头颈部双能减影CTA质量评估及临床应用

【作者】 陈钰；

【导师】 金征宇；

【作者基本信息】 中国协和医科大学 ， 临床医学， 2008， 博士

【摘要】 第一部分头颈部双能减影CTA图像质量评估及其与64层螺旋CT的对照研究研究目的:旨在对头颈部双能减影CTA的图像质量及其相关因素进行初步分析,以及双能减影与64层螺旋CT头颈部动脉成像的对比研究。评价患者年龄、身高、体重及BMI对双源CT头颈部CTA动脉强化程度的影响。材料及方法:30例行头颈部双能减影CTA的患者(A组,男:女=16:14,年龄53.7±17.3岁)及30例行64层螺旋CT头颈部CTA(B组,男:女=17:13,年龄55.2±13.0岁)的患者。A组患者采用西门子双源CT(Somatom Definition,Siemens Medical Solutions,Forchheim,Germany)以5.0 ml/s的流率注入80ml高浓度非离子对比剂碘普罗胺(商品名:优维显Ultravist)370mgI/ml和50 ml生理盐水。B组患者采用西门子64层螺旋CT(Somatom Sensation 64,SiemensMedical Solutions,Forchheim,Germany)进行扫描,以5.0 mL/s的流率注入60ml非离子对比剂碘普罗胺(商品名:优维显Ultravist)370mgI/ml和50 ml生理盐水。在轴位图上分别测量颈总动脉(颈总动脉分叉处)及同层面颈内静脉,大脑中动脉M1段及同层面脑内静脉窦CT值,冈上肌及竖脊肌的SD值,同时测量增强期DLP,测量平扫期与增强期DLP的总和,比较双源CT及64层螺旋CT头颈部CTA的图像强化程度、噪声以及扫描剂量。结果:A组(双源CT)与B组(64层螺旋CT)患者的颈总动脉与大脑中动脉强化程度无显著性差异,A组颈内静脉污染明显高于B组,脑内静脉污染两组无显著差异。A组患者肩部与颈部肌肉的SD值明显低于B组(P＜0.001)。A组总DLP(745 mGy·cm)比B组(549 mGy·cm)高出29%。颈总动脉强化值与体重(r=0.64),身高(r=0.453),BMI(r=0.453)均有较强负性关系(P＜0.05)。结论:双源CT头颈部CTA的图像质量与64层螺旋CT相近,且前者的图像噪声低于后者,可满足临床需要。在年龄、身高、体重及BMI中,体重因素是影响双源CT头颈部CTA图像质量的主要因素。第二部分头颈部双能减影CTA对血管狭窄程度的评估分析及其与MRA、DSA的对照研究研究目的:(1)在动脉粥样硬化性疾病中,分析双能减影CTA(DESCTA)对血管狭窄程度的可评价性;(2)研究钙化斑块对双能减影CTA评价血管狭窄程度能力的影响。(3)将DESCTA与MRA进行对比研究,评价二者检验血管狭窄程度的一致性。(4)将DESCTA与DSA进行对比研究,计算DESCTA的敏感性、特异性、准确性、阳性预测值及阴性预测值。材料及方法:49例高度怀疑动脉粥样硬化的患者行双能减影CTA扫描,采用西门子双源CT扫描机(Somatom Definition,Siemens Medical Solutions,Forchheim,Germany),以5.0ml/s速度注入80ml高浓度非离子对比剂(370mgI/ml)和50ml生理盐水。采用双能软件(Dual energy)中的头部去骨功能(HeadBone Removal)进行后处理,得到双能减影图像(去骨、去斑块)。(1)将图像质量依4分评分系统进行评分;(2)对于颈总动脉分叉部及颈内动脉虹吸段的钙化斑块进行进一步分析,测量钙化斑块的体积及环绕管腔比例,评价钙化斑块对双能减影CTA评价血管狭窄程度能力的影响;(3)其中32例患者的DESCTA与MRA结果对照,评价两者对诊断颈动脉系统血管狭窄程度的一致性;(4)其中20例患者的DESCTA与DSA结果对照,计算双源CT头颈部DESCTA对血管狭窄程度评价的敏感性、特异性、准确性、阳性预测值及阴性预测值。结果:(1)双能减影CTA显示了49例患者头颈部846段血管,其中可评价的动脉为99.1%(838/846,可评价性评分≥3分)。(2)双能减影中,颅外段血管狭窄程度可评价性与钙化斑块体积及管腔环绕狭窄程度均无明显相关性(斑块体积,Spearman检验,P=0.453;管腔狭窄程度,Pearson chi-square检验,P=0.090),颅内段血管图像质量与钙化斑块体积有明显相关性(Spearman检验,P=0.007),与钙化斑块)不绕管腔程度仅有轻度相关性(Pearson chi-square,P=0.046)。(3)DESCTA与MRA对照,狭窄程度相符的占96.6%(486/503),Wilcoxon检验二者的狭窄程度有显著差异(Z=-4.716,P＜0.001)。(4)DESCTA与DSA对照,准确性97.6%(361/370),DESCTA诊断闭塞血管的敏感性及特异性均为100%;诊断头颈部血管≥50%狭窄的敏感性95.5%,特异性99.4%,准确性99.2%,阳性预测值91.3%,阴性预测值99.7%;DESCTA诊断头颈部血管≥70%狭窄的敏感性92.3%,特异性99.2%,准确性98.9%,阳性预测值80%,阴性预测值99.7%。结论:双源CT头颈部双能量减影CTA有较高的图像质量,可用于对头颈部动脉的显示。对于颅外段血管,双能减影CTA可以很好的避免钙化斑块对管腔狭窄程度评估的影响,对于颅内段血管,双能减影的方法仍不能完全避免钙化斑块对管腔狭窄程度评估的影响。与MRA相比,DESCTA对头颈部动脉狭窄程度评价的一致性较好,但DESCTA存在一定程度的过评价现象。与金标准DSA相比,DESCTA评价血管狭窄程度准确性较高。更多还原

【Abstract】 OBJECTIVE.Compare the image quality and radiation dose of traditional 64-slice spiral CTA with DS-CTA of cervical and cranial regions.Evaluate the effect of age, height,weight,body mass index(BMI) on contrast enhancement in head and neck CTA.MATERIALS.AND METHODS.We retrospectively analyzed two groups of patients undergoing 64-slice spiral CTA and DS-CTA examination of cervical and cranial regions:with different scan protocols.The DS-CTA dataset(groupA,N=30, M:F=16:14,mean age=54y) was obtained with 1.0mm axial thickness,0.6mm interval, 140/80 kVp,64/272 mA,0.6 pitch factor,80 mL of contrast medium.The CTA 64-slice spiral dataset(groupB,N=30,M:F=17:13;mean age=55y) was obtained with 0.6mm axial thickness,0.6mm interval,120 kVp,230mA,1.5pitch factor,60 mL of contrast medium.We compared image quality,vascular enhancement,noise and radiation dose.The attenuation values and SD values were measured on transverse images at 4 different vessels(the distal part of common carotid artery and adjacent vein in same axial image;the Mls and sigmoid sinus or confluences of sinus in same image) and two muscles(one in neck region presenting average soft tissue enhancement and one adjacent to shoulder joint presenting regions of great artifact).. RESULTS.DS-CTA was significantly better than 64-slice spiral CTA in noise of soft tissues no matter artifact was absent(P＜0.001) or not(P＜0.001).In cranial region the arterial enhancement and venous contamination were similar.DS-CTA had greater venous contamination in cervical region(P＜0.001),since the mean attenuation value of common carotid artery was still higher than jugular vein by 130 Hu,this was compensative and didn’t affect the delineation and analysis of cervical arteries.The total DLP of DS-CTA was 745 mGy.cm,which was 29%greater than 64-slice spiral CTA(579 mGy·cm).Strong inverse correlations were seen between attenuation of common carotid arteries and weight(r=0.64),height(r=0.453),BMI(r=0.453) (P＜0.05 for all).CONCLUSION.DS-CTA had comparable image quality to 64 slice spiral CTA,and its scan dose was greater.Among the age,height,weight and BMI,weight is the main factor that effects on the contrast enhancement of the head and neck DS-CTA. OBJECTIVE.To evaluation the image quality of dual energy subtracted CTA (DESCTA),and assess the correlations beween the calcificaion and image quality. Investigated the stenosis agreement of DESCTA and magnectic resonace angiography (MRA).Compare DESCTA and DSA to detection and measurement of stenosis in head and neck arteries.MATERIALS AND METHODS.Forty nine patients with suspicious of head and neck artery atherosclerosis underwent dual energy CT scan,along with a 3D TOF-MRA(n=32) or DSA(n=20) examination 1 days to three months before or after CTA.CT scan was performed using dual source CT(Definition,Siemens Medical Solution,Forchheim,Germany).80 ml ultravist(370 mgI/ml,Bayer Schering) was used as contrast agent followed by 50ml saline flash at speed of 5ml/s.A maximum intensity(MIP) image was first automatically obtained through dual energy subtraction(Software,Siemens).Ratings were based on a 1-4 scale for the MIP image: 1 no diagnostic,2 partially diagnostic,3 diagnostic,4 excellent.Calcium volume and surrounding percentage were calculated.Stenosis of internal carotid arteries obtained from DESCTA,MRA,DSA was evaluated basing on North American Symptomatic Carotid Endarterectomy Trial(NASCET) criteria by consensus with 2 experienced radiologists.The consistency of DESCTA and MRA,DESCTA and DSA were tested with the Wilcoxon test.RESULTS.(1)The head and neck arteries were divided into 21 segments.Among them,the internal carotid arteries were divided into six anatomical segments according to Fischer(1938):cervical,petrous(C5),caverous(C4),clinoidal(C3), cerebral(C2) and ascending(C1) segment.Totally 846 vessel segments from 49 patients were calculated except total occlusive(n=26),stents(n=5) and aneurysm(n=4). The scorc 3 and 4 segments of DESCTA occupied 99.1%(838/846).(2) There is no significant correlation between the calcium volume(spearman test,P=0.453), surrounding;percentage(Pearson chi-square,P=0.090) and external cranial arteries (Spearman test,P＜0.05).There is a strong correlation between calcium volume and internal cranial arteries(Spearman test,P=0.007 ),while a moderately correlation between calcium surrounding percentage and internal cranial arteries (Pearson chi-square test,P=0.046).(3) The agreement of the calculated degrees of stenoses between DESCTA and MRA is 96.6%(486/503)(Wilcoxon test,P＜0.001). (4) Compared with DSA,the accuracy of DESCTA is 97.6%(361/370).DESCTA was 100%sensitive and 100%specific for the total occlusion.Using a 50%cutoff value for stenosis,DESCTA and DSA were in agreement in 99.2%,DESCTA was 95.5% sensitive and 99.4%specific,and the positive predictive value was 91.3%,the negative predictive value was 99.7%.Using a 70%cutoff value for stenosis,DESCTA and DSA were in agreement in 98.9%,DESCTA was 92.3%sensitive and 99.2% specific,and the positive predictive value was 80%,the negative predictive value was 99.7%.CONCLUSION.DESCTA with MIP image gives good detail assessment for head and neck arteries atherosclerosis.The calcium volume and surrouding percentage effect variously on the image quality.DESCTA has the same ability for diagnosis of stenosis of as DSA.However,there is significant difference between DESCTA and MRA for the severity of stenosis.更多还原