CT理论与应用研究

The Study of Local Distortion in Magnetotelluric Using Three-dimensional Modeling

CAI Jun-tao, ZHAO Guo-ze, XU Xi-wei

2017, 26(4): 391-402. doi: 10.15953/j.1004-4140.2017.26.04.01

Abstract(481) PDF(5)

Abstract:
Local distortion by small-scale structures has impeded the interpretations of the magnetotelluric method (MT) for several years. The developing of three-dimensional (3D) MT modeling makes it is possible for the study of the local diction and reliable imaging of the subsurface electrical conductivity structure. In this paper, several general 3D local distortion models are designed and model responses are computed by 3D modeling. The apparent resistivity curve of polarization mode with electric field perpendicular to the electrical interface, which is corresponding to TM mode in three-dimensional (2D), will upward shift at first and then downward shift when it across small conductive surface body. While crossing resistive body, the curve will downward shift at first and then upward shift. This phenomenon is associated with secondary electric field caused by the accumulative surface electric charges at the boundaries of the anomaly. In 3D model, the variation in horizontal slice of apparent resistivity and phase for YX mode and XY mode are approximate vertically symmetrical, which is consistent with the case that curves of polarization mode with electric field perpendicular to the electrical interface. When the survey line along the east-west direction, the YX mode of the 3D response corresponds to the TM mode in the 2D case. While the survey line along the south-north direction, the XY mode of the 3D response corresponds to the TM mode in the 2D case. The distortion on regional response caused by small conductive inhomogeneous are more severe than that of resistive inhomogeneous. The apparent resistivity and phase of both two polarization modes are obviously affected by local distortion of small conductive anomaly, while the distortion on TM mode response is slightly lesser than that on TE mode caused by electrical anomaly. Therefore, when two-dimensional inversion is used for MT data, it is preferable to fit the TM model data. At the position located directly over the small inhomogeneous, the difference between 3D distortion response and 2D corresponding regional response is much large. But this 3D distortion response can be equivalent to a 2D response. It is more important to pay more attention to this false 2D response caused by local distortion in MT interpretation.

Imaging Microstructures of Mouse Inner Ears in Situ by Phase Contrast Micro-CT

YIN Hong-xia, ZHANG Peng, LIU Yun-fu, YANG Zheng-han, LI Jing, ZHAO Peng-fei, LV Han, XIAO Ti-qiao, XIAN Jun-fang, WANG Zhen-chang

2017, 26(4): 403-410. doi: 10.15953/j.1004-4140.2017.26.04.02

Abstract(408) PDF(4)

Abstract:
Objective: Aim of the study was to image the mouse inner ears in situ by phase contrast Micro-CT, and explore the ability of this technique to display the microstructures. Method: The experiment was performed according to our institution's guidelines on the care and use of laboratory animals. An adult mouse was anesthetized and sacrificed, followed by phase contrast Micro-CT scan for both inner ears. The CT data sets were reconstructed using the filtered back-projection (FBP) algorithm. Different pixel-size CT images, including 9 μm, 18μm, 36 μm, 54 μm and 72 μm, were obtained after image processing. Results: The CT images of 9 μm pixel size visualized clearly the microstructures of inner ears, including modiolus, osseous spiral lamina, utricular macula and saccular macula. The edge sharpness of the microstruetures was decreasing when the pixel size of the images became bigger. The CT images of 18~tm and 36 ktm pixel size also displayed all of the microstructures. The microstructures were seen in the CT images of 54μm pixel size, but their edges were blurry. The CT images of 72~m pixel size showed an indistinct outline only of the modiolus and osseous spiral lamina, while the outline of utricular macula and saccular macula was not observed. Conclusion: Phase contrast Micro-CT was demonstrated to have the potential to visualize the microstructures of mouse inner ears in situ.

Meso-structural Evolution of Expansive Soil in Nanyang during Wetting-drying Cycles under Loading Condition

ZHU Guo-ping, CHEN Zheng-han, WEI Chang-fu, LV Hai-bo, WANG Zhi-bing, LIANG Wei-yun

2017, 26(4): 411-424. doi: 10.15953/j.1004-4140.2017.26.04.03

Abstract(372) PDF(5)

Abstract:
In order to study the meso-structural evolution of expansive soil during wetting-drying cycles, the CT-consolidation apparatus was developed; A number of tests of wetting-drying cycles were carried out for intact and remolded expansive soil under loading condition, and CT scanning was taken on samples after each wetting and drying finished.The research results indicate that during wetting-drying cycles the amount of shrinkage and swell of samples are large. After three times of wetting-drying cycles, the volume of soil samples under the same saturation is no longer changed. Both wetting and drying can induce the structural damage of expansive soil samples. After first drying, cracks generate on expansive soil samples obviously. Along with the experiment, cracks continue to expand, soil damage accumulate. The upper load has some inhibitory effect on the crack development and influences the development of the crack and the shape of the crack-network. The crack of undisturbed expansive soil is developed around the first formation of main crack while remolded expansive soils crack is a turtleback. The CT data M_E of samples are bigger in saturation of 85% than in saturation of 25%. TheCT data M_E of samples in both wet and dry states are all approximately linear with the number of wetting-drying cycles and the slope of the former is relatively flat, while the latter is steeper. Meso-structural evolution parameters are defined, and the relationship between meso-structural evolution parameters and saturation, wetting-drying cycle times is proposed, the predicted results are close to the experimental data.

The Application of No-well Impedance Inversion in Xisha Area Hydrate Research

XU Yun-xia, WEN Peng-fei, ZHANG Ru-wei, ZHANG Bao-jin, XUE Hua

2017, 26(4): 425-434. doi: 10.15953/j.1004-4140.2017.26.04.04

Abstract(412) PDF(4)

Abstract:
In order to research the distribution form of hydrate and occurrence of gas hydrate in Xisha area of quasi three dimensional wave impedance inversion of seismic data. Demonstrates the processing in detail about no Wells impedance inversion: According to the geophysical characteristics of hydrate do zero phase of seismic data processing; According to the characters of seismic data itself, in the work area of multiple tectonic region extraction of seismic wavelet, to ensure the stability of the wavelet to calculate the average wavelet; According to the stacking velocity, by smoothing, filtering, conversion and interpolation to calculate the 3D low frequency model. Finally got the inversion result of clear geological phenomenon, and can be accurate image the distributed area of the hydrate, favor to the comprehensive analysis of the subsequent hydrate research.

Abel Transformation Based Adaptive Regularization Approach for Image Reconstruction

DU Jian-peng, LIANG Hai-xia, WEI Su-hua

2017, 26(4): 435-445. doi: 10.15953/j.1004-4140.2017.26.04.05

Abstract(526) PDF(5)

Abstract:
In this paper, we discuss an adaptive regularization approach for density reconstruction of axially symmetric object whose tomography comes from a single X-ray projection. The method we proposed is based on the combination of total variation regularization and high-order total variation regularization. Its main advantage is to reduce the staircase effect while keeping sharp edges and recovering smoothly varying regions. Moreover, it simplifies the use of parameters. We apply the augmented Lagrangian method to solve the optimization involved. Numerical results show that the proposed method has improved the accuracy of density edges and values. Besides, the method is not sensitive to the measured data noise.

Study on Automatic Identification Algorithm for X-ray Diffraction Spots of Single Crystal Superalloy

ZHANG Zhe, ZHU Jin-xia, ZHUANG Kai, XIE Guang, QIN Xiu-bo, WEI Cun-feng

2017, 26(4): 447-455. doi: 10.15953/j.1004-4140.2017.26.04.06

Abstract(435) PDF(12)

Abstract:
Single crystal superalloy has been widely used as hot components of aeroengine and gas turbine for its good anti-fatigue performance and high temperature creep property. At the same time, the defects like crystal off-orientation and mixed crystal would be produced during the manufacture of single crystal superalloy. Nowadays, Lane X-ray diffraction method is already widely used for nondestructive testing of these crystal defects on single crystal turbine blades all over the world. However, this method is not appropriate for mass testing as a result of its high dependency of manual identification, low efficiency and weak repeatability of the result. This article presents an automatic identification algorithm addressed on Laue X-ray diffraction spots patterns based on practical engineering needs, including pre-processing of diffraction pattern, contour detection, shape filtering of contours, and contour coincidence check. This algorithm can automatically find out spots on diffraction patterns, and offer their positions with measurement errors. Finally, the crystal orientation of the tested sample can be calculated based on these positions of spots with diffraction analysis method and so can those crystal defects on tested turbine blades sample be evaluated.

The Value of 2D MRI and 3D MRI Sequences in Preoperative Staging of Rectal Cancer

TAN Jing-wen, PAN Zi-lai, ZHANG Huan, SHI Bo-wen, ZHU Lan, GAO Xiao-yuan

2017, 26(4): 457-465. doi: 10.15953/j.1004-4140.2017.26.04.07

Abstract(395) PDF(4)

Abstract:
Objective: To evaluate the accuracy of the preoperative local-regional staging of the rectal cancer by a two-dimensional (2D) T2-weighted TSE sequence and a three-dimensional (3D VISTA) T2-weighted turbo spin-echo (TSE) magnetic resonance (MR) sequence. Materials and Methods: This retrospective study was conducted of 33 patients who diagnosed rectal cancer pathologically from January to April in 2016. Two radiologists independently assessed the radiologic images for T and N staging. All patients were performed with both 2D-T2WI MRI and 3D VISTA MRI of the rectum by Philips 3.0T MR imager. The accuracy and consistence with pathological results of TN staging using 2D and 3D sequences were calculated using SPSS 23. Results: in 33 cases, T staging accuracy values of 2D and 3D VISTA data were 70% and 85%, respectively (Kappa value were 0.576 and 0.790) for reviewer 1 (P=0.274) and 73% and 82% (Kappa value were 0.618 and 0.746) for reviewer 2 (P=0.454), The agreement of VISTA T sequences between 3D staging and pathologic results was excellent and better than that of 2D sequences; N category lesion staging accuracy values for 2D and 3D VISTA data were 58% and 70%, respectively (Kappa value were 0.252 and 0.407) for reviewer 1 (P=0.182) and 58% and 67% (Kappa value were 0.267 and 0.376) for reviewer 2 (P=0.218). The agreement of N staging 2D and VISTA 3D staging with pathological results were both poor agreement. Conclusion: Preoperative staging with conventional 2D MR imaging sequence and 3D VISTA T2-weighted imaging protocols for rectal cancer patients showed no significant differences in accuracy of TN staging. However, compared to 2D sequence, 3D VISTA sequence has its advantages in preoperative MR staging.

A Preliminary Study of Correlation between Dynamic Contrast Enhancement MRI and ¹⁸F-FDG PET/CT in Small Peripheral Lung Cancer

FENG Feng, XIA Gan-lin, QIANG Fu-lin, SHI Dong-hui, SHEN Ai-jun, FU Ai-yan, LI Hai-ming, ZHANG Ming-zhu

2017, 26(4): 467-472. doi: 10.15953/j.1004-4140.2017.26.04.08

Abstract(406) PDF(6)

Abstract:
Objective: To investigate the correlations of the dynamic contrast enhancement MRI (DCE-MRI) and glucose metabolism determined by the maximum standardized uptake value (SUV_max) at ¹⁸F-FDG PET/CT in small peripheral cell lung cancer. Methods: ¹⁸F-FDG PET/CT and DCE-MRI wereperformed in 27 consecutive patients with histologically verifiedsmall peripherallung cancer (maximal diameter ≤ 3 cm). The quantitative MR pharmaeokineticparameters including K^trans, K_ep, V_e and SUV_max were measured. Pearson's correlations were conducted between the three MR parameters and SUV_max.Results: Positive correlations were found between K^trans and SUV max, K_ep and SUV_max (P < 0.05). No significant correlation was found for thecomparison of V_e and SUV max (P>0.05). Conclusions: Positive correlationswere found between K^trans and SUV_max, K_ep and SUV_max. Combination of three parameters can reflect the malignant feature of lung cancer.

Exploration of CT Imaging Features of Chronic Severe Hepatitis Complicated with Invasive Pulmonary Fungal Infection

WU Yan-chun, LIU Yao, YAN Zhi-han

2017, 26(4): 473-479. doi: 10.15953/j.1004-4140.2017.26.04.09

Abstract(499) PDF(6)

Abstract:
Objective: To explore CT imaging features of chronic severe hepatitis complicated with invasive pulmonary fungal infection and provide the basis for the diagnosis and treatment of patients. Methods: 92 patients with chronic severe hepatitis complicated with invasive pulmonary fungal infection from October 2014 to October 2016 were randomly divided into two groups (n=46). The control group was treated with conventional therapy, and the observation group was treated with fluconazole on the basis of routine treatment. The CT imaging features of the two groups before and after treatment were compared. Results: All 92 patients with chronic severe hepatitis complicated with invasive pulmonary fungal infection, a total of 176 strains of pathogens were cultured. The percentage of Candida species was the highest in the two groups, 44.44% in the control group and 41.05% in the observation group, followed by Aspergillus, the distribution of all pathogens in the two groups was not statistically significant (P 〉 0.05). After treatment, the proportion of nodule, ground glass, grid or line and pleural effusion in the observation group was significantly lower than that in the control group (P 〈 0.05). Of the patients, 42 were aspergillous and 35 were Candida infections. There were significant differences in the type and number of nodules between patients with Candida and Aspergillus infection (P 〈 0.05). Conclusion: It is important to diagnose CT in patients with chronic severe hepatitis complicated with invasive pulmonary fungal infection. Candida and Aspergillus are the main pathogens, and the CT imaging features of patients with different pathogens are different.

Diagnostic Value of CT and MRI in Grynfelt-Lesshaft's Hernia

SUN Ying-ying, DING Zhang-qing, LUO Hui, BAI Lin-peng, ZHANG Yu-na, DING Ai-lan, WANG Xue-lu

2017, 26(4): 481-488. doi: 10.15953/j.1004-4140.2017.26.04.10

Abstract(423) PDF(3)

Abstract:
Objective: To study the diagnosis and differential diagnosis values of CT and MRI in Grynfelt-Lesshaft's hernia. Methods: From August 2013 to December 2016,in our hospital, the data of clinical and imagings of 28 patients with Grynfelt-Lesshaft's hernia confirmed by operation or clinical were retrospectively analyzed. All patients underwent multi-slice spiral CT examination, and three of them also underwent MRI examination. Results: Of all the 28 patients, 20 were male, 8 were female, age: 44 to 80 years (average 69.04~3.5 years). Unilateral in 16 cases (right side in 12 cases, left side in 4 cases), bilateral in 12 cases. On the imagings of CT and MRI, the hernia located in the Grynfelt-Lesshaft triangular (superior lumbar triangular) region, which his boundaries were formed superiorly by the 1 lth or 12th thoracic rib, medially by the erector spinae muscle group, laterally by the internal oblique muscle. The floor of this triangle was formed by aponeurosis of the transversalis muscle, and the roof was formed by the latissimus dorsi muscle. CT or MRI showed oval or flask shaped mass of extraperitioneal fat with or without peritoneum and visceral contents protruded through the defecting fascia floor into lumbar triangle, and the size of the hernia contents was out of proportion with the hernia ring.Hernia ring in diameter ranged from 1.5 to 8.7cm, and the hernia sac size ranged from 1.6 cm- 1.3cm to 9.2cm-5.4 cm. Imagings of CT and MRI were easy to differentiate Grynfelt hernia from other lesions such as outborrd and posterior abdominal wall hernia, bulging or pseudohernia abdominal wall hernia, lipoma and other soft tissue tumors, hematoma and abscess. Conclusion: CT and MRI can clearly show the ring size of Grynfelt-Lesshaft's hernia hernia, the hernia contents and possible complications, the weak and defect degree of the abdominal wall muscles around. CT and MRI are helpful for diagnosis of Grynfelt-Lesshaft's hernia and differentiation from other diseases, and worthy of application.

MSCT Features of Central Airway Primary Leiomyoma

LIU Jian, ZU De-gui, DENG Mao-song, YANG Ying, LIU Jian-xin, WANG Xu, WU Ge, YIN Xiao-ming

2017, 26(4): 489-496. doi: 10.15953/j.1004-4140.2017.26.04.11

Abstract(376) PDF(3)

Abstract:
Objective: To discuss the MSCT features of central airway primary leiomyoma and improve the diagnostic ability of this disease. Methods: The MSCT findings, clinical characteristics and pathological findings of 7 patients with pathologically confirmed central airway leiomyoma were retrospectively analyzed. Results: 1 male and 6 females with age of 19-65 years old were included, all with nonspecific respiratory symptoms. There were 2 cases located in trachea, 1 case in carina, 3 cases in left main bronchus and 1 case in right main bronchus, with maximum diameter of 0.6-2 cm. MSCT showed the shape of tumors were round or oval in 6 cases and lobular in one case. 6 cases were entophytic growth type and 1 case was both entophytic and helophytic growth type. 7 cases of patients CT scan without contrast showed homogeneous density with no calcification or fat. Enhanced CT scan showed 6 cases with moderate to marked enhancement and 1 case with mild enhancement. No necrosis or cystic degeneration were observed in 7 cases, no meditational adenopathy or pleural effusion either. There were 2 cases with obstructive change. Conclusion: There are some features of central airway leiomyoma on MZCT such as regular tumor in the lumen, often demonstrate marked enhancement. CT and post processing techniques have a certain value in showing size, range and the relationship with adjacent structures of the tumor.

Relationship of Atherosclerosis between Carotid Arteries and Coronary Arteries by CTA Evaluation:A Retrospective Study

BAO Li-wei, WANG Ze-feng, SUN Zhen-ting, MENG Ling-xin, ZHAO Lei

2017, 26(4): 497-504. doi: 10.15953/j.1004-4140.2017.26.04.12

Abstract(349) PDF(6)

Abstract:
Objective: To evaluate and forecast the occurrence of obstructive coronary artery disease (CAD) and development through carotid artery atherosclerotic plaque and luminal stenosis degree. Methods: 81 patients who had exarned both with head-and-neck CTA and coronary CTA were retrospectively analyzed, evaluating image quality and the nature of the atherosclerotic plaque, and calculate the degree of stenosis. According to the carotid artery stenosis degree can be divided into two groups: moderate or more narrow and mild stenosis group, and the corresponding coronary artery luminal stenosis degree for independent samples t test between the two groups respectively. Line and according to the patients with head and neck CTA inspection head CT scan results grouping: cerebral infarction group and cerebral infarction, and t test between the two groups. According to the common carotid, internal carotid artery level is above moderate stenosis group and mild stenosis group transient ischemic attack (TIA) of the probability for a chi-square test. Static analysis of 81 cases of patients ECG, angina pectoris, and transient ischemic attack incidence and presence of cerebral infarction and carotid-the relationship between the degree of internal carotid artery stenosis. Results: in 81 cases of simultaneously or successively in the patients with head and neck CTA and coronary CTA, head CT scan of cerebral infarction, coronary artery plaque formation corresponding degree of stenosis, the t test results between the two groups have statistically significant difference (P< 0.05). The corresponding degree of coronary artery stenosis cerebral infarction group than in cerebral infarction group, t test results between the two groups have statistically significant differences (P < 0.05). Of common carotid, internal carotid artery stenosis degree of TIA probability of McNemar test have a statistically significant difference (P < 0.05). In 81 cases with analysis of its static ECG, TIA set of static electrocardiogram ST-T change and rate of angina pectoris occurred was obviously higher than that of the TIA group (P<0.05).Conclusion: carotid, internal carotid artery stenosis degree and the development of coronary atherosclerosis lesions corresponding correlation. There was a moderate or above internal carotid artery stenosis, the incidence of TIA, and the TIA group client static ECG ST-T period of change and the incidence of angina pectoris were higher than without the TIA group.

Imaging Features and Misdiagnosis of Giant Cell Tumor of Bone

WU Wei-bin, PENG Tao, PAN Xian-wei, MENG Jia-xiao, ZOU Ying-wen, HE Jun

2017, 26(4): 505-510. doi: 10.15953/j.1004-4140.2017.26.04.13

Abstract(444) PDF(5)

Abstract:
Objective: Analyze the imaging appearances of X-ray, CT and MRI in giant cell tumor of bone (GCT) and the causes of misdiagnosis to improve the diagnostic accuracy. Methods: Collect 30 cases of GCT confirmed by operation and pathology and analyze the X-ray, CT and MRI imaging findings retrospectively. Results: 13 cases located in distal femur, 6 in proximal tibia, 4 in proximal femur, 3 in proximal humerus, 2 in distal radius, l in lumbar spine, and 1 in iliac bone. There are 5 cases, about 16.7%, mis-diagnosed before operation. Conclusion: X-ray, CT and MRI reflect the pathological changes of GCT from different aspects. Combining the three methods of imaging can display the GCT imaging features well and conducive to diagnosis and differential diagnosis.

CT Diagnosis Value of Tubal Pathological Changes

DAI Yan-zeng, ZHANG Yan, QIU Shu-fen

2017, 26(4): 511-517. doi: 10.15953/j.1004-4140.2017.26.04.14

Abstract(363) PDF(4)

Abstract:
objective: Analysis of CT imaging characteristics of tubal pathological changes, to explore the clinical application value of CT in the diagnosis of the disease. Methods: 58 cases were confirmed by surgery and pathology was retrospectively analyzed the CT manifestation of tubal pathological changes, and with laparoscopic and conventional surgical and pathological results contrast analysis. Results: CT diagnosis of hydrosalpinx 20 cases, empyema 8 cases of fallopian tubes, oviduct ovarian abscess in 1 case, tubal torsion in 1 case, 5 cases of tubal pregnancy, mesosalpin. Conclusion: Tubal pathological changes have certain characteristic CT performance, CT scan as attachment area circuitry tubular cystic density, according to the characteristics of CT enhancement, closely combined with clinical and attaches great importance to the comprehensive analysis of the imaging manifestations of the disease, can make a definite diagnosis.

Coronary Artery CT Angiography in Coronary-pulmonary Fistula:A Retrospective Study

DONG Jian, YANG Lei, YAN Nuan, WEN Jing, ZHANG Chun-yan, CHEN Xiao-bo, WEN Ting-guo, WANG Ren-gui

2017, 26(4): 519-524. doi: 10.15953/j.1004-4140.2017.26.04.15

Abstract(341) PDF(3)

Abstract:
Objective: To investigate the clinical value of coronary CT angiography in detection of coronary-pulmonary artery fistula (CPF). Materials and Methods: Thirteen patients with the diagnosis of CPF were enrolled in this study. All the patients were performed with retrospective ECG-gated coronary CTA, including 8 males and 5 females (age range, 53-71 years, mean age, 62 years old). The heart rate ranged from 61 to 73 bpm. All the raw data were reconstructed with VR, MIP, MPR and CPR, and all the CPF were retrospectively analyzed. Results: In all 13 patients with CPF, 7 were fed with unilateral coronary artery, while the number of bilateral coronary blood supply was 6. The main feeding artery was proximal left anterior descending in 8 patients (61.5%). All CPF demonstrated dilated vascular coat presenting as "clustering shape" on the surface of the heart. All 13 patients demonstrated dilated feeding artery, 7 with "jet sign" in pulmonary artery fistula, while "smoking sign" were demonstrated in 6 patients. 5 aneurysms were detected in the feeding artery, and 9 feeding artery were found stenosis in the proximal point. Conclusion: Coronary CT angiography demonstrates capability in the diagnosis of CPF with characteristic imaging features of"clustering vessel coat" and "jet" sign.

The Clinical Diagnostic Value of MSCT in Primary Epiploic Appendagitis

XU Guan-zhen, ZOU Wen-yuan, SHI Lei, LIU Yue, CENG Lei, JI Tao-tao, LI Jing-jing, LIN Hua

2017, 26(4): 525-532. doi: 10.15953/j.1004-4140.2017.26.04.16

Abstract(419) PDF(6)

Abstract:
Objective: To investigate the imaging features of primary epiploic appendagitis, and to discuss their diagnostic value. Methods: 3 cases were retrospectively analyzed clinical and imaging data of the different parts of the patients with PEA. Combined with the relevant literatures, their imaging characteristics were discussed. Results: 3 cases of PEA, CT scan revealed than there were 3 cases in colon, 1 case in sigmoid colon, 1 case in ileocecal region, 1 case in ascending colon, The lesions were ovoid fatty mass abutting the colon, High density ring with adjacent fat stranding was present in 3 patients, lesions in the central point, linear density. Anti-inflammatory therapy effect is obvious, to avoid the surgical intervention. Conclusion: primary epiploic appendagitis has classical imaging appearance, CT scan is valuable in the diagnosis and differential diagnosis of primary epiploic appendagitis.

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2017 Vol. 26, No. 4