【作者】 张丽娟；

【导师】 吕发金；

【作者基本信息】 重庆医科大学 ， 影像医学与核医学， 2010， 硕士

【摘要】 第一部分容积CT数字减影血管造影与同步匹配蒙片去骨法对比实验研究第一节同步与非同步扫描对容积CT数字减影血管造影图像质量的影响目的:探讨同步与非同步扫描对64层容积CT数字减影血管造影( volume computed tomographic digital subtraction angiography, VCTDSA)图像质量的影响。方法:建立紧贴骨结构的血管模型,采用64层螺旋CT进行扫描:(1)未注射对比剂螺旋扫描20次,球管曝光时间为2.1 s,扫描间隔时间分别为1.9 s、3.9 s、5.9 s、7.9 s、9.9 s、11.9 s、13.9 s、15.9 s、17.9 s、19.9 s,2.9 s、4.9 s、6.9 s、8.9 s、10.9 s、3.0 s、4.0 s、5.0 s、6.0 s、7.0 s。(2)注射对比剂后螺旋扫描10次,扫描间隔时间分别为9.9 s、11.9 s、13.9 s、15.9 s、17.9 s,10.9 s、12.9 s、11.0 s、12.0 s、13.0 s,其余扫描参数同(1)。减影后数据行3D容积再现(volume rendering, VR)及最大密度投影(maximum intensity projection, MIP)图像重组,评价减影后图像质量、测量减影后全幅图像CT值、记录球管曝光角度差。结果:注射对比剂前后同步扫描15次,减影后图像质量均为Ⅰ级,非同步扫描15次,减影后图像质量Ⅰ级2次、Ⅱ级12次、Ⅲ级1次;20次未注射对比剂减影后图像CT值比较,非同步扫描减影后图像CT值均数大于同步扫描;同步扫描的球管曝光角度差均数明显小于非同步扫描。结论:同步扫描保证球管曝光的起始位置相同,明显提高了VCTDSA减影后的图像质量。第二节同步匹配蒙片去骨法的建立及其与容积CT数字减影血管造影的比较研究目的:探讨同步匹配蒙片去骨(Matched Mask Bone Elimination,MMBE)减影技术显示脑血管的可行性并比较其与容积CT数字减影血管造影(volume computed tomographic digital subtraction angiography, VCTDSA)的减影图像质量。方法:应用64层螺旋CT扫描血管模型:(1)未注射对比剂同步和非同步扫描各10次;(2)注射对比剂后同步和非同步扫描各5次。用MMBE减影后行3D容积再现(volume rendering, VR)及最大密度投影(maximum intensity projection, MIP)图像重组评价减影图像质量;测量减影全幅图像CT值(无对比剂);前后提取两组骨蒙片相减并评价图像质量(无对比剂);比较同步MMBE与VCTDSA的减影图像质量。结果:采用MMBE减影同步与非同步扫描图像质量均为Ⅱ级13例、Ⅲ级2例,差异无统计学意义(P>0.05 );10例非同步扫描减影后全幅图像CT值均数为(676.17±0.41) HU,高于同步扫描减影后全幅图像CT值均数(676.04±0.60)HU,但差异亦无统计学意义(P>0.05);10例同步扫描骨蒙片相减图像质量均为Ⅰ级,而非同步扫描骨蒙片相减图像质量Ⅱ级8例、Ⅲ级1例、Ⅰ级1例,骨蒙片相减后图像质量同步扫描优于非同步扫描,差异有统计学意义(P<0.05);15例同步MMBE减影图像质量Ⅱ级13例、Ⅲ级2例,15例VCTDSA减影图像质量均为Ⅰ级。结论:同步扫描可提高MMBE减影后的图像质量,同步MMBE技术在显示脑血管方面具有可行性;VCTDSA减影图像质量优于同步MMBE。第二部分容积CT数字减影血管造影与同步匹配蒙片去骨法的临床应用比较研究第一节同步匹配蒙片去骨法的阈值优化研究目的:探讨同步匹配蒙片去骨(Matched Mask Bone Elimination,MMBE)法提取骨蒙片的最佳阈值。方法:分析在我院行VCTDSA检查且符合纳入标准的30例患者资料,设定5个大小依次递增的骨蒙片阈值点,分别为107HU、126HU、145HU、160HU及183HU,依据以上5个阈值点从平扫数据中提取5组骨蒙片,再行MMBE减影后获得5组减影原始数据,减影后数据行3D容积再现(volume rendering, VR)及最大密度投影(maximum intensity projection, MIP)图像重组,分别以颅内动脉与静脉系统作为两组不同观察对象从多角度、多方位评价减影图像质量,记录图像等级。结果:以动脉系统为主要观察对象时,骨蒙片阈值为145HU减影图像质量Ⅰ-Ⅲ级分别为16例、14例、0例,阈值为107HU减影图像质量Ⅰ-Ⅲ级分别为0例、7例、23例,阈值为145HU减影图像质量最优,以145HU为中心随着阈值递增或递减,减影图像质量随之降低;以静脉系统为主要观察对象时,骨蒙片阈值为160HU减影图像质量Ⅰ-Ⅲ级分别为24例、6例、0例,阈值为107HU减影图像质量Ⅰ-Ⅲ级为0例、4例、26例,阈值为160HU减影图像质量最优,以160HU为中心随着阈值递增或递减,减影图像质量随之降低。结论:以颅内动脉为观察对象,骨蒙片阈值为145HU减影图像质量最优,以颅内静脉为观察对象,骨蒙片阈值为160HU减影图像质量最优,根据观察重点的不同设定不同的阈值,可提高同步MMBE的减影图像质量,有利于血管病变的显示。第二节容积CT数字减影血管造影与同步匹配蒙片去骨法对颅内动脉瘤诊断价值的比较研究目的:探讨容积CT数字减影血管造影(volume computed tomographic digital subtraction angiography, VCTDSA)与同步匹配蒙片去骨(Matched Mask Bone Elimination,MMBE)法对颅内动脉瘤的诊断价值。方法:分析在我院行VCTDSA检查临床怀疑有颅内动脉瘤的57例患者资料,其中47例经三维数字减影血管造影( 3 Dementional digital subtraction angiography,3-D DSA)和/或手术证实,比较VCTDSA与MMBE的减影图像质量、检出动脉瘤的位置、大小、敏感性、特异性、阳性预测值、阴性预测值以及二者图像后处理时间。结果:本组经3-D DSA和/或手术证实47例共53个动脉瘤,在检出动脉瘤患者方面,VCTDSA的敏感性、特异性、阳性预测值及阴性预测值均为100%,均高于MMBE;在检出动脉瘤数目方面,VCTDSA的敏感性为96%、特异性100%、阳性预测值100%、阴性预测值75%,均高于MMBE;在检出动脉瘤所在位置方面,VCTDSA检出颈内动脉瘤的敏感性为94%、特异性为100%、阳性预测值为100%、阴性预测值90%,均高于MMBE,其余大脑前动脉、大脑中动脉及后循环三个位置VCTDSA与MMBE检出动脉瘤未见明显差异;VCTDSA与MMBE均能检出﹤3mm的微小动脉瘤,VCTDSA检出﹤3mm的动脉瘤的敏感性(87%)明显高于MMBE(67%)。VCTDSA的减影图像质量优于MMBE;VCTDSA的平均图像后处理时间短于MMBE。结论:VCTDSA是一种方便、快速的检查方法,图像真实、可靠,对颅内动脉瘤的检出与诊断优于同步MMBE。更多还原

【Abstract】 SECTION1 IMPACT OF SYNCHRONOUS AND ASYNCHRONOUS SCANNING ON IMAGE QUALITY OF VOLUME CT DIGITAL SUBTRACTION ANGIOGRAPHYObjective: To investigate the effects on image quality of volume computed tomographic digital subtraction angiography (VCTDSA) with synchronous and asynchronous scanning.Methods: Vascular model which was closely attached to bony structures was scanned by 64-slice spiral CT.①Helical scanning was performed without contrast medium injection for 20 times and the tube exposure time was 2.1 s, scanning intervals differently were 1.9 s, 3.9 s, 5.9 s, 7.9 s, 9.9 s, 11.9 s, 13.9 s, 15.9 s, 17.9 s, 19.9 s, 2.9 s, 4.9 s, 6.9 s, 8.9 s, 10.9 s, 3.0 s, 4.0 s, 5.0 s, 6.0 s, 7.0 s.②After contrast medium injection, the vascular model was scanned for 10 times using the same parameters as above, but the scanning intervals differently were 9.9 s, 11.9 s, 13.9 s, 15.9 s, 17.9 s, 10.9 s, 12.9 s, 11.0 s, 12.0 s, 13.0 s. The resulting images were reformatted as 3D volume rendering (3D VR) and maximum intensity projection (MIP) images. The quality of subtraction images was then analyzed. CT values of the overall view were measured on subtracted images and the differences of tube exposure angle were recorded.Results: Subtracted images quality of VCTDSA was rated gradeⅠwith synchronous scanning for 15 times before and after contrast medium injection, while with asynchronous scanning for 15 times, 2 times were gradeⅠ, 12 times were gradeⅡand 1 time was gradeⅢ. In 20 times, the average CT value of subtracted images with asynchronous scans was higher than which with synchronous scans without contrast injection. The differences of tube exposure angle with synchronous scans were obviously less than which with asynchronous scans.Conclusion: The position of tube can be well matched with synchronous scanning, so the image quality of VCTDSA is improved significantly. SECTION2 ESTABLISHMENT OF SYNCHRONOUS MMBE AND COMPARATIVE STUDY BETWEEN SYNCHRONOUS MMBE AND VCTDSAObjective: To evaluate the feasibility of subtraction CT angiography of the cerebral vessels with synchronous matched mask bone elimination(MMBE)technique and compare the image quality of MMBE with that of volume computed tomographic digital subtraction angiography (VCTDSA).Methods:Vascular model was scanned by 64-slice spiral CT. (1) Synchronous and asynchronous scans were independently performed for 10 times without contrast medium injection. (2)Then with contrast medium injection, the same scans mentioned above were repeatedly performed each for 5 times. The image quality of MMBE was analyzed, which were reformatted and displayed with 3D volume rendering (VR) and maximum intensity projection (MIP). The CT value of the overall view was measured on subtracted images (without contrast medium). Two sets of bone masks were extracted for subtraction and the image quality was evaluated (without contrast medium). Also the image quality of VCTDSA was compared with those of synchronous MMBE.Results: With synchronous and asynchronous scan,the image quality of MMBE was both rated gradeⅡin 13 cases, gradeⅢin 2 cases. There was no significant difference in the average CT value of subtracted images between the two methods.(P>0.05). With synchronous scan the image quality of subtracted bone mask was rated gradeⅠin 10 cases. While with asynchronous scan,1 case was gradeⅠ, 8 cases were gradeⅡand 1 case was gradeⅢ. The image quality of synchronous MMBE was rated gradeⅡin 13 cases, gradeⅢin 2 cases. For VCTDSA, the image quality was rated gradeⅠin 15 cases. Conclusion:Synchronous MMBE is a feasible imaging method for evaluation of cerebral vessels. The subtracted image quality is significantly improved with this technique. However, the image quality of VCTDSA is still superior to that of synchronous MMBE. PART2 THE COMPARATIVE STUDY ON THE CLINICAL APPLICATION OF VCTDSA AND SYNCHRONOUS MMBE SECTION1 OPTIMIZATION FOR THRESHOLD OF SYNCHRONOUS MMBE Objective: To investigate the optimal threshold of bone mask which used for synchronous MMBE.Methods:VCTDSA data that matches research inclusion criteria of 30 patients in our hospital were analyzed.Five points of threshold were set which increased by turns.There were differently 107HU、126HU、145HU、160HU and 183HU. F ive sets of bone masks were extracted according to the five points of threshold. Then five sets of subtracted data were obtained with MMBE. The resulting images were reformatted as 3D volume rendering (3D VR) and maximum intensity projection (MIP) images.Then the image quality of MMBE was analyzed according to two sets of observed objects, which were differently cerebral artery and cerebral vein systems, and the grade of images were recorded.Results:When the cerebral artery was observed , the image quality of MMBE was rated gradeⅠin 16 cases, gradeⅡin 14 cases and gradeⅢin 2 cases , as the threshold of bone masks was 145HU. As the threshold was 107HU, the image quality of MMBE was rated gradeⅡin 7 cases , gradeⅢin 23 cases, and no case in gradeⅠ. The subtracted image quality was optimal when the threshold was 145HU.As the central threshold of 145HU, the image quality got degraded with the threshold increased and decreased progressively. When the cerebral vein was observed , the image quality of MMBE was rated gradeⅠin 24 cases, gradeⅡin 6 cases and no case in gradeⅢ, as the threshold was 160HU. As the threshold was 107HU, the image quality of MMBE was rated gradeⅡin 4 cases , gradeⅢin 26 cases, and no case in gradeⅠ. And the subtracted image quality was optimal when the threshold was 160HU.Also as the central threshold of 160HU, the image quality got degraded with the threshold increased and decreased progressively.Conclusion:When the cerebral artery is observed,the threshold of 145HU is optimal.While the cerebral vein is observed,the threshold of 160HU is optimal. So the image quality of MMBE is improved with different threshold setting when different objects are observed. It is helpful to display vascular lesion.SECTION2 COMPARISON OF VCTDSA AND SYNCHRONOUS MMBE IN THE DIAGNOSIS OF INTRACRANIAL ANEURYSMSObjective:To investigate the diagnostic performance of volume computed tomography digital subtraction angiography(VCTDSA) and synchronous matched mask bone elimination(MMBE)in the detection of intracranial aneurysms.Methods: VCTDSA datas of 57 patients that suspected of having intracranial aneurysms in clinic in our hospital were analyzed.47 patients of the total were confirmed by 3 Dementional digital subtraction angiography (3-D DSA) and/or by surgery. With VCTDSA , The subtracted image quality,time of reconstruction,location and size of aneurysms, sensitivity , specificity , Positive Predictive Value (PPV) and Negative Predictive Value (NPV) in aneurysms detection were compared with synchronous MMBE.Results:53 aneurysms were detected in 41 patients who confirmed by 3-D DSA and/or by surgery. On a per-patient basis, the sensitivity, specificity, and positive and negative predictive values for VCTDSA were all 100%,which higher than that of synchronous MMBE.On a per-aneurysm basis, the sensitivity, specificity, and positive and negative predictive values for VCTDSA respectively were 96%, 100%, and 100% and 75%, which all higher than that of synchronous MMBE. On a per-location basis, the sensitivity, specificity, and positive and negative predictive values for VCTDSA were 94%, 100%, and 100% and 90% in detection of internal carotid artery aneurysm, which also all higher than that of synchronous MMBE. As for the other three locations of anterior cerebral artery, middle cerebral artery and posterior circulation, there was no significant difference between the two methods in detection aneurysms. Aneurysms smaller than 3 mm could be detected both by VCTDSA and synchronous MMBE .The sensitivity(87%) of VCTDSA was obviously higher than that(67%) of synchronous MMBE in detection of aneurysms smaller than 3 mm.The image quality of VCTDSA was superior to that of synchronous MMBE. And the postprocessing time of VCTDSA was shorter than that of synchronous MMBE.Conclusion: VCTDSA is a convenient and fast technique, and the resulting images are actual and reliable.VCTDSA is superior to synchronous MMBE in detection and diagnosis of intracranial aneurysm.更多还原