Abstract: The pore structure of the low permeability sandstone reservoir is complex and has strong heterogeneity in two-dimensional and three-dimensional space, and it has a dramatic effect on logging response of reservoir. However, the mercury intrusion curves, NMR T2 spectrum and thin section three kinds of data each reflects the different characteristics of the pore structure in some way. In this paper, the microscopic pore structure parameters of three kinds of data were extracted for correlation analysis, finally, pore structure classification was achieved respectively by PCA-FCM, and the classification result is consistent with the mercury intrusion curve fractal method.
Abstract: We deduce the double curl equations of secondary magnetic vector potential and electric scalar potential of frequency domain MCSEM method, then we derive the finite element linear equations of MCSEM three-dimensional forward modeling. In order to eliminate the singularity of the source, the total electromagnetic fields are decomposed into the primary field and the secondary field, where the primary field is expressed quasi-analytically in terms of the Schelkunoff potentials. We realize the three-dimensional finite element forward modeling algorithm of MCSEM method based on structured meshes. In the method, the hexahedral mesh is employed to the model subdivision, the Dirichlet boundary condition is considered, and the symmetric successive over-relaxation preconditioned conjugate gradient (SSOR-PCG) algorithm is used to solve large linear system derived from three-dimensional finite element MCSEM forward modeling. The high accuracy and reliance of our algorithm are validated by the one-dimensional numerical example. Finally, the applicability of the algorithm is illustrated on a resistivity model incorporating a step topography. The effect of submarine topography on MCSEM response is analyzed.
Abstract: K-edge filter is often used in dual-energy X-ray bone densitometry. However, its use with multi-energy bin photon counting detector without Ce and dual-energy with Ce in bone densitometry requires further studies and comparisons. We chose to optimize the spectrum of broad X-ray by using the K-edge characteristic of cerium (Ce) of rare earth material, so as to obtain the dual-energy spectrum. A corresponding energy-threshold calibration method is proposed for dual-energy spectrum in this case, hoping to improve the accuracy of material decomposition in bone densitometry. In this paper, we did a comparison experiment between the triple/dual-energy decomposition without Ce and the dual-energy decomposition after Ce filtration. The experimental results show that the accuracy of the triple-energy decomposition is higher than that of the dual-energy decomposition when without the Ce filtration, and the accuracy of the dual energy decomposition after the addition of Ce filtration is better than that of all the non-Ce filtration obsolete.
Abstract: Objective: To evaluate the value of double low-dose CT coronary angiography (CTCA) by single cardiac cycle acquisition with 320-detector row CT. Methods: 51 patients with low heart rate and normal body type enrolled this study from October 2017 to January 2018. All patients were divided into two groups (Group A and Group B). Group A included 25 patients with tube voltage 80 kV and tube current tailored to body mass index (BMI) (300-500 mA), the injection rate and volume of contrast agent (20-30 mL) tailored to body mass (BM). Group B included 26 patients with tube voltage 100 kV and tube current tailored to BMI (300-500 mA), the injection rate and volume of contrast agent (35-45 mL) tailored to BM. Two groups were evaluated by contrast agent, radiation dose and image quality. P values below 0.05 were considered to be statistically significant. Results: All patients successfully underwent single cardiac cycle CTCA. The mean contrast agent for group A was 28.20 mL; this represents a 30% reduction as compared with that group B (mean, 45.58 mL; t=-9.935, P<0.001). The mean effective dose for group A was 0.96 mSv; this represents a 45% reduction as compared with that group B (mean, 1.76 mSv; t=-10.412, P<0.001). The mean image quality score was 3.59±0.58 obtained with Group A versus 3.66±0.53 obtained with Group B (Z=-1.618, P=0.106). The mean CNR was 20.26±7.34 obtained with Group A versus 23.29±7.06 obtained with Group B (t=-3.350, P=0.001). Conclusion: Double low dose CTCA may decrease the contrast agent and radiation dose keeping image quality assessable in specify patients.
Abstract: Objective: To study the clinical application value of spectral CT combined with cardiac function assessment software in detecting myocardial activity, so as to provide a novel and reliable imaging diagnostic system for the detection of regional myocardial activity. Methods: 40 patients with coronary heart disease were scanned with the high resolution density coronary CT angiography (HDCTA) and the gemstone spectral imaging (GSI) modes. In addition, all cases had the Cardiac MRI scan within a week. HDCTA images were used to measure stenoses. Detect the myocardial perfusion sparse areas on the GSI images. HDCTA images were reconstructed into 20 phases, from 0% to 95%, with 5% interval, and then input them into the cardiac function analysis software package of AW4.4 workstation, it automatically calculate the bullseye map of left ventricular function. Record the average segmental wall motion and wall thickening of the bullseye map corresponding to the myocardial perfusion sparse areas and normal areas of GSI images, and were performed with two-sample t test. Do the consistency test between CT and MRI evaluation results. Results: Spectral CT have detected 27 regions of myocardial perfusion sparse areas on the GSI images, a total of 126 segments corresponding to the bullseye map. All myocardial perfusion sparse areas of the GSI images had associated coronary artery with more than 50% stenosis of the intravascular diameter. There were significant differences in the average segmental wall motion and wall thickening of the bullseye map corresponding to the myocardial perfusion sparse areas and normal areas of GSI images:(3.51±1.54 and 7.57±1.94, P=0.00), (26%±8.8% and 62%±11.3%, P=0.00). The results have high consistency with cardiac cine-MRI imaging and myocardial perfusion imaging. Conclusions: The coronary CTA scan combined with the delayed scan of dual energy spectral imaging in the same scan of Spectral CT, not only can analyze the coronary artery morphology and evaluate the myocardial blood supply, improve the efficiency of the detection of myocardial ischemia, but also can evaluate myocardial function with functional analysis software.
Abstract: During gas reservoir developing, both reservoir effective pressure and gas saturation vary. It is significant for residual gas distribution predicting, using time-lapse seismic technology, to research on effects of effective pressure variation and gas saturation variation on seismic response characters. Acoustic properties between gas and oil are obviously different, and research results of oil reservoir time lapse seismic cannot be applied to gas reservoir, so it is necessary to develop time lapse seismic research in gas reservoir. Using Shapiro model to characterize dry rock modulus varying with effective pressure, and employing Batzle-Wang equation to describe fluid velocity varying with pressure, and jointing Gassmann theory to implement fluid substitution and describe velocity of fluid saturated rock varying with gas saturation, rock physics model of fluid saturated rock velocity varying with pressure and gas saturation is established. Based on the model, multi-wave time lapse seismic AVO (Amplitude-Variation-with-Offset) responses of gas reservoir model are simulated in different gas saturation and different effective pressure. Results demonstrate that effective pressure and gas saturation can be discriminated by multi-wave time lapse AVO technology and it is a guide to develop multi-wave time lapse seismic fluid monitor.
Abstract: The road collapse has been a serious threat for safety of the traffic, and it is of great practical significance to study the detection method of road collapse. This paper analysis the technique and its application of three dimensional ground penetrating radar (GPR) for detecting certain road collapse. In order to find out the spatial distribution characteristics of the road collapse zone, the 23 survey lines are set up in the collapse area by a observed mesh with size of 1.0 m×0.5 m, the data collection are carried out. The observed GPR data are processed by conventional method and the two and three dimensional radar profile were obtained. The comprehensive analysis and explanation of the processed profile are conducted with the geological condition, and the location, depth and development of the collapse are accurately found which proved that the interpretation results are reliable. Engineering practice shows that the application of three dimensional GPR can be rapid, and efficient in road subsidence detection, the detection result can provide key reference for prevention and control of subsidence of subsequent construction and safety.
Abstract: The cross-well electromagnetic wave CT technology is based on the difference of the physical properties between the media. Different materials have different reflective and absorbing abilities to electromagnetic waves. Interwell electromagnetic wave CT technology has a good effect in detecting Karst cracks and other aspects. In this paper, using interwell electromagnetic wave CT technology to tested the underground Karst development area of Sujiatang. Through studying the difference of rock electromagnetic wave absorption coefficient in the working area. Four layers of Karst development areas of underground were divided. The correctness of the detection results was verified by comparing with the core data of boreholes. The detection results provide necessary basic data for engineering design and construction.
Abstract: Acoustic televiewer is a geophysical logging system which utilizes acoustic travel time and amplitude parameters for borehole wall imaging. The system has such that characteristics:high image resolution, fast logging speed, working in turbid well fluid, data processing and analysis process relatively simple because of its perfect software with digital technology and configuration. It is an effective means to study the structure surface of the rock strata. In the evaluation of the rock mass stability of a copper-cobalt mine in Congo (DRC), the acoustic logging method is used to obtain the dominant structural surface of the rock mass. The reliable data are provided for determining the slope angle of the open mining pit and shear strength index of the rock mass. The principle and method of the RG Acoustic televiewer logging are introduced in this paper. And rock mass structure surfaces and fractures revealed by borehole in wall image were analyzed, taking DK02 as a example. Engineering practice shows that the acoustic television in deep rock mass in situ investigation has obvious advantages.
Abstract: Objective: To investigate the application of diffusion tensor imaging (DTI) and susceptibility weighted imaging (SWI) in the changes of substantia nigra in patients with early primary Parkinson's disease. Methods: Conventional sequence, DTI, and SWI scans were performed on 13 patients with early primary Parkinson's disease and 13 volunteers as controls using a 3 T magnetic resonance imaging system. The FA and ADC values of the substantia nigra of the two groups and the size of the substantia nigra pars compacta were measured. Results: The FA values of bilateral substantia nigra were reduced in the PD group compared with the control group, the difference was statistically meaning (P<0.05). There was no significant difference in the ADC values of the substantia nigra between the two groups (P>0.05). The size of the substantia nigra pars compact in the PD group was smaller than that in the control group, the difference was statistically meaning (P<0.05). Conclusions: The FA value of the substantia nigra and the size of the substantia nigra pars compacta contribute to the early diagnosis of PD. DTI and SWI have a synergistic effect and may provide valuable clues for the early diagnosis of PD.
Abstract: Objective: To review the CT manifestations, clinical features and ultrasonic results of patients with Acute abdominal vascular disease, and summarize the diagnostic experience to improve the diagnosis. Method: 156 cases with acute abdomen vascular disease of clinical data and imaging data underwent emergency abdominal CT examination in the emergency department of our hospital from January 2012 to March 2017, are analyzed retrospectively. According to the different types of vascular lesions and the different vessels involved, the cases are divided into five major types, and the number of cases, the typical CT image performance and the positive rate of ultrasound are analyzed respectively. Results: The classification as follows:(a) Arterial dissection and aneurysm (53 cases). Among them, there were 17 cases of arterial dissection, including 15 cases of thoracic aortic dissection downward continuation, 1 cases of limited dissection of the inferior segment of abdominal aorta, 1 cases of abdominal aortic dissection extending to the right iliac artery; and 36 cases of aneurysm:including 30 cases of abdominal aortic aneurysm, 3 cases of abdominal aorta pseudoaneurysm, 1 case of splenic artery pseudoaneurysm, 1 case of rupture of abdominal aortic aneurysm after stent implantation and 1 case of right iliac artery aneurysm. (b) Mesenteric vascular diseases (30 cases). Among them, there were 12 cases of superior mesenteric artery embolism, 1 cases of inferior mesenteric artery embolism, 15 cases of mesenteric vein embolism (including 5 cases with portal vein embolism), 1 case of superior mesenteric artery dissection and 1 cases of mesenteric artery intramural hematoma. (c) Portal vein system diseases (52 cases). Among them, there were 19 cases of portal hypertension, 17 cases of portal vein thrombosis, 9 cases of portal vein tumor thrombus, 3 cases of cavernous change of portal vein, and 4 cases of portal venous gas. (d) Spleen infarction or renal infarction (12 cases). e) Other types of acute abdominal vascular disease (9 cases). Conclusion: For acute abdominal vascular disease, enhanced CT has a greater advantage than plain CT and ultrasound. Different types of acute abdominal vascular disease have different typical CT manifestations. Both clinical and imaging doctors need to strengthen the recognition and attention to the disease, summarize the diagnostic experience, reduce misdiagnosis and misdiagnosis, and finally improve the level of diagnosis of this kind of disease.
Abstract: objective: To investigate the application value of automatic injection of iodine with colonic imaging in children with colon and small intestine lesions. Methods: 55 cases of children with suspected lower gastrointestine lesions were collected in our hospital. All patients were diagnosed with colon and small intestine lesions by automatic injection of iodine colonic examination. Results: Automatic injection of iodine with colonic angiography showed the location of the lesion. The diagnosis was 5 cases of congenital jejunal stenosis, 10 cases of congenital jejunum atresia with small colon, 20 cases of congenital ileum atresia with small colon, 2 cases of congenital small intestine, and 4 cases of congenital anal atresia with rectal vaginal fistula. Congenital giant colon 12 cases, colon polyp 2 cases. Conclusion: Automatic injection of iodine colonic examination is simple, safe, fast and effective. It is not only the best method to diagnose children's colon and small intestine lesions, but also can reduce the radiation damage of children and their accompanying family members.
Abstract: Objective: To analyze the value of 64 slice spiral CT and DSA in evaluating the degree of patency and stenosis after coronary artery stent implantation. Methods: 250 patients with acute coronary syndromes treated in our hospital from January 2013 to April 2018 were selected as the subjects of this group. 64 layers of spiral CT and DSA were used to evaluate the degree of patency and stenosis after coronary stent implantation in patients with acute coronary syndromes. The evaluation value of both was analyzed. Results: There was no significant difference in coronary artery imaging scores of different sites by 64 slice spiral CT and DSA (P>0.05). 64 layers of spiral CT and DSA were used for coronary artery imaging score of different diameter stents (P>0.05). 64 layers of spiral CT and DSA examination were used for different scaffolds. There was no significant difference in the results of the arteriography score (P>0.05); 96 stents were placed in 52 patients. The patients were examined with 64 spirals CT and DSA. The results showed that there was no statistical difference between 64 layers of spiral CT and DSA (P>0.05). Conclusions: 64 rows of spiral CT coronary angiography were used to evaluate the degree of patency and stenosis after coronary stent implantation in patients with acute coronary syndromes and the results were in high agreement with the results of DSA.
Abstract: Objective: Based on the ABCD2 score, the predictive value of DWI and CTA combined with the risk of cerebral infarction after a short-term TIA was evaluated. Methods: A total of 170 patients with TIA (average age 62.4±5.4 years) were selected consecutively from January 2015 to June 2017 in this hospital. All patients underwent DWI and CTA examinations and were followed up for 3 months. The ABCD2 score, DWI positive results, and CTA diagnosis of large artery atherosclerosis (LAA) were recorded at 7 and 3 months, respectively, to evaluate the predictive value of all patients with a short-term cerebral infarction risk. Results: Of the 170 patients, 68 (40%) were DWI positive and 43 (25%) were diagnosed with LAA. Unilateral limb weakness in DWI-positive patients (OR=2.3; 95% CI, 1.1-4.8), duration of TIA symptoms ≥ 60 minutes (OR=3.7; 95% CI, 1.4-9.9), ABCD2 >5 (OR=5.4); 95% CI, 1.5-18.8), LAA (OR=2.7; 95% CI, 1.3 to 5.5). During follow-up, 1 case of cerebral infarction occurred within 7 days, and 6 cases of cerebral infarction occurred within 7 days to 3 months. ABCD2 score was greater than 5 (OR=24.4; 95% CI, 2.5-238.7), and DWI positive result (OR=9.8; 95% CI, 1.1-83.1), LAA (OR=20.4; 95% CI, 2.4-175.1). With the exception of one patient, patients with cerebral infarction within 3 months were all positive for DWI. The ABCD2 score, DWI positive results, and LAA were associated with an increased risk of cerebral infarction at 7 days and 3 months. Conclusion: The introduction of DWI and CTA examinations based on the ABCD2 score as an aid can improve the ability to predict stroke risk after TIA.
Abstract: Positron emission computed tomography (PET) is a molecular functional-level imaging technique that can reflect the functional metabolism of an aspect of the body through the development of a specific tracer injected in the body. In recent years, the application values of PET diagnosis has been more and more clinically recognized, and the imaging system has also developed rapidly, like a variety of functional PET instruments have been developed and introduced. In 2017, the world's first panoramic dynamic scan PET/CT (axial vision Field is 196.6 cm) launched at home. Therefore, this paper will review the technical developments of PET/CT in recent years and the breakthroughs of dynamic scanning PET/CT.