目的探讨最佳自适应统计迭代重建(ASIR)百分比联合最优单能量技术提高腹部图像质量,优化腹部血管显示。方法搜集临床腹部能谱CT检查的32例腹部疾病患者资料,应用能谱分析软件,采用70 ke V、55ke V分别联合0%、30%、50%、70%ASIR模式进...目的探讨最佳自适应统计迭代重建(ASIR)百分比联合最优单能量技术提高腹部图像质量,优化腹部血管显示。方法搜集临床腹部能谱CT检查的32例腹部疾病患者资料,应用能谱分析软件,采用70 ke V、55ke V分别联合0%、30%、50%、70%ASIR模式进行腹部动脉期及门静脉期重建,比较70 ke V联合不同ASIR百分比模式下动脉期及门静脉期肝实质噪声(LN)、胰腺噪声(PN),竖脊肌噪声(SMN)以及肝CNR(LCNR)、胰腺CNR(PCNR)、门静脉CNR(PV-CNR)及主观图像质量评分之间差异有无统计学意义。同时比较55 ke V联合不同ASIR百分比模式下动脉期及门静脉期腹部动脉血管、门静脉CNR等相关指标及主观图像质量评分,并采用单因素方差分析进行比较。结果 70 ke V组不同ASIR比例中,LN、PN,SMN、LCNR及PCNR差异均有统计学意义(P<0.05)。主观图像质量评分显示动脉期及静脉期不同ASIR组间比较,30%组伪影最低;诊断信心度方面30%最高;噪声方面70%最低,微小结构及病变显示方面各ASIR组间无统计学差异。55 ke V组间,除了动脉期LCNR各组间差异无统计学意义,腹部各动脉血管CNR及PV-CNR,LN,SMN,PN,主观评分及门静脉期LCNR在不同ASIR组间差异均有统计学意义(P<0.05);主观评分方面以50%ASIR组最优(P<0.05)。结论 70 ke V+30%ASIR及55ke V+50%ASIR分别成为优化腹部图像质量及血管成像的最优化组合。展开更多
目的探讨应用能谱CT最佳单能量成像联合40%自适应统计迭代重组(ASIR)技术对肠系膜上动脉及静脉图像质量的优化。方法搜集临床腹部能谱CT检查的25例腹部疾病患者资料,应用能谱分析软件,得出能谱CT成像中最佳单能图像,分别采用70 ke V、...目的探讨应用能谱CT最佳单能量成像联合40%自适应统计迭代重组(ASIR)技术对肠系膜上动脉及静脉图像质量的优化。方法搜集临床腹部能谱CT检查的25例腹部疾病患者资料,应用能谱分析软件,得出能谱CT成像中最佳单能图像,分别采用70 ke V、最佳单能量、最佳单能量+40%ASIR模式进行肠系膜上动脉、肠系膜上静脉重组,比较70 ke V、最佳单能量、最佳单能量+40%ASIR 3组肠系膜上动静脉的CT值、背景噪声(SDn)及背景CT值、对比噪声比(CNR)、信噪比(SNR)及主观图像质量评分,并采用两因素方差分析进行比较。结果肠系膜上动脉及静脉最佳CNR单能量水平集中在55~62 ke V左右,平均为60 ke V。最佳单能量组(60 ke V)、70 ke V单能量组、最佳单能量(60 ke V)+40%ASIR组肠系膜上动脉的CNR分别20.41±7.66,17.16±6.79,22.85±8.24;图像质量评分分别为4.24±0.35、3.86±0.19和4.25±0.36。肠系膜上静脉CNR分别为5.80±1.99、4.37±1.22和7.27±2.51;图像质量评分分别为3.78±0.35、3.46±0.27和3.81±0.32,差异均有统计学意义(P<0.05)。60 ke V+40%ASIR组CNR、SNR均高于70 ke V组及60 ke V组;60 ke V+40%ASIR组主观评分高于70 ke V组(P<0.05),与60 ke V组无统计学差别(P>0.05)。结论能谱肠系膜上动脉及静脉成像中最佳单能量(60ke V)+40%ASIR图像较70 ke V及60 ke V图像成像质量有所提高,可以在临床血管成像方面广泛应用。展开更多
Water erosion remains the major problem in many countries, especially those with an extension in the arid and semi-arid area and those marked by a long dry season. The intensification of land degradation which is a re...Water erosion remains the major problem in many countries, especially those with an extension in the arid and semi-arid area and those marked by a long dry season. The intensification of land degradation which is a result of the strong erosive dynamics on a global scale has stimulated the initiative of multidisciplinary researchers investigate the issue of water erosion from its various facets [1] [2]. The goal is to preserve water and soil, two resources threatened. Multiple attempts were made to diagnose and implement empirical and experimental methods for quantitative estimation of soil loss caused by diffuse erosion. Indeed, the Eastern slope of the high mountains of Asir (Saudi Arabia), formerly worn and cut by the depression of rivers and undeniable branching of the river system, deserves to be studied in detail given the release of a huge erosive potential that is responsible for soil losses that are increasing gradually and continuously. The purpose of this paper was to validate the suitability of agricultural terraces in terms of soil preservation, using the results of the soil loss application as an indicator of the state of function of these latter. Many studies have addressed the agricultural terraces, however, only a few of them have focused on the relationship between erosion and agricultural terraces through an experimental approach. Previous work has concentrated mainly on their socio-economic impact;whilst the knowledge of their environmental impact remained scarce. In terms of the climate change context, soil erosion is becoming a central problem in Asir region. Thus, in this way, the application of the universal equation of soil loss was very helpful to explain and predict the role of each factor. Nevertheless, extreme caution and great care must be taken because of the application of this model outside its frame.展开更多
The mineralogical data materialized in the present work suggest that the previously described skarns at Ad Darb in the literature are actually marble deposits intercalated with schists and phyllites of different compo...The mineralogical data materialized in the present work suggest that the previously described skarns at Ad Darb in the literature are actually marble deposits intercalated with schists and phyllites of different compositions. The marble and associated metasediments lie to the west of striking ridges of marbles that are nearly aligned in the NNW-SSE direction. Garnet at Al Madhiq occurrence often occurs in the form of bands conformable with rock foliation (gneissosity and schistosity). It is suggested that the paragenesis “quartz-gar- net-epidote” is developed due to the percolation of some Al-rich solutions along rock foliation of the horn- blende gneiss, i.e. metasomatic garnet. Careful field investigation collaborated with petrographic and SEM studies, suggest the occurrence of another garnetiferous paragenesis associating quartz, mica and feldspar in pegmatites, aplites and quartz veins, i.e. exclusively igneous garnet. Metasomatic garnet in the calc-silicates of Al Madhiq is of grossular composition. It is commonly unzoned but some distinctly to slightly zoned crystals are observed where the core is andradite-rich and the rim is grossular. Metasomatic events responseble for growth of garnet in the calc-silicates led also to formation of epidote post-dating grossular. Hand specimens, microscopic investigation and BSE images prove that this epidote post-dates and replaces gros sular, and even rims it in some instances. Igneous garnet at Al Madhiq (almandine-spessartine) is found only in pegmatites and aplites that are genetically related to alkali granitoids. Sulphides (dominated by pyrite) occur in intemate association with domains rich in grossular and hence these sulphides are more likely hydrothermal indicating reducing conditions for formation of grossular.展开更多
A large variation in elevation and gravity anomaly prevails from the Red Sea coast to the interior of the Arabian Shield (AS) across the Asir Igneous Province (AIP);The Asir Mountain (AM) is developed on AIP. Here the...A large variation in elevation and gravity anomaly prevails from the Red Sea coast to the interior of the Arabian Shield (AS) across the Asir Igneous Province (AIP);The Asir Mountain (AM) is developed on AIP. Here the elevation varies from 45 - 2700 m, corresponding changes in F.A. are from –30 to + 220 mgal and B.A. from +22 to –175 mgal. Regression relationships between elevation and gravity anomalies demonstrate significant changes in trend at about 400 m threshold of elevation across the pediment west of AM, at about 45 km inland of the shoreline, flanking the Hizaz-Asir Escarpment (HAE). Gravity anomaly variation along a traverse taken across HAE and AIP is interpreted here in terms of anomalous masses in crust as well as due to deeper crustal configuration. 2D gravity interpretation is, in part, constrained by surface geology, available geologic cross-sections for crust, interpretations from the IRIS Deep-Seismic Refraction Line, and to a lesser extent by the available gross results from shear-wave splitting and receiver function analysis. The gravity model provides probable solutions for the first time on geometric configuration and geophysical identification: a) for the seaward margin of the mid-Tertiary Mafic Crust (TMC) below sediment cover of the Asir pediment that coincides with the 400 m threshold elevation. This signifies an anomalous uplift at the rifting phase. Moho below TMC extends from 10 - 22 km depth across HAE and west margin of AIP, b). Thinned continental crust below the Asir margin whose upper layer coincides with a seismic reflector is at about 22 km depth, c). Rift-margin characteristic detachment fault associated with basaltic flows on top surface of TMC at its inner margin, d). Two geologically mapped low-angle normal faults dipping to the east developed between the basic rocks intruding the AIP and e). felsic pluton farther east within AS. Large scale igneous activity followed by intense deformation affecting AIP clearly owes their origin to the rifting architecture of the AS at 展开更多
The present study utilized a porcine model for qualitative and quantitative assessment of the diagnostic quality of non-contrast abdominal computed tomography (CT) images generated by Adaptive Statistical Iterative Re...The present study utilized a porcine model for qualitative and quantitative assessment of the diagnostic quality of non-contrast abdominal computed tomography (CT) images generated by Adaptive Statistical Iterative Reconstruction (ASIR, GE Healthcare, Waukesha, Wisconsin, USA), Model-Based Iterative Reconstruction (GE company name VEO), and conventional Filtered back projection (FBP) technique. Methods: Multiple CT whole-body scans of a freshly euthanized pig carcass were performed on a 64-slice GE CT scanner at varying noise indices (5, 10, 15, 20, 30, 37, 40, 45), and with three different algorithms (VEO, FBP, and ASIR at 30%, 50%, and 70% levels of ASIR-FBP blending). Abdominal CT images were reviewed and scored in a blinded and randomized manner by two board-certified abdominal radiologists. The task was to evaluate the clarity of the images according to a rubric involving edge sharpness, presence of artifact, anatomical clarity (assessed at four regions), and perceived diagnostic acceptability. This amounted to seven criteria, each of which was graded on a scale of 1 to 5. A weighted formula was used to calculate a composite score for each scan. Results: VEO outperforms ASIR and FBP by an average of 0.5 points per the scoring system used (p < 0.05). Above a threshold noise index of 30, diagnostic acceptability is lost by all algorithms, and there is no diagnostic advantage to increasing the dose beyond a noise index of 10. Between a noise index of 25 - 30, VEO retains diagnostic acceptability, as opposed to ASIR and FBP which lose acceptability above noise index of 25. Conclusion: Model-based iterative reconstruction provides superior image quality and anatomical clarity at reduced radiation dosages, supporting the routine use of this technology, particularly in pediatric abdominal CT scans.展开更多
文摘目的探讨最佳自适应统计迭代重建(ASIR)百分比联合最优单能量技术提高腹部图像质量,优化腹部血管显示。方法搜集临床腹部能谱CT检查的32例腹部疾病患者资料,应用能谱分析软件,采用70 ke V、55ke V分别联合0%、30%、50%、70%ASIR模式进行腹部动脉期及门静脉期重建,比较70 ke V联合不同ASIR百分比模式下动脉期及门静脉期肝实质噪声(LN)、胰腺噪声(PN),竖脊肌噪声(SMN)以及肝CNR(LCNR)、胰腺CNR(PCNR)、门静脉CNR(PV-CNR)及主观图像质量评分之间差异有无统计学意义。同时比较55 ke V联合不同ASIR百分比模式下动脉期及门静脉期腹部动脉血管、门静脉CNR等相关指标及主观图像质量评分,并采用单因素方差分析进行比较。结果 70 ke V组不同ASIR比例中,LN、PN,SMN、LCNR及PCNR差异均有统计学意义(P<0.05)。主观图像质量评分显示动脉期及静脉期不同ASIR组间比较,30%组伪影最低;诊断信心度方面30%最高;噪声方面70%最低,微小结构及病变显示方面各ASIR组间无统计学差异。55 ke V组间,除了动脉期LCNR各组间差异无统计学意义,腹部各动脉血管CNR及PV-CNR,LN,SMN,PN,主观评分及门静脉期LCNR在不同ASIR组间差异均有统计学意义(P<0.05);主观评分方面以50%ASIR组最优(P<0.05)。结论 70 ke V+30%ASIR及55ke V+50%ASIR分别成为优化腹部图像质量及血管成像的最优化组合。
文摘目的探讨应用能谱CT最佳单能量成像联合40%自适应统计迭代重组(ASIR)技术对肠系膜上动脉及静脉图像质量的优化。方法搜集临床腹部能谱CT检查的25例腹部疾病患者资料,应用能谱分析软件,得出能谱CT成像中最佳单能图像,分别采用70 ke V、最佳单能量、最佳单能量+40%ASIR模式进行肠系膜上动脉、肠系膜上静脉重组,比较70 ke V、最佳单能量、最佳单能量+40%ASIR 3组肠系膜上动静脉的CT值、背景噪声(SDn)及背景CT值、对比噪声比(CNR)、信噪比(SNR)及主观图像质量评分,并采用两因素方差分析进行比较。结果肠系膜上动脉及静脉最佳CNR单能量水平集中在55~62 ke V左右,平均为60 ke V。最佳单能量组(60 ke V)、70 ke V单能量组、最佳单能量(60 ke V)+40%ASIR组肠系膜上动脉的CNR分别20.41±7.66,17.16±6.79,22.85±8.24;图像质量评分分别为4.24±0.35、3.86±0.19和4.25±0.36。肠系膜上静脉CNR分别为5.80±1.99、4.37±1.22和7.27±2.51;图像质量评分分别为3.78±0.35、3.46±0.27和3.81±0.32,差异均有统计学意义(P<0.05)。60 ke V+40%ASIR组CNR、SNR均高于70 ke V组及60 ke V组;60 ke V+40%ASIR组主观评分高于70 ke V组(P<0.05),与60 ke V组无统计学差别(P>0.05)。结论能谱肠系膜上动脉及静脉成像中最佳单能量(60ke V)+40%ASIR图像较70 ke V及60 ke V图像成像质量有所提高,可以在临床血管成像方面广泛应用。
文摘Water erosion remains the major problem in many countries, especially those with an extension in the arid and semi-arid area and those marked by a long dry season. The intensification of land degradation which is a result of the strong erosive dynamics on a global scale has stimulated the initiative of multidisciplinary researchers investigate the issue of water erosion from its various facets [1] [2]. The goal is to preserve water and soil, two resources threatened. Multiple attempts were made to diagnose and implement empirical and experimental methods for quantitative estimation of soil loss caused by diffuse erosion. Indeed, the Eastern slope of the high mountains of Asir (Saudi Arabia), formerly worn and cut by the depression of rivers and undeniable branching of the river system, deserves to be studied in detail given the release of a huge erosive potential that is responsible for soil losses that are increasing gradually and continuously. The purpose of this paper was to validate the suitability of agricultural terraces in terms of soil preservation, using the results of the soil loss application as an indicator of the state of function of these latter. Many studies have addressed the agricultural terraces, however, only a few of them have focused on the relationship between erosion and agricultural terraces through an experimental approach. Previous work has concentrated mainly on their socio-economic impact;whilst the knowledge of their environmental impact remained scarce. In terms of the climate change context, soil erosion is becoming a central problem in Asir region. Thus, in this way, the application of the universal equation of soil loss was very helpful to explain and predict the role of each factor. Nevertheless, extreme caution and great care must be taken because of the application of this model outside its frame.
文摘The mineralogical data materialized in the present work suggest that the previously described skarns at Ad Darb in the literature are actually marble deposits intercalated with schists and phyllites of different compositions. The marble and associated metasediments lie to the west of striking ridges of marbles that are nearly aligned in the NNW-SSE direction. Garnet at Al Madhiq occurrence often occurs in the form of bands conformable with rock foliation (gneissosity and schistosity). It is suggested that the paragenesis “quartz-gar- net-epidote” is developed due to the percolation of some Al-rich solutions along rock foliation of the horn- blende gneiss, i.e. metasomatic garnet. Careful field investigation collaborated with petrographic and SEM studies, suggest the occurrence of another garnetiferous paragenesis associating quartz, mica and feldspar in pegmatites, aplites and quartz veins, i.e. exclusively igneous garnet. Metasomatic garnet in the calc-silicates of Al Madhiq is of grossular composition. It is commonly unzoned but some distinctly to slightly zoned crystals are observed where the core is andradite-rich and the rim is grossular. Metasomatic events responseble for growth of garnet in the calc-silicates led also to formation of epidote post-dating grossular. Hand specimens, microscopic investigation and BSE images prove that this epidote post-dates and replaces gros sular, and even rims it in some instances. Igneous garnet at Al Madhiq (almandine-spessartine) is found only in pegmatites and aplites that are genetically related to alkali granitoids. Sulphides (dominated by pyrite) occur in intemate association with domains rich in grossular and hence these sulphides are more likely hydrothermal indicating reducing conditions for formation of grossular.
文摘A large variation in elevation and gravity anomaly prevails from the Red Sea coast to the interior of the Arabian Shield (AS) across the Asir Igneous Province (AIP);The Asir Mountain (AM) is developed on AIP. Here the elevation varies from 45 - 2700 m, corresponding changes in F.A. are from –30 to + 220 mgal and B.A. from +22 to –175 mgal. Regression relationships between elevation and gravity anomalies demonstrate significant changes in trend at about 400 m threshold of elevation across the pediment west of AM, at about 45 km inland of the shoreline, flanking the Hizaz-Asir Escarpment (HAE). Gravity anomaly variation along a traverse taken across HAE and AIP is interpreted here in terms of anomalous masses in crust as well as due to deeper crustal configuration. 2D gravity interpretation is, in part, constrained by surface geology, available geologic cross-sections for crust, interpretations from the IRIS Deep-Seismic Refraction Line, and to a lesser extent by the available gross results from shear-wave splitting and receiver function analysis. The gravity model provides probable solutions for the first time on geometric configuration and geophysical identification: a) for the seaward margin of the mid-Tertiary Mafic Crust (TMC) below sediment cover of the Asir pediment that coincides with the 400 m threshold elevation. This signifies an anomalous uplift at the rifting phase. Moho below TMC extends from 10 - 22 km depth across HAE and west margin of AIP, b). Thinned continental crust below the Asir margin whose upper layer coincides with a seismic reflector is at about 22 km depth, c). Rift-margin characteristic detachment fault associated with basaltic flows on top surface of TMC at its inner margin, d). Two geologically mapped low-angle normal faults dipping to the east developed between the basic rocks intruding the AIP and e). felsic pluton farther east within AS. Large scale igneous activity followed by intense deformation affecting AIP clearly owes their origin to the rifting architecture of the AS at
文摘The present study utilized a porcine model for qualitative and quantitative assessment of the diagnostic quality of non-contrast abdominal computed tomography (CT) images generated by Adaptive Statistical Iterative Reconstruction (ASIR, GE Healthcare, Waukesha, Wisconsin, USA), Model-Based Iterative Reconstruction (GE company name VEO), and conventional Filtered back projection (FBP) technique. Methods: Multiple CT whole-body scans of a freshly euthanized pig carcass were performed on a 64-slice GE CT scanner at varying noise indices (5, 10, 15, 20, 30, 37, 40, 45), and with three different algorithms (VEO, FBP, and ASIR at 30%, 50%, and 70% levels of ASIR-FBP blending). Abdominal CT images were reviewed and scored in a blinded and randomized manner by two board-certified abdominal radiologists. The task was to evaluate the clarity of the images according to a rubric involving edge sharpness, presence of artifact, anatomical clarity (assessed at four regions), and perceived diagnostic acceptability. This amounted to seven criteria, each of which was graded on a scale of 1 to 5. A weighted formula was used to calculate a composite score for each scan. Results: VEO outperforms ASIR and FBP by an average of 0.5 points per the scoring system used (p < 0.05). Above a threshold noise index of 30, diagnostic acceptability is lost by all algorithms, and there is no diagnostic advantage to increasing the dose beyond a noise index of 10. Between a noise index of 25 - 30, VEO retains diagnostic acceptability, as opposed to ASIR and FBP which lose acceptability above noise index of 25. Conclusion: Model-based iterative reconstruction provides superior image quality and anatomical clarity at reduced radiation dosages, supporting the routine use of this technology, particularly in pediatric abdominal CT scans.
