MR 平面回波快速成像技术应用研究

目的 结合不同类型ＥＰＩ成像技术的特点,研究不同对比度ＥＰＩ的颅脑疾病诊断中的临床应用价值。方法 各类颅脑疾病患者１３６例所有病例行常规的ＭＲ扫描及ＥＰＩ。结果 ①应用ＥＰＩ扩散加像（及ＡＤＣ图）与ＥＰＩ－Ｔ２加权像对超急性期脑中风的诊断灵敏性与特异性均为１００％,联合ＴＳＥ－Ｔ２ＷＩ与Ｔ１ＷＩ的灵敏性与特异性分别为０％与４２．８５％（ｘ＾２＝１４．０８,Ｐ〉０．０１）。②常规ＭＲＩ上胆脂瘤表现为     

磁共振回波平面成像的特点与临床应用

磁共振回波平面成像（ｅｃｈｏｐｌａｎａｒｉｍａｇｉｎｇ;ＥＰＩ）是由Ｍａｎｓｆｉｅｌｄ于１９７７年首先提出,它是目前应用于临床的速度最快的ＭＲ成像序列,可在５０～１００ｍｓ内完成整个成像。由于成像速度奇快,该序列可消除运动伪影。因此,尤其适用于动态扫描及不合作患者。１　ＥＰＩ的原理特性（１）回波与速度：ＥＰＩ具有一系列梯度回波,其成像速度大于其他任何ＭＲ成像序列。可以冻结在常规ＳＥ序列上可能产生伪影的运动。并能消除失相位对比信号（图１）。（２）激励方式：ＥＰＩ采用单激励方式,即一次激励脉冲可产生…     

梗阻性肾病的磁共振肾功能成像

目的：通过对Ｔ１ＷＩ图像肾皮质－髓质分界（ＣＭＤ）的观测和应用磁共振肾灌注成像对肾功能损害进行测定。材料与方法： ４６例用重Ｔ２ＷＩ ＦＡＳＥ序列作磁共振尿路造影（ＭＲＵ）的患者。在Ｔ１ＷＩ图像上,对肾皮质－髓质分界（ＣＭＤ）进行观测。应用平面回波成像技术（ＥＰＩ）对１２例进行磁共振肾灌注成像,测定肾功能损害。结果：正常肾皮质－髓质分界（ＣＭＤ）消失０／４６例,病肾ＣＭＤ消失４３／４６例,经Ｘ２检验,有显著差异（Ｐ＜０．００５）。肾灌注曲线呈反抛物线形,正常两侧的肾灌注曲线几乎是重叠的。病肾与正常肾肾灌注曲线相比,波始时间、达波谷时间均延长,经ｔ检验,有显著差异（Ｐｔｏ．００１）,并且病肾的波幅小于正常肾。结论：对肾皮质－髓质分界（ＣＭＤ）的观测,可反映肾功能损害。应用平面回波成像技术（ＥＰＩ）,进行肾灌注成像,可进一步评价肾功能。     

中场强单激发磁共振尿路造影技术与临床应用探讨

探讨单激发快速自旋回波序列（ＳＳＦＳＥ）尿路造影技术及其临床应用价值。资料与方法：１５例正常和４２例尿路梗阻患者,在ＧＥ０．５Ｔ超导ＭＲ成像仪上采用ＳＳＦＳＥ序列进行ＭＲＵ成像,４９例加做２ＤＦＳＥ重Ｔ２加权经最大信号强度重建ＭＲＵ图像,结果：ＳＳＦＳＥ ＭＲＵ图像可清晰显示正常尿路,图象效果优于２ＤＦＳＥ重建ＭＲＵ图象,二者对尿路梗阻患者均可显示梗阻部位及程度,定性诊断正确率达８３．３％。结论：     

FLAIR 成像技术在颅脑疾病中的应用

目的 评价ＦＬＡＩＲ（液体反转恢复）序列在颅疾病中临床应用价值。方法 对７３例颅脑疾病患者行快速自旋回波（ＦＳＥ）序列及ＦＬＡＩＲ序列扫描。比较ＦＬＡＩＲ序列及Ｔ２像在显示颅病变的差异。结果 在７３例颅脑疾病中,ＦＬＡＩＲ共显示病灶１８７个,而Ｔ２加权像只显示１２６个。有６１个病灶仅在ＦＬＡＩＲ图像中显示,１０５个病灶的内部结构、边界在ＦＬＡＩＲ像较Ｔ２像显示清晰。结论 ＦＬＡＩＲ像显示颅脑中邻过     

磁共振胰胆管成像在胰胆管疾病诊断中的应用探讨

目的：探讨磁共振胰胆管成像（ＭＲＣＰ）在胰胆管疾病诊断中的临床应用价值。方法：５４例胰胆管疾病病人行ＭＲＣＰ检查，同时行磁共振常规扫描。６例病人在ＭＲＣＰ检查后一周内行ＥＲＣＰ检查。１４例经手术和病理证实。ＭＲＣＰ采用重度Ｔ２加权ＴＳＥ快速成像序列，加用脂肪压抑技术，图像经三维最大信号强度投影（ＭＩＰ）后处理。结果：冠状位ＭＲＣＰ图像与ＥＲＣＰ图像相似，空间分辨率略逊于ＥＲ－ＣＰ，能较好地显示胰胆管疾病的病变部位、梗阻程度及梗阻两端的情况。结论：ＭＲＣＰ作为一种安全非侵入性影像学诊断技术，能较好地显示胰胆管系统的解剖和病理变化，无放射性损伤，不用造影剂，对ＥＲＣＰ检查失败者或显示不完全的病例ＭＲＣＰ能获得较为满意的胰胆管图像。与ＥＲＣＰ相辅相成，可提高胰胆管疾病的诊断水平     

对MR灌注曲线始端下挫现象的实验研究

目的：探讨ＭＲ灌注成像过程中信号强度－时间曲线始端下挫现象产生的原因。材料与方法：在不注射造影剂的情况下，分别采用ＦＬＡＳＨ序列和ＥＰＩ序列对正常人脑及水膜进行实验扫描。保持其它参数不变，单独改变ＴＲ蔌ＴＤ，观察曲线的形态变化，并分别计算始端下挫值、始端下挫率以及后续图像上ＲＯＩ的平均信号强度（ＳＩｍ）。结果：所有受试序列均出现始端下挫现象，而且ＥＰＩ序列比ＦＬＡＳＨ序列明显。相同扫描序列正常脑实验比水模实验明显。延长ＴＲ或ＴＤ可以使后续图像的平均信号也有不同程度的增加，始端下挫的幅度减小以至完全校正。在ＦＬＡＳＨ序列，延长ＴＲ对始端下挫的校正效果比延长ＴＤ明显。结论：导致灌注曲线始端下挫现象产生的主要原因是饱和现象和失相，而与注射造影剂无关；始端下挫现象的存在会在一定程度上降低了灌注成像的质量，可以通过延长Ｔ     

3 T MR颅脑容积成像增强扫描序列在脑发育性静脉异常上的应用

【摘要】 目的 探讨3 T MR颅脑容积成像增强扫描序列在脑发育性静脉异常诊断上的应用价值。 方法 对24例MR诊断为脑发育性静脉异常病例的临床资料进行回顾性分析,所有病例均行常规MR平扫、增强及颅脑容积成像增强扫描序列。结果 26个病灶于平扫序列上可发现病灶,常规增强序列上可显示病灶强化,三维颅脑容积成像增强扫描序列上所有病例均清楚显示引流静脉及髓静脉,通过MIP、VR及MPR,可多方位特征性地显示水母头样征象。结论 3T三维颅脑容积成像增强扫描序列显示脑发育性静脉异常优势明显,是诊断该病准确、可靠的扫描序列。     

心肌缺血的MRI评价

随着磁共振成像（ＭＲＩ）技术的发展和临床应用范围的不断扩大,它在心肌缺血评价中的应用已成为心血管影像学研究的热点之一。１　心肌梗塞的ＭＲＩ诊断在心肌梗塞的急性或亚急性期,受累区域的心肌细胞变性、坏死及间质充血和水肿等因素使其Ｔ１、Ｔ２弛豫时间延长。尽管常规平扫Ｔ２自旋回波（ＳＥ）序列可用于该病的诊断,但由于其时间分辨力低以及心腔血液流空效应较差,对其显示不很理想,临床应用价值有限。常规Ｔ１、Ｔ２ＳＥ序列对慢性或陈旧性心肌梗塞诊断具有优良价值,因心肌坏死后已形成纤维瘢痕组织,局部心室壁可有不同程度…     

脑血肿的低场MR成像

１材料与方法本文９７例，男５２例，女４５例，年龄３３～８９岁。全部病例经临床确诊或ＣＴ扫描证实为脑实质出血。ＭＲ检查用ＡＳＰ－０１５Ｔ扫描仪，场强０．１５Ｔ。常规作轴位成像，成像矩阵２５５×２５６。扫描参数：ＳＥＴ１加权：ＴＲ／ＴＥ＝５００ｍｓ／３０...     

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.