Objective:To explore the possible influencing factors for image quality of digital subtraction CT angiography(DSCTA).Methods:Vascular model of the skull base was observed using 16-slice spiral CT(Brightspeed elite).(1)Each parameter was scanned for 10 times at both spiral and non-spiral axial view.(2)Two uniform parameters were compared in the same sequence at different exposure intervals(2.3s,3.5s,4.1s,4.7s,5.9s;4s,5s,6s,7s,8s)and different slices(32,41,48,51,55;60,64,72,77, 80)and scanned twice.(3)After injection simulation,the vascular model was scanned for 5 times using the same parameters as above and 80 slices were collected at an exposure interval of 2.4s. Results:The subtraction was 100% successful by non-spiral scanning, while 20% by spiral scanning in 10 times. Within the same sequence, the subtraction was successful only if the tube repetition exposure interval time was integrally divided by 0.6s. The subtraction rate was 85%, in different slices used. The tube exposure interval was 9s. The clear vascular image was obtained after scanning for 5 time. Conclusion Home position of tube is critical to the DSCTA image quality and can be maintained only If the tube repetition exposure interval time integrally divided by the rotation speed. Width of detector has no influence on the DSCTA image quality.

Objective:To investigate MR imaging features and diagnostic value of bone contusion. Methods:70 consecutive patients with bone contusion were prospectively analyzed, the time between bone injury and MR examination, sensitivity of MR series to detecting lesions of contusion and distribution of lesions were evaluated; a knee contusion follow-up images and a bone contusion pathologic data was analyzed. Results:MR examination of bone contusion were mostly less than two weeks, but a few patients were longer than one year;STIR,T1WI were more sensitive lesion detection series in bone contusion(100% and 95.7%).Bone contusion mostly occur at knee, and lesions mainly distributed in the margin area of articular(69.8%), in superior portion of vertebral body(74.1%). Bone contusion following-up showed a line-like hyperostosis and osteosclerosis in contusion area. Histological manifestations of bone contusion were local trabecular micro fractures, edema, hemorrhage and injury of fat tissue. Conclusion:MR imaging is a sensitive method of diagnosis in bone contusion, could display position and course of bone contusion. Bone contusion is local trabecular microfractures, early diagnosis can allow patients early treatment, the important diagnostic tool is MRI.

0.05. While between IJV and SSS it was 1.31 second, between MCA and SSS 6.06 second, between CCA and IJV 7.59 second. At the same time of TP, the left common carolid artery adjacent to the fourth cervical verlebrae and IJV enhanced significantly more than the M1 segment of lett middle cerebral artery and SSS. Conclusion:The TP in Cerebral Vessels and Cephalic and Cervical Vessel was not obviously difference testing by contrast agenl mass injection method. So we can deduce lhe scan-delay-time in cerebral and cervix with VCTDSA by the TP with CT perfusion dynamic scan.

Objective:To evaluate the diagnostic value of subtraction CT angiograph(SCTA)and volume CT Digital subtractionangiography(VCTDSA) in detecting intracranial aneurysms,and compare their performance.Methods:Previously publishedliteratures concerning the diagnostic performance of SCTA between 1990 and 2008 were retrospectively reviewed(seven in English andtwo in Chinese),and were analyzed and compared with the performance of VCTDSA in detecting and characterizing of intracranial aneurysms.Then the correlated information was extracted,and the diagnostic sensitivity and specificity of intracranial aneurysms by the two kinds of technique were analyzed.Results:Except the data of Imakita、Romijn which the sensitivity of detecting intracranial aneurysms were 92% and 99%,the sensitivity of others were 100%,and the specificity of detecting intracranial aneurysms were 90% to 100%.88.9% of images were excellent quality(8/9)in the display of cerebral vessels and diagnostic information of intracranial aneurysms.The image quality of VCTDSA was excellent compared with other subtraction CT angiography,and it could completely display the whole cerebral vessels,including 5 grade branches and the clear relationship among artery-veins,aneurysms and parent artery of aneurysms.Conclusion:Compared with Subtraction CT angiography,VCTDSA has an advantage in the diagnosis of intracranial aneurysms.

Objective:To investigate the influence of the type and extentofhead motion on subtraction image quality of 64-slice volume CT digital subtraction angiography(VCTDSA). Methods:Forty-four consecutive patients(18 male,26 female;mean age,(52.6?17.6) years)underwent VCTDSA for the evaluation of cerebral vascular disorders. We performed the scanning with two different registration methods:test bolus injection without head fixation and registration with rigid head fixation. Imaging data of two different scan modes were then analyzed. The type and extent of head motion between two scan modes as well as the manifestation,degree of artifacts after subtraction were evaluated. Results:There were three forms of head motion during test bolus scan:intra-lamina(r77.3%),inter-lamina(r4.5%)and mixed motion (18.2%). High density motion artifacts of subtraction images were observed near the border of the anatomic structures. Motion artifacts were obviously reduced by head fixation. With head fixation approach,the subtraction angiograms without motion artifact increased from 13.6% to 59.1%,and images with moderately to severe artifacts reduced from 47.1% to 11.4%. Conclusion:There were three forms of head motion without head fixation,and different form motion artifacts were observed after subtraction. Head fixation prevents motion artifacts and greatly improves subtraction image quality.

National level excellent courses' construction is an important part of the quality and reform in education .We explored the teaching methods of medical imaging under the construction of the excellent course to improve the quality education.

Case based study emphasizes on the training of students' practical clinical ability. With the development of computer technology, picture archiving and communication system was widely applied, providing bases for case based study. According to the characteristics of radiology, appli-cation of case based study in medical imaging practice teaching was believed to stimulate students' learning interest, improve their analytical ability and thinking capacity, make them combine theory with practice better and develop their clinical thinking ability.

To improve the quality of practice teaching in medical imaging,we explored the teaching methods on the basis of quality-oriented education,combining the special nature of the medical imaging and the clinical medicine program.

Comparative imaging can be used to analyse and compare diseases in different respects,which can not only conduce to students’transversal contrast of knowledge they have learned, but also improve the teaching effect of medical imaging and the students’clinical skills,and at the same time,lay a solid foundation of the research for future.

Objective To compare the image quality between large dose smart tracking technique and low dose test bolus technique for gem spectral CT pulmonary angiography(CTPA).Methods A total of 106 cases with suspected pulmonary embolism were divided into two groups.Group A(54 cases)was carried out with large dose smart tracking technique.Group B(52 cases)was carried out with low dose test bolus technique.We compared the image quality between the two groups.Results There were significant differences in the CT value of the right pulmonary artery and the content of iodine in the lower lobe of the right pulmonary artery of two groups(P<0.01).There was significant difference of image quality between the two groups(P<0.05).The rate of excellent or good image quality in group A was higher than that in group B,and the difference was statistically significant(P<0.05).Conclusion Large dose smart tracking technique can track the artifacts of pulmonary artery imaging with less artifacts and uniform vascular fixation.The image quality of pulmonary artery imaging is better than that of small dose contrast agent.