磁共振弥散张量成像技术在新生儿脑白质发育中的研究

目的运用磁共振弥散张量成像(DTI)技术研究分析新生儿脑白质发育规律和特点。材料与方法本研究纳入38名新生儿,包括18例适于胎龄早产儿,20例正常出生体重足月儿,按胎龄分为3组,分别测量各兴趣区FA值进行分析。结果新生儿脑实质FA值无左右差异。外周白质FA值小于深部白质,在深部脑白质中,胼胝体压部FA值高于膝部,内囊后肢高于前肢,胼胝体压部高于内囊后肢;在外周脑白质中,半卵圆中心层面中部白质FA值最高,半卵圆中心前、后白质的FA值均无统计学差异(P0.05)。Ⅲ组各兴趣区FA值均高于Ⅰ组,且差异有统计学意义(P0.05),相邻胎龄组比较,只有部分兴趣区有统计学差异。结论 DTI技术在研究新生儿脑白质成熟方面具有重要价值,FA值可定量评估髓鞘发育。     

新生儿缺氧缺血性脑病中扩散张量成像对脑白质损伤及预后的诊断价值

  目的  分析扩散张量成像（DTI）在新生儿缺氧缺血性脑病诊断中对脑白质的损伤和预后的价值。  方法  将本院于2018年8月~2021年6月收治的60例行MRI检查的新生儿作为研究对象，年龄均 < 2周岁，且均有缺氧缺血性脑病史。将患者分为脑瘫组和非脑瘫组（30例/组），记录其常规颅脑平扫征象和得分，于DTI图像上找出感兴趣区域并测定各向异性分数（FA）值和表观弥散系数（ADC）值。测定的白质区包括:内囊前肢、丘脑后辐射、额叶白质、中脑大脑脚、胼胝体压部、下纵束、胼胝体体部、内囊后肢、视辐射、内囊膝部、皮质脊髓束、半卵圆中心、听辐射、胼胝体膝部和顶叶白质等。生成胼胝体纤维束和皮质脊髓束的三维图像。对比分析两组患儿平扫的征象和FA值与ADC值；采用Logistic回归分析多因素筛选脑白质损伤的独立影响因素，并评估其拟合度和效能。  结果  经MRI平扫，两组患儿颅脑左侧的丘脑、两侧的半卵圆中心区和胼胝体体部的征象差异具有统计学意义（P < 0.05）；其中脑瘫组患儿各个部位的FA值均比非脑瘫组小，且两组患儿的FA值在内囊后肢、听辐射、双侧中脑大脑脚、视辐射、顶叶白质、皮质脊髓束、胼胝体压部、下纵束、半卵圆中心、胼胝体膝部、丘脑后辐射、胼胝体体部和左侧豆状核的差异具有统计学意义（P < 0.05）；两组患儿的ADC值在双侧半卵圆中心、胼胝体体部、左侧内囊后肢、左侧丘脑后辐射、双侧皮质脊髓束、左侧顶叶及压部和左侧丘脑差异具有统计学意义（P < 0.05）；左侧内囊后肢、胼胝体压部和左侧皮质脊髓束的FA值可作为脑白质损伤的独立预测因素，三者联合用于缺氧缺血性脑病患儿脑白质损伤的ROC AUC是0.887，特异性和敏感度分别是90.38% 和85.12%，准确度为0.761。  结论  缺氧缺血性脑病会使其白质纤维束发生损伤，使其FA值降低，ADC值升高，DTI可明确反映出患儿神经纤维束发育和受损的程度，可作为缺氧缺血性脑病的诊断和预后依据。      

扩散张量成像评价颈总动脉交感神经网剥脱术治疗儿童脑瘫的价值

目的应用磁共振扩散张量成像(diffusion tensor imaging,DTI)及扩散张量纤维束成像(diffusion tensor tracking,DTT),探讨其对脑瘫患儿颈总动脉交感神经网剥脱术后脑白质恢复的评估价值。材料与方法对30例痉挛型单侧脑瘫患儿手术前、后进行临床评估和常规MRI、DTI检查,测量并比较术前术侧和对侧、术前和术后双侧内囊后肢及大脑脚的各向异性分数(fractional anisotropy,FA)值,并对白质纤维束进行三维重建。运用粗大运动功能分级系统(gross motor function classification system,GMFCS)评价患儿运动功能。采用配对样本t检验比较术前术侧和对侧、术前和术后脑白质不同部位FA值的差异,以Spearman相关分析不同白质纤维束DTI参量与GMFCS的相关性。结果术前术侧不同部位白质纤维束FA值均显著低于对侧,差异有统计学意义(P0.01)。术后6个月脑瘫患儿术侧不同部位白质纤维束FA值与术前相比显著增加(P0.01),粗大运动功能获得改善。术后6个月患儿对侧不同部位白质纤维束FA值与术前相比差异无统计学意义(P0.05)。患儿临床GMFCS与FA值呈负相关(P0.01),且与内囊后肢、大脑脚的相关性都较高(r=-0.933,P0.01;r=-0.873,P0.01)。结论 DTI联合DTT可用于定量评价脑瘫患儿术后脑白质的恢复情况,对辅助临床治疗和预后评估具有重要作用。     

自闭症儿童脑结构的MRI研究

目的通过MRI研究自闭症儿童的脑结构异常。方法对26例自闭症儿童和16例正常儿童进行脑部磁共振扫描,比较两组全脑各向异性分散(FA)的差异,分析自闭症儿童各被检测部位的FA值与儿童行为评估量表(CBQ-R)得分的相关性。结果 (1)自闭症组右侧额下回、左侧额中回、右侧颞下回邻近白质的FA值(0.32±0.12、0.28±0.03、0.17±0.09)低于对照组(0.76±0.08、0.57±0.01、0.61±0.36),P<0.05;自闭症组左顶小叶邻近白质的FA值(0.75±0.47)高于对照组(0.42±0.90),P<0.05。(2)自闭症组右侧胼胝体压部FA值与CBQ-R的语言评分值呈负相关(r=-0.419,P<0.05)。(3)自闭症组内囊后肢、胼胝体膝部FA值高于对照组,差异有统计学意义(P<0.05)。结论自闭症儿童的多个脑部位的白质纤维的完整性遭到破坏,胼胝体神经纤维连接存在异常。     

弥散梯度方向数目对DTI测量值的影响

目的 探讨弥散张量成像(DTI)中不同数目的梯度方向对成人脑组织各向异性分数(FA)的离散程度及其信噪比(SNR)的影响.方法 应用7种不同弥散梯度方向数目(NDGD)对8名健康志愿者脑组织进行DTI扫描并获取FA图,计算FA图中4个感兴趣区(ROI)(胼胝体膝部、胼胝体压部、内囊膝部、内囊后肢)的FA值及其SNR,分析其随NDGD增加的变化趋势.结果 脑内各个ROI的FA值不随NDGD的增加而显著变化;信号强的ROI(胼胝体膝部、胼胝体压部)内FA值方差随机波动,其SNR增加不大;信号弱的ROI(内囊膝部、内囊后肢)内FA值方差随着NDGD的增加而逐渐减小.结论 在DTI的临床应用中,要根据检查的部位选择最适宜的NDGD.     

精神分裂症患者脑白质的磁共振扩散张量成像研究

目的应用磁共振扩散张量成像技术(DTI)对精神分裂症患者额叶及胼胝体压部脑白质损伤情况与临床症状之间的关系进行初步研究。方法对22例精神分裂症患者和20例健康志愿者进行脑部DTI扫描后,测量双侧额叶和胼胝体压部的各向异性分数值(FA),应用成组t检验对精神分裂症患者和正常健康对照组的相应区域进行比较,并用部分相关性检验对精神分裂症患者脑中各部位相应FA值与PANSS量表评分之间的关系进行统计。纤维束成像技术(DTT)重建胼胝体和扣带束。结果精神分裂症患者双侧额叶和胼胝体压部的FA值与正常对照组存在显著性差异(P<0.05),额叶FA值与PANSS量表评分之间存在正相关性(r=0.703,P<0.05),纤维束成像技术不能显示病例组和对照组的差别。结论精神分裂症患者与正常健康对照组存在脑白质细微结构的差异,DTI技术能够在一定程度上反映精神分裂症患者脑白质受损与临床症状的关系。     

常规MRI和扩散张量成像在足月新生儿HIE的诊断价值

目的探讨磁共振成像常规序列和扩散张量成像(diffusion tensor imaging,DTI)的分数各向异性(factionalanisotropy,FA)值和平均扩散系数(averagediffusion coefficient,ADC)值在足月儿缺血缺氧性脑病(hypoxicischemicencephalopathy,HIE)诊断中的价值。材料与方法 2016年12月至2017年12月收住我院的41例HIE足月儿进行颅脑常规MRI和DTI检查,另取10例正常足月儿作为对照组,分析内囊后肢、胼胝体膝部和压部、额枕叶深部白质、半卵圆中心和豆状核的ADC值、FA值特点、与新生儿行为神经评分(neonatal behavioral neurological assessment,NBNA)的相关性及其诊断HIE的准确度。结果常规MRI的内囊后肢、基底节和丘脑病变仅见于中重度HIE(P<0.05)。除胼胝体膝部和压部外,相同ROI双侧ADC值、FA值无差异(P>0.05)。中度HIE额叶深部白质和重度HIE除豆状核外的ADC值及中重度HIE除豆状核外的FA值低于对照组(P<0.01),轻度HIE各ROI的ADC值及FA值与对照组相仿(P>0.05)。轻度和中重度组间额叶深部白质,轻重度组间胼胝体膝部,轻中度和重度组间枕叶深部白质和半卵圆中心的ADC值及各组间除豆状核外的FA值差异有统计学意义(P<0.05)。结论 FA值反映HIE脑白质损伤程度、范围和预后评估优于ADC值和常规MRI,内囊后肢的FA值与NBNA评分相关性最高。     

扩散峰度成像评价阿尔茨海默病患者脑白质微观结构的改变

目的 采用扩散峰度成像(DKI)探讨阿尔茨海默病(AD)患者脑白质微观结构的改变。方法 对23例AD患者(AD组)和24名健康对照者(HC组)进行常规MR序列及DKI扫描,手动测量额叶、顶叶、枕叶及颞叶皮层下白质、内囊(前、后肢)、外囊、胼胝体(膝、干、压部)的DKI参数,包括扩散峰度(MK)、横向峰度(Ka)、径向峰度(Kr)、平均扩散率(MD)、横向扩散率(Da)、径向扩散率(Dr)及FA值。采用ROC曲线下面积评价各参数值诊断AD的效能。结果 与HC组相比,AD组的顶叶及颞叶皮层下白质、外囊的MK、Ka、Kr值均降低;枕叶皮层下白质的MK、Kr值均降低;内囊前肢、胼胝体膝的MK、Ka值均降低;胼胝体干的MK、Kr值均降低;胼胝体压、内囊后肢的Ka值降低(P均<0.05)。额叶皮层 下白质、内囊前肢、胼胝体干的MD、Da、Dr值均升高;顶叶及颞叶皮层下白质、外囊的MD、 Dr值均升高;胼胝体压部的MD、Da值均升高;内囊后肢、胼胝体膝的MD值均升高;枕叶皮层下白质的Dr值升高(P均<0.05)。额叶、顶叶、枕叶及颞叶皮层下白质、胼胝体干、胼胝体膝、内囊前肢、外囊的FA值减小(P均<0.05)。颞叶皮层下白质Dr值的ROC曲线下面积最大,为0.95。所有部位的MK、Ka、Kr及FA值与MMSE评分均呈正相关;MD、Da及Dr值与MMSE评分呈负相关。结论 DKI参数可反映AD患者脑白质微观结构的改变,颞叶皮层下白质的Dr值是鉴别AD患者与正常人的最佳指标。     

基于DTI成像研究脑梗死后单侧运动通路损伤的大脑结构改变

目的：探讨单侧运动通路受损脑梗死患者大脑结构的改变。方法：选择单侧运动通路受损的脑梗死患者66例,匹配性别、年龄相当的健康受试者66例。采用3.0 T磁共振扫描仪对所有受试者行DTI序列的扫描。采用基于纤维束示踪的空间分析方法（TBSS）对两组脑图像进行处理,比较脑梗死受试者组和健康受试者组在大脑结构上的不同。结果：和健康受试者相比,脑梗死受试者的胼胝体FA值明显降低的脑区为胼胝体膝部、胼胝体体部;双侧FA值降低的相关脑区为双侧放射状前冠、双侧上放射冠;患侧FA值降低的相关脑区为皮质脊髓束、大脑脚、内囊前脚、内囊后脚、内囊豆状核后部、后放射冠、丘脑后放射冠（包括视辐射）、外囊、上纵束、额枕上束和右侧绒毡层（P<0.001）。结论：单侧运动通路损伤后大脑的结构出现双侧性变化,其中枢神经机制可能是胼胝体纤维受损;患侧除了运动相关脑白质纤维结构受损,非运动相关的脑白质纤维同样会受到影响。     

磁共振弥散张量成像在儿童脑发育迟缓的临床研究

目的:探讨磁共振弥散张量成像(DTI)在儿童脑发育迟缓的检测价值。方法:以100例发育迟缓患儿为对象,以同期100例神经系统查体阴性在我院行颅脑MRI检查的发育正常儿童为对照组。均接受DTI检查,对比两组儿童均扩散率(MD)值、部分各向异性(FA)值。结果:发育迟缓组额叶、颞叶、枕叶、半卵圆中心MD值高于对照组(P<0.05)。两组脑白质胼胝体膝部、胼胝体压部、内囊后肢、内囊前肢、视放射FA值比较无差异(P>0.05);发育迟缓组额叶、颞叶、枕叶、半卵圆中心FA值低于对照组(P<0.05)。结论:DTI检查显示发育迟缓儿童脑白质浅部FA值低于正常儿童,MD值高于正常儿童。     

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.