128层螺旋CTA联合彩色多普勒超声在诊断颈动脉狭窄中的应用研究

目的:探讨128层螺旋CT血管造影联合彩色多普勒超声(CDFI)在诊断颈动脉狭窄性病变(CAS)中的应用价值。方法:58例颈动脉狭窄患者分别于1周内行128层螺旋CTA及彩色多普勒血管超声检查,共计116个节段,以DSA检查结果为金标准,比较分析MSCTA与CDFI对颈动脉狭窄诊断的结果。结果:MSCTA检出轻度狭窄9支,中度狭窄12支,重度狭窄18支,完全闭塞14支;经CDFI诊断轻度狭窄9支,中度狭窄13支,重度狭窄19支,完全闭塞13支。对颈动脉轻、中、重度狭窄及闭塞的诊断符合率分别为84.6%、79.5%、86.7%、92.8%及82.6%、76.7%、85.1%、91.2%,MSCTA与CDFI对不同程度颈动脉狭窄检查结果一致性极佳(佳2=247.56,ν=17,P<0.001,Kappa=0.872)。结论:MSCTA与CDFI对颈动脉狭窄性病变诊断具有良好的一致性,两者联合可广泛用于颈动脉狭窄性病变的筛查和诊断,为治疗方案的选择提供重要的参考依据,可作为基层医院颈动脉狭窄的重要筛查依据而推广应用。     

B超与CT对诊断壶腹癌的临床价值

本文回顾性分析经手术病理证实的１４例壶腹癌，Ｂ超诊断准确率７１．４％，ＣＴ诊断准确率８５．７％，两者结合准确率达９２．９％，对于大多数中，晚期壶腹癌，Ｂ超与ＣＴ表现大致相同，但ＣＴ对显示较小，较早期的病变所致阻塞性黄疸其阻塞部位，阻塞程度及阻塞性质有较高的准确性。     

超声与16层螺旋CT在小肝癌诊断中的应用研究

目的: 应用超声和16层螺旋CT进行小肝癌联合诊断的对照研究。 方法: 采用常规超声及高质量扫描模式的16层螺旋CT对18例小肝癌和17例肝脏良性小肿瘤进行对照诊断研究,所有病例均经手术病理或超声引导下穿刺证实。 结果: 大部分肝脏良恶性小肿瘤在超声图像上有其典型的特征,与CT和病理检查结果相符的有小肝癌14例和良性小肿瘤15例。但,超声诊断怀疑为血管瘤1例和增生结节3例,CT和病理诊断为小肝癌;超声误诊为小肝癌2例而CT和病理均诊断为硬化结节1例,另1例CT诊断与超声相符,但病理确证后为炎性假瘤。 结论: 超声是肝脏常规检查的首选方法,对肝脏良恶性肿瘤均有较高的检出率,但对一些不典型病例还需16层螺旋CT和病理检查以做出进一步的定性诊断,提高诊断的准确率,二者联合诊断能提高对肝脏良恶性肿瘤的早期诊断率。     

超声造影与16层螺旋CT在肝脏肿瘤诊断中的对照研究

目的 分析肝脏肿瘤超声造影后的组织血流特征与16层螺旋CT三个时期的强化特征,评价其临床诊断价值。方法: 研究分析30例病例在超声造影与16层螺旋CT三个时期的各自不同的典型图像。采用经手背静脉注射“全氟显”超声造影剂,利用相干谐波成像技术分析三个时期表现,而16层螺旋CT采用高质量扫描模式,扫描参数:层厚7.5mm,通过拆分成1.25mm,螺距1.375:1,电压120KA,管电流280mA。增强三期扫描分别注射对比剂,动脉期16-25s,门脉期35-55s,延迟期是1min10s-3min。高压注射器单相注射,非离子型造影剂,注射速率2.5ml/s,剂量70-85ml,浓度300mg/ml,通过工作站的技术分析,明确肝肿瘤的强化特点。结果 对30例肝脏肿瘤患者进行超声造影与16层螺旋CT检查,其中原发性小肝癌18例,5例小血管瘤,3例局灶性脂肪肝,3例转移性肝癌,1例退变结节。其中有2例超声造影未检测出肿瘤样特征性图像改变,而经CT检测出并诊断为小肝癌1例和退行性结节1例。所有病例均经手术、病理和穿刺证实。结论 超声造影与16层螺旋CT对肝脏肿瘤的诊断和鉴别诊断均具有较高的临床应用价值。但对一些特殊肝脏肿瘤患者,联合检测可提高早期诊断的检出率。     

Observation of Sea Breeze Front and its Induced Convection over Chennai in Southern Peninsular India Using Doppler Weather Radar

Sea breeze, the onshore wind over a coastal belt during daytime, is a welcoming weather phenomenon as it modulates the weather condition by moderating the scorching temperature and acts as a favourable mechanism to trigger convection and induce precipitation over coastal and interior locations. Sea breeze aids dispersal of pollutants as well. Observational studies about its onset, depth of circulation and induced precipitation have been carried out in this paper for the period April to September, 2004–2005 using a S-band Doppler Weather Radar functioning at Cyclone Detection Radar Station, India Meteorological Department, Chennai, India. The onset of sea breeze has been observed to be between 0900 and 1000 UTC with the earliest onset at 0508 UTC and late onset at 1138 UTC. The frequency is greater during the southwest monsoon season, viz., June – September and the frequency of initial onset is greater in north Chennai. The modal length of sea breeze is between 20 and 50 km with extreme length as high as 100 km also having been observed. Though the inland penetration is on average 10 to 20 km, penetration reaching 100 km was also observed on a number of cases. The induced convection could be seen in the range 50–100 km in more than 53% of the cases. The mean depth of sea breeze circulation is 300–600 m but may go well beyond 1000 m on conducive atmospheric conditions.     

三维测量光流恢复算法结合BIM对震后建筑倾斜度测量的研究

震后危险建筑倾斜度的移动测量过程较为复杂,常规测量方法会存在对称偏差。为了提高震后危险建筑倾斜度测量的准确性,设计三维测量光流恢复算法结合BIM的震后建筑倾斜度测量方法。采用BIM技术采集并整合全部建筑倾斜度信息,构建危险建筑信息模型;采用三维测量光流恢复算法获取所构建建筑信息模型内多个目标特征点,设计震后危险建筑倾斜度的三维测量模型。仿真实验说明,所提方法测量震后危险建筑三维坐标值误差率均小于0.4%,平均评估时间仅为2.5 s,说明该方法可提高建筑倾斜度评估效果。     

Study of Nonlinear Earthquake Flow Functions and Their Application to the Space Increased Probability of Strong Earthquake (SIP)

The definition and abnormality discriminatory criteria of earthquake flow function are introduced in this paper based on the algorithm of Space Increased Probability (SIP). Nine earthquake flow functions were defined by the method. The retrospect test that applied the SIP algorithm with the nonlinear earthquake flow function to 7 earthquakes, which occurred from 1975 to 1989 in Eastern China, with a magnitude of 6 or greater depicted that 6 of the 7 strong earthquakes (86%) were located in the SIP areas, and the SIP covers about 32% of the total research time-space domain. These suggest that the R-value, an effective scale for earthquake forecast, is 54% and may imply that the nonlinear earthquake flow function introduced in this paper can be applied to the intermediate-term earthquake forecast research.     

非线性地震流函数在强震概率增长空间域预测中的应用研究

在ＳＩＰ算法的基础上,确立了地震流函数的定义方法和异常判别准则,定义了９个非线性地震流函数,通过对中国东部近期７次６级以上强震的ＳＩＰ回溯性研究表明,７次强震中的６次落入ＳＩＰ预测空间域内,有震报为８６％,ＳＩＰ预测警戒空间域为３２％,Ｒ值评分为０．５４,证明非线性地震流函数用于中期地震预测具有较发的前景。     

Preliminary Study on Horizontal Deformation and Tectonic Activity in the Northern Part of North China Using GPS Remeasurement Results

In this paper, the baseline variation and displacement vector was analyzed using the calculated results of GPS measurements carried out from 1995 to 1996 in North China. Based on these analytical results, we studied the recent tectonic activity. In general, the regional extension is dominant in the direction of proximately EW, but there is a difference in the SN direction. Extension is significant in the Shanxi fault-depression zone and Bohai region, while compression with strike-slip is characterized along the Yishui-Tancheng segment of the Tanlu fault zone. The baseline shortening zone is distributed along the Baotou-Zhangjiakou-Ninghe areas. It is a boundary zone of regional variation where many differences of crustal horizontal deformation are discovered between the southern part and the northern part of this zone. The baseline shortening zone in NE direction is distributed along the Jianchang-Tangshan-Gucheng area. It is consistent with the Tangshan-Xingtai seismic zone which indicates that tectoni     

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

In areas with strong velocity gradients, traditional reverse time migration based on cross-correlation imaging condition not only produces low-frequency noise but also generates diving wave artefacts. The artefacts caused by diving waves have no typical low-frequency characteristics and cannot be eliminated by simple high-pass filtering approaches. We apply the wave-field decomposition imaging condition to analyse the causes of false images in reverse time migration by decomposing the full wave-field into up-going and down-going components in the angle domain. We find that artificial diving wave imaging artefacts, which are generated by the cross-correlation between the up-going source and down-going receiver wave-fields in areas with strong velocity gradients, arise at large angles. We propose an efficient strategy by means of the wavelength-dependent smoothing operator to eliminate artefacts from artificial diving waves in reverse time migration. Specifically, the proposed method provides more reasonable down-going wave-fields in areas with sharp velocity constructs by considering the factor of varying seismic wavelengths during wave propagation, and the artificial components of diving waves are eliminated in a straightforward manner. Meanwhile, the other wave-field components that contribute to true subsurface images are minimally affected. Benefiting from a smoothed velocity, the proposed method can be adapted to the traditional reverse time migration imaging frame, which reveals significant implementation potential for the seismic exploration industry. A salt model is designed and included to demonstrate the effectiveness of our approach.