120例胶质瘤及瘤周水肿MRI影像组学在评估肿瘤复发中的价值

目的 探讨胶质瘤及瘤周水肿(PTE)MRI影像组学在评估肿瘤复发中的价值。 方法 选取山东大学齐鲁医院2013年1月至2020年12月经术后病理证实的胶质瘤患者120例,包括55例复发和65例无复发患者,根据术前T₂WI和T₁WI增强图像对肿瘤和PTE进行三维容积感兴趣区勾画,并按照8∶2的比例分为训练组和验证组,分析两者及联合的组学特征与肿瘤复发的关系。使用受试者工作特征(ROC)曲线下面积(AUC)与准确性矩阵,比较和评价不同影像组学模型的训练结果。 结果 对于PTE,K临近法(KNN)分类器预测效能最好:训练组AUC值、敏感度、特异度分别为0.910、0.84、0.88,验证组分别为0.916、0.82、0.93。对于肿瘤,逻辑回归(LR)分类器预测效能最好:训练组AUC值、敏感度和特异度分别为0.777、0.69、0.67,验证组分别为0.758、0.82、0.92。当肿瘤+PTE联合时,逻辑回归(LR)分类器预测效能最好:训练组AUC值、敏感度、特异度为0.977、0.88、0.89,验证组则为0.841、0.73、0.83。 结论 胶质瘤PTE和肿瘤影像组学特征在预测胶质瘤术后复发方面具有一定的价值,其中PTE的KNN组学模型效能最佳。     

Monitoring of Ion Mobility in the Cement Matrix to Establish Sensitivity to the ASR Caused by External Sources

The possibility of the formation of an alkali–silicate reaction (ASR) is a crucial issue for the service life of concrete. The coexistence of key parameters such as the presence of alkalis, reactive SiO₂, humidity, and temperature predetermine the possibility of its formation and application. When an ASR gel forms, it results in the concreting cracking and spalling as well as in the deterioration of its overall properties. The risk of ASR depends on the concentration of alkalis and their mobility, which influence their ability to penetrate the concrete. The objective of this study was to determine the ionic mobility of not only Na⁺ and K⁺, but Ca²⁺ as well, from external sources (0.5 and 1.0 mol/L solutions of Na/K carbonate, nitrate, and hydroxide) to a cementitious matrix as the precursor for ASR. The concentrations of ions in both the immersion solutions (ICP) and the cementitious matrix itself (SEM-EDX) were studied as a function of time, from 0 to 120 days, for leaching, and according to temperature (25 and 40 °C). The reaction products were characterized using SEM-EDX. Different diffusion rates and behavior were observed depending on the anion type of the external alkali source. Both sodium and potassium ions in all the three environments studied, namely carbonate, hydroxide, and nitrate, penetrated into the composite and further into its structure by different mechanisms. The action of hydroxides, in particular, transformed the original hydration products into calcium-silicate-hydrate (CASH) or ASR gel, while nitrates crystallized in pores and did not cause any changes in the hydration product. The driving force was the increased temperature of the experiment as well as the increased concentration of the solution to which the test specimen was exposed.     

Characterizing the Mechanical Behavior of Bone and Bone Surrogates in Compression Using pQCT

Many axial and appendicular skeleton bones are subjected to repetitive loading during daily activities. Until recently, the structural analysis of fractures has been limited to 2D sections, and the dynamic assessment of fracture progression has not been possible. The structural failure was analyzed using step-wise micro-compression combined with time-lapsed micro-computed tomographic imaging. The structural failure was investigated in four different sample materials (two different bone surrogates, lumbar vertebral bodies from bovine and red deer). The samples were loaded in different force steps based on uniaxial compression tests. The micro-tomography images were used to create three-dimensional models from which various parameters were calculated that provide information about the structure and density of the samples. By superimposing two 3D images and calculating the different surfaces, it was possible to precisely analyze which trabeculae failed in which area and under which load. According to the current state of the art, bone mineral density is usually used as a value for bone quality, but the question can be raised as to whether other values such as trabecular structure, damage accumulation, and bone mineralization can predict structural competence better than bone mineral density alone.     

Age and sex effects on brain morphology

1. 1. Brain morphology can be assessed readily in vivo using magnetic resonance imaging (MRI).

2. 2. In this study, the effects of age and sex on whole-brain morphology were examined using an operator-controlled computer-segmentation protocol.

3. 3. Results indicated that age was associated with gray-matter volume reduction.

4. 4. Brain-size differences between males and females were primarily attributable to whitematter volume.

5. 5. This study confirms the importance of controlling for age and sex in brain-morphology studies.

     

妊娠相关性脑静脉及静脉窦血栓形成和可逆性后部白质脑病的磁共振鉴别

目的探讨MRI和MRV在妊娠相关性脑静脉及静脉窦血栓形成(CVST)和可逆性后部白质脑病综合征(RPLS)鉴别诊断中的价值。方法回顾性分析3例妊娠相关性CVST和6例重度子痫前期、子痫发生RPLS患者的影像学资料。所有患者均行MRI和DSA检查,其中7例患者行MRV检查。结果 3例CVST患者中,1例孤立性大脑上静脉前组血栓形成,MRI表现为相应部位T1WI低、等信号,T2WI、FLAIR等、稍高信号,DWI为等、高信号,ADC图为低、稍高信号;2例横窦血栓形成,表现为双侧枕叶皮质、皮质下白质片状T1WI低信号,T2WI、FLAIR高信号,DWI、ADC高信号,可不对称性地累及顶叶、小脑半球,MRV与DSA检查结果相符。6例RPLS患者MRI显示双侧顶、枕叶皮质、皮质下白质多发性、斑片状、对称性病变,部分严重患者大脑半球呈弥漫性、大片状受累,表现为T1WI低信号,T2WI、FLAIR高信号,DWI、ADC高信号;1例患者MRV检查示左侧横窦未显影,DSA检查示左侧横窦通畅。结论横窦血栓形成和RPLS患者MRI均显示血管源性脑水肿,两者脑水肿主要发生于双侧枕、顶叶,但前者范围较局限,后者范围更广泛,可累及基底节、额叶、颞叶。RPLS患者MRV检查可有假阳性,DSA是鉴别两者的重要检查方法。     

阿尔茨海默病患者血-脑屏障功能障碍神经影像学研究进展

近年研究表明血-脑屏障功能障碍在认知功能障碍和痴呆的病理生理学机制中扮演重要角色。血-脑屏障可以调节脑微环境稳态,调控营养物质(如葡萄糖和氨基酸)转运,阻止血源性产物、病原体和神经毒性物质进入脑组织。神经影像学技术可以实现血-脑屏障完整性破坏的定位和定量分析,为阐明阿尔茨海默病发病机制提供新的切入点。     

Reorganization of brain activity for multiple internal models after short but intensive training

Internal models are neural mechanisms that can mimic the input-output properties of controlled objects. Our studies have shown that: 1) an internal model for a novel tool is acquired in the cerebellum (Imamizu et al., 2000); 2) internal models are modularly organized in the cerebellum (Imamizu et al., 2003); 3) their outputs are sent to the premotor regions after learning (Tamada et al., 1999); and 4) the prefrontal and parietal regions contribute to the blending of the outputs (Imamizu et al., 2004). Here, we investigated changes in global neural networks resulting from the acquisition of a new internal model. Human subjects manipulated three types of rotating joystick whose cursor appeared at a position rotated 60 degrees, 110 degrees, or 160 degrees around the screen's center. In a pre-test after long-term training (5 days) for the 60 degrees and 160 degrees joysticks, brain activation was scanned during manipulation of the three joysticks. The subjects were then trained for the 110 degrees for only 25 min. In a post-test, activation was scanned using the same method as the pre-test. Comparisons of the post-test to the pre-test revealed that the volume of activation decreased in most of the regions where activation for the three rotations was observed. However, there was an increase in volume at a marginally significant level (p < .08) only in the inferior-lateral cerebellum and only for the 110 degrees joystick. In the cerebral cortex, activation related to 110 degrees decreased in the prefrontal and parietal regions but increased in the premotor and supplementary motor area (SMA) regions. These results can be explained by a model in which outputs of the 60 degrees and 160 degrees internal models are blended by prefrontal and parietal regions to cope with the novel 110 degrees joystick before the 25-minute training; after the acquisition within the cerebellum of an internal model for the 110 degrees, output is directly sent to the premotor and SMA regions, and activation in these regions increases.     

Heritability of the limbic networks

Individual differences in cognitive ability and social behaviour are influenced by the variability in the structure and function of the limbic system. A strong heritability of the limbic cortex has been previously reported, but little is known about how genetic factors influence specific limbic networks. We used diffusion tensor imaging tractography to investigate heritability of different limbic tracts in 52 monozygotic and 34 dizygotic healthy adult twins. We explored the connections that contribute to the activity of three distinct functional limbic networks, namely the dorsal cingulum (‘medial default-mode network’), the ventral cingulum and the fornix (‘hippocampal-diencephalic-retrosplenial network’) and the uncinate fasciculus (‘temporo-amygdala-orbitofrontal network’). Genetic and environmental variances were mapped for multiple tract-specific measures that reflect different aspects of the underlying anatomy. We report the highest heritability for the uncinate fasciculus, a tract that underpins emotion processing, semantic cognition, and social behaviour. High to moderate genetic and shared environmental effects were found for pathways important for social behaviour and memory, for example, fornix, dorsal and ventral cingulum. These findings indicate that within the limbic system inheritance of specific traits may rely on the anatomy of distinct networks and is higher for fronto-temporal pathways dedicated to complex social behaviour and emotional processing.     

散发性Creutzfeldt-Jakob病头部磁共振表现

目的 探讨散发性Creutzfeldt-Jakob病(sCJD)头部磁共振的表现及其与临床的关系。方法 对10例sCJD于病后第2—12个月进行头部磁共振扫描，其中脑活检证实6例，14-3-3蛋白检测8例，脑电特异性改变8例及朊蛋白基因分析8例。结果5例双侧尾状核、壳核于T2，加权像或Flair像呈对称性高信号，苍白球与丘脑正常，T1加权像无改变；2例脑萎缩，1例少许脑腔隙梗死，另有2例正常。结论 (1)4例甲硫氨酸纯合型(129Met／Met)底节T2异常信号发现时间平均2．5个月，存活时间平均10．5个月；1例甲硫氨酸杂合型(129Met／Val)底节异常信号发现时间为12个月，存活时间为16个月；(2)底节T2异常信号者平均病程为12．2个月，长于底节无异常信号者(平均5．5个月)；(3)双侧尾核、壳核T2加权像对称性高信号是sCJD重要影像学改变，在特定的临床背景下为sCJD临床诊断依据之一。     

脑胶质瘤卒中MRI诊断及鉴别诊断

目的探讨脑胶质瘤卒中MRI影像学特点,提高临床认识。方法对病理证实的12例胶质瘤卒中影像表现进行分析。结果间变性星形细胞瘤7例,多形性胶质母细胞瘤3例,少突胶质瘤1例,低级别胶质瘤1例。MRI表现7例肿瘤征象与出血征象并存;5例出血征象掩盖肿瘤组织。结论胶质瘤卒中MRI正确诊断率与瘤出血量相关,对瘤出血量大,掩盖肿瘤组织易误诊。应结合MRI信号及临床与其他出血性疾病鉴别。