目的探讨肝脏血管周上皮样细胞肿瘤（PEComas）的多层螺旋CT（MSCT）特点。方法回顾性分析12例经病理证实肝脏PEComas的MSCT影像资料并复习相关文献。结果肿瘤位于肝右叶7例,左叶4例,尾状叶1例。瘤灶最大直径5~10 cm 10例,〉10 cm 2例...目的探讨肝脏血管周上皮样细胞肿瘤（PEComas）的多层螺旋CT（MSCT）特点。方法回顾性分析12例经病理证实肝脏PEComas的MSCT影像资料并复习相关文献。结果肿瘤位于肝右叶7例,左叶4例,尾状叶1例。瘤灶最大直径5~10 cm 10例,〉10 cm 2例。平扫表现：密度不均12例,病灶内出血2例,不规则钙化1例,完整包膜9例,边界较清晰10例。增强表现：增强后动脉期明显强化10例,病灶不均匀强化且不明显2例;门脉期至延迟期病灶强化程度稍减退6例,其中不均匀减低4例。肿瘤压迫周围血管7例,其中肝动脉及门静脉骑跨肿瘤边缘3例,门脉右支穿行肿瘤内2例,门脉左支受侵犯1例,左肝静脉早期显影1例,所有病例均无门静脉癌栓。结论肝脏PEComas的MSCT表现有一定特点,MSCT对诊断该类疾病有重要价值。展开更多
Lake ice thickness(LIT)is important for regional hydroclimate systems,lake ecosystems,and human activities on the ice,and is thought to be highly susceptible to global warming.However,the spatiotemporal variability in...Lake ice thickness(LIT)is important for regional hydroclimate systems,lake ecosystems,and human activities on the ice,and is thought to be highly susceptible to global warming.However,the spatiotemporal variability in LIT is largely unknown due to the difficulty in deriving in situ measurements and the lack of an effective remote sensing platform.Despite intensive development and applications of lake ice models driven by general circulation model output,evaluation of the global LIT is mostly based on assumed“ideal”lakes in each grid cell of the climate forcing data.A method for calculating the actual global LIT is therefore urgently needed.Here we use satellite altimetry to retrieve ice thickness for 16 large lakes in the Northern Hemisphere(Lake Baikal,Great Slave Lake,and others)with an accuracy of~0.2 m for almost three decades.We then develop a 1-D lake ice model driven primarily by remotely sensed data and cross-validated with the altimetric LIT to provide a robust means of estimating LIT for lakes larger than 50 km^(2)across the Northern Hemisphere.Mean LIT(annual maximum ice thickness)for 1313 simulated lakes and reservoirs covering~840,000 km^(2)for 2003–2018 is 0.63±0.02 m,corresponding to~485 Gt of water.LIT changes are projected for 2071–2099 under RCPs 2.6,6.0,and 8.5,showing that the mean LIT could decrease by~0.35 m under the worst concentration pathway and the associated lower ice road availability could have a significant impact on socio-economic activities.展开更多
文摘目的探讨肝脏血管周上皮样细胞肿瘤（PEComas）的多层螺旋CT（MSCT）特点。方法回顾性分析12例经病理证实肝脏PEComas的MSCT影像资料并复习相关文献。结果肿瘤位于肝右叶7例,左叶4例,尾状叶1例。瘤灶最大直径5~10 cm 10例,〉10 cm 2例。平扫表现：密度不均12例,病灶内出血2例,不规则钙化1例,完整包膜9例,边界较清晰10例。增强表现：增强后动脉期明显强化10例,病灶不均匀强化且不明显2例;门脉期至延迟期病灶强化程度稍减退6例,其中不均匀减低4例。肿瘤压迫周围血管7例,其中肝动脉及门静脉骑跨肿瘤边缘3例,门脉右支穿行肿瘤内2例,门脉左支受侵犯1例,左肝静脉早期显影1例,所有病例均无门静脉癌栓。结论肝脏PEComas的MSCT表现有一定特点,MSCT对诊断该类疾病有重要价值。
基金supported by the National Natural Science Foundation of China(92047301,91547210,and 51722903)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0105)。
文摘Lake ice thickness(LIT)is important for regional hydroclimate systems,lake ecosystems,and human activities on the ice,and is thought to be highly susceptible to global warming.However,the spatiotemporal variability in LIT is largely unknown due to the difficulty in deriving in situ measurements and the lack of an effective remote sensing platform.Despite intensive development and applications of lake ice models driven by general circulation model output,evaluation of the global LIT is mostly based on assumed“ideal”lakes in each grid cell of the climate forcing data.A method for calculating the actual global LIT is therefore urgently needed.Here we use satellite altimetry to retrieve ice thickness for 16 large lakes in the Northern Hemisphere(Lake Baikal,Great Slave Lake,and others)with an accuracy of~0.2 m for almost three decades.We then develop a 1-D lake ice model driven primarily by remotely sensed data and cross-validated with the altimetric LIT to provide a robust means of estimating LIT for lakes larger than 50 km^(2)across the Northern Hemisphere.Mean LIT(annual maximum ice thickness)for 1313 simulated lakes and reservoirs covering~840,000 km^(2)for 2003–2018 is 0.63±0.02 m,corresponding to~485 Gt of water.LIT changes are projected for 2071–2099 under RCPs 2.6,6.0,and 8.5,showing that the mean LIT could decrease by~0.35 m under the worst concentration pathway and the associated lower ice road availability could have a significant impact on socio-economic activities.
