各组最低密度区CT值、最高密度区CT值和低密度区体积差异,评价时间及血水混合物浓度对木质异物CT参数的影响及其交互作用。结果 随时间延长,各组时间-最低密度区CT值曲线呈速升-缓升型,时间-最高密度区CT值曲线呈速升-平台型;NC组和T25组时间-低密度区体积曲线呈速降型,T50组、T75组及T100组时间-低密度区体积曲线呈缓降型。血水混合物浓度及时间均对木质异物最低密度区CT值、最高密度区CT值及低密度区体积存在影响（P均<0.05）,且二者对最低密度区CT值和低密度区体积存在交互作用（P均<0.05）。结论 血水混合物浓度及留存时间均影响木质异物CT表现。     

MRI动态增强对鼻咽癌及其放疗后改变的诊断价值

目的 探讨MRI动态增强对鼻咽癌及其放疗后改变的诊断价值.方法 收集原发或放疗后的鼻咽癌患者57例,将其分为未经治疗组、放疗后纤维化组及复发组,所有病例治疗前的病理诊断均为鳞状细胞癌.采用Flash序列获取三组病例动态增强的时间-信号强度曲线（TIC）并对其达峰时间（TTP）、曲线最大斜率（Slopemax）、曲线下面积（AUC）三个参数进行统计学分析,获取参数伪彩图.结果 3组病例MRI动态增强TTP、Slopemax、AUC的均值行组间两两比较,未经治疗组和纤维化组的3个参数差别均有统计学意义,而纤维化组与复发组仅Slopemax均值存在统计学差异.参数伪彩图可直观地显示肿瘤或放疗后纤维化组织相应的血流灌注情况.结论 动态增强TIC的类型、Slopemax有助于鉴别鼻咽癌复发和纤维化.     

基于因子分析的高级别脑胶质瘤MR灌注定量分析

目的 采用动态结构因子分析法（FADS）对5例高级别脑胶质瘤MR灌注图像进行定量分析,以准确提取脑胶质瘤MR灌注图像ROI的时间-信号曲线（TISCs）。方法 采用替代-近似算法对FADS模型求解,并分析从胶质瘤和正常组织区域提取的时间-信号曲线（TISCs）和因子图的特点。分别计算和比较胶质瘤与正常组织及病例间TISCs的相关系数。结果 采用FADS法从胶质瘤和正常组织中均提取到1条波峰向上的曲线（即升峰曲线）和2条波峰向下的曲线（分别为降峰曲线a和b）。胶质瘤与正常组织升峰曲线的相关系数平均值为0.75±0.10,明显低于胶质瘤患者间升峰曲线相关系数平均值0.84±0.05（P<0.05）。胶质瘤降峰曲线a与正常组织降峰曲线相关系数最大均值和胶质瘤降峰曲线b与正常组织降峰曲线相关系数最大均值差异有统计学意义（P<0.05）。胶质瘤患者因子图中瘤周区域主要对应升峰曲线,而胶质瘤区域主要对应两条降峰曲线。结论 采用FADS能自动提取到胶质瘤的TISCs,初步证明利用曲线的生理参数进行胶质瘤分级诊断具有可行性。     

鼻咽癌放疗前后CT灌注成像及与微血管密度的相关性

目的 观察CTPI在鼻咽癌放疗前、后的价值,分析灌注参数与微血管密度(MVD)的相关性.方法 对51例鼻咽癌放疗前、后患者行CTPI,将获得的340幅连续图像传人GE AW4.2工作站,利用Perfusion 3软件行后处理,软件自动生产灌注参数(BF、BV、PS、MTT),免疫组化标记MVD,对结果进行统计学分析.结果 鼻咽部灌注BF、BV、PS、MTT值三组组间差异有统计学意义,BF、BV、PS以局部复发组最高,MTT以纤维化组最高;疗前组、复发组和纤维化组的MVD平均值之间差异有统计学意义(P<0.01);三组BF、BV、PS,MTT值与肿瘤MVD呈正相关.结论 CTPI可提供关于鼻咽癌及其放疗前、后患者的定量信息,有助于鉴别鼻咽癌放疗后复发与纤维化.     

计数时间窗位置对SPECT测定肾小球滤过率的影响

目的 观察计数时间窗位置对SPECT测定肾小球滤过率(GFR)的影响。 方法 以231名北京地区健康居民为研究对象,分别采用双血浆法和^99mTc-DTPA肾动态显像法测定GFR(GFR_dt和GFR_Gates)。在以血流灌注相峰值点时间(峰时)为新时间原点的时间-计数率曲线上依次移动时间窗,于25个时间点上提取计数,并分别计算各点上的GFR_Gates。分析不同药物累积相峰时GFR_Gates与GFR_dt的相关性。 结果 ①左右肾脏血流灌注相峰时均值分别为(19.69±5.20)s和(20.29±5.19)s,基本呈正态分布。②肾滤过累积相峰时均值为(166.19±50.22)s,呈偏态分布,频数峰为132 s。③时间窗位于累积相峰值区时GFR_Gates达到最大,在峰值两侧,GFR_Gates均减小。④时间窗位于累积相峰值左侧上升区时,GFR_Gates与GFR_dt的相关系数随时间窗后移而增加;当后移到时间窗内含有部分峰值区段时,相关系数增速变缓;随着时间窗与峰值区段的重叠增加,相关系数达拐点,随后开始减小。 结论 在以肾血流灌注相峰时为原点的时间-计数率曲线上,提取86~145 s时间窗计数,可获得受时间影响较小的GFR。     

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.