ISSN 1004-4140
CN 11-3017/P

2015 Vol. 24, No. 3

Display Method:
CT Theory
The Optimization Research of Tube Voltage and Filter in a Dedicated Breast CT
ZHANG Xue-yan, WEI Cun-feng, WANG Yan-fang, WANG Zhe, LI Gong-ping, SHI Rong-jian, WEI Long
2015, 24(3): 327-336. doi: 10.15953/j.1004-4140.2015.24.03.01
The image quality and the radiation dose are important performance indicator of dedicated breast CT(DBCT). In this paper, the factors of tube voltage and filter were studied by Monte Carlo simulation method which have effect on the image quality and radiation dose which for comprehensive assessing the relationship between them that introduced the dose efficiency η that related to image resolution, noise and radiation dose. Research results show favorable dose efficiency can be gained if reasonable voltage values are selected and that optimization of filter shape can reduce dosage which human body absorbs. Therefore, rational setting of parameters can decrease radiation dose and provide significant reference for clinical application of dedicated breast CT while guaranteeing image quality as far as possible.
Statistics Difference of Five Radiation Gage Points for Multi-slice Spiral CT
ZHENG Hai-liang, LI Xing-dong, ZHANG Peng, TAN Chun-rong, FENG Shu-li, WEN Ting-guo, DUAN Yong-li, FU Yan
2015, 24(3): 337-343. doi: 10.15953/j.1004-4140.2015.24.03.02
Object: To investigate the statistic relationship between 5 clock positions of CTDI100 and stabilization of radiation. Method: Radiation meter and phantom are used to 12 time repeating tests on the radiation dose of a spiral CT at 5 Clock positions and then one-way ANOVA method is used to character the their difference significance of those 5 clock positions. Result: The relevant standard difference of measurements at 5 test clock positions are 0.33%(center), 0.73%(3 clock), 0.32%(6 clock), 1.00%(9 clock), 0.32%(12 clock) respectively; meanwhile the average of measurements at 3 clock is much close to that at 9 clock and no significant difference is found in one-way ANOVA test;Moreover the relative deviation between mean value of 12 Clock plus 6 Clock and 3 Clock is 0.5%. Conclusion: The tested spiral CT shows good radiation stability and 3 Clock position have equal effect with 9 clock's in CTDI100 measuring, moreover, peripheral CTDI of that can be simplified except for non-acceptance test or operational condition test.
Application of Cross-well Seismic Tomography in Detecting Buried Fault
HU Gang, DUAN Bao-ping, HE Zheng-qin, YE Tai-lan
2015, 24(3): 345-355. doi: 10.15953/j.1004-4140.2015.24.03.03
This paper discusses the problems existed in active-fault exploration, in the area of breakpoint based on ground reflection seismic exploration, making use of Cross-well Seismic Tomography to detect active-fault and determine the depth of Up-breakpoint and deduced its activity era. It describes the application status of the Cross-well Seismic Technology and introduces some algorithm of Cross-well Seismic Tomography, also in actual test; discussed the data acquisition and data processing methods for Cross-well travel time tomography. Using Curved-Ray tracing algorithm obtained the P-wave velocity structure image across the Luhuatai buried fault. This study shows that the result is highly similar to drilling profile.
Wave Field Numerical Simulation of Low Velocity Zone and Preliminary Analysis of Influencing Factors
XIAO Wen, ZHANG Jun-hua, ZHANG Zai-jin, TAN Ming-you, ZHANG Yun-yin, CUI Shi-ling, QU Zhi-peng
2015, 24(3): 357-366. doi: 10.15953/j.1004-4140.2015.24.03.04
The complexity of near surface and geological underground structure can intensify the diversity of seismic wave field, affect the quality of seismic records strongly, especially the existence of low velocity zone(LVZ) has great effect on seismic wave field. Low velocity zone characteristic of the "free surface, low velocity and high absorption" can cause the reduction of reflection wave energy, strong dispersion and distortion of surface wave field, which affects the accuracy of seismic exploration. However the seismic acquisition will face the following problems of low velocity zone inevitably:(1) what effect will be caused by the low velocity zone to seismic wave propagation;(2) Near-surface change is big, so how to get the accurate parameters of low velocity zone;(3) when there exists the low velocity zone, what effect will seismic acquisition parameters of the shooting depth, the best dosage(related to wavelet frequency) and the best coupling(related to LVZ velocity) bring to the seismic data quality. This paper analyzes the relation of low velocity zone with shooting depth, speed, wavelet frequency(dose effect), etc. based on the seismic numerical simulation method. At the same time, this paper discusses the grid and the absorbing boundary of the seismic numerical simulation under the background of low velocity zone. The wave field characteristics and low-velocity layer parameters influencing mechanism analysis will have theoretical significance and guiding effect to the field seismic wave shooting and to get high quality seismic data.
The Experimental Study of SNMR in the Detecting of the Dam Safety
WANG Hong, NIU Zhao-wei, ZHANG Guo-dong, LI Zhen-yu
2015, 24(3): 367-376. doi: 10.15953/j.1004-4140.2015.24.03.05
Surface Nuclear Magnetic Resonance(SNMR) is the unique and direct geophysical exploration technology for the groundwater information exploration. Recently, this nondestructive detection technique was applied to test for the earth-rockfill dam safety detecting of seepage. Due to the detecting signal of Nuclear Magnetic Resonance(NMR) coming from the hydrogen's proton of groundwater, it can be ensured that NMR response only relates to groundwater information. Therefore, the SNMR is the unique and direct geophysical exploration technology for the groundwater information exploration. Geophysicists taking advantage of SNMR exploring groundwater directly, the saturated face attempts to be detected, and the seepage of some dykes and dams could be identified. And a convenient, efficient and reusable approach is provided for diagnosing seepage path of dykes and dams especially the small dilapidated reservoir dams and embankment where accidentsfrequently happened. With NUMISPOLY multi-channel Magnetic Resonance Sounding tested for detecting the safety of a certain dam body, the saturated face of a certain dam body is acquired, and the seepage of the dam isassessed for hidden trouble. The results show that the SNMR can provide a new, effective and reliable technology for the seepage hidden trouble detection of dams.
Resistivity Inversion and its Application
SONG Wen-jie, LIU Yu-hua, GE Fu-gang, LÜ Chun-shuai, TIAN Dan
2015, 24(3): 377-382. doi: 10.15953/j.1004-4140.2015.24.03.06
For the majority of sedimentary rocks are bedding structure of electricity from its point of view, they are different types of resistivity of the composition of the strata, so that the resistivity of the formation and adoption of one of the direction of current, showing a anisotropic. Made use of two-dimensional layered media background resistivity inversion perturbation method, based on observations of the background cross-section of apparent resistivity profiles, to determine the context of electricity market structure, the use of resistivity perturbation method to calculate sensitivity matrix, through experiments get good results.
Industrical CT
Selective Projection-rebin FDK Algorithm and its Efficient GPU Implementation
ZHANG Wen-kun, YAN Bin, CAI Ai-long, WEI Feng, DENG Lin, LI Lei
2015, 24(3): 383-392. doi: 10.15953/j.1004-4140.2015.24.03.07
FDK algorithm is widely used in computed tomography. However, the traditional rebin FDK algorithm heavily consumes memories, thus the reconstruction efficiency is low. Aiming to solve the problem, a selective projection-rebin FDK algorithm is proposed in this paper. By analyzing the geometrical relationship between the original projections and rebined ones, the least amount of cone-beam projections during each round of data rearrangement is derived. Circular queue is used to selectively load certain frames of cone-beam projections, which substantially reduces the memory-consumption. Based on graphic processing unit, the new algorithm is optimized for its parallelism performance, and the speed of the parallel method is boosted significantly. Experiments for the reconstruction of 5123 are performed to verify the effectiveness of the algorithm. Without loss of reconstruction accuracy, its memory consumption is reduced to 1/3 and 1/5 of the traditional for simulation data and real data respectively. The new algorithm, reducing the memory-consumption substantially, is the development of traditional rebin FDK algorithm, and it solves the problem of reconstruction for mass projections.
Analysis and Evaluation of Two Assessment Techniques for ICT Scanner Spatial Resolution Measurement
GUO Zhi-min, NI Pei-jun, CAO Yu-ling, QI Zi-cheng, QIAO Ri-dong
2015, 24(3): 393-399. doi: 10.15953/j.1004-4140.2015.24.03.08
Spatial resolution is the two most important parameters of CT image quality, and the test work of this parameter is main part of CT scanner's quality assurance. This paper represents two methods, which were dedicated for the assessment of spatial resolution in CT system, and analysis spatial resolution of CT system by using software tools. The comparative study of the two methods was carried out in 3 ICT systems under the same experiment condition. We found that the test result of disc phantom method is significantly higher than the result of practical-MTF method, and then the relationship between the test results of the two methods was discussed.
Medical CT
Clinical Research of 80 kV-CT Coronary Angiography for Prospectively Gated Axial Technique
BAO Li-wei
2015, 24(3): 401-408. doi: 10.15953/j.1004-4140.2015.24.03.09
Objective: To evaluate image quality and radiation dose for coronary artery computed tomographic angiography(CTA) obtained with 80 kV. Methods: 61 patients enrolled in this study were randomly divided into two groups. The group A was 32 patients with tube voltage 80 kV and tube current(200-350)mA. The group B was 29 patients with tube voltage 120 kV and tube current(300-450)m A. Two groups were evaluated for the image quality score, mean attenuation, noise, signal-to-noise ratio(SNR) and contrast-to-noise(CNR) in aortic root and radiation dose. The image quality and radiation dose was compared by Chi-square test and unpaired t-test. A P value below 0.05 was considered to be statistically significant. Results: The aortic root showed significantly higher mean image quality score, mean attenuation, noise and CNR in group A than in group B(P = 0.000, P = 0.000, P = 0.000, P = 0.047, respectively). The SNR was not statistically significant for group A versus group B(P = 0.471). The percentage of assessable coronary artery segments was no statistically significant for group B versus group A(χ2= 3.276, P = 0.070). The mean effective dose was statistically significant for the group A was 0.95 mSv versus 2.07 mSv for the group B(t =-28.052, P = 0.000). Conclusion: 80 kV-CTCA with higher tube current could offer assessable image quality and substantially reduced effective radiation dose.
CT and MRI Diagnosis of Orbital Muscle Cone Hemangiopericytoma
YANG Tao, ZHANG Yu-sheng, CHENG Jing-liang
2015, 24(3): 409-414. doi: 10.15953/j.1004-4140.2015.24.03.10
Objective: To investigate the orbital muscle cone hemangiopericytoma(HPC) CT and MRI manifestations and pathologic characteristics, in order to improve the understanding of HPC. Methods: The literatures review, review findings, pathologic characteristics, treatment and prognosis of HPC images in 1 case proved by operation and pathology. Results: HPC CT showed soft tissue density, MRI performance with the T1 signal, T2 signal, see feature multiple small flow void signal, intraocular muscle and optic nerve were compressed, existence, fat gap ball after enhanced scanning lesions showed homogeneous enhancement. Conclusion: In depth understanding of CT and MRI manifestations and pathologic features of HPC, it has significant value in diagnosis, treatment and prognosis of HPC.
The Diagnostic Value of Conventional CTA and Subtraction CTA on Carotid Artery Stenosis
BAI Shao-jun, LI Li
2015, 24(3): 415-420. doi: 10.15953/j.1004-4140.2015.24.03.11
Objective: To investigate the value of conventional CT angiography(CTA) and subtraction CTA(SCTA) on the discrimination of degree and diagnosis of carotid artery stenosis. Methods: The conventional CTA, subtraction CTA and digital subtraction angiography(DSA) were used to perform carotid arteriography in 45 cases of suspected patients with carotid artery stenosis. The evaluation method of diagnostic assay was used to compare the concordance rate of the degree of carotid stenosis between the two CTAs and DSA, and their diagnostic value on carotid artery stenosis. Results: Conventional CTA showed 62 carotid stenosis, 80 by SCTA and 76 by DSA. There had no differences between SCTA and DSA detection of carotid stenosis(P<0.05). The sensitivity, specificity, positive predictive value and negative predictive value of conventional CTA in diagnosis of carotid artery stenosis were 78.9%(60/76), 85.7%(12/14), 96.8%(60/62) and 42.9%(6/14), respectively. The sensitivity, specificity, positive predictive value and negative predictive value of SCTA in diagnosis of carotid artery stenosis were 98.7%(75/76), 64.3%(9/14), 93.7%(75/80) and 90.0%(9/10). Compared with the conventional CTA, the sensitivity in SCTA was higher(P<0.05). Conclusions: SCTA has a better ability on discrimination of degree of carotid artery stenosis than the conventional CTA.
CT Features and Follow-up Analysis of Autoimmune Pancreatitis
ZHANG Bin-bin, ZHANG Jie, JIN Er-hu, ZHANG Shu-tian, ZHENG Xin, YANG Zheng-han, MA Da-qing
2015, 24(3): 421-428. doi: 10.15953/j.1004-4140.2015.24.03.12
Objective: To explore CT features of autoimmune pancreatitis(AIP) at initial diagnosis and during follow-up period. Materials and Methods: Clinical and CT features were retrospectively analyzed in 6 patients with AIP, and the abdominal CT examinations included CT before and after steriod treatment, CT in the periods of disease recurrence, and CT in the routine follow-up. Results: At initial diagnosis, pancreatic parenchyma showed diffuse enlargement in 5 patients and focal enlargement in 1 patient, and gradual enhancement in the involved pancreatic parenchyma was seen. Hypo-attenuation rim was seen in 2 patients, pancreatic duct within the diseased pancreas was not visible in 6 patients, and intra-pancreatic bile duct wall thickening was seen in 6 patients. On the abdominal CT after steroid treatment, the size of the diseased pancreas decreased gradually in 6 patients with recheck and 4 patients with routine follow-up CT, the atrophy of the pancreatic parenchyma and progressive enhancement were seen in 2 patients. The hypo-attenuation rim around the pancreas disappeared in 2 patients. The diameter of the narrowed bile duct returned to normal in 6 patients. The pancreatic lesions recurred in 3 patients, diffuse enlargement of the pancreas, and focal enlargement in the pancreatic head was shown in 1 patient accompanying the atrophy of the pancreatic body and tail. The pancreatic duct was not visible in 3 patients. A pseudocyst in the front of pancreas was found in 1 patient. Conclusion: CT features of AIP were similar at initial diagnosis and disease recurrence, the main findings included diffuse or focal enlargement of the pancreas and invisible pancreatic duct; the pancreatic parenchyma decreased gradually, even atrophied, may be seen during follow-up after steroid treatment.
MSCT in TNM Staging and Surgical Pathology of Gastric Cancer Control Study
XU Guan-zhen, CHEN Yu-feng, ZOU Wen-yuan, CAO Yang, HU Jiu-min, HOU Ming-wei, XIONG Liang, TONG Cheng-wen, JI Lei, YANG Qian-qian, ZHOU Lin, CAO Min
2015, 24(3): 429-435. doi: 10.15953/j.1004-4140.2015.24.03.13
Objective: To explore preoperative diagnostic and staging value of multislice spiral CT(MSCT) for gastric carcinoma. Mothods: Methods a retrospective analysis of 67 cases of patients with gastric cancer after operation, the CT staging and pathological staging results comparison, observation of MSCT in the diagnosis of gastric cancerbefore operation and TNM staging accuracy. Results: MSCT on gastric cancer T, N, M and TNM staging accuracy were 82.08%, 74.35%, 100%, 86.56%. Conclusion: MSCT enhanced examination, TNM staging of gastric cancer is higher accuracy, has important guiding significance for gastric cancer radical surgery.
The Application of Low Tube Voltage and Low Volume Contrast Agent Protocol in Aorta CTA
FU Chuan-ming, CHEN Shao-bo, WU De-hong, WANG Zhong-ping, XU Lin, CHEN Lun-gang, YU Guang-ju
2015, 24(3): 437-444. doi: 10.15953/j.1004-4140.2015.24.03.14
Objective: To evaluate the effect and its feasibility in clinical application of double-low technology(the low tube voltage and low volume contrast agent protocol) for aorta CT Angiography(CTA) on the image quality and radiation dose. Method: Totally 90 continuous patients with clinically suspected aortic lesion underwent aorta CT Angiography. They were randomly divided into two groups(control group and double low group) based on different scan protocol, prospectively. Control group included 45 patients using following parameters: tube voltage 120 kVP and contrast agent volume 1.5 mL/kg(consentration: 350 mg I/m L). Double low group included 45 patients using following parameters: tube voltage 100 kVP and contrast agent volume 1.0 mL/kg(consentration: 300 mg I/m L). Other scanning parameters were same and all subjects were used automatic tube current modulation(ATCM) technology and Smart prep technology. CT dose volume index(CTDIvol) and dose length product(DLP) in the CTA dose report were read and the dosage of contrast agent and its iodine contrast agent volume were recorded. Two associate chief radiologists evaluated the image quality and its contents consisted of the average CT values of the targeted vessels and background, image signal-to-noise ratio(SNR), contrast to noise ratio(CNR), the display and sharpness of aortic and its major branches. The clinical information, radiation dose, iodine contrast agent volume, objective and subjective assessment of image quality of these two groups were analyzed by independent t test. Results: The differences of sex, age and body mass index(BMI) of two groups were not statistically significant(P<0.05). The radiation dose and the volume of iodine received in double low group was significantly lower than that of control group, with significant statistic difference(P<0.05). The difference of subjective assessment score of image quality in two groups was not statistically significant(P>0.05). The average CT values of the aortic trunk and its major branches in two groups were higher than 300 HU, with no significant statistic difference(P>0.05). The differences of SNR and CNR in two groups were not statistically significant also(P>0.05). Although image noise in double low group was slightly higher than that of control group, there is no influence on clinical diagnosis. Conclusion: Aorta CT angiography using 100 kVP as tube voltage, contrast agent volume 1.0 mL/kg(consentration: 300 mg I/m L) and automatic tube current modulation(ATCM) technology was feasible, which can effectively reduce the radiation dose and the volume of iodine contrast agent and meet the needs of clinical diagnosis at the same time.
Spiral CT Manifestations of Askin Tumor
LIU Wei-nan, LIU Jin-bo, HE Zhong-jie, MA Jun-li, YOU Xiao-ting, GUAN Yu-bao
2015, 24(3): 445-450. doi: 10.15953/j.1004-4140.2015.24.03.15
Objective: To describe the spiral CT appearances of Askin tumors and to facilitate the understanding and differential diagnosis of Askin tumors. Materials: The CT features of twenty pathology-confirmed Askin tumors were reviewed retrospectively. Results: Based on the locations of lesions, 20 Askin tumors were divided into two groups, including sixteen Askin tumors of the chest wall, four Askin tumors of the mediastinum. Askin tumors of the chest wall were soft tissue mass originated from the chest wall. Fourteen tumors were large with heterogeneous density which showed cystic degeneration and necrosis on CT scans. Two tumors were small with homogeneous density. CT scans showed rib destruction in eleven cases, pleural effusion in ten cases, lung and bone metastasis in two patients, and calcification in two tumors. Askin tumor of the mediastinum was seen as soft tissue mass with heterogeneous density originated from mediastinum. Askin tumor of the mediastinum showed anterior chest wall invasion. Conclusion: Askin tumors showed soft tissue mass with heterogeneous density in the chest wall or the mediastinum on CT scans, usually accompanied with rib destruction and pleural effusion. Askin tumor should be considered in children and teenagers as a differential diagnosis for soft-tissue mass in the chest wall or the mediastinum.
Chest and Abdominal CT Findings and Diagnosis Analysis of Giant Lymph Cell Hyperplasia
GU Yan-mei, TIAN Bin, GUO Jing, PAN Jun, REN Yan-jun
2015, 24(3): 451-457. doi: 10.15953/j.1004-4140.2015.24.03.16
Objective: To analyze the chest and abdominal CT findings and diagnosis of giant lymph cell hyperplasia. Methods: 60 cases of giant lymph cell hyperplasia patients who were collected from January 2000 to September 2014 were selected by random sampling method, all patients were plain and enhanced by Siemens 16-slice CT scan, then the chest and abdominal CT findings and diagnosis of the patients were analyzed. Results: 15 cases of patients were with low or slightly low density, 10 cases were lack of uniform density. Under normal circumstances, the mass had a more uniform density, retroperitoneal tumor and part were lack of uniform density changes; retroperitoneal mass part of a sheet had high-density exists in the center, there was no significant enhancement to strengthen presence in the central, and thoracic and abdominal tumors were significantly strengthen, partly inhomogeneous enhancement; tumor location, size, shape and edge enhancement pattern were direct signs and pressure near the organ case were its indirect signs. Conclusion: Giant lymph cell hyperplasia has a higher rate of misdiagnosis of the chest and abdomen, and enhance scan lesions are significantly enhanced, the degree of enhancement in the thoracic and abdominal aorta are almost simultaneous, the delay continued moderate enhancement, it has very important clinical significance in the diagnosis of giant cell hyperplasia.
Clinical Value of Multislices Spiral CT Angiography Combining with CT Urography in the Diagnosis of Urinary System Diseases
HUANG Fen-yao, ZHANG Chao-liang, XIA Ting-ting, YOU Xiao-ting, GUAN Yu-bao
2015, 24(3): 459-465. doi: 10.15953/j.1004-4140.2015.24.03.17
Objective: To evaluate clinical application of multislices CT angiography(CTA) combining with CT urography(CTU) in the diagnosis of urinary system diseases. Methods: 58 patients with urinary system diseases had CT plain scan, renal dual-phase enhanced scan and delayed urinary system scan. The scan data were sent to post-processing workstation to get two-dimensionally and three-dimensionally reconstructed CTA combining with CTU images, such as maximum intensity project(MIP), multiplannar reconstruction(MPR), curved projection reconstruction(CPR) and volume rendering(VR). Results: Among 58 patients, there were 28 cases of calculi in urinary system, 6 cases of renal cancer, 4 cases of renal pelvis carcinoma, 2 cases of ureter carcinoma, 3 cases of bladder carcinoma which invaded ureter, 11 cases of external ureteral stricture, 4 cases of congenital renal dysplasia. 42 cases were confirmed by surgery pathology and 16 cases were proved by clinical examination. CTA combining with CTU can distinctly show lesions in the relationship with the surrounding tissues, organs and blood vessels. Conclusion: CTA combining with CTU can display the relationship between the urinary system and adjoining blood vessels by two-dimensionally and three-dimensionally reconstructed with post-processing technique. It is a very important evidence for clinic diagnosis and treatment plan in urinary system diseases,and should be used in routinely clinical application.
MSCT and MR on Chemical Shift Imaging Features of Minimal Fat Renal Angiomyolipoma Correlated with Pathology
HUANG Hai-dong, LIU Hong, CAO Wei, GAO Li-yong, ZHAO Rui, HE Guang-zhen
2015, 24(3): 467-474. doi: 10.15953/j.1004-4140.2015.24.03.18
Objective: To explore the Multi-slice CT(MSCT) and chemical shift imaging(CSI) manifestations of minimal fat renal angiomyolipoma(RAML) with pathology results and to improve its accuracy of diagnosis. Methods: The data of 16 cases of RAML patients were retrospectively analyzed in comparison with pathological results, including tumor size, shape, density, enhancement degree and patterns, CSI imaging features. Results: 16 lesions were all solid tumor masses. 10 lesions showed round, 6 lesions irregular in shape. moreover, split sign appearance was found in 9 lesions, cup sign in 6 lesions and cortical up sign in 5 lesions. On precontrast CT, 11 cases showed hyperattenuation, including 4 heterogeneous lesions with focal low density. Three pattern were demonstrated by enhanced scanning including wash-in and wash-out, continuous enhancement and delayed enhancement. but peak enhancement degree was lower than the renal cortex. Furthermore, 5 lesions showed hyperintensity on T2-weighted MRI. Hypointensity on out-phase CSI were seen in 3 lesions. Among them, one case showed high signal center surrounded by linear low signal ring. Conclusion: MSCT and MRI examination of minimal fat RAML demonstrates certain characteristic signs, thin layer out-phase CSI may be helpful for diagnosis of the disease.