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作者报告了１００例脑脓肿，其中一般性脑脓肿６２例、脑内小脓肿３８例（强化灶小于１．５ｃｍ），并对发病部位，临床表现及ＣＴ表现的主要特点进行了讨论。 相似文献
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本文通过对２０例小于１ｃｍ的肺内微小结节病灶的分析，比较了螺旋ＣＴ扫描，常规ＣＴ扫描，及胸部平片在临床应用的价值，认为螺旋ＣＴ扫描高分辨薄层重建可以提高肺内微小结节的检出率，并有利于研究结节的内部，边缘和结节的周围情况，从而对早期肺癌的定性诊断和鉴别诊断有重要价值。 相似文献
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目的:探讨不典型肝脓肿的CT动态增强表现及其病理基础,提高对肝脓肿及胆管细胞癌的鉴别诊断水平。方法:回顾性分析经手术病理证实的3例不典型肝脓肿的临床资料及CT表现。结果:不典型肝脓肿的CT表现具有多样性,CT平扫病灶呈均匀或不均匀低密度区,形态呈类圆形,边缘模糊或较清楚。增强扫描动脉期病灶呈轻度强化,门静脉期及延迟扫描病灶呈小环状、蜂窝状及不均匀强化,部分形如"花瓣状"改变,类似肝内胆管细胞癌的影像学表现。结论:螺旋CT动态多期增强扫描对鉴别肝内胆管细胞癌与不典型肝脓肿有一定价值。 相似文献
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肝癌的CT影像特征分析和诊断 总被引：1，自引：0，他引：1
本文回顾分析了１１５例肝癌的ＣＴ形像特征,发现肝癌病灶如小于５ｃｍ,因其分化程度较好,ＣＴ图像上多呈现圆形结节影,密度均匀,低或稍低;多数病灶（７５％）边缘光整,部分病灶（２８％）有包膜显示,但随着病灶的增大,病变可突破包膜呈浸润性生长;增强后小肝癌和非小肝癌都可使病灶边缘显示清晰。且病灶较平扫有缩小;肝癌在ＣＴ片上还可以发现的有门脉癌栓和／或肝门、胰周、腹腔淋巴结转移的征象。 相似文献
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腔隙性脑梗塞的CT诊断及临床特点 总被引：1，自引：1，他引：0
本文回顾性分析了１２０例脑腔隙性梗塞的ＣＴ诊断及临床特点,认为梗塞病灶可被清晰、准确的发现。有助于临床的定性分析,为治疗提供了依据。ＣＴ是目前诊断脑腔隙性梗塞的最有效的检查手段。 相似文献
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ＨＲＣＴ（高分辨ＣＴ）图像是较常规ＣＴ具有更清晰的空间分辨率的图像。可明显提高图像质量，从而提高病灶细节以及正常和异常细微结构的显示能力，对配合临床诊断及指导临床治疗有着很高的实用价值。如何利用普及型ＣＴ机获得ＨＲＣＴ图像。我们做了技术上的改进，并在不增加硬件设备的基础上利用软件功能，提高一些技术参数，主要是扫描层厚，管电流及扫描时间，高分辨薄层重建，尽可能的缩小显示野，加大矩阵等。所得到的图像分辨率明显高于常规ＣＴ，如肺小结节的显示，腔隙性梗塞的检出率，可疑小腔隙与大的像素颗粒的辨别等。我们认为，进一步开发软件功能。会获得更加理想的ＨＲＣＴ图像 相似文献
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目的．应用高分辨率ＣＴ（ＨＲＣＴ）扫描方法,增加对头颅腔隙梗塞诊断的可靠性．材料和方法：对临床疑有腔隙的病人在基底节区及可疑部位加用ＨＲＣＴ扫描,遇到腔隙病灶与像素颗粒难以区分时,在相同层面或上下１～２ｍｍ处做ＨＲＣＴ扫描．结果：有２０８例常规ＣＴ正常的病例中发现了腔隙灶,在遇到的３２０例不易诊断的可疑病灶中,经ＨＲＣＴ确诊的真正腔隙灶８９例,伪腔隙（像素）２３１例,同时发现对正常腔组织结构的显示要较常规ＣＴ优越得多,结论：ＨＲＣＴ不仅能提高腔隙梗塞的诊断率,还能辨别伪腔隙是弥补常规ＣＴ对腔隙诊断不足的较好手段。 相似文献
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ＨＲＣＴ（高分辨ＣＴ）图像是较常规ＣＴ具有更清晰的空间分辨率的图像。可明显提高图像质量，从而提高病灶细节以及正常和异常细微结构的显示能力，对配合临床诊断及指导临床治疗有着很高的实用价值。如何利用普及型ＣＴ机获得ＨＲＣＴ图像。我们做了技术上的改进，并在不增加设备的基础上利用软件功能，提出一些技术参数，主要是扫描层厚，管电流及扫描时间，高分辨薄层重建，尽可能的缩小显示野，加大矩阵等。所得到的图像分辨率 相似文献
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笔者收集２９例经ＣＴ诊断单发性脑内转移瘤，其中经手术病理证实的２３例，通过对２９个单发病灶的ＣＴ表现进行分析，着重讨论该病灶的出现位置，并对其原因进行了探讨性分析，旨在进一步提高对颅内单发病灶的诊断水平。 相似文献
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弓形虫病（ｔｏｘｏｐｌａｍｏｓｉｓ）是由刚地（ｇａｎｄｉｉ）弓形引起的一种寄生虫病。世界各地广泛分布,中国从１９５７年开始报告临床病例,但脑电改变报告不多。本文拟就探讨其脑电及ＣＴ的变化。所有２４例病人均经间接血凝试验（ＩＨＡ）检查明确诊断,并做脑电检测及头颅ＣＴ扫描。结果发现２４例脑电全部为程度不等的异常,异常率１００％。头颅ＣＴ扫描２０例中有８例阳性病灶,阳性率４０％。结论是系统症状原弓形虫感 相似文献
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M. N. French R. L. Bras W. F. Krajewski 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(1):27-45
A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities. 相似文献
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Gtz Schroth Luciana Ferreira Da Silva Marc‐Andree Wolf Wenceslau Geraldes Teixeira Wolfgang Zech 《水文研究》1999,13(10):1423-1436
The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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M. A. Kahn 《洁净——土壤、空气、水》2000,28(2):95-101
Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate. 相似文献