超极化13C MRI研究进展

“超极化”指通过动态核极化方法使原子核自旋极化达热平衡之上，以增强分子MRI信号。近年来，超极化MRI日益发展，可克服传统MR信号低、无法实时监测体内代谢过程的缺点，在检测肿瘤及其他疾病的代谢中显示出一定应用价值。本文就常用超极化¹³C生物探针、超极化MR设备及超极化¹³C MRI的研究进展进行综述，并对其发展趋势进行展望。     

超极化磁共振波谱的原理和应用

通过动态核极化(dynamic nuclear polarization,DNP)的方法使原子核自旋极化达到热平衡之上来增强分子磁共振10,000倍以上的信号,这一过程称为超极化(hyperpolarization,HP)。溶解性DNP允许超极化分子以液体形式转移至生物体内,可实时观测体内的生物灌注、代谢产物的运输和代谢反应。该技术的发明克服了传统磁共振信号低,不能实时监测体内代谢过程的缺点。本文旨在介绍动态核极化的定义和技术、常用的超极化生物探针、超极化磁共振波谱图像的结果分析以及初步的动物实验和临床试验结果。     

磁共振分子影像学研究进展

磁共振分子影像是分子影像学的重要分支,具有其他成像技术不可比拟的优越性和广阔的发展前景.近年来,新型磁共振靶向探针及成像序列的研发取得了一系列进展,包括可激活探针、19F成像、超极化成像以及化学交换饱和转移成像等方面,进一步拓展了磁共振分子影像的应用范围.此外,磁共振分子成像在多系统疾病的早期诊断、代谢成像、细胞示踪及基因分析等方面也发挥着巨大优势.尽管磁共振分子成像距离临床转化还存在着一定差距,随着成像技术的日新月异,其在临床疾病诊治中必将发挥重要价值.     

磁共振波谱空间定位技术进展

磁共振波谱技术（Magnetic resonance spectropy,MRS）是目前临床上唯一能够进行活体内分析特定代谢产物的技术。常用于MRS分析的原子核，包括氢（^1H）、磷（^31P）、碳（^13C）和氟（^19F）。从活体研究来说，涵盖了大脑、心脏、肝脏、肌肉等组织器官；从研究肿瘤病理生理而言，包括了肿瘤定性及分级、能量代谢、糖代谢、药物药代动力学过程（特别是含氟抗肿瘤药物）。     

正电子发射断层在临床肿瘤学中的应用

<正> 许多疾病的发生发展过程中生理生化方面的变化,往往早于形态学的改变。正电子发射型计算机断层(PET)系以正电子发射型核素标记物在体内的生化代谢为基础进行显像,反映病变组织的机能变化和生物学特性。常用的示踪剂有~(18)F—氟脱氧葡萄糖(FDG),~(11)C—氨基酸、~(13)N—氨基酸和~(15)O—水。近年来关于PET在肿瘤诊断、评价放/化疗效果方面的应用报道日趋增多。1.脑胶质瘤CT和磁共振(MRI)给以清楚的病理形态学信息,但这两种影像检查均不能反映出     

胆红素脑病磁共振及磁共振波谱研究进展

胆红素脑病是由于新生儿时期严重的高胆红素血症所致的神经综合征。磁共振与磁共振波谱分别利用原子核在磁场内共振所产生的信号重建成像，和化学位移作用原理测定化合物信号，无创性地研究疾病发生时脑内组织代谢及生理生化改变，为进一步明确胆红素脑病的发病机制和早期准确地评估预后提供了一种手段和方法。本文对它的应用价值及进展作一综述。     

心脏磁共振成像在心肌缺血级联中的应用价值

缺血性心脏病(IHD)从局部血流灌注减少到心肌梗死这一过程被称为心肌缺血级联,其包括早期灌注减少、代谢失调、运动功能障碍、心电图异常以及心肌梗死这一系列病理生理改变过程。心脏磁共振(CMR)能综合评价心脏形态及功能。本文旨在综述CMR在心肌缺血级联反应中对心肌灌注、心室运动功能以及心肌梗死的应用价值。     

颞部巨细胞修复性肉芽肿1例

正患者,女,13岁,因左侧听力渐进性下降伴左耳流少量透明液体5+个月就诊。否认外伤史。我院中耳CT所见(图1A、1B):左侧颞骨、蝶骨、乳突骨质呈膨胀性吸收破坏,左侧颞叶见一巨大占位,灶内可见小片状更低密度影,环状及小点状高密度影。磁共振成像(magnetic resonance imaging,MRI)平扫(图1C、1D)示:左侧颞部病灶呈等稍长T1、短T2信号,并见小片状短T1、稍长T2信号,左侧颞叶脑组织受压周围见片状水     

3.0T磁共振成像对幕上分水岭脑梗死的诊断及分型

目的讨论磁共振成像对幕上分水岭脑梗死的诊断及分型,为临床诊断、治疗、预后提供帮助。方法对本院100例磁共振诊断为幕上分水岭脑梗死患者进行回顾性分析。结果磁共振根据病灶的信号特点、位置及形态,能够对幕上分水岭脑梗死做出准确的诊断及分型,包括皮质型脑梗死44例(皮质前型6例,皮质后上型11例,皮质后下型13例,皮质上型14例),皮质下型56例(皮质下上型13例,皮质下下型10例,皮质下前型5例,皮质下后型15例,皮质下外型13例)。结论磁共振检查对幕上分水岭脑梗死的诊断及分型具有重要价值,为临床及早诊治、改善预后起到较大作用。     

浅析静滴极化液低血糖反应的原因及护理

低血糖反应是血糖浓度〈3．0mmol／L而导致脑细胞缺糖的临床综合征，可因多种原因引起。心内科在冠心病、急性心肌梗死、心肌病等治疗中常静滴极化液，以促进尽肌摄取和代谢葡萄糖，使钾离子进入细胞内，恢复细胞膜内的极化状态，以利于心脏的正常收缩，减少心律失常，使ST段恢复到等电位。但在静滴极化液过程中及静滴结束后低血糖反应并不罕见。     

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.