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颅底脑膜瘤双期多排螺旋CT血管造影的临床应用 总被引：3，自引：0，他引：3
目的:探讨双期注药多排螺旋CT血管造影(MSCTA)对颅底脑膜瘤及其周围组织的显示能力,评价其临床应用价值。材料和方法:收集我院诊治的资料完整的脑膜瘤病人13例,所有病例均行CT平扫和双期注药、一次延迟CT血管造影检查。图像送至SUN工作站进行多平面重建(MultiplannerReconstruction,MPR)、最大密度投影(MaximumIntensityProjection,MIP)、容积再现(VolumeRendering,VR)、表面遮蔽法(ShadedSurfaceDisplay,SSD)后处理观察。结果:13例均为前、中颅凹单发脑膜瘤,重建图像显示瘤体充分强化,willis环血管充盈满意,颅骨、血管、肿瘤三者立体关系显示清楚,主要的征象包括:颈内动脉、大脑前或中动脉被肿瘤包绕,颅骨受侵犯,肿瘤周围组织移位等。结论:双期注药多排螺旋CT血管造影可以充分显示颅底脑膜瘤的影像特征,使颅底血管充分强化,重建后可清楚显示肿瘤、血管及其与邻近组织的关系,有助于脑膜瘤的诊断及治疗方案的制订,评估手术风险,值得在临床推广应用。 相似文献
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Abstract An important and relatively complete fossil mysticete cetacean specimen was collected from the Oligocene age Ashiya Group in Kyushu, Japan. The specimen includes a complete skull, with the anterior part of the vertebral column, several ribs, and the left pectoral limb. It provides significant information about the early evolution of cetotheres and transitional steps from the Archaeoceti to Mysticeti. Several features of the specimen, such as the anterior position of the nasal opening and large mandibular foramen, are primitive, but others are derived, such as the wide maxilla, broad supraorbital process of the frontal, occipital shield overhanging the temporal fossae, and the flat articulation of the distal end of the humerus. This animal, therefore, has a mixture of primitive and derived characters. It represents a stage of evolution in mysticetes that has been previously unrecognized. 相似文献
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Abstract Desmostylians from the Pacific coasts of Japan and North America are compared and taxonomy and adaptations in the mammalian order Desmostylia discussed. The taxonomy is based mainly on teeth and skulls. Feeding adaptations and habitat are discussed using teeth and restored skeletons, respectively. In the extinct order two families, six genera and 10 species can now be recognized. Each genus is distinguished by a set of tooth characters. The three species of the genus Paleoparadoxia have different body sizes. Two species of the genus Desmostylus can be distinguished on morphological differences in the cranium. As a result it is clear that both species, D. hesperus , which had long been recognized only in North America, and D. japonicus , which has hitherto been recognized only in Japan, inhabited both coasts of the Pacific. All genera of the Order Desmostylia share a common and distinctive body form, interpreted by Inuzuka as having a laterally placed limb posture. Based on this body form, the optimum habitat is thought to have been an intertidal sandy beach. The dental morphology is variable, and derived species show an adaptation for wear by an abrasive diet. In conclusion, we theorize that the Order Desmostylia was adapted for a coastal habitat from its inception, with each genus adapting to a different sort of herbivorous diet. 相似文献
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目的:探讨卷积神经网络（CNN）在颅底骨折CT诊断的应用价值。方法:回顾性搜集3 100例颅底骨折患者及2 467例正常患者的颅骨CT图像数据,经纳排标准筛选,最终选用2 488例颅底骨折及1 628例正常患者的颅底CT图像数据。对CT图像进行骨折标注后,随机分配训练集和测试集后。通过CNN构建颅骨区域识别算法模型和颅骨骨折检测算法模型,随后在测试中以颅底骨折区域识别和头颅骨折、颅底骨折对模型进行验证,验证指标为精准率（precision）、召回率（recall）、平均诊断耗时;与人工组（低年资放射科医师）测试进行诊断效能对比。结果:通过CNN运算获得的稳定模型后进行测试对比,结果显示全颅底区域骨折、前、中、后颅底骨折精准度均<0.5,低于人工组（均>0.63）;召回率>0.89,均优于人工组（均<0.8）;平均诊断时间为（3.12±2.67）s,明显少于人工组诊断时间。分别在颅底骨折区域测试中,精准度率:前颅底>中颅底>后颅底,召回率:中颅底>后颅底>前颅底。结论:基于CNN颅底骨折算法模型对于颅脑外伤患者CT诊断颅底骨折在召回率、诊断耗时均优于人工测试结果,在辅助临床诊断、降低漏诊及诊断耗时方面具有一定的价值。 相似文献
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Abstract Fossil otariid pinnipeds of the extinct genera Prototaria Takeyama and Ozawa, 1984, and Neotherium Kellogg, 1931, known from Middle Miocene deposits bordering the North Pacific Ocean, are small, primitive pinnipeds in the subfamily Imagotariinae. They have a small supraorbital process of the frontal or have lost it entirely, a three-rooted first molar, small paroccipital process, and ear morphology indicating that they belong in the subfamily Imagotariinae. Their unique derived characters include extreme intertemporal constriction and highly modified cheek teeth, the premolars having become molarized by the addition of protocones and lingual cingula. Prototaria Takeyama and Ozawa, 1984, the most primitive known imagotariine genus, contains two species, P. primigena Takeyama and Ozawa, 1984, and P. planicephala Kohno, 1994, both of early Middle Miocene age from Japan. Prototaria has a few derived characters, including a large antorbital process, narrow intertemporal region, and large orbit, but its primitive characters apparently were inherited from enaliarctine ancestors. The long enigmatic Neotherium mirum Kellogg, 1931, of Middle Miocene age from California, USA, is related to Prototaria, but differs by having an elongate skull, very slender zygomatic arch, ventrally exposed median lacerate foramen, and smaller but more molarized premolars. A more primitive new genus and species, Proneotherium repenningi Barnes, related to N. mirum, is from the early Middle Miocene Astoria Formation, coastal Oregon, USA. It shares some derived characters with Prototaria, and shares many other important derived characters with N. mirum. Imagotariines probably arose from some species of Early Miocene enaliarctines, became diverse in Middle and Late Miocene time, and are only known from the North Pacific realm. Although they might include the ancestors of true walruses of the subfamily Odobeninae, no known imagotariines appear to have been adapted for mollusk feeding as are the highly evolved modern walruses. Instead, imagotariines appear to have retained a primitive piscivorous diet, as did the fur seals and sea lions of the subfamily Otariinae. 相似文献
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The skull and mandible of a Late Miocene fossil pig,Chleuastochoerus,are compared morphologically with those of extant pigs and peccaries,and subjected to a functional analysis.The presence of a rostral bone in the skull and relatively strong rostral muscles indicates that Chleuastochoerus possessed considerable digging ability,though the relatively narrow occipital surface and the shortness of the skull would have restricted the range of motion through which the skull could be swung.The distinctive pre-zygomatic plate and over-canine arch-niche may have played a role in protecting the skull and canines during digging.The massive masticatory muscles,reconstructed based on well-developed parietal and zygomatic crests,would have enabled the mouth to close quickly and contributed to moving the mandible both longitudinally and laterally.The configuration of the cranio-mandibular joint and its relatively high position show clearly that Chleuastochoerus was capable of both crushing and grinding movements during mastication.The comparatively simple structure of the crown surfaces of the cheek teeth suggests that the food of Chleuastochoerus may have been softer than that of extant suids.The diet of Chleuastochoerus is postulated to fall between those of true forest pigs and open habitat pigs,and the habitat of Chleuastochoerus to be relatively humid forest edge or nearby areas of open steppe. 相似文献
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目的：对颅脑转移瘤的来源、分布部位及瘤周水肿三者关系进行分析与探讨。方法：将54例颅脑转移瘤检出93个病灶，行平扫及增强扫描。将颅脑分为三个区：1区指大脑半球皮髓质交界区；2区指大脑半球；3区指小脑、脑干。水肿分为四个级别：0度无水肿；1度ETR<=1；2度1相似文献
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吕新荣 《CT理论与应用研究》2011,20(1):73-82
颅骨是人体中最重要的组成部分之一,起着保护和支撑脑部组织的作用.现实中由于种种原因,许多人承受着颅骨缺损的痛苦,不仅影响外观,而日还可能导致脑组织损坏.如何有效地修复缺损的颅骨成了国际研究的热点.目前,医生主要是通过观察病人的CT影像确诊病人颅骨损坏情况,并通过手工制作修复体,这极大地依赖于医生的技术和经验.为了解决这... 相似文献
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大型工业企业的地震灾害具有经济损失高、破坏性强、次生灾害突出、受影响范围广等特点。依据大型工业企业的生产特点，结合工业企业防震减灾的需求，分析了工业企业的震害预测信息系统结构和特征，详细阐述了使用地理信息系统应用软件ArcView为开发平台，建立工业企业GIS震害预测信息系统的基本方法和步骤，并阐明了系统的主要功能和特点。 相似文献
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MRI对鼻咽癌、颅底转移及放疗中、后改变的诊断与评价 总被引：3，自引：0，他引：3
目的：探讨MRI对及MRI对放疗中、放疗后改变及放疗后残存与复安全的保障价值。材料与方法：搜集30进行放疗前、放疗中及放疗后的MRI检查。放疗后状态的病例均追随3-6个月复查。结果：在30例鼻咽癌患者中,存在颅底骨骨转移病例1例。经放射治疗,21例呈放疗后状态,其中包括2例液化性坏死,6例凝固性坏死;9例放疗后残存。结论：MR平扫及增强扫描对鼻咽癌、鼻咽癌颅底骨转移、鼻咽癌放疗中、后改变及放疗后复发有较高的诊断、评估价值。 相似文献
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Abstract Kentriodon hobetsu , a new species, is described from a partial skull from the Middle Miocene Takinoue Formation, in Hokkaido, Japan. The holotype skull includes the base of the rostrum and a fairly well preserved braincase. The new species is distinguished clearly from previously described species of Kentriodon Kellogg, 1927, by the shape of the anterior margin of the pterygoid sinus fossa, the large premaxilla, rounded facial margin, and lesser development of rugosities and processes. This new record of Kentriodon , the first named kentriodontid dolphin from the western North Pacific, extends the geographic range of the genus significantly. 相似文献
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东海陆架盆地及其周边海域地质、地球物理场特征 总被引：7，自引：5，他引：7
分东海陆架盆地及其周边海域的重、磁场特征、对研究区域的地球物理场资料进行了小波变换与多尺度分布与计算，计算了研究了海域重，磁资料的1－4阶小波变换逼近、细节、根据分析与计算可知，在东海陆架盆地及其周边域，重、磁异常的主要特征没有内陆盆地那样明显，但盆地内的绝大部分地区均位于异常相对缓变区，在盆地内部有时有局部异常的圈闭及剧变区，但总的特征为缓变的，而周边区域多为相对剧变区，但也存在局部区域的缓变, 、磁场特征表明，盆地基底相对盆地周边区域主要由密度较大，磁性中的岩石组成，因此盆地中部以高正磁异常为主，布格重力异常 对周边地区高，东海陆架盆地及其周边海域的重力场的主要走向为NNE向，局部重力异常较为平缓，磁异常走向没有重力异常明显，但主要也为NNE向，重、磁场的分布特征表明，东海陆架盆地及其邻域的地质构造为大陆架构造的延伸。 相似文献
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文章分析了广东省及其邻近地区几次中、小地震前水化学异常变化的特征,讨论了它与国内大震前水化学异常变化的差异及其原因,并指出了水化学灵敏震兆组分的存在。 相似文献
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SHI QinQin 《中国科学:地球科学(英文版)》2014,57(2):258-266
A new species of Tsaidamotherium(Bovidae,Artiodactyla),T.brevirostrum,described here represents only the second discovery of the genus.Tsaidamotherium is a mid-sized late Miocene bovid with an odd-looking plate-like horn-core apparatus so far known only from northwestern China.The holotype of T.brevirostrum is a cranial part of skull from the Liushu Formation(late Miocene)of the Linxia Basin.The new species differs from the type species,T.bohlini,mainly in horn-core morphology,having the frontal horn-cores proper much smaller and less distinctly separated from the plate-shaped posterior portion.Furthermore,the new species has smaller frontal sinuses,but a thicker layer of compact bone beneath the horn-core apparatus as seen in frontal section.A complete skull with a smaller horn-core apparatus is considered to represent a female individual of T.brevirostrum.The facial part of the skull,which is first known for this genus,is very short and high,with a high nasal cavity,strongly retracted nasals,and shortened premaxillae and premolar rows.All this probably suggests that the animal with an enlarged nasal cavity,like the modern Saiga and Budorcas,may have had a special adaptation to the high plateau environment. 相似文献
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大跨度悬索桥振动控制的双向TMD参数研究 总被引：1，自引：1，他引：0
用时域内的逐步积分法对无ＴＭＤ和带有不同参数ＴＭＤ的悬索桥进行了时程分析,结果表明,ＴＭＤ的参数对结构的动力特性的抑振效果均有较大的影响,ＴＭＤ的频率不仅影响振动控制的效果也影响结构的表观阻尼,扭转振动的控制可由侧向ＴＭＤ来实现。 相似文献
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