CT理论与应用研究

Separation of Single Order Marine Surface-related Multiples

YE Yueming, REN Haoran, XU Zhicheng, LI Lisheng, WANG Libao, YANG Cun

2021, 30(2): 139-147. doi: 10.15953/j.1004-4140.2021.30.02.01

Abstract(381) PDF(21)

Abstract:
High energy surface multiples are commonly developed in marine seismic data.Traditional surface multiples suppression(SRME) can predict all order surface multiples,but surface multiples were stack together.In order to utilize different order surface multiple independently to image subsurface structure and reduce the influence of interference,it is necessary to separate different order surface multiples.In this paper,we proposed a way of separating single order surface related multiple based on extended SRME.First,all order surface related multiples were predicted by SRME.Second,the boundary conditions of conventional SRME were modified,and the predicted surface multiples from the first step were updated.Third,single order surface multiple can be obtained by the adaptive subtraction between multiples from the first step and the second step by which surface multiples of different orders can be separated gradually.Numerical model and a deep-sea real data test show the effectiveness of this method.Different order multiples were separated effectively,which supports the application of multiples imaging technology.

Research on Spectral Whitening Method of Seismic While Drilling Ahead Detection Signals Based on VMD

JI Ziqi, ZHANG Xueqiang, ZHANG Haijiang, CHA Huasheng, MEI Huan, CHENG Tingting

2021, 30(2): 148-160. doi: 10.15953/j.1004-4140.2021.30.02.02

Abstract(290) PDF(12)

Abstract:
Seismic source of seismic while drilling ahead detection is consistent and uncontrollable,which requires to convert continuity source records into equivalent pulse source records by cross-correlation to obtain effective reflected signals.However,as the signal often contain dominant frequencies with narrow frequency band and relatively large amplitude,so the method of cross-correlation processing will lead to serious interference.This article proposes to apply the Hilbert spectral whitening method which based on VMD(variational mode decomposition) to signals of seismic while drilling ahead detection.Firstly,this method decomposes the seismic signals into multiple IMF(intrinsic mode function) with VMD,then the IMF is decomposed by Hilbert transform,finally,the Hilbert spectrum is whitened by a whitening filter.The numerical simulation results show that the Hilbert spectrum whitening method which based on VMD can not only ensure well consistency of signals for each trace,but also equalize the different frequency components of signals,effectively suppress the false lineups in the cross-correlation records,and accelerate the attenuation of the sidelobe of the main peak.The method proposed in the article is applied to the actual data of a tunnel in Yangzhuang coal mine,Huaibei,Anhui province,and the fault structure in front of the tunnel face is successfully detected,which shows that the method is very practical.

Study on the Manufacture Technical of Eye Beads Unearthed from Sampula Cemetery

ZHANG Xueyan, GUO Jinlong, CHENG Qian, WANG Bo, LEI Yong

2021, 30(2): 161-169. doi: 10.15953/j.1004-4140.2021.30.02.03

Abstract(257) PDF(9)

Abstract:
The Sampula cemetery is located in 14 kilometers southwest of Luopu county, Khotan, Xinjiang province, which is on the southern route of the ancient Silk Road. In the 1980 s, archaeologists carried out several excavations at Sampula cemetery, which a total of 1,369 glass beads were found. Based on the X-ray Computed tomography, this paper analyzes the structure of the four typical eye beads, so as to infer the production process of the eye beads under the background of the times.

Study on Concrete Mesoscopic Damage Under Dynamic Loading Using CT Image Segmentation and Gray Level Co-occurrence Matrix Eigenvalue

DING Weihua, ZHU Lin, HUANG Li, ZHANG Le, QIN Junrong, LI Aiguo

2021, 30(2): 170-182. doi: 10.15953/j.1004-4140.2021.30.02.04

Abstract(327) PDF(10)

Abstract:
The process of concrete internal damage development to fracture is completely recorded by series CT images of concrete under dynamic loading.However,macroscopic damage of concrete has occurred when the microscopic cracks can be observed at CT image.The core of concrete CT image analysis is to excavate the microscopic damage information in concrete damage stages.In this research,image segmentation technology and gray co-occurrence matrix theory(GLCM) were used to extract the porosity and four eigenvalues(contrast,energy,correlation and homogeneity) respectively to study the change law of these parameters with stress in different cross sections under uniaxial dynamic compression using CT.Results show that porosity presents a general trend of monotonous increase with the increase of stress,while the porosity in some parts shows little change with the increase of stress when the stress level is small,which reflects the influence of concrete density compression effect.Contrast increases and decreases with the increase of stress at low stress level due to the influence of density compression effect.The index of energy is not sensitive to stress change.Correlation and homogeneity increase monotonously with the increase of stress,which are more sensitive for reflecting the whole damage process of concrete.This study shows that the sectionalized porosity,homogeneity and correlation of GLCM is helpful to reflect the mesoscopic damage process of concrete under dynamic load.

CT Value Study of Small Intestinal Loop Aggregation in Predicting Mesenteric Contracture in Patients with Pseudomyxoma Peritonei

JIA Hongmin, ZHAI Xichao, WANG Zhiqun, WEI Hongjiang

2021, 30(2): 183-191. doi: 10.15953/j.1004-4140.2021.30.02.05

Abstract(273) PDF(9)

Abstract:
Objective: To investigate the diagnostic value of CT scanning combined with multiplane reconstruction(MPR) and volume reconstruction(VR) for evaluating small intestinal loop aggregation in predicting small mesenteric contracture in patients with pseudomyxoma peritonealis(PMP). Methods: From January 2018 to December 2019, 179 patients with pseudomyxoma peritonei confirmed by surgery and pathology in our hospital were retrospectively analyzed. Among them, 31 cases were confirmed with mesenteric contracture during operation, and 148 cases were without mesenteric contracture. Axial CT, MPR and VR were used to determine the aggregation of small intestinal loops, and to further predict the diagnosis and treatment of mesenteric contracture. Single factor logistic regression, ROC curve and Spearman rank correlation analysis were used to analyze the efficacy, P<0.05 was considered as significant statistical difference. Results: the detection rate of small intestinal loop aggregation was analyzed by univariate logistic regression: VR > coronal > axial > sagittal, and the prediction of diagnostic efficiency of mesangial contracture was VR > coronal > axial > sagittal. ROC curve was used to analyze the diagnostic efficacy of small intestinal loop aggregation in predicting mesenteric contracture: axial sensitivity 58.8%, specificity 79.6%, positive predictive value 46.5%, negative predictive value 86.5%; coronal sensitivity 55.9%, specificity 89.6%, positive predictive value 61.4%, negative predictive value 87.1%; sagittal sensitivity 50.0%, specificity 72.6%, positive predictive value 35.4%, negative predictive value 87.1%, the sensitivity, specificity, positive predictive value and negative predictive value of VR were 76.5%, 78.8%, 52% and 91.8%, respectively. Spearman rank correlation analysis: axial, coronal, sagittal and VR were highly correlated to predict the results of small intestinal mesangial contracture. Conclusion: The single axial CT image has limited effectiveness in the evaluation of small intestinal loop aggregation. Combined with coronal and VR images, it is helpful to improve the accuracy of small intestinal loop aggregation evaluation; There is a high correlation between the small intestinal loop aggregation and the results of predicting mesenteric contracture. The sensitivity and specificity of using the small intestinal loop aggregation to determine mesenteric contracture are limited, so further research is needed to improve the detection rate of preoperative diagnosis of mesenteric contracture.

CT Features Analysis of Peripheral Primitive Neuroectodermal Tumor

SUN Pengtao, DOU Xuechao, SUN Xiaoli, WEI Hailiang, ZHAO Tong, SUN Ying, WANG Rengui

2021, 30(2): 192-198. doi: 10.15953/j.1004-4140.2021.30.02.06

Abstract(317) PDF(6)

Abstract:
Objective: To investigate the CT manifestations of peripheral primitive neuroectodermal tumor(pPNET) in order to improve the diagnostic ability of the disease. Methods: CT images of 14 pPNET confirmed by pathology were analyzed retrospectively, and the imaging features were summarized, including location, size, shape, density, enhancement mode, boundary and metastasis. Results: 6 females and 8 males patients were included. The median age was 34 years. Among the 14 pPNET, 4 cases occurred in the abdominal cavity, 3 cases in the retroperitoneum, 3 cases in the pelvis, 2 cases in the posterior mediastinum, 1 case in the rib, and 1 case in the pelvis. 8 cases were single mass, 6 cases were multiple mass or nodule. In 12 cases(85.71%), the diameter of lesions was more than or equal to 5 cm. The single lesion usually showed irregular lobulation. On nonenhanced CT scan, the density was not uniform, low density necrosis area was found in the focus, and spot calcification was found in 4 cases. The average CT attenuation of solid part of the lesions was about 41.18 HU, and the enhanced lesions showed light to medium enhancement. The average CT value of arterial phase, portal phase and delayed phase increased by 14.85 HU, 21.42 HU and 22.50 HU, respectively. Multiple lesions appear as nodule or mass of varying sizes. The density, borders, and enhancement characteristics of multiple lesions was similar to single lesion. There were 2 cases with peripheral venous thrombosis. Among the 12 cases, 7 had lymph node metastasis. Peritoneal metastasis was found in 3 patients. Conclusion: The CT manifestations of pPNET have some features. Enhanced CT can clearly show the extent of lesions, surrounding invasion and metastasis and provide important diagnostic information for clinical work.

Chest CT Features of COVID-19 and Its Evolution

SHEN Jing, YU Jing, YAN Yingnan, SANG Yarong, JU Ronghui, PAN Long, LI Guize, LI Xin, WU Jianlin

2021, 30(2): 199-207. doi: 10.15953/j.1004-4140.2021.30.02.07

Abstract(362) PDF(10)

Abstract:
Objective: To analyze the chest CT features of COVID-19 and its evolution. Method: Retrospectively analyze the chest CT features of 52 cases of COVID-19, including location, distribution, density and others. The CT features after treatment of COVID-19 were also analyzed. Results: Within 52 patients, the CT of 2 light type patients was negative, the other 50 patients(43 common and 7 severe types) were positive for the first time CT scan. 45 patients(45/50, 90.00%) had multiple GGOs in both lungs, of which 30 patients(30/50, 60.00%) showed as partial consolidation and 15 patients(15/50, 30.00%) showed as pure GGO(pGGO), the lesions mainly distributed in the peripheral area of the lungs; only 5 patients(5/50, 10.00%) showed as consolidation. Most of the lesions were patchy, multiple and leafy distributed. About 74.00%(37/50) cases showed thickening blood vessels, 52.00%(26/50) cases showed air bronchus sign, 54.00%(27/50) cases showed halo sign and 36.00%(18/50) cases showed paving stone sign. 25 cases accepted CT scan after treatment(2~10 d), GGO lesions showed partial absorption in 14 cases(56.00%), density and lesions increased in 11 cases(44.00%). Conclusion: The main chest CT features of COVID-19 were multiple patchy GGO with or without pulmonary consolidation in the peripheral areas of lungs, which may be accompanied with thickening blood vessels, air bronchus sign and "paving stone sign". After treatment, the lesions of lungs can be absorbed, the density decreased, or the lesions can become consolidation, fibrosis and so on. Based on the above recognition of CT signs, it is helpful for clinicians to make early diagnosis and timely evaluation of COVID-19 therapeutic effect.

The Application Value of Dual-Energy CT Virtual Monoenergetic Imaging in the Differential Diagnosis of acute and Chronic Spinal Compression Fractures

KONG Lingling, XU Chijie, ZHAO Minyue, DENG Xiaoyi

2021, 30(2): 209-216. doi: 10.15953/j.1004-4140.2021.30.02.08

Abstract(279) PDF(12)

Abstract:
Objective: To explore the value of dual-energy CT virtual monoenergetic imaging in the differential diagnosis of acute and chronic spinal compression fractures. Methods: A total of 85 patients with spinal compression fractures were underwent DECT examination and retrospective analyzed, including 50 acute spinal compression fractures(60 vertebral bodies) and 35 chronic spinal compression fractures(48 vertebral bodies). All lesions were diagnosed by surgical pathology or clinical follow-up. The dual-energy CT virtual monoenergetic images were reconstructed into 9 groups(40~120 ke V). Two radiologists scored the image quality of the dual energy CT virtual monoenergetic imaging at different energy levels. Kappa test was used to evaluate the consistency between observers. A senior radiologist measured the CT values of spinal vertebral bodies with acute and chronic compression fractures under different energy levels of dual-energy CT virtual monoenergetic imaging. The Mann-Whitney U test was used to compare the differences between CT values. The ROC curve was used to analyze the differential diagnostic performance of virtual monoenergetic imaging for acute and chronic spinal compression fractures. Results: The subjective assessment of image quality between the two observers was consistent(Kappa = 0.805), and the image quality score was highest at 80 ke V virtual monoenergetic level. There were statistically significant differences in CT values between spinal acute and chronic vertebral bodies at different levels of virtual monoenergetic imaging, with P values < 0.05. ROC curve analysis showed that the highest AUC value at 120 ke V was 0.72, and the corresponding sensitivity was 86.7%. Conclusion: Compared with conventional CT, dual-energy virtual single-energy imaging can perform qualitative and quantitative comprehensive evaluation through morphological features and CT values. It can better identify acute and chronic compression fractures of the spine, which can help guide clinical treatment decisions and improve patient prognosis.

The Role of CT Examination in 2019 New Coronavirus Epidemic

XIE Jing, LV Shuangzhi

2021, 30(2): 217-224. doi: 10.15953/j.1004-4140.2021.30.02.09

Abstract(311) PDF(9)

Abstract:
Objective: Analyze the role of CT examination in the 2019 new coronavirus epidemic. Methods: Retrospectively analyze all 8 864 cases of CT examination of the chest and heart group from the radiology department of The First Affiliated Hospital, College of Medicine, Zhejiang University from January 19 to February 19, 2020. The CT diagnosis results of these patients were summarized and analyzed. Result: 77.17% of the cases with CT diagnosis suspected to be Coronavirus disease(COVID-19) were confirmed. The number of CT examinations per capita for 55 discharged patients during hospitalization was 4 times, and 23 patients underwent CT re-examination after discharge. Conclusion: Imaging examination cannot replace nucleic acid testing, but it plays a vital role in the screening and treatment evaluation of new coronary pneumonia.

The Value of CT Quantitative Analysis in the Diagnosis of COVID-19

SHU Yi, ZHONG Linze, CAO Libo, BAI Hongli, SUN Jiayu

2021, 30(2): 225-233. doi: 10.15953/j.1004-4140.2021.30.02.10

Abstract(301) PDF(10)

Abstract:
Objective:Study of the correlation between the CT quantitative analysis and clinical manifestation of the COVID-19 based on High Resolution Computed Tomography (HRCT) images.Methods:We collected 38 cases of the COVID-19 patients in which 38 cases displayed positive test,and the rest of the cases were clinically proven and identified at the West China Hospital of Sichuan University.We classify patients displaying moderate clinical symptoms as non-severe patient group,and we identified the rest of the patients in the sample as severe group.By using the quantitative analysis tool Volume,we measured the following quantities,mean density (MD),Total pulmonary volume (TV),and COVID-19 infected total volume (including ground-glass opacity PI_-700~-534,senile idiopathic pulmonary interstitial fibrosis PI_-534~-188,and pulmonary consolidation with PI_>-188).We thus investigated the correlation between the oxygen saturation level and pulmonary injury level for these two groups of our sample of 38 cases of COVID-19 patients.Results:In our sample of study,we classified 30 patients as moderate group,and the rest of 8 patients as severe group.Both groups displayed insignificant distribution in age and gender with P>0.05.(1) severe group has higher volumetric Lesion volume and mean density of the infected area this includes (including PI_-700~-534,PI_-534~-188,PI_>-188).The distribution of lesions in the lungs of patients with two types is different comparing with the moderate group (P<0.05).(2) In the general group,the proportion of ground-glass lesions (PI_-700~-534) was the largest,followed by the proportion of grid-like lesions (PI_-534~-188) and the proportion of pulmonary consolidation with PI>-188 (P<0.05).In severe patients,there was no significant difference in the proportion of ground-glass lesions and grid-shaped lesions (P>0.05),but higher than the proportion of pulmonary consolidation with PI>-188 (P<0.05).(3) The distribution characteristics of lesions in the lungs of patients with different clinical types were different (P<0.05).(4) The oxygen saturation has a negative correlation with the VCOVID-19 and PI_-534~-188.(The correlation coefficients were-0.449,-0.443,respectively).Conclusion:From our study,we concluded that the CT quantitative analysis is applicable as a clinical tool to diagnose patients with COVID-19.It could also be used to measure the pathological level and lesions ranges in these patients as well.

Accuracy Evaluation of Coronary Artery Calcification Score Based on AI chest CT Plain Scan

CHEN Jie, SUN Huili, ZHANG Huan, CUI Bin, GUO Chao, WU Xiaoyin, GUO Ning, WANG Zhiqun

2021, 30(2): 234-242. doi: 10.15953/j.1004-4140.2021.30.02.11

Abstract(453) PDF(26)

Abstract:
Objective: To explore the consistency of artificial intelligence-based non-gated low-dose CT(LDCT) plain scanning with ECG gated-CTA on risk stratification of coronary artery calcification score(CACS). Methods: A total of 100 patients with coronary artery CTA scan were analyzed retrospectively. All patients were selected for both coronary ECG gated-CTA scan and routine non-gated chest LDCT plain scan. Agatston calcification score software was applied to record ECG gated-CTA calcification score in Siemens post-processing workstation, and Shukun artificial intelligence analysis software was applied to record non-gated chest CT plain scan calcification score. With the original standard threshold, Kappa test was applied to stratify the risk of non-gated chest LDCT plain scan and ECG gated-CTA assessed CACS. The subject operating characteristic(ROC) curve was adopted to test the diagnostic efficacy of non-gated chest LDCT plain scan and to obtain the optimal new threshold value. The CACS value evaluated by the non-gated chest LDCT with the new threshold value and by ECG gated CTA with old threshold value were selected for further Kappa test. Pearson correlation of calcification integral between the two methods was compared. P<0.001 was set as statistically significant difference. Results: On non-gated chest LDCT plain scan, the risk of CACS was stratified according to the original threshold value, and it was consistent with the ECG-gated CACS value. Kappa value was 0.804 with P<0.001. When comparing the non-gated chest with CACS measured by chest LDCT and that measured by ECG gated-CTA, The area under ROC curve(AUC) of low-medium risk group was 0.910 with P<0.001, and the optimal diagnostic threshold was 112.35. The AUC of the medium-high risk group was 0.988 with P<0.001, and the best diagnostic threshold was 398.31. Consistency test was performed on the risk stratification of CACS measured by non-gated chest LDCT plain scan according to the optimal diagnostic threshold, and the risk stratification of CACS measured with ECG-gated CTA scan according to the original threshold. The Kappa value was 0.850, P<0.001. The Pearson correlation coefficient measured by the two methods was 0.985 and P<0.001, showing a significant correlation. Conclusion: The evaluation of coronary artery calcification by non-gated CT scan based on artificial intelligence and ECG-gated CTA technology is highly consistent. In this study, a new standard for risk stratification of CACS values under non-gated conditions was established, which further improved the accuracy of CACS values evaluated by non-gated chest LDCT and contributed to the early detection of coronary heart disease.

The Value of Four-dimensional Dual Energy CT on Diagnosis of Parathyroid Adenoma

GAO Shuai, ZHAO Teng, GU Hua, JIANG Tao, LI Hui, LI Xinyue, WEI Bojun

2021, 30(2): 244-252. doi: 10.15953/j.1004-4140.2021.30.02.12

Abstract(261) PDF(6)

Abstract:
Objective: To investigate the imaging characteristics and material tissue characteristics of parathyroid adenoma(PA) with four-dimensional dual energy computed tomography(4D-DECT), and to evaluate the value of localization and qualitative diagnosis. Materials and methods: the clinical and 4D-DECT imaging data of 53 patients with PA confirmed by operation and pathology were retrospectively analyzed. The CT signs were observed and recorded, and CT value, iodine concentration, Rho, Z value and DEI were measured and analyzed. Results: In 53 patients, 52(98.11%) cases of PA were solitary, 1(1.89%) case with multiple nodules, a total of 54 lesions were found, 32(59.26%) of which were located in the trachea-esophageal sulcus, 10(18.52%) lesions were ectopic adenomas, and 22(40.74%) lesions showed "short line sign", 14(25.93%) showed "polar vessel sign"; there was no significant difference in CT value between PA and thyroid in arterial phase(90 kV), but the CT value of PA, thyroid and lymph nodes were different in non-contrast, arterial phase(M 0.5, 150 kV) and venous phase(90 kV, M 0.5, 150 kV). Iodine concentration, Z value and DEI of lymph nodes in arterial and venous phase were significantly lower than those of PA and thyroid, iodine concentration, Z value and DEI of PA in venous phase were significantly lower than those of thyroid; Rho of thyroid in arterial and venous phase was significantly higher than that of PA, and Rho of PA in arterial phase was significantly higher than that of lymph nodes. Conclusion: 4D-DECT can better display the imaging features of PA, and can also provide the analysis of iodine concentration and a variety of material tissue characteristics information, which is helpful to improve the diagnostic accuracy of PA.

Application and Research Progress of Spectral CT in Hypervascular Hepatic Lesions

PENG Jiaxuan, JIANG Guangbin, JIANG Lun

2021, 30(2): 253-262. doi: 10.15953/j.1004-4140.2021.30.02.13

Abstract(292) PDF(9)

Abstract:
Liver lesions are a common disease in our clinical work. Early intervention and accurate diagnosis are very important for treatment selection and improving the survival of patients. Spectrum CT, as new imaging technology, can provide single-energy imaging and multiple energy spectrum parameters for quantitative and qualitative evaluation of liver diseases, especially for highlighting the blood supply characteristics of liver diseases, which are contributed to the early detection, diagnosis and postoperative evaluation. This article reviews the application and research progress of spectral CT in those hypervascular liver lesions.

Progress on Analytical CT Reconstruction Methods:From Circular Trajectory Scanning to Multi-source Linear Trajectory Scanning Imaging

CHEN Changyu, GAO Hewei, ZHANG Tao, XING Yuxiang, ZHANG Li, CHEN Zhiqiang

2021, 30(2): 263-277. doi: 10.15953/j.1004-4140.2021.30.02.14

Abstract(508) PDF(83)

Abstract:
Since the first X-ray computed tomography(CT) scanning was performed by Hounsfield in 1971,CT has mainly walked through five generations and deeply influenced us in many fields,such as medical applications and security inspections.With the development in CT scanning configurations,their reconstruction theories have been growing rapidly.Compared with iterative methods,analytical algorithms can achieve faster reconstruction with simpler error analysis and fewer computing resources,which makes them rather popular in CT products.This review strives to illustrate analytical CT reconstruction methods following the development of scanning modes,from circular and helical trajectories to nonstandard trajectories.As a special case of nonstandard trajectories,recent progress on multi-source linear CT is also highlighted.Finally,we discuss some opportunities and challenges of CT scanning configurations in the future.

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2021 Vol. 30, No. 2