目的观察^(18)F-flortaucipir tau PET联合APOEε4基因携带状态对轻度认知障碍(MCI)的诊断价值。方法于阿尔茨海默病神经成像倡议(ADNI)数据集中选取213例MCI(MCI组)及402名健康对照(HC组),对比分析其神经心理学信息、APOEε4基因携带...目的观察^(18)F-flortaucipir tau PET联合APOEε4基因携带状态对轻度认知障碍(MCI)的诊断价值。方法于阿尔茨海默病神经成像倡议(ADNI)数据集中选取213例MCI(MCI组)及402名健康对照(HC组),对比分析其神经心理学信息、APOEε4基因携带状态、tau PET及高分辨结构MRI数据;利用随机森林法筛选tau PET诊断MCI的重要脑区,比较tau PET鉴别携带/未携带APOEε4基因MCI与HC的效能。结果利用tau PET诊断MCI的重要脑区依次为杏仁核、海马旁回、内嗅皮层、后扣带回、颞下回、梭状回及颞中回。基于上述7个脑区ROI构建的tau PET标准摄取值比值(SUVR)模型鉴别携带APOEε4基因MCI与HC的准确率及曲线下面积(AUC)分别为86.68%及0.784,高于其鉴别MCI与HC、未携带APOEε4基因MCI与HC(准确率分别为70.57%及75.05%,AUC分别为0.711及0.609)。结论基于杏仁核、海马旁回、内嗅皮层、后扣带回、颞下回、梭状回及颞中回构建的^(18)F-flortaucipir tau PET SUVR模型可用于诊断MCI;联合APOEε4基因可进一步提高其诊断效能。展开更多
报道了9-[(4氟-)-3羟-基甲基丁基]鸟嘌呤(FHBG,Ⅱ)的改进合成方法,对起始原料喷昔洛韦(Ⅲ)的氨基和一个羟基用4-甲氧基氯化三苯甲烷保护,对另一个羟基磺酯化,得到N2-(p-甲氧基苯酰基二苯基甲基)-9-[(4甲-苯磺酰)-3-p-甲氧基苯酰基二苯基...报道了9-[(4氟-)-3羟-基甲基丁基]鸟嘌呤(FHBG,Ⅱ)的改进合成方法,对起始原料喷昔洛韦(Ⅲ)的氨基和一个羟基用4-甲氧基氯化三苯甲烷保护,对另一个羟基磺酯化,得到N2-(p-甲氧基苯酰基二苯基甲基)-9-[(4甲-苯磺酰)-3-p-甲氧基苯酰基二苯基-甲氧基甲基丁基]鸟嘌呤(Ⅴ),收率为70.5%;再用四丁基氟化铵(TBAF)对化合物Ⅴ亲核取代4-甲苯磺酰基团,水解脱去保护基,即得FHBG。产品经1HNMR、IR、MS表征,并用HPLC分析了Ⅴ和Ⅱ,保留时间分别为5.89 m in和4.41 m in,积分计算质量分数分别为w(Ⅴ)=99.5%和w(Ⅱ)=99.3%。展开更多
Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionall...Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.展开更多
目的利用呼吸运动体模研究均匀运动状态的四维CT(four-dimensional computed tomography, 4DCT)图像重建的准确性。方法采用呼吸运动体模模拟肺部肿瘤在头脚方向做余弦波运动,根据呼吸运动幅度(A)和周期(T)分为6组(A=0.5 cm, T=6 s;A=0....目的利用呼吸运动体模研究均匀运动状态的四维CT(four-dimensional computed tomography, 4DCT)图像重建的准确性。方法采用呼吸运动体模模拟肺部肿瘤在头脚方向做余弦波运动,根据呼吸运动幅度(A)和周期(T)分为6组(A=0.5 cm, T=6 s;A=0.5 cm, T=3 s;A=1.0 cm, T=6 s;A=1.0 cm, T=3 s;A=1.5 cm, T=6 s;A=1.5 cm, T=3 s)。采用Philips大孔径CT模拟机进行4DCT扫描。6组运动采用相同的扫描参数分别采集2次。在重建的4DCT图像上勾画内靶区(internal target volume, ITV),统计ITV的体积和长度,并与理论值比较,分析4DCT重建误差。结果 ITV在6组4DCT重建图像上均有误差,TIV体积误差相对值范围为1.13%~27.64%;ITV长度误差范围为-0.95~0.03 cm, ITV长度平均误差为0.25 cm。在A=1.5 cm, T=6 s时,ITV重建误差最大,前后2次扫描的体积误差分别为27.64%和19.04%,长度误差分别为0.11 cm和0.84 cm。呼吸运动参数和扫描参数完全一致的前后2次4DCT图像重建的靶体积和长度也均存在差异,在A=0.5 cm, T=6 s时,前后2次的ITV体积误差分别为14.47%和4.43%,相差达10.00%。结论均匀运动情况下4DCT图像重建存在误差,且误差大小随机化,具有不可预见性。展开更多
文摘目的观察^(18)F-flortaucipir tau PET联合APOEε4基因携带状态对轻度认知障碍(MCI)的诊断价值。方法于阿尔茨海默病神经成像倡议(ADNI)数据集中选取213例MCI(MCI组)及402名健康对照(HC组),对比分析其神经心理学信息、APOEε4基因携带状态、tau PET及高分辨结构MRI数据;利用随机森林法筛选tau PET诊断MCI的重要脑区,比较tau PET鉴别携带/未携带APOEε4基因MCI与HC的效能。结果利用tau PET诊断MCI的重要脑区依次为杏仁核、海马旁回、内嗅皮层、后扣带回、颞下回、梭状回及颞中回。基于上述7个脑区ROI构建的tau PET标准摄取值比值(SUVR)模型鉴别携带APOEε4基因MCI与HC的准确率及曲线下面积(AUC)分别为86.68%及0.784,高于其鉴别MCI与HC、未携带APOEε4基因MCI与HC(准确率分别为70.57%及75.05%,AUC分别为0.711及0.609)。结论基于杏仁核、海马旁回、内嗅皮层、后扣带回、颞下回、梭状回及颞中回构建的^(18)F-flortaucipir tau PET SUVR模型可用于诊断MCI;联合APOEε4基因可进一步提高其诊断效能。
文摘报道了9-[(4氟-)-3羟-基甲基丁基]鸟嘌呤(FHBG,Ⅱ)的改进合成方法,对起始原料喷昔洛韦(Ⅲ)的氨基和一个羟基用4-甲氧基氯化三苯甲烷保护,对另一个羟基磺酯化,得到N2-(p-甲氧基苯酰基二苯基甲基)-9-[(4甲-苯磺酰)-3-p-甲氧基苯酰基二苯基-甲氧基甲基丁基]鸟嘌呤(Ⅴ),收率为70.5%;再用四丁基氟化铵(TBAF)对化合物Ⅴ亲核取代4-甲苯磺酰基团,水解脱去保护基,即得FHBG。产品经1HNMR、IR、MS表征,并用HPLC分析了Ⅴ和Ⅱ,保留时间分别为5.89 m in和4.41 m in,积分计算质量分数分别为w(Ⅴ)=99.5%和w(Ⅱ)=99.3%。
文摘Conventional electron and optical microscopy techniques require the sample to be sectioned, polished or etched to expose the internal surfaces for imaging. However, such sample preparation techniques have traditionally prevented the observation of the same sample over time, under realistic three-dimensional geometries and in an environment representative of real-world operating conditions. X-ray microscopy (XRM) is a rapidly emerging technique that enables non-destructive evaluation of buried structures within hard to soft materials in 3D, requiring little to no sample preparation. Furthermore in situ and 4D quantification of microstructural evolution under controlled environment as a function of time, temperature, chemistry or stress can be done repeatable on the same sample, using practical specimen sizes ranging from tens of microns to several cm diameter, with achievable imaging resolution from submicron to 50 nm. Many of these studies were reported using XRM in synchrotron beamlines. These include crack propagation on composite and construction materials; corrosion studies; microstructural changes during the setting of cement; flow studies within porous media to mention but a few.
文摘目的利用呼吸运动体模研究均匀运动状态的四维CT(four-dimensional computed tomography, 4DCT)图像重建的准确性。方法采用呼吸运动体模模拟肺部肿瘤在头脚方向做余弦波运动,根据呼吸运动幅度(A)和周期(T)分为6组(A=0.5 cm, T=6 s;A=0.5 cm, T=3 s;A=1.0 cm, T=6 s;A=1.0 cm, T=3 s;A=1.5 cm, T=6 s;A=1.5 cm, T=3 s)。采用Philips大孔径CT模拟机进行4DCT扫描。6组运动采用相同的扫描参数分别采集2次。在重建的4DCT图像上勾画内靶区(internal target volume, ITV),统计ITV的体积和长度,并与理论值比较,分析4DCT重建误差。结果 ITV在6组4DCT重建图像上均有误差,TIV体积误差相对值范围为1.13%~27.64%;ITV长度误差范围为-0.95~0.03 cm, ITV长度平均误差为0.25 cm。在A=1.5 cm, T=6 s时,ITV重建误差最大,前后2次扫描的体积误差分别为27.64%和19.04%,长度误差分别为0.11 cm和0.84 cm。呼吸运动参数和扫描参数完全一致的前后2次4DCT图像重建的靶体积和长度也均存在差异,在A=0.5 cm, T=6 s时,前后2次的ITV体积误差分别为14.47%和4.43%,相差达10.00%。结论均匀运动情况下4DCT图像重建存在误差,且误差大小随机化,具有不可预见性。
