1 Results Polymer electrolyte fuel cells (PEFCs) have beenintensively developedfor future vehicle applications andon-site power generation owing to its high energy efficiency and high power density.In PEFCs ,appropria...1 Results Polymer electrolyte fuel cells (PEFCs) have beenintensively developedfor future vehicle applications andon-site power generation owing to its high energy efficiency and high power density.In PEFCs ,appropriatewater management to maintain polymer electrolyte membrane (PEM) hydratedis of great i mportance ,becausethe ion conductivity of membraneislower at lower water content .Consequently,it is of great interest to watercontent and water transport process in PEMs during fuel cell operation.展开更多
Magnetic resonance imaging(MRI)is a promising non-invasive method to assess cartilage regeneration based on the quantitative relationship between MRI features and concentrations of the major components in the extracel...Magnetic resonance imaging(MRI)is a promising non-invasive method to assess cartilage regeneration based on the quantitative relationship between MRI features and concentrations of the major components in the extracellular matrix(ECM).To this end,in vitro experiments are performed to investigate the relationship and reveal the underlying mechanism.A series of collagen(COL)and glycosaminoglycan(GAG)solutions at different concentrations are prepared,and T_(1)and T_(2)relaxation times are measured with or without a contrast agent(Gd-DTPA2−)by MRI.Fourier transform infrared spectrometry is also used to measure the contents of biomacromolecule-bound water and other water,allowing theoretical derivation of the relationship between biomacromolecules and the resulting T_(2)values.It has been revealed that the MRI signal in the biomacromolecule aqueous systems is mainly influenced by the protons in hydrogens of biomacromolecule-bound water,which we divide into inner-bound water and outer-bound water.We have also found that COL results in higher sensitivity of bound water than GAG in T_(2)mapping.Owing to the charge effect,GAG regulates the penetration of the contrast agent during dialysis and has a more significant effect on T_(1)values than COL.Considering that COL and GAG are the most abundant biomacromolecules in the cartilage,this study is particularly useful for the real-time MRI-guided assessment of cartilage regeneration.A clinical case is reported as an in vivo demonstration,which is consistent with our in vitro results.The established quantitative relation plays a critical academic role in establishing an international standard ISO/TS24560-1:2022‘Clinical evaluation of regenerative knee articular cartilage using delayed gadolinium-enhanced MRI of cartilage(dGEMRIC)and T_(2)mapping’drafted by us and approved by International Standard Organization.展开更多
目的:基于MRI定量非对称回波最小二乘估算水脂分离(iterative decomposition of water and fat with echo asymmetry and least-squares estimation image quantitation,IDEAL-IQ)技术探讨成年人腰椎不同节段骨髓脂肪与年龄和性别的关...目的:基于MRI定量非对称回波最小二乘估算水脂分离(iterative decomposition of water and fat with echo asymmetry and least-squares estimation image quantitation,IDEAL-IQ)技术探讨成年人腰椎不同节段骨髓脂肪与年龄和性别的关系。方法:收集298例受检者的MRI IDEAL-IQ脂肪分数图像,其中男性138例,女性160例,年龄20~69岁。将所有患者按照每10岁为一个年龄段分为5组:20~29岁(20~组),男24例,女20例;30~39岁(30~组),男47例,女39例;40~49岁(40~组),男36例,女47例;50~59岁(50~组),男20例,女37例;60~69岁(60~组),男11例,女17例。使用脂肪分数图在GE ADW4.6工作站测量L1~L5的骨髓质子密度脂肪分数(proton density fat fraction,PDFF)。结果:同一年龄组、不同性别间PDFF存在差异,20~、30~、40~组人群中,男性L1~L5椎体PDFF均高于女性(P<0.05);50~组人群中男性L1~L5椎体PDFF与女性的差异无统计学意义(P>0.05);60~组人群,男性L1~L5椎体PDFF均低于女性(P<0.05)。腰椎椎体PDFF与年龄呈正相关,女性(r=0.72,P<0.05)相关性高于男性(r=0.32,P<0.05)。从20~69岁,男性L4 PDFF增长率最大(21.08%),女性L1 PDFF增长率最大(65.68%);男性各椎体PDFF增长主要集中在30~及50~组,其中L1、L4、L5椎体PDFF在50~组增长率最大,L2、L3椎体PDFF在30~岁组增长率最大;女性各椎体PDFF在30~组呈轻微下降趋势,此后各椎体PDFF逐渐升高,增长主要集中在40~、50~、60~三个年龄组,其中50~组增长率最大。结论:成人不同年龄组男女性各椎体脂肪分布存在差异,椎体PDFF增长率也有所不同;腰椎不同节段椎体PDFF均与年龄呈正相关。展开更多
目的 探讨非对称回波最小二乘估算法迭代水脂分离序列(iterative decomposition of water and fat with echo asymmetrical and least-squares estimation quantitation sequence, IDEAL-IQ)来源的R2^(*)值在乳腺良恶性肿瘤鉴别诊断中...目的 探讨非对称回波最小二乘估算法迭代水脂分离序列(iterative decomposition of water and fat with echo asymmetrical and least-squares estimation quantitation sequence, IDEAL-IQ)来源的R2^(*)值在乳腺良恶性肿瘤鉴别诊断中的价值,并与传统多回波T2^(*)梯度回波(gradient recalled echo, GRE)序列来源的R2^(*)值进行比较。材料与方法 回顾性分析2021年9月至2023年10月在中国医科大学附属第一医院连续收治的42名患者的50个良性肿瘤病灶,在本院影像归档和通信系统(picture archiving and communication systems, PACS)中使用倾向性评分匹配方法匹配肿瘤所在最大层面的最长径,按1∶3的比例纳入150名患者的150个恶性肿瘤病灶。将恶性肿瘤根据预后因子[雌激素受体(estrogen receptor, ER)、孕激素受体(progesterone receptor, PR)以及人表皮生长因子受体2(human epidermal growth factor receptor 2, HER-2)]的阳性/阴性表达情况进行分组。所有患者均接受包含IDEAL-IQ和多回波T2*GRE序列的多参数MRI,测量以下定量参数:IDEAL-IQ序列R2^(*)值(R2^(*)IDEAL)、多回波T2*GRE序列R2^(*)值(R2^(*)GRE)、表观扩散系数(apparent diffusion coefficient, ADC)及肿瘤长径。根据原始资料类型的不同,分别利用单因素分析(独立样本t检验、Mann-Whitney U检验等方法)对比分析各参数的差异。采用Spearman相关性分析R2^(*)IDEAL与R2^(*)GRE及二者与ADC的相关性。采用配对样本t检验比较R2^(*)IDEAL与R2^(*)GRE的差异。采用logistic回归分析建立联合诊断模型,并使用受试者工作特征(receiver operating characteristic, ROC)曲线及曲线下面积(area under the curve,AUC)分析单独及联合参数鉴别乳腺肿瘤良恶性的效能。结果 相关性分析显示乳腺肿瘤患者的R2^(*)IDEAL与R2^(*)GRE呈中度相关(r=0.763,P<0.001),二者与ADC值均呈负性弱相关[r=-0.300(R2^(*)IDEAL),-0.306(R2^(*)GRE),P<0.001]。良性组与恶性组中,R2^(*)IDEAL与R2^(*)GRE均呈中度相关(r=0.745、0.680,P<0.001),二者与ADC均无相关性。两种序列所得的R2^(*)值差异有统计学意义(P<0.001)。R2^(*)IDEAL在良恶性组间差异有统计学意义(P<0.001),管腔HER-2阴性型R2^(*)值最高。对于单一参数,ADC值鉴别良恶性的AUC最高(0.857);对于联合参数,R2^(*)IDEAL+ADC鉴别良性组与管腔阴性组的AUC最高(0.927);差异均有统计学意义(P<0.05)。结论 IDEAL-IQ序列生成的R2^(*)值可用于区分良恶性乳腺肿块,可能成为除ADC外辅助乳腺肿瘤良恶性鉴别的又一无需对比剂参数。展开更多
目的利用神经突方向离散度与密度成像(neurite orientation dispersion and density imaging,NODDI)探索颞叶癫痫认知障碍(cognitive impairment of temporal lobe epilepsy,TLE-CI)患者、颞叶癫痫认知正常(cognitive normal of tempora...目的利用神经突方向离散度与密度成像(neurite orientation dispersion and density imaging,NODDI)探索颞叶癫痫认知障碍(cognitive impairment of temporal lobe epilepsy,TLE-CI)患者、颞叶癫痫认知正常(cognitive normal of temporal lobe epilepsy,TLE-CN)患者海马微观结构的变化,并探讨其与临床发病特征之间的关系。材料与方法分析35例TLE-CI、31例TLE-CN及40例健康对照(healthy controls,HC)的头颅MRI,采用MRtrix3对NODDI图像的不同指标图:各向同性水分子体积分数(free-water isotropic volume fraction,fiso)、方向离散度指数(orientation dispersion index,ODI)及神经突密度指数(neurite density index,NDI)进行计算。然后与经过FreeSurfer分割后的结构像叠加,得到海马区的NODDI各指标值。比较三组参与者组间的NODDI指标差异,并将差异指标与患者的临床发病特征进行相关性分析。结果TLE-CI组患侧与对侧海马fiso值显著高于HC组(P=0.004,P=0.017);ODI值在组间分析中未见显著性差异;TLE-CI组患侧海马NDI值显著低于HC组(P<0.001),同时,TLE-CN组患侧海马NDI值显著低于HC组(P=0.004)。TLE-CI组患侧海马的NDI值与发病年龄呈正相关(r=0.491,P=0.003),与病程呈负相关(r=-0.424,P=0.011)。结论该研究显示了NODDI技术检测颞叶癫痫患者海马微结构变化的能力,其中,NDI值可能是TLE-CI患者较为敏感且进行性的生物标记物。展开更多
文摘1 Results Polymer electrolyte fuel cells (PEFCs) have beenintensively developedfor future vehicle applications andon-site power generation owing to its high energy efficiency and high power density.In PEFCs ,appropriatewater management to maintain polymer electrolyte membrane (PEM) hydratedis of great i mportance ,becausethe ion conductivity of membraneislower at lower water content .Consequently,it is of great interest to watercontent and water transport process in PEMs during fuel cell operation.
基金supported by National Natural Science Foundation of China(grant no.52130302).W。
文摘Magnetic resonance imaging(MRI)is a promising non-invasive method to assess cartilage regeneration based on the quantitative relationship between MRI features and concentrations of the major components in the extracellular matrix(ECM).To this end,in vitro experiments are performed to investigate the relationship and reveal the underlying mechanism.A series of collagen(COL)and glycosaminoglycan(GAG)solutions at different concentrations are prepared,and T_(1)and T_(2)relaxation times are measured with or without a contrast agent(Gd-DTPA2−)by MRI.Fourier transform infrared spectrometry is also used to measure the contents of biomacromolecule-bound water and other water,allowing theoretical derivation of the relationship between biomacromolecules and the resulting T_(2)values.It has been revealed that the MRI signal in the biomacromolecule aqueous systems is mainly influenced by the protons in hydrogens of biomacromolecule-bound water,which we divide into inner-bound water and outer-bound water.We have also found that COL results in higher sensitivity of bound water than GAG in T_(2)mapping.Owing to the charge effect,GAG regulates the penetration of the contrast agent during dialysis and has a more significant effect on T_(1)values than COL.Considering that COL and GAG are the most abundant biomacromolecules in the cartilage,this study is particularly useful for the real-time MRI-guided assessment of cartilage regeneration.A clinical case is reported as an in vivo demonstration,which is consistent with our in vitro results.The established quantitative relation plays a critical academic role in establishing an international standard ISO/TS24560-1:2022‘Clinical evaluation of regenerative knee articular cartilage using delayed gadolinium-enhanced MRI of cartilage(dGEMRIC)and T_(2)mapping’drafted by us and approved by International Standard Organization.
文摘目的:基于MRI定量非对称回波最小二乘估算水脂分离(iterative decomposition of water and fat with echo asymmetry and least-squares estimation image quantitation,IDEAL-IQ)技术探讨成年人腰椎不同节段骨髓脂肪与年龄和性别的关系。方法:收集298例受检者的MRI IDEAL-IQ脂肪分数图像,其中男性138例,女性160例,年龄20~69岁。将所有患者按照每10岁为一个年龄段分为5组:20~29岁(20~组),男24例,女20例;30~39岁(30~组),男47例,女39例;40~49岁(40~组),男36例,女47例;50~59岁(50~组),男20例,女37例;60~69岁(60~组),男11例,女17例。使用脂肪分数图在GE ADW4.6工作站测量L1~L5的骨髓质子密度脂肪分数(proton density fat fraction,PDFF)。结果:同一年龄组、不同性别间PDFF存在差异,20~、30~、40~组人群中,男性L1~L5椎体PDFF均高于女性(P<0.05);50~组人群中男性L1~L5椎体PDFF与女性的差异无统计学意义(P>0.05);60~组人群,男性L1~L5椎体PDFF均低于女性(P<0.05)。腰椎椎体PDFF与年龄呈正相关,女性(r=0.72,P<0.05)相关性高于男性(r=0.32,P<0.05)。从20~69岁,男性L4 PDFF增长率最大(21.08%),女性L1 PDFF增长率最大(65.68%);男性各椎体PDFF增长主要集中在30~及50~组,其中L1、L4、L5椎体PDFF在50~组增长率最大,L2、L3椎体PDFF在30~岁组增长率最大;女性各椎体PDFF在30~组呈轻微下降趋势,此后各椎体PDFF逐渐升高,增长主要集中在40~、50~、60~三个年龄组,其中50~组增长率最大。结论:成人不同年龄组男女性各椎体脂肪分布存在差异,椎体PDFF增长率也有所不同;腰椎不同节段椎体PDFF均与年龄呈正相关。
文摘随着人类寿命的延长,以衰老为主要危险因素的神经退行性疾病的患病率也在增加,这导致了严重的医学和社会经济问题。扩散张量成像(diffusion tensor imaging,DTI)是一种能无创探测脑微观结构改变的磁共振成像技术,广泛应用于神经退行性疾病的临床和研究。但是由于部分容积效应等原因,可能影响了DTI测量的准确性。自由水扩散张量成像(free water DTI,FW-DTI)不仅在很大程度上弥补了上述缺陷,还可以增强标准DTI指标对神经退行性疾病的敏感性。本文将针对目前FW-DTI技术在神经退行性疾病中的研究进展予以综述,以期为今后的研究提供新的思路。
文摘目的利用神经突方向离散度与密度成像(neurite orientation dispersion and density imaging,NODDI)探索颞叶癫痫认知障碍(cognitive impairment of temporal lobe epilepsy,TLE-CI)患者、颞叶癫痫认知正常(cognitive normal of temporal lobe epilepsy,TLE-CN)患者海马微观结构的变化,并探讨其与临床发病特征之间的关系。材料与方法分析35例TLE-CI、31例TLE-CN及40例健康对照(healthy controls,HC)的头颅MRI,采用MRtrix3对NODDI图像的不同指标图:各向同性水分子体积分数(free-water isotropic volume fraction,fiso)、方向离散度指数(orientation dispersion index,ODI)及神经突密度指数(neurite density index,NDI)进行计算。然后与经过FreeSurfer分割后的结构像叠加,得到海马区的NODDI各指标值。比较三组参与者组间的NODDI指标差异,并将差异指标与患者的临床发病特征进行相关性分析。结果TLE-CI组患侧与对侧海马fiso值显著高于HC组(P=0.004,P=0.017);ODI值在组间分析中未见显著性差异;TLE-CI组患侧海马NDI值显著低于HC组(P<0.001),同时,TLE-CN组患侧海马NDI值显著低于HC组(P=0.004)。TLE-CI组患侧海马的NDI值与发病年龄呈正相关(r=0.491,P=0.003),与病程呈负相关(r=-0.424,P=0.011)。结论该研究显示了NODDI技术检测颞叶癫痫患者海马微结构变化的能力,其中,NDI值可能是TLE-CI患者较为敏感且进行性的生物标记物。
