CT理论与应用研究

The Application of FLASH Scanning Mode with Double-low Dose Technique in Coronary CT Angiograph

LIANG Yu, ZHANG Xiao-qin, ZHANG Kai, ZHANG Fei-fei, WANG Min, LIU Rui, DUAN Hu-bing

2015, 24(5): 637-645. doi: 10.15953/j.1004-4140.2015.24.05.01

Abstract(687) PDF(1)

Abstract:
Objective: To evaluate the potential of acquiring the diagnostic images of coronary CT angiography with prospective ECG-triggered high pitch flash spiral acquisition in 100 kV tube voltage combined with iterative reconstruction and contrast of iodixanol(270 mgI/mL). Methods: The 60 patients were divided into A and B two groups randomly, whose heart rate ≤ 70 /min. In the A group, their coronary CT angiography images were collected with prospective ECG-triggered high pitch flash spiral mode in 100 kV tube voltage combined with iterative reconstruction(convolution kernel B26f) and contrast of iodixanol(270 mgI/mL). In the B group, their coronary CT angiography images were collected with prospective ECG-triggered sequence mode in 120 kV tube voltage combined with filtered back projection(convolution kernel B26f) and contrast of iopromide(370 mgI/mL). The image quality and effective radiation dose of two groups were assessed. Results:(1) There were no significant differences in age, heart rate and BMI between the two groups.(2) Image qualities: There were no significant differences in the subjective image quality evaluation between the two groups.In objective image quality assessment, in addition to the left coronary artery of SD and SNR numerical difference was statistically significant, no statistically significant difference were observed in the other indicators.(3) Radiation dose: The average effective radiation dose was(0.94 ±0.05)mSv in group A and(4.31 ±1.21) mSv in group B respectively. The differences between the two groups have statistical significance. In effective dose group A decreased sharply than group B by about 78.2%. Conclusions: In coronary CT angiography with prospective ECG-triggered high pitch flash spiral acquisition in 100 kV tube voltage combined with iterative reconstruction and contrast of iodixanol(270 mgI/mL) which image quality can meet the demand of clinical diagnosis, it compared with prospective ECG-triggered sequence mode in 120 kV tube voltage, could decrease the effective dose by about 78.2%.

CT Prostate Segmentation Based on Random Forest

SHAO Ye-qin, YANG Xin

2015, 24(5): 647-655. doi: 10.15953/j.1004-4140.2015.24.05.02

Abstract(598) PDF(1)

Abstract:
Due to the low contrast of CT image, uncertain position of prostate and variable bowel gas, automatic and accurate CT prostate segmentation is a challenging task. In this paper, a prostate identification method is proposed based on random forest. Using the auto-context model, a sequence of Random Forest classifiers is trained. Then the trained classifiers are applied on the testing image to improve the classification response map iteratively. The experimental results show that, compared with other state-of-the-art methods, our method achieves a better performance.

Experimental Studies of Ultrasonic Tomography on Fangshan Granite under Uniaxial Compression

HE Tai-ming, LIU Zheng-yi, LI Shi-yu

2015, 24(5): 657-665. doi: 10.15953/j.1004-4140.2015.24.05.03

Abstract(651) PDF(3)

Abstract:
Fangshan granite ultrasonic velocity was measured under uniaxial compression in Lab and its tomographic imaging was conducted at the different deformation. The imaging processes used 26 sensors putting around the sample. The p velocity continues to increase with increasing application of uniaxial compression in the whole body of the granite at the stages of compaction and linear elastic. Before catastrophic rock failure, the increasing velocity region gradually shrinks and the low-belt velocity zones are forming, on which the catastrophic failure takes place.

Finite Element Method with Arbitrary Quadrilateral Meshes for Numerical Modeling of Seismic Wave Based on Compact Storage

LIU Rui-he, ZHOU Jian-ke, ZHOU Xue-feng, YIN Xing-yao, CAO Dan-ping

2015, 24(5): 667-680. doi: 10.15953/j.1004-4140.2015.24.05.04

Abstract(629) PDF(1)

Abstract:
In general, we apply finite element method with triangular meshes to accurately modeling wave field under complex structures; however, in the condition of the same number of nodes, computational accuracy of triangular element is lower than that of rectangular element. It is difficult to implement the computer program which locates the non-zero elements of global stiffness matrix when we adopt triangular elements to fit complex geometrical interface. Using rectangular elements to divide geological model containing dipping or rugged interface will result in diffraction noise, and infilling grid will increase computational amount. For these reasons, this paper applies finite element method to solve 2-D acoustic wave equation, arbitrary quadrilateral meshes is adopted to fit dipping or rugged interface, which can avoid introducing “ladder” interface resulted from discrete rectangular grid, and discrete diffraction noise is eliminated effectively in the condition of no increasing computational amount and memory occupation. Diagonal lumped mass matrix is used to replace consistent massmatrix to avoid matrix inversion and improve the computational efficiency of explicit finite element method. In addition, we employ compact storage format to store global stiffness matrix, and the elements need to be stored in each row is no more than 5, the zero elements are not involved in computing at the same time, by this method, not only reducing the memory occupation, but also improving the computational efficiency.

A Detecting Method for Rock Mass Fracture Based on Elastic Wave CT Technique

LI Gao, ZHENG Xu-hui, ZHANG Bao-jun, SONG Ya-xin, XIANG Ai-qin, CHU Na

2015, 24(5): 681-688. doi: 10.15953/j.1004-4140.2015.24.05.05

Abstract(621) PDF(3)

Abstract:
Elastic wave tomography technique, short for "elastic wave CT scanning". As is known, there is a linear integral relationship between the travel time and amplitude of the elastic wave ray propagating through stratum and some physical parameters of the stratum. By using this key characteristics, elastic wave CT scanning can retrieve 3d velocity structure and attenuation characteristics of strata on the premise of no damage to the object. In this paper, based on the elastic wave CT technique, through the inversion of the rock mass slowness between holes and synthesizing the drill core record and engineering site situation, fractures development of Banbi Mountain in Chengde City was interpreted, the location and size of the risk rock mass fractures were determined. It is proved that fractures position detected by the elastic wave CT technique is consistent with the situation in the field after drilling, which provides basis for the comprehensive improvement of the risk rock mass.

Ray Tracing Illumination Analysis on Marine Seismic Vertical Cable Acquisition System

HE Yong, ZHANG Jian-zhong

2015, 24(5): 689-700. doi: 10.15953/j.1004-4140.2015.24.05.06

Abstract(570) PDF(1)

Abstract:
The vertical cable recording geometry is showing considerable promise as a seismic acquisition technology of marine exploration. Based on the ray tracing algorithm, the article adopts the method of bilinear interpolation on irregular cell boundaries and fast wave-front expansion to determine ray paths and reflection points on target layer. And the distribution density of reflection points on target layer is served as the key parameter to measure the acquisition geometry. The illumination analysis of marine seismic vertical cable is implemented by a series of experiments with the three-dimensional models of the seabed strata, shots, vertical cables and hydrophones. By the illuminating analysis experiment, the rules that the factors related the acquisition geometry affect the reflection point distribution are understood, which provide the basis for designing optimal vertical cable geometry and enhancing seismic imaging quality.

The Property Analysis of the Convergent Solution to Kaczmarz Method

KANG Chuan-gang, ZHOU Heng

2015, 24(5): 701-709. doi: 10.15953/j.1004-4140.2015.24.05.07

Abstract(681) PDF(4)

Abstract:
Kaczmarz method is an important algebraic reconstruction techniques(ART) and play an important role in medical imaging and diagnosis. With the development of computer hardware, these iterative algorithms, such as ART, SIRT, attract people's attention due to their excellent performance in image reconstruction problems with anti-interference and absent data. In this paper, on the basis of the definition and the properties of the generalized inverse, we prove that the limit of the iterative sequence from Kaczmarz method is Moore-Penrose generalized solution as x⁽⁰⁾∈R(A^T)^⊥. The theoretical results show that Kaczmarz method is 'well-posed' method for consistent and inconsistent problems. In this paper, we verify the 'well-posed' of Kaczmarz method and its 'semi-convergence' for perturbed problems by numerical test. In additional, Kaczmarz method is also a regularization method as x⁽⁰⁾∈R(A^T)^⊥.

MSCT Diagnosis of Giant Cystic Intrahepatic Bile Duct Cystadenomatous Tumor

WEI Wan-qing, WU De-hong, MU Hua-guo, CHEN Ping-you

2015, 24(5): 711-716. doi: 10.15953/j.1004-4140.2015.24.05.08

Abstract(572) PDF(1)

Abstract:
Objective: To explore the MSCT class features of giant cystic intrahepatic bile duct cystadenomatous tumor, and to evaluate the diagnostic value. Methods: Retrospective analysis MSCT performance of 4 cases of cystadenoma and 2 cases of cystadenocarcinoma of biliary which had been proved by operation pathology, including the location of the lesion, cyst fluid density uniformity, without separation or not, mural nodules and enhancement features, adjacent liver within cystic lesions, dilatation of intrahepatic bile duct and the perfusion of adjacent liver parenchyma. Results: All of 6 cases were cystic, 5 cases near the hilar, 1 case of in under the posterior lobe of liver; 4 cases' hydatid fluid were uniformity, but two cases were not; 5 cases were discretely intracapsular, 1 case not; 2 cases had mural nodules and enhanced significantly, 2 cases separate and wall calcification; 2 cases with of liver small cystic(1-2) near lesions; 5 cases' intrahepatic bile duct were dilated far side of the hilar, 1 case not; 5 cases' surrounding liver parenchyma were abnormal perfusion in the arterial lesions. Conclusion: The MSCT performancegiant of cystic intrahepatic bile duct cystadenomatous tumor with a characteristic have a greater value of the diagnosis, differential diagnosis and clinical treatment.

Radiologic Signs Comparative Analysis of Osseous Epithelioid Hemangioendothelioma

XIA Shu-lin, LUO Hui-jun, YI Jiao-e, CHENG Xiao-guang

2015, 24(5): 717-724. doi: 10.15953/j.1004-4140.2015.24.05.09

Abstract(605) PDF(1)

Abstract:
Objective: To improve knowledge and imaging diagnosis of bone epithelioid hemangioendothelioma(EHE). Methods: We retrospectively analyzed X-ray, CT, MR and pathological data of six cases of bone epithelioid hemangioendothelioma which confirmed by operation and pathology, and summarize its imaging features. Results: Three patients' lesions, characterized by multiple osteolytic destruction, were located in distal femur, tibia, fibula and foot. Two cases of lesions were located in the lower tibia. One case of lesion was located in the proximal femur. The imaging features of X-ray and CT of these lesions were multifocal osteolytic bone destruction, hardening of the edge and there were fence-like lesions bone crests in part of the lesions. MR image features of these lesions were slightly long T1 WI and long T2 WI, and they had significant enhancement after contrast-enhanced scanning. Immunohistochemical studies showed that tumor cells CD3 l, Vimentin, CK(+), CD69(Spotty+), CD163(spot), FLI-1(+), Ki67(+<10%). Conclusion: EHE have some imaging characteristics. CT and MR imaging can provide valuable information for clinical diagnosis and differential diagnosis.

The Diagnosis and Differential Diagnosis of Primary Gastrointestinal Lymphoma by Multislice Spiral Computed Tomography

XING Jin-li, LI Hong-jiang

2015, 24(5): 725-732. doi: 10.15953/j.1004-4140.2015.24.05.10

Abstract(613) PDF(3)

Abstract:
Objective: To investigate the value of multislice spiral computed tomography(MSCT) in the diagnosis and differential diagnosis of primary gastrointestinal lymphoma. Methods:The clinical imaging data of 40 cases of primary gastrointestinal lymphoma confirmed by surgery and pathology in our hospital were retrospectively analyzed. Results:40 PGILs all belonged to non-Hodgkin's lymphoma, including 31 cases of primary gastric lymphoma(PGL) and 9 cases of primary small intestinal lymphoma(PSIL). 19 cases of PGL showed diffuse homogeneous gastric wall thickening in MSCT. They all clearly showed mucosa white line sign and track sign. The wall thickening of the gastrointestinal tracts were not consistent with the stenosis of the lumens of the lesions occurred in 39 cases. 4 cases showed aneurysm-like intestinal dilatation. 1 case showed the hamburger sign. Clinical imaging rarely showed obstruction. Conclusion:To recognize the typical CT imaging features of primary gastrointestinal lymphoma, can improve the preoperative diagnostic accuracy of the disease.

Application of MSCT-VHSG in the Diagnosis of Fallopian Tube Patency

WANG Ye-qing, JIA Zheng-wei, LI Hao, LI Xiao-feng

2015, 24(5): 733-738. doi: 10.15953/j.1004-4140.2015.24.05.11

Abstract(620) PDF(1)

Abstract:
Objective: To explore the clinic value of Multi-slice spiral CT-virtual hysterosalpingography in diagnosing fallopain tube patency. Methods: The pelvic cavity MSCT was performed on 40 infertility patients, MSCT-VHSG was performed with a 64-row CT scanner using 64×0.625 mm² collimation and 0.625 mm slice thickness. A total volume of 20 mL of an iodine contrast dilution was injected into the uterine cavity. The duraion of the CT scan and the grade of patient discomfort of the procedure were documented. Images were analyzed on a workstation. Retrospective thin-slice reconstruction 0.625 mm to 1.5 mm after multi-slice spiral CT scan, the techniques such as MPR, CPR, VR and MIP, were used to observe fallopain tube patency. Results: No complications occurred during the procedure. The mean scan time was(3.4 ±0.4)s; the mean patient effective dose was(2.58 ±0.75)mSv. The stereo pictures of the uterus cave were obtained on MSCT-VHSG. The fallopian tube was clearly visualized without obvious adverse reactions occurring. Forty fallopian tube were diagnosed as patent,8 as partially patent and 32 as non-patent by MSCT-VHSG. Conclusion: A 64-row CT-VHSG provides a reliable, non-invasive alternative diagnostic technique in the infertility workup algorithm.

CT and MRI Findings of Malignant Fibrous Histiocytoma

ZHAO Lei, HAI Ling, WANG Yu-fang, XIE Sheng-hui, GAO Yang

2015, 24(5): 739-745. doi: 10.15953/j.1004-4140.2015.24.05.12

Abstract(613) PDF(1)

Abstract:
objective: To approach the CT/MRI imaging signs of the malignant fibrous histiocytoma(MFH). Methods: 12 patients of MFH with CT/MRI imaging were retrospectively analyzed. The tumors of location, size, margins, density/signal, morphological characteristics, change of adjacent structure, enhance performance, local and distant metastasis of tumors were evaluated.Results The tumors have well-defined margins, poor uniformity of the density/signal, variable heterogeneous enhancement, lobulated or ellipse soft-tissue mass. Conclusion: The CT/MRI imaging findings have more characters for differential diagnosis in MFH,was a useful diagnosis instrument for clinical

Diagnostic Value of Post-processing Technology of Multi-slice Spiral CT Image for Pulmonary Sequestration

YE Fu-li, SHI Gui-lian

2015, 24(5): 747-752. doi: 10.15953/j.1004-4140.2015.24.05.13

Abstract(580) PDF(2)

Abstract:
Objective: To investigate the multi-slice CT reconstruction techniques in the diagnosis of pulmonary sequestration value to evaluate it for the role of the clinical diagnosis of pulmonary sequestration. Method: By surgery and pathology confirmed 13 cases of pulmonary sequestration were retrospectively analyzed. All checks with GE lightspeed 64-slice spiral CT Scanner, the first CT scan, the line dual-phase enhanced scan, the scan line after the end of the multi-planar reconstruction(MPR), maximum intensity projection(MIP) and volume rendering image(VR). Results: 13 cases of pulmonary sequestration patients, 10 cases of lesions located in the left lower lobe basal segment, 3 cases of lesions located in the lower lobe basal segment, after the abnormal body from 9 cases of thoracic aortic artery, 4 cases of abdominal aorta. CT scan of leaf shape(3 cases), circular or ovoid in 3,7 cases of irregular shape. Enhancement and reconstruction after 13 cases showed abnormal blood flow in arteries. Conclusion: Multislice CT and reconstruction techniques can accurately display abnormal arterial blood supply and venous return, in the isolated pulmonary sequestration has significant value in diagnosis and preoperative assessment.

The Relationship of between Subacromial Impingement Syndrome and Shoulder Typing under MSCT

LI Ya-chao, YU Bei, LI Xiao-li

2015, 24(5): 753-759. doi: 10.15953/j.1004-4140.2015.24.05.14

Abstract(744) PDF(2)

Abstract:
Objective: To study the relationship between subacromial impingement syndrome and shoulder typing under MSCT. Methods: 110 patients diagnosed with shoulder impingement syndrome in our hospital from January 2013 to January 2015 were undergone with MSCT scanning, all the patients were grouped according to different ages, gender, location shoulder to compare different shoulder peak shape in different age groups. Results: and ⅠⅡ shoulder gradually decreased in proportion with age, Ⅲtype shoulder gradually increased in proportion with age. Type Ⅱshoulder proportion of A group group was 51.6%, which was significantly higher compared with group B and group C, type Ⅲshoulder proportion of A group group was 22.6%, which was significantly lower compared with group B and group C. Ⅰ, Ⅱ, Ⅲtype acromion morphology of male group and female group didn't have the significant difference in proportion(P>0.05). Ⅲtype shoulder had the right shoulder more, the proportion was 52.5 percent, which was significantly higher than the left shoulder group(P<0.05). Conclusion: MSCT can clearly show the shape and structure of the shoulder, curved shoulder of subacromial impingement syndrome patiens gradually reduce the proportion with age increasing, hook shoulder is in the right shoulder more, and the proportion increases with age gradually increasing.

A 3D Graphical Representation Method to Deposit Geology Using Volxer

GONG Sheng-ping, YANG Ya-bin, WANG Ming-ming, ZHANG Guang-zhi, CHEN Liang

2015, 24(5): 761-768. doi: 10.15953/j.1004-4140.2015.24.05.15

Abstract(660) PDF(3)

Abstract:
Deposit geology dimensional graphical representation method can express the complex geological structure, the deposit geology in three-dimensional morphology forms, can be effectively applied to mineral exploration oil and gas exploration, coal geological exploration, mine production and management, geological disasters governance and other geological sciences fields. Using a Copper-molybdenum mine as an example, a research work is presented for a three-dimensional graphical representation method of deposit geology. Build a three-dimensional geological model, exhibit geological characteristics of the deposit with multi-angle, multi-level.

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2015 Vol. 24, No. 5