CT理论与应用研究

Reviews of Image Reconstruction from Few-View Projections

DUAN Xin-hui, ZHANG Li, CHEN Zhi-qiang, CHENG Jian-ping

2007, 16(4): 1-7.

Abstract(1218) PDF(4)

Abstract:
We briefly recall previous literature about the few-view projection reconstruction problems.The few-view projection problem belongs to the uncompleted data reconstruction,which means the projection number is much fewer than common conditions,such as one tenth,or twentieth.Because of the similarity,some of the ideas are from the reconstruction algorithms of the limited angle problems.There are mainly two thoughts of the reconstruction: one is sinogram recovery methods,such as the angular interpolation,transform-based iterative-analytic reconstructions;the other is image recovery methods,such as reconstruction methods incorporating a priori information,TV constraint.

Overview of Statistical Reconstruction Algorithms

WANG Zhen-tian, ZHANG Li, XING Yu-xiang, KANG Ke-jun

2007, 16(4): 8-21.

Abstract(850) PDF(2)

Abstract:
In this paper,the statistical reconstruction algorithms for PET and SPECT are discussed,including the history,the new improvements and the future.Three concepts that have significant meanings in the development of statistical reconstruction are summarized: Ordered Subset(OS),Incremental Method and Optimization Transfer(OT).In order to show the outline of statistical reconstruction in the past years,this paper focuses on the algorithms that have significant innovations in both concept and method,and introduces the main ideas and motivations of these algorithms.

The Application of Resistivity Tomography Method in Cave Exploration

LI Jing-hui, LI Qing-lin, YIN Jian-wu, FANG Qing-yin, LI Jun

2007, 16(4): 22-30.

Abstract(549) PDF(0)

Abstract:
The Resistivity Tomography method is based on ordinary to collect the high-density data and then to form a high-density and rich-content resistively section.It can reflect the basic characteristics of geologic body objectively and exactly through the analysis and processing of the geoelectric data.This paper makes a brief overview on the resistivity tomography of principle,method and mechanism of the formation of cave.The detection and discovery of the cave at Xihuling Scenic Area in Lushi county,that has great significance and value for the development of this place.Using resistively tomography method can make the explanation work more convenient and intuitive,and has good relevance,effectiveness and feasibility.

Fast Accomplishment of Reconstruction Algorithm for Cone Beam CT

WU Sheng-li, PAN Rui-yi, WEN Bin

2007, 16(4): 31-37.

Abstract(1024) PDF(6)

Abstract:
Based on the analysis of traditional FDK filtered-backprojection algorithm for Cone-beam CT reconstruction,two kinds of improvements are presented to accelerate the reconstruction.Together with algorithm improvements,the parallel programming technology Open MP and the SSE,MMX instructions are adopted to optimize the code.The reconstruction from actual cone-beam CT projections shows that these improvements can make the reconstruction much fast while keeping the image quality as good as the traditional FDK algorithm.

The Multislice CT Perfusion Imaging in Uterus and Uterine Leiomyoma

XIANG Zi-yun, YIN Liang, YE Qu-yang, ZHAN Yong, WANG Jing-bo, LUO Liang-ping

2007, 16(4): 38-43.

Abstract(865) PDF(0)

Abstract:
Objective: The purpose of this study was to explore the application of multislice CT perfusion imaging in uterus and uterine leiomyoma.Methods: Routine pelvic CT was performed in 17 cases and then CT perfusion imaging was made at selecting slice.The contrast material was bolus injected through forearm superficial vein,while 4 slices of dynamic scan was performed for 40 seconds.The dynamic images were processed by Perfusion CT software package,and then the Blood Flow,Blood Volume and Time to Peak of the uterine leiomyoma and the normal uterine tissue(around the tumor) were measured and documented respectively.Results: All cases of multislice perfusion imaging were successfully performed.A significant difference in Blood Flow between uterine leiomyoma and the normal uterine tissue(around the tumor) was showed.The Blood Flow,Blood Volume and Time To Peak of the uterine leiomyoma were(54.87±19.09)ml.100g^-1.min^-1,(12.41±4.07)% and(18.61±5.31)s.The Blood Flow,Blood Volume and Time To Peak of the normal uterine tissue(around the tumor) were(32.82±17.68)ml.100g^-1.min^-1,(8.78±6.25)% and(20.64±5.71)s.Conclusion: Multislice CT perfusion imaging provided a new imaging method for measuring the uterine hemadynamic.

Clinical Application of 3D and MIP with MSCT in Hepatic Carcinoma with Arterioportal Shunt

YANG Li-min, XU Kai, GU Yu-ming

2007, 16(4): 44-50.

Abstract(741) PDF(0)

Abstract:
Objective: To investigate the clinical applicable value of three-dimensional(3D) and maximum intensity projection(MIP) with 16-row helical CT in diagnosing the hepatic carcinoma with arterioportal shunt.Methods: 64 Cases of hepatic carcinoma with arterioportal shunt underwent 16-row helical CT enhanced volume scans.To be reconstructed with MIP and 3D techniques,All reconstructed imagines were observed and analysed(compaired with imagines of trans-axia and DSA).Results: 16-row helical CT MIP and 3D reconstruction could produce clear and comprehensive images of the hepatic carcinoma with arterioportal shunt,and produce the change of hemodynamics which resulted in arterioportal shunt.Conclusion: 16-row helical CT MIP and 3D reconstruction as important techniques of trans-axial,could display the characteristical of the hepatic carcinoma with arterioportal shunt with no traumatic,intuitionistic and quickly,which could afford the powerful evidence for clinical diagnose and treat with the hepatic carcinoma with arterioportal shunt.

Lateral Ventricular Ependymomas: MR Imaging Features and Differential Diagnosis

LÜ Guo-shi, XU Yi-kai

2007, 16(4): 51-55.

Abstract(1574) PDF(2)

Abstract:
Objective: To study the MR imaging features of lateral ventricular ependymomas.Materials and Methods: 38 cases of lateral ventricular ependymomas with histologically confirmed were retrospectively reviewed in terms of location,size,pattern of growth,signal intensity,enhancement pattern as well as the presence or absence of cyst on MR imaging.Results: Almost of tumors were iso-or hypointense on T₁WI and all of tumors were hyperintense on T₂WI.A cystic component was seen in 73.7% of lateral ventricular ependymomas and intratumoral hemorrhage was rare.Almost of tumors were irregular margins.22(57.9%)cases of tumors infiltrated vicinity of brain tissue and 30(78.9%) cases extended to opposite side ventricle or third ventricle.Almost of tumors(89.5%)showed obviously non-uniform enhancement and 4 cases showed slight non-uniform enhancement.Conclusion: Lateral ventricular ependymomas have certain MR features,which are very help to make correct preoperative diagnosis and different diagnosis.

Application of 64 Multi-Detector Helical CT in Evaluation of Fracture of Accessory Nasal Cavity

FENG Wei, YAN Chen, ZHANG Li-li, WU Ge, HUO Jian-wei, CENG Qing-yu

2007, 16(4): 56-60.

Abstract(840) PDF(1)

Abstract:
Objective: To evaluate the diagnostic value of 64 multi-detector helical CT in fracture of accessory nasal cavity.Methods: 188 cases suspected fracture of accessory nasal cavity were performed with 64-MDCT.The data was transmitted to ADW4.2 workstation,and reconstructed by MPR,MIP,VR and generally analyzed with original axial images.Results: All the 69 fracture of accessory nasal cavity were demonstrated clearly by MDCT,and it can revealing the location,types,level and complication of fracture change.Conclusion: 64-MDCT is reliable and accurate in evaluating fracture of accessory nasal cavity,gradually become necessary modality examination in patients after trauma of facial surface.

Analysis MRI of Hemangioblastoma

LIU Jin-cai, CHEN Hua-ping

2007, 16(4): 61-65.

Abstract(666) PDF(0)

Abstract:
Objective: To discuss the MRI features of Hemangioblastoma.Methods: Ten cases of Hemangioblastoma which confirmed by operation and pathology were examined with conventional MRI and Gd-DTPA enhanced MRI.Results: In some cases of Hemangioblastoma,there was a big cyst and a small mural node in the MRI imaging,In solid type of Hemangioblastoma,where the tumor was revealed as a huge solid mass,deflective cyst,abnormal tumor bloodstream and the masses enhanced obviously,In Cystic type the tumor showed a cyst.Conclusion: Cyst,mural node,abnormal tumor bloodstream and enhanced obviously were the MRI features of Hemangioblastoma,and so MRI is the most reliable method to diagnose Hemangioblastoma.

Initial Trial in Diagnosis of Rectal Cancer by Using Open-Configuration Lower Strength Magnetic Resonance Scanner and Signs Analysis

ZHONG Hong-bo, LI Xiao-yang, LI Ji

2007, 16(4): 66-69.

Abstract(712) PDF(0)

Abstract:
Objective: To discuss the value of the open lower magnetic resonance(MR) scanner in detecting rectal cancer,and to analyze the signs.Materials and methods: We have collected sixteen cases of rectal cancer diagnosed by our pathology examination.The sixteen patients would cooperate throughout the entire scanning process and they didn’t have serious diseases in the heart,liver,lung or kidney.The intestinal tract was prepared on the previous day.Spasmolysant was given to the patients fifteen minutes before scanning,after that,about 1000ml of normal saline was inpoured through the cannula inside of the anus,followed by about 1000ml of air to expand the intestinal canal as large as possible.Inpouring was stopped when the patients experienced discomfort.Before the examination,the patients were trained to inhale and exhale calmly and to diminish their breath extent to the limit.Patients used supine and prone positions while being examined.Result: The main MR manifestations of rectal cancer were local or diffuse thickening of the intestinal walls and forming of lumps,which appears as a middle-to-low-signal-intensity in T1 MR imaging with distinct border and a relative higher-signal-intensity in T2 MR imaging.The cancer was shown as irregular strengthening images by Gd-DTPA.The surrounding organs such as the uterus,urinary bladder,prostate gland and pelvic cavity wall could be well displayed by MR.Conclusion: The open-configuration lower strength MR scanner is relatively easy to operate in the process of diagnosing rectal cancer and can show clearly the pathological change of rectal cancer.At the same time,it brings few sufferings and little trouble to patients.It is a new method and shows high value in assisting in the diagnosis of rectal cancer.

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2007 Vol. 16, No. 4