灯盏花素对大鼠肺纤维化的预防作用及其机制

 目的 观察灯盏花素对肺纤维化大鼠肺组织炎症程度、胶原纤维形成的影响,探讨灯盏花素对肺纤维化的干预作用及其机制.方法 将30只SD大鼠随机分为模型组、对照组和灯盏花素组.模型组以博来霉素气管内注入建立模型,对照组以生理盐水气管内注入,灯盏花素组以博来霉素气管内注入并以灯盏花素进行干预治疗,于第29天将大鼠处死并检测.以HE染色和细胞核颗粒计数观察肺组织炎症程度,以胶原染色检测总胶原蛋白,以免疫组化法检测Ⅰ型胶原纤维,以原位杂交法检测TGF-β RⅡ mRNA和Smad4 mRNA,以实时荧光定量PCR法检测TGF-β1 mRNA.结果 灯盏细辛组相比模型组在炎症程度、总胶原纤维、Ⅰ型胶原纤维、Smad4 mRNA、TGF-β1 mRNA的表达均有下降.结论 灯盏花素可抑制肺内炎症反应、总胶原纤维和Ⅰ型胶原纤维的合成,对博来霉素所致大鼠肺纤维化具有一定的预防作用.     

钆类和氧化铁类MR对比剂在诊断急性梗塞中的应用

近十年ＭＲ对比剂的发展迅猛，开发了多种顺磁性和超顺磁性对比剂。对比剂的应用进一步拓宽了影像学技术的检查范围的广度和深度，尤其是对超急性期缺血性脑梗塞诊断。本文主要简述与缺血性脑梗塞ＭＲ诊断有关的钆类和超顺磁性氧化铁类对比剂的进展概况，和不同ＭＲ检查方法诊断缺血性脑梗塞的原理。     

灯盏花素对创伤性脑损伤大鼠学习记忆功能的影响

目的 观察灯盏花素对创伤性脑损伤大鼠学习记忆功能和脑氧自由基的影响.方法 通过液压损伤法建立大鼠创伤性脑损伤模型,水迷宫实验和避暗实验测定大鼠学习记忆功能,并于测试后取脑测定总超氧化物歧化酶（T-SOD）、丙二醛（MDA）含量.结果 在Morris水迷宫实验中,灯盏花素能明显缩短脑创伤大鼠逃避潜伏期;在避暗实验中,灯盏花素能显著延长脑创伤大鼠学习记忆潜伏期,减少错误次数.灯盏花素可以显著降低脑创伤大鼠脑组织MDA含量和显著增加T-SOD含量.结论 灯盏花素可改善脑创伤大鼠学习记忆功能,其作用与抑制氧自由基反应有关.     

功能MRI在评价对比剂诱导急性肾损伤中的研究进展

对比剂诱导急性肾损伤（CI-AKI）是注射碘对比剂后严重的并发症之一,早期诊断和治疗可以改善或延缓肾损伤。目前多种功能MRI（fMRI）技术可用于肾损伤后肾脏微循环和病理生理学的评估,包括扩散加权成像（DWI）、体素内不相干运动（IVIM）成像、扩散张量成像（DTI）、扩散峰度成像（DKI）、血氧水平依赖（BOLD）成像、动脉自旋标记（ASL）成像等。这些技术不但可以对肾功能损害进行定量分析,还可以在肾损伤的早期诊断和监测方面提供更多信息。就CI-AKI的发病机制及fMRI评价CI-AKI的研究现状做一综述。     

灯盏花素对急性脑梗死患者C反应蛋白及智能的影响研究

目的：观察灯盏花素对急性脑梗死患者C反应蛋白（CRP）和智能的影响。方法：选择急性脑梗死120例,随机分为观察组和对照组各60例,对照组采用脑梗死常规治疗,观察组在对照组治疗基础上加用灯盏花素治疗,15天后测定CRP水平变化,采用简易精神状态检查表（MMSER）和行为量表（BBS）评价治疗前后的认知能力和行为能力。结果：治疗后观察组CRP水平较对照组下降更为显著（P〈0．05）;观察组MMSE及BBS积分均较对照组显著改善（P〈0．05）。结论：灯盏花素对急性脑梗死后痴呆的发生有明显干预作用。     

磁共振大分子对比剂的研究进展

本文综述了大分子磁共振对比剂的作用机理、种类、重点讨论了大分子对比剂作为血池及靶向对比剂的研究进展,并提出了这些对比剂目前存在的总是及可能解决的途径。     

磁共振大分子对比剂的研究进展

本文综述了大分子磁共振对比剂的作用机理、种类,重点讨论了大分子对比剂作为血池及靶向对比剂的研究进展,并提出这些对比剂目前存在的问题及可能解决的途径.     

钆类和氧化铁类MR对比剂在诊断急性脑梗塞中的应用

近十年MR对比剂的发展迅猛,开发了多种顺磁性和超顺磁性对比剂。对比剂的应用进一步拓宽了影像学技术的检查范围的广度和深度,尤其是对超急性期缺血性脑梗塞诊断。本文主要简述与缺血性脑梗塞MR诊断有关的钆类和超顺磁性氧化铁类对比剂的进展概况,和不同MR检查方法诊断缺血性脑梗塞的原理。     

磁共振靶向对比剂的研究进展

ＭＲ靶向对比剂是ＭＲ顺磁性或超顺磁性对比剂和特定的载体结合,能够特异地靶向一定的组织或器官,具有高度选择性和特异性,能够确定病变性质。其种类按磁性物质可分为顺磁性或超顺磁性对比剂,载体种类有单克隆抗体、受体蛋白、多聚糖、脂质体、细胞等,不同载体将对比剂靶向目的组织和器官后,呈现不同的病灶和实质器官的对比。本文主要综述肝脏、淋巴结、胰腺、神经组织、肿瘤等的ＭＲ靶向对比剂的应用研究。     

脂质体MRI对比剂的研究进展

脂质体作为诊断和治疗靶向药物的载体,进入体内后具有被动靶向和主动靶向2种作用,近年来,随着脂质体制备技术的进展和各种新型脂质体的出现,使其在MR靶向成像中的应用有了较快的发展,介绍了MR脂质体对比剂的特性及其制备的基本原理,总结了不同脂质体对比剂在MRI靶向成像中的应用价值.     

缺血性脑卒中的血氧水平依赖磁共振成像研究进展

缺血性脑卒中具有高发病率、高病死率、高致残率的特点[1],因而早期发现具有脑卒中风险的人群,并及时进行干预治疗,对脑卒中患者具有重要的意义。血氧水平依赖磁共振成像(blood-oxygenation-level-de-pendent MRI,BOLD MRI)可以反映局部脑组织氧代谢与氧供应间的差异,通过测量大脑氧代谢率和氧摄取分数,实现对脑缺血状态的监测,早期发现脑卒中并可以对治疗后的疗效进行评估。本文对缺血性脑卒中的 BOLD MRI 研究进展进行综述和讨论。     

血氧水平依赖磁共振成像在肾功能不全中的应用

目的：探讨血氧水平依赖磁共振成像（BOLD MRI）在诊断肾功能不全以及鉴别不同分级肾功能不全的应用价值。方法对15名健康志愿者和55名不同分级肾功能不全患者进行BOLD MRI扫描,测量各组肾脏皮质、髓质的R2＊值并计算髓质／皮质R2＊值,对比分析各组数据。结果①正常对照组及不同分级的肾功能不全患者的皮质、髓质以及髓质／皮质R2＊值间均存在统计学差异（ P ＜0．05）;②皮质R2＊值与肾功能分级呈正相关,而髓质R2＊值及髓质／皮质R2＊比值与肾功能分级呈负相关。结论血氧水平依赖磁共振成像作为反映肾脏功能改变程度的敏感指标在肾功能不全的诊断及分级鉴别中起到重要的作用。     

3.0T磁共振成像对视-隔发育不良的诊断价值

目的 探讨3.0T磁共振成像对视-隔发育不良诊断价值,旨在提高对SOD认识.方法 收集本院经临床确诊8例视-隔发育不良患者,所有患者经历常规MRI及DTI扫描,将原始图像传至ADW4.4工作站上进行数据后处理,量化分析ADC值及FA值.结果 全部患者均有透明膈缺如及不同程度视觉通路发育障碍,单纯性以透明膈发育部分缺如或完全缺如,双侧或单侧视神经萎缩、变细为主,双侧侧脑室额角呈典型“盒子状”;复杂性常合并多种脑发育畸形,其中以胼胝体发育不全较为常见(＜60％),DTI显示胼胝体纤维束稀少,ADC值、FA值减低.结论 SOD是一种罕见遗传发育基因缺陷疾病,根据临床表现,难以诊断,常规MRI及DTI能够一次性清晰、全面显示SOD病理改变,为临床诊断提供有效诊断依据.     

3．0T磁共振扩散成像在甲状腺的成像分析

目的探讨3．0T磁共振扩散成像在甲状腺的成像技术方法和信号特点。方法分别取b值为0、300、500、700s／mm。对24例志愿者甲状腺行扩散加权成像,对信号强度、信噪比及表观弥散系数（ADC）值进行分析。结果图像信号强度、信噪比及ADC值随b值增大而减低;b值分别为0、300、500、700s／mm2时,信号强度分别为：50±21、30±14、24±11、20±8,F=41．25,P〈0．05;信噪比分别为：49±21、44±17、32±13、29±12,F=15．07,P〈0．05．b值分别为300、500、700s／mm2时,ADC值分别为：（1981±388）、（1647±293）、（1408±211）mm2／s,F=42．323,P〈0．05。结论随着b值增加,图像信号强度、信噪比及ADC值逐渐减小,b值在0—300s／ramz区间信号强度减低明显,b值在300～500s／mm2区间信噪比减低明显;ADC值在300～700s／mm2区间呈逐渐均匀性减小。     

Detection of acute renal ischemia in swine using blood oxygen level-dependent magnetic resonance imaging

PURPOSE: To determine the feasibility and sensitivity of blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) to detect acute renal ischemia, using a swine model, and to present the causes of variability and assess techniques that minimize variability introduced during data analysis. MATERIALS AND METHODS: BOLD MRI was performed in axial and coronal planes of the kidneys of five swine. Color R2* maps were calculated and mean R2* values and 95% confidence intervals (CIs) for the cortex and medulla were determined for baseline, renal artery occlusion and reperfusion conditions. Paired Student's t-tests were used to determine significance. RESULTS: Mean R2* measurements increased from baseline during renal artery occlusion in the cortex (axial, 13.8-24.6 second(-1); coronal, 14.4-24.7 second(-1)) and medulla (axial, 19.3-32.2 second(-1); coronal, 20.1-30.7 second(-1)). These differences were significant for both the cortex (axial, P < 0.04; coronal, P < 0.005) and medulla (axial, P < 0.02; coronal, P < 0.0005). No significant change was observed in the contralateral kidney. CONCLUSION: R2* values were significantly higher than baseline for medulla and cortex during renal artery occlusion. More variability exists in R2* measurements in the medulla than the cortex and in the axial than the coronal plane.     

Direct magnetic resonance imaging of histological tissue samples at 3.0T.

Direct imaging of a histological slice is challenging. The vast difference in dimension between planar size and the thickness of histology slices would require an RF coil to produce a uniform RF magnetic (B1) field in a 2D plane with minimal thickness. In this work a novel RF coil designed specifically for imaging a histology slice was developed and tested. The experimental data demonstrate that the coil is highly sensitive and capable of producing a uniform B1 field distribution in a planar region of histological slides, allowing for the acquisition of high-resolution T2 images and T2 maps from a 60-microm-thick histological sample. The image intensity and T2 distributions were directly compared with histological staining of the relative iron concentration of the same slice. This work demonstrates the feasibility of using a microimaging histological coil to image thin slices of pathologically diseased tissue to obtain a precise one-to-one comparison between stained tissue and MR images.     

Evaluation of pancreatic cancer by multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging at 3.0T

Objective

To investigate the microcirculation in pancreatic cancer by pharmacokinetic analysis of multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging at 3.0 T.

Materials and methods

Multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging was performed in 40 healthy volunteers and 40 patients with pancreatic cancer proven by histopathology using an axial three-dimensions fat-saturated T1-weighted spoiled-gradient echo sequence at 3.0 T. A two compartment model with T1 correction was used to quantify the transfer constant, the rate constant of backflux from the extravascular extracellular space to the plasma and the extravascular extracellular space fractional volume in pancreatic cancer, obstructive pancreatitis distal to the malignant tumor, adjacent pancreatic tissue proximal to the tumor and normal pancreas. All parameters were statistically analyzed.

Results

Statistical differences were noticed in both the transfer constant (p = 0.000075) and the rate constant of backflux (p = 0.006) among different tissues. Both the transfer constant and the rate constant of backflux in pancreatic cancer were statistically lower than those in normal pancreas and adjacent pancreatic tissue (p < 0.05). Both the transfer constant and the rate constant of backflux in obstructive pancreatitis were statistically lower than those in normal pancreas and adjacent pancreatic tissue (p < 0.05). The extravascular extracellular space fractional volume in pancreatic cancer was statistically lager than that in normal pancreas (p = 0.002).

Conclusion

Multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging offers a useful technique to evaluate the microenvironment in pancreatic cancer at 3.0 T. Compared to normal pancreas, pancreatic cancer has lower transfer constant, rate constant of backflux and larger extravascular extracellular space fractional volume.     

Physiological origin of low‐frequency drift in blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI)

We investigated the biophysical mechanism of low‐frequency drift in blood‐oxygen‐level‐dependent (BOLD) functional magnetic resonance imaging (fMRI) (0.00–0.01 Hz), by exploring its spatial distribution, dependence on imaging parameters, and relationship with task‐induced brain activation. Cardiac and respiratory signals were concurrently recorded during MRI scanning and subsequently removed from MRI data. It was found that the spatial distribution of low‐frequency drifts in human brain followed a tissue‐specific pattern, with greater drift magnitude in the gray matter than in white matter. In gray matter, the dependence of drift magnitudes on TE was similar to that of task‐induced BOLD signal changes, i.e., the absolute drift magnitude reached the maximum when TE approached T whereas relative drift magnitude increased linearly with TE. By systematically varying the flip angle, it was found that drift magnitudes possessed a positive dependence on image intensity. In phantom experiments, the observed drift was not only much smaller than that of human brain, but also showed different dependence on TE and flip angle. In fMRI studies with visual stimulation, a strong positive correlation between drift effects at baseline and task‐induced BOLD signal changes was observed both across subjects and across activated pixels within individual participants. We further demonstrated that intrinsic, physiological drift effects are a major component of the spontaneous fluctuations of BOLD fMRI signal within the frequency range of 0.0–0.1 Hz. Our study supports brain physiology, as opposed to scanner instabilities or cardiac/respiratory pulsations, as the main source of low‐frequency drifts in BOLD fMRI. Magn Reson Med 61, 2009. © 2009 Wiley‐Liss, Inc.     

Neuroimaging at 1.5 T and 3.0 T: comparison of oxygenation-sensitive magnetic resonance imaging.

Noise properties, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal responses were compared during functional activation of the human brain at 1.5 and 3.0 T. At the higher field spiral gradient-echo (GRE) brain images revealed an average gain in SNR of 1.7 in fully relaxed and 2.2 in images with a repetition time (TR) of 1.5 sec. The tempered gain at longer TRs reflects the fact that the physiological noise depends on the signal strength and becomes a larger fraction of the total noise at 3.0 T. Activation of the primary motor and visual cortex resulted in a 36% and 44% increase of "activated pixels" at 3.0 T, which reflects a greater sensitivity for the detection of activated gray matter at the higher field. The gain in the CNR exhibited a dependency on the underlying tissue, i.e., an increase of 1.8x in regions of particular high activation-induced signal changes (presumably venous vessels) and of 2.2x in the average activated areas. These results demonstrate that 3.0 T provides a clear advantage over 1.5 T for neuroimaging of homogeneous brain tissue, although stronger physiological noise contributions, more complicated signal features in the proximity of strong susceptibility gradients, and changes in the intrinsic relaxation times may mediate the enhancement. Magn Reson Med 45:595-604, 2001.