基于冠状动脉CT血流储备分数预测老年冠心病患者远期结局的研究

目的评估冠状动脉CT血流储备分数(CT-FFR)在预测老年冠心病患者远期结局中的价值。方法回顾性分析2018年4月至2019年3月在东部战区总医院放射诊断科的一项前瞻性队列研究中收治的临床可疑冠心病患者1133例,最终纳入330例老年冠心病患者。根据患者是否发生主要不良心血管事件(MACE)分为无MACE组295例和MACE组35例。患者基于冠状动脉CT血管成像(CCTA)数据分析所有病变血管的斑块特征并测量CT-FFR值。通过Cox比例风险回归模型、Kaplan-Meier生存曲线及ROC曲线分析斑块特征及CT-FFR与MACE之间的关系。结果MACE组冠状动脉狭窄≥50%、CT-FFR≤0.8比例显著高于无MACE组(P<0.01)。单因素Cox分析显示,狭窄程度≥50%及CT-FFR≤0.8是发生MACE的危险因素(P<0.01),经多因素Cox分析校正后,仅CT-FFR≤0.8是发生MACE的独立危险因素(HR=17.037,95%CI:5.060~57.358,P=0.000)。此外,基于CT-FFR的风险预测模型显著优于基于CCTA狭窄程度的风险预测模型(C指数:0.820vs0.696,P=0.000)。结论CT-FFR≤0.8是预测老年冠心病患者远期MACE的重要独立危险因素。根据CT-FFR值进行临床风险分层,可能优化老年冠心病患者的预后管理策略。

Study of the Reservoir Damage during Cyclic Injection and Extraction Process in the Hutubi Gas Storage

During the injection and extraction process in gas storage,cyclic loading stress is applied to the reservoir pore structure,affecting the capacity and service life of gas storage. To study the influence of cyclic injection and extraction on reservoir physical property,a finite-element model of reservoir elastoplastic damage under the effect of pore pressure is established based on elastoplastic mechanics and fatigue-damage mechanics. Considering the mechanical property of the Hutubi reservoir and the injection-extraction mode of gas storage,the finite-element model is used to study the pore pressure and porosity change,fault safety,and ground surface deformation. The results show that the change in pore pressure and porosity,the deformation of the Hutubi fault,as well as the uplift and sink of the grounds surface are controlled by the fatigue damage of the reservoir pore structure during the injection-extraction process. After a 6-year service life, the cumulative deformation of the reservoir pore reaches its limit,causing pore structure collapse and porosity decrease. As a result,storage capacity declines and the ground surface starts to sink. Through this study,the safety of the Hutubi gas storage is evaluated,and some suggestions for field operations are offered.

Influence of Bedding and Mineral Composition on Mechanical Properties and Its Implication for Hydraulic Fracturing of Shale Oil Reservoirs

The premise of hydraulic fracturing is to have an accurate and detailed understanding of the rock mechanical properties and fracture propagation law of shale reservoirs. In this paper,a comprehensive evaluation of the mechanical properties of the shale oil reservoir in the south of Songliao Basin is carried out. Based on the experiments and the in-situ stress analysis, the fracture propagation law of three types of shale reservoirs is obtained,and the suggestions for fracturing are put forward. The results have shown that the fracture propagation of pure shale and low mature reservoir is easy to open along the bedding plane under compression loading,which is greatly influenced by the bedding. Sand-bearing shale is slightly better,the fractures of which are not easy to open along the bedding plane. The mechanical experimental results show that all the samples have the characteristics of low compressive strength,low Young’s modulus and strong anisotropy,indicating that the shale oil reservoir is certain plastic,which is related to its high clay mineral content and controlled by the bedding development. Compared with pure shale and low mature shale,the sandbearing shale has less clay content and less developed bedding,which maybe the main reason for its slightly better brittleness. Overall,the expansion of hydraulic fracture is controlled by in-situ stress and bedding. Because of the development of bedding,it is easy to form horizontal fractures. Thus it is not suitable for horizontal well fracturing.Because of the high content of clay minerals,the applicability of conventional slick hydraulic fracturing fluid is poor. It is suggested to use vertical well or directional well to carry out volume fracturing. In this way,the effect of bedding can be effectively used to open and connect the bedding and form a larger fracture network.

冠状动脉周围脂肪密度指数与斑块参数及血流储备分数关系分析

目的探讨冠状动脉斑块周围脂肪密度指数(FAI)与血流储备分数(FFR)及斑块参数间的关系。方法回顾性收集2015年5月至2019年1月东部战区总医院放射科及上海市第六人民医院放射科113例稳定型冠心病患者(共141个斑块)的资料,其中男78例,女35例,年龄40~83(63±9)岁。所有患者均接受冠状动脉CT血管成像(CCTA)和有创FFR检查。测量斑块及管腔的定量指标(如斑块长度、体积)和定性指标(如斑块性质、高危斑块)以及斑块周围的脂肪密度指数。以斑块周围是否FAI≥-70 HU,将患者和斑块分为FAI阳性组(47例,56个斑块)与FAI阴性组(66例,85个斑块)。分析比较两组间年龄、斑块长度和体积、最小管腔面积(MLA)、CCTA狭窄程度等参数,以及斑块类型、高危斑块数量和特征、心肌缺血(即FFR<0.75)的例数和斑块数。采用logistic回归模型分析心肌缺血与年龄、斑块长度、MLA、FAI等指标之间的关系。采用受试者工作特征曲线比较各指标对心肌缺血的诊断效能。结果 FAI阳性组最小管腔面积较FAI阴性组显著减小[(2.00±1.33)mm2比(4.13±2.41)mm2,P<0.001]。FAI阳性组心肌缺血的病例比例和血管比例高于FAI阴性组(21.3%比4.5%;23.2%比8.2%)(均P<0.05),高危斑块所占比例差异无统计学意义(21.2%比16.1%,P=0.451)。FAI对预测心肌缺血具有一定价值[曲线下面积(AUC)=0.666,P=0.021],且具有增量价值(0.915比0.951,P= 0.033)。结论 FAI较高者MLA更小,心肌缺血的发生率更高,同时FAI对心肌缺血具有一定的预测效能和增量价值。

测量位点对CT瞬时无波比值诊断冠状动脉缺血特异性狭窄性能的影响

目的探究测量位点对CT瞬时无波比值(iFRCT)诊断冠状动脉缺血特异性狭窄准确度的影响。方法回顾性收集2009年2月至2018年5月在东部战区总医院放射诊断科行冠状动脉CT血管成像(CCTA)检查并接受有创性血流储备分数(FFR)检查的44例患者的资料,其中男27例,女17例,年龄40~83(59.3±9.3)岁。基于CCTA图像通过流体力学模拟计算不同位点(狭窄处、狭窄处下游近端、狭窄处下游2 cm、狭窄处下游3 cm、狭窄处下游4 cm)的iFRCT值。以有创性FFR≤0.80作为诊断冠状动脉缺血特异性狭窄的金标准,采用受试者工作特征(ROC)曲线分析不同测量位点iFRCT的诊断性能。采用Bland-Altman图和Spearman相关系数分析iFRCT与FFR间的相关性,采用组内相关系数(ICC)检验iFRCT观察者内和观察者间的一致性。结果狭窄处下游近端(最狭窄处下游约1 cm)iFRCT值诊断冠状动脉缺血特异性狭窄的性能优于其他测量位点,其阈值、曲线下面积、敏感度、特异度、准确度分别为0.91、0.87(95%CI:0.76~0.96)、82%(95%CI:48%~97%)、76%(95%CI:57%~88%)、77%(95%CI:63%~87%)。Bland-Altman分析结果显示狭窄处下游近端iFRCT与FFR之间的差异均值为0.07[95%一致限(LOA):0.06~0.09],r= 0.53(P<0.001)。狭窄处下游近端观察者内ICC为0.92(95%CI:0.85~0.95),r=0.85(P<0.001);观察者间ICC为0.85(95%CI:0.60~0.94),r=0.75(P<0.001)。结论以有创性FFR值为金标准,iFRCT对冠状动脉缺血特异性狭窄具有较好的诊断性能,最佳测量位点为狭窄处下游近端。