【作者】 陈艳；

【导师】 韩萍；

【作者基本信息】 华中科技大学 ， 影像医学与核医学， 2007， 博士

【摘要】 第一部分16层螺旋CT冠状动脉成像质量控制第一节16层螺旋CT冠状动脉成像不同触发扫描方式的对比研究目的对比分析16层螺旋CT小剂量预实验、对比剂示踪技术的不同阈值(100HU、150HU)所确定的延迟时间对冠状动脉及大血管密度的影响,以期获得一种能取得更好冠脉图像质量的触发方式。材料与方法将90例行冠状动脉CT检查的患者依据不同的触发方式分为三组:第一组(组Ⅰ)应用阈值为100HU的对比剂示踪技术进行触发扫描;第二组(组Ⅱ)应用阈值为150HU的对比剂示踪技术进行触发扫描;第三组(组Ⅲ)应用小剂量预实验技术。前两组的升主动脉内密度达到设定阈值时,延迟4秒进行冠脉扫描;第三组取得的峰值时间再加2秒为扫描延迟时间。记录各组的延迟时间。冠脉扫描范围自气管隆突下至心脏膈面。CT扫描参数:准直器宽度0.75mm,床进速度2.8mm/圈,卷积函数值35f,管电压和有效管电流分别为120KV和500mAs。重建层厚1.0mm、重建间隔0.5mm。采用横断位图像测量冠状动脉(左主干、前降支、回旋支、右冠)起始部、大血管(主动脉根部、肺动脉、上腔静脉)、右心房以及冠状静脉窦的CT值。将扫描延迟时间、冠状动脉、大血管、右心房以及冠状静脉窦的CT值进行方差分析,对三组中的数据进行两两比较。结果四支冠状动脉以及主动脉根部的密度以组Ⅲ中的最低,且与其他两组相比具有极显著性差异;组Ⅰ与组Ⅱ的冠状动脉密度以及主动脉根部密度较高,且无显著性差异。肺动脉、上腔静脉以及右心房的密度以组Ⅰ中的最高,其中肺动脉密度在组Ⅰ与组Ⅲ中有显著性差异,而与组Ⅱ的肺动脉密度无显著性差异;组Ⅰ中上腔静脉以及右心房的密度与组Ⅱ、组Ⅲ相比均有显著性差异。三组冠状静脉窦的密度以组Ⅱ的最低,三组间相比均无显著性差异。延迟时间以组Ⅲ最短,且与组Ⅰ、组Ⅱ的延迟时间均有极显著性差异,而组Ⅰ、组Ⅱ的延迟时间无显著性差异。结论对比剂示踪技术较小剂量预实验在减少对比剂的同时能取得更好的冠状动脉密度图像,兼顾周围大血管及右心房的显示,阈值为150HU的对比剂示踪技术较100HU的对比剂示踪技术能取得更好的冠状动脉图像。在临床工作中可推广应用。第二节重建时相及心率对MSCT冠状动脉图像质量影响的研究目的探讨重建时相及心率对16层螺旋CT冠状动脉图像质量的影响,并确定冠状动脉各分支在不同心率的最佳重建时相。材料与方法93名患者行16层螺旋CT冠状动脉成像,所有患者均采用小剂量对比剂预实验确定延迟时间进行冠状动脉扫描,扫描范围自气管隆突下至心脏膈面。扫描参数如下:准直器宽度0.75mm,床进速度2.8mm/圈,卷积函数值35f,管电压和有效管电流分别为120KV和500mAs。扫描完成后,以10%的间隔回顾性重建20%～80%时相的冠脉图像。根据心率将患者分三组(组Ⅰ:≤60次/分、组Ⅱ:60～70次/分、组Ⅲ:≥70次/分),每组分别有45人、33人、15人。由两名医师在不知道重建时相和心率的情况下对图像进行评价。重建时相的评价采用三维容积重建(VRT)图像进行评价,将VRT图像根据冠脉显示情况进行分级并评分,意见不同时进行协商共同判定,计算冠脉各分支平均得分。冠脉各节段显示情况的评价采用冠脉图像质量最好的横断位及MPR图像进行评价,血管边缘清楚为可评价,边缘模糊为不可评价,计算冠脉各段的显示率。结果左主干在各重建时相、各组心率的图像质量均能达到临床诊断要求(重建时相以60%、70%最佳);在组Ⅰ、组Ⅱ、组Ⅲ中,左前降支(LAD)显影良好的时相分别为50%～70%(以70%重建时相最佳)、60%～70%(以60%重建时相最佳)、60%;左回旋支(LCX)显影良好的时相分别为50%～60%(以60%重建时相最佳)、60%、40%;右冠(RCA)显影良好的时相分别为60%、50%～60%(以60%重建时相最佳)、40%。LM、LAD近段显示率在三组心率间无显著性差异;LAD中、远段,LCX各段以及RCA近段、远段的显示率在心率≥70次/分时最低,且与心率<70次/分的冠脉显示率有显著性差异,在心率≤60(次/分)组与心率在60～70(次/分)组的冠脉段显示率无显著性差异;RCA中段在各心率组间的显示率均有显著性差异。结论16层螺旋CT在心率小于70次/分的情况下,采用多时相重建可明显提高冠状动脉的成像质量。第二部分16层螺旋CT冠状动脉成像临床应用研究第一节16层螺旋CT正常冠状动脉管径的测量目的采用16层螺旋CT测量正常冠状动脉,探讨国人活体冠状动脉管径的正常值范围。材料与方法收集经临床及影像学检查无冠状动脉疾患,行16层螺旋CT冠状动脉检查且图像质量良好的患者104人,采用小剂量对比剂预实验或自动触发扫描技术确定延迟时间行冠状动脉扫描,方法同第一部分第一节。扫描参数:准直器宽度0.75mm,床进速度2.8mm/圈,卷积函数值35f,管电压和有效管电流分别为120KV和500mAs。扫描完成后采用多时相重建,重建层厚1.0mm、重建间隔0.5mm,选取质量最好的图像进行测量。将患者按照年龄及冠脉分布类型进行分组。按年龄分为3组:青年组(<45岁)、中年组(45-64岁)、老年组(≥65岁),每组分别有22人、67人、15人;按冠状动脉的分布类型分为三组:均衡型组、右优势型组、左优势型组,每组分别有37人、60人、7人。冠状动脉的分段采用美国心脏协会15分段法,用CT测量右冠近段、中段及远段,左主干,前降支近段、中段及远段,回旋支近段及远段的起始部短轴位直径。结果右冠近、中、远段开口径平均值分别为4.05mm、3.70mm、3.29mm;左主干开口径平均值为4.59mm;前降支近、中、远段开口径平均值分别为3.98mm、3.60mm、2.85mm;回旋支近、远段开口径分别为3.39mm、2.28mm。冠状动脉各段管径在青年组至老年组中依次增大,除老年组左主干管径较青、中年组有显著性差异外,其余冠脉段管径在各年龄组间均无显著性差异。左主干的管径以左优势型组中最大,与其他两型的左主干管径相比均有显著性差异,后两者左主干管径无显著性差异。前降支各段管径以左优势型组中最大,各段管径在三组间无显著性差异。回旋支各段管径以左优势型组最大,右优势型组最小,其中左优势型组的回旋支近段管径与其他两型相比有显著性差异,而后两者间无显著性差异;回旋支远段管径在三组间均有极显著性差异。右冠各段管径以右优势型组中最大,左优势型组最小,其中右优势型组的右冠近段管径与其他两型相比有显著性差异,而后两者间无显著性差异;右冠中、远段管径在三组间均有显著性差异。结论16层螺旋CT进行冠状动脉测量能为冠状动脉以及引起其形态改变的病变提供有价值的影像学依据。第二节16层螺旋CT冠状动脉造影与X线冠状动脉造影的对比研究目的评价16层螺旋CT冠状动脉成像在冠状动脉狭窄中的临床应用价值以及不同性质的斑块对管腔狭窄评价的影响。材料与方法收集53名行16层螺旋CT冠脉成像的患者,均行X线冠脉造影(CAG)检查。CT采用小剂量对比剂预实验或自动触发扫描技术确定延迟时间行冠状动脉扫描,方法同第一部分第一节。扫描完成后对图像进行多时相重建,重建层厚1.0mm、重建间隔0.5mm,选取质量最好的图像由两名经验丰富的医生事先不知CAG结果的情况下以横断位及多种后处理方法对冠状动脉CT图像进行综合分析。冠脉狭窄的分析采用两种方式:以病人为单位进行分析、以冠脉节段为单位进行分析。当以病人为单位进行分析时,仅确定冠状动脉最严重的狭窄程度,而无论病变的个数和位置。当以冠脉节段为单位进行分析时,确定冠脉每段是否有病变以及管腔狭窄程度。意见不同时协商后共同判定。CT评价冠脉粥样硬化斑块时认为CT值<60HU为软斑块,CT值是60-129HU的为中间斑块,CT值≥130HU为钙化斑块。将所有斑块分为钙化斑块、混合斑块(钙化斑块和其他2种斑块或其中的一种并存的斑块)、非钙化斑块(软斑块和中间斑块),对存在的斑块计数并系统分析。CAG图像的评价采用国际上通用的目测直径法。以CAG为诊断的“金标准”,将MSCT冠脉造影与CAG进行对比。MSCT评价冠脉中度以上狭窄(≥50%)以及不同性质的斑块对冠脉中度以上狭窄评价的影响的诊断指标以敏感度、特异度、阳性预测值及阴性预测值表示。结果当以病人为单位进行分析时,16层螺旋CT诊断冠状动脉中度及其以上狭窄程度的敏感度、特异度、阳性预测值、阴性预测值分别为93.5%、71.4%、82.9%、88.2%。当以冠脉节段为单位分析时,16层螺旋CT诊断冠脉中度及以上狭窄程度的总敏感度、特异度、阳性预测值、阴性预测值分别为88.4%、94.3%、73.1%、97.9%。对钙化斑块、混和斑块以及未钙化斑块导致的冠脉中度及其以上狭窄评价的敏感度、特异度、阳性预测值、阴性预测值分别为80%、64.4%、43.5%、90.4%;96.7%、82.4%、90.6%、93.3%;95.5%、80.0%、91.3%、88.9%。16层螺旋CT对混合斑块以及未钙化斑块所造成的冠脉管腔狭窄程度的评价有较高价值,而对钙化斑块造成的冠脉狭窄程度的评价有一定的局限性。结论16层螺旋CT冠状动脉成像是一种简便易行、安全可靠的无创性检查方法。对冠状动脉中度以上狭窄以及未钙化斑块的显示具有良好的价值,可作为冠心病的筛选手段和冠脉术前评价的首选方法。第三节应用MSCT评价冠状动脉斑块及血管重塑与稳定型和不稳定型心绞痛的关系目的应用MSCT研究不同类型心绞痛患者的冠状动脉斑块密度以及重塑指数的特点,探讨二者与不同类型心绞痛的关系。材料与方法11例稳定型心绞痛患者和10例不稳定型心绞痛患者均行16层螺旋CT冠状动脉造影检查。CT采用小剂量对比剂预实验或自动触发扫描技术确定延迟时间行冠状动脉扫描,方法同第一部分第一节。用轴位图像结合多平面重组图像检测患者的未钙化斑块,对于有多个斑块的患者,选取导致冠状动脉管腔狭窄程度最严重的斑块进行测量。测量斑块CT值时,以斑块所在冠状动脉的短轴位多平面重组图像作为测量平面,对斑块不同点进行测量,避开斑块边缘部分,至少测量四次,取其中最低CT值作为斑块的最低密度。冠脉重塑指数的测量及计算:用冠状动脉短轴位进行测量,测量指标包括斑块处血管面积、斑块近端以及远端5mm范围内正常参照部位冠脉面积。重塑指数(Remodeling Index, RI)为斑块处血管面积与病变近端和远端参照部位正常血管面积平均值的比值。结果稳定型心绞痛患者斑块的平均CT值为69.7±17.3HU(39-97HU),不稳定心绞痛患者斑块的平均CT值为36.0±9.6HU(27-57HU),两者间有显著性差异。计算重塑指数后,不稳定型心绞痛患者中正性重塑有7人(70%)、负性重塑有2人(20%),无重塑1人;稳定型心绞痛患者中,正性重塑有2人(18.2%),负性重塑7人(63.6%),无重塑2人,两组间正性重塑及负性重塑均有显著性差异。结论CT测量的斑块密度和重塑指数有助于斑块易碎性的评价,可作为无创的急性冠心病事件的预测手段。第四节成年人先天性冠状动脉变异的多层螺旋CT诊断目的探讨16层螺旋CT在成年人先天性冠状动脉变异诊断中的临床应用价值。材料与方法回顾性研究总结538例成年人患者的16层螺旋CT冠状动脉造影资料,评价各种先天性冠状动脉变异。CT采用小剂量对比剂预实验或自动触发扫描技术确定延迟时间行冠状动脉扫描,方法同第一部分第一节。由两名经验丰富的医生用轴位图像以及各种后处理图像共同评价冠脉各支是否存在、起始位置及行程有无异常,若发现异常则判断冠脉变异的类型。意见不同时互相协商后取得一致意见。结果538例中检出冠状动脉开口及走行变异23例(4.28%),包括左主干高位开口11例,右冠起源于左冠状窦5例,前降支、回旋支分别独立开口于左冠状窦3例,回旋支缺如2例,单支冠状动脉1例,回旋支起源于右冠状窦1例;538例中检出冠状动脉心肌桥116例(21.6%),共有137支壁冠状动脉。结论MSCT无创、准确、可重复性强,是诊断先天性冠状动脉变异的有效方法。更多还原

【Abstract】 PartⅠQuality Control of 16-slice CT Coronary Artery AngiographyChapterⅠComparative Study of Bolus Timing Technique at 16-slice CT Coronary AngiographyObjective To compare test bolus, bolus tracking of different threshold (100HU, 150HU) techniques for timing the scan of 16-slice CT coronary angiography. Materials and Methods 90 patients were randomized into three groups according to bolus timing technique: group1(bolus tracking, threshold 100HU, following 100ml contrast material+20ml saline chaser), group2(bolus tracking, threshold 150HU, following 100ml contrast material+20ml saline chaser), group3(20ml test bolus, following 100ml contrast material+20ml saline chaser). All patients performed ECG-gated 16-slice CT coronary angiography successfully. In group1and group2, the threshold in ascending aorta triggered acquisition, with an additional 4s delay. In group3, test bolus peak time adding 2s was used as a delay. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. All the delay time was recorded. Attenuation was measured in main vessels (ascending aorta, main pulmonary artery, superior vena cava and coronary sinus), right atria and the root of coronary artery (left main artery, left anterior descending artery, left circumflex artery and right coronary artery). One-Way ANONA was used to analyze all the data.Results The attenuation values of coronary arteries and aorta were the lowest in group 3, which had significant difference comparing group 1 and group 2, and there were no significant differences between group1 and group2. The attenuation values of pulmonary artery (PA), superior vena cava (SVC) and right atria (RA) were the highest in group 1. There were significant difference between group 1 and group 3 in the attenuation value of PA, which had no significant differences between group1 and group2. There were significant differences between group1 and group2, group3 in the attenuation of SVC and RA. There were no significant differences between any two groups in the attenuation of coronary sinus, but the attenuation values of coronary sinus in group 2 were the lowest. The delay time in group 3 was the shortest, which had significant differences comparing group2 and group3.Conclusion Bolus tracking was better than test bolus in gaining optimum coronary attenuation. Bolus tracking which threshold was defined 150HU was superior to bolus tracking which was defined 100HU.ChapterⅡInfluence of Reconstruction Phase and Heart Rate on MSCT Coronary AngiographyObjective To investigate the influence of reconstruction phase and heart rate on image quality of 16-slice CT coronary angiography, and confirm the optimal reconstruction time in patients of different heart rate.Material and methods 16-slice CT coronary angiography were performed in 93 patients. Test bolus technique was used in all patients. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. Images were reconstructed at 20%-80% of the cardiac cycle in increments of 10%. Patients were classified three groups according to heart rate (groupⅠ:≤60bpm,groupⅡ:60～70bpm,groupⅢ:≥70bpm). The image quality of reconstruction image quality was evaluated by VRT image, and the display of coronary artery was evaluated by axial image and MPR image.Results The best reconstruction time of Left anterior descending artery(LAD)was 50%-70%,60%-70%,60% respectively from groupⅠto groupⅢ; that of left circumflex artery(LCX) was 50%-60%,60%,40% respectively; that of right coronary artery(RCA) was 60%,50%-60%,40% respectively. The proximal segments of LM,LAD were not statistically significant in all groups, the mid and distant segments of LAD, all segments of LCX, proximal segments of RCA were not statistically significant between groupⅠand groupⅡ, but those were statistically significant compared to groupⅢ; the mid segments of RCA were statistically significant in any group.Conclusion With multi-reconstruction phase, 16-slice computed tomography coronary angiography can achieve good image quality in patients who heart rates are below 70beats per minute.PartⅡthe Clinical Application of 16-slice Computed Tomography Coronary Artery AngiographChapterⅠThe Measurement of Coronary Artery Size using 16-slice Computed TomographyObjective To investigate and measure the diameter of coronary artery using 16-slice computed tomography.Materials and methods 16-slice CT coronary angiography was performed in 104 cases whose coronary arteries were normal. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. 104 cases were divided into 3 groups according to age: the youth group (<45y), the middle group(45-64y) and the elder group(≥65y).104 cases were also divided 3 groups according to dominant pattern of coronary artery: balanced dominant pattern, right dominant pattern and left dominant pattern. The diameter of right artery (RCA) proximal, middle and distant segment were measured using CT, so as the diameter of left main artery (LM), left anterior descending artery (LAD) proximal, middle and distant segment, left circumflex artery proximal and distant segments.Results The diameter of RCA proximal segment, middle segment and distant segment was 4.05mm, 3.07mm and 3.29mm separately; the diameter of LM was 4.59mm; The diameter of LAD proximal segment, middle segment and distant segment was 3.98mm, 3.60mm and 2.85mm separately; the diameter of LCX proximal segment and distant segment was 3.39mm, 2.28mm separately.The diameters of coronary arteries were larger with the increasing of age. There was significant difference of LM diameter between the elder group and the youth, middle group, and there was no significant difference in the youth group and the elder group. There was no significant difference of other coronary artery segment’s diameter in any two groups.The diameter of LM in left dominant pattern was the largest, and it had significant difference comparing other two groups, but there was no significant difference between the latter two groups. The diameters of LAD and LCX in left dominant pattern were the largest, and that of in right dominant pattern were the smallest. The diameter of LAD had no significant difference among three groups. The diameter of LCX proximal segment had no significant difference between balanced dominant pattern and right dominant pattern, but they had significant difference comparing the left dominant pattern. The diameters of LCX distant segment had significant difference between any two groups. The diameter of RCA in right dominant pattern was the largest. The diameters of RCA proximal segments had no significant difference between balanced dominant pattern and left dominant pattern, and there was significant difference in any other groups.Conclusion coronary artery size measured by MSCT can provide valuable information for coronary disease.ChapterⅡComparative Study Between 16-slice CT Coronary Angiography and Conventional Coronary AngiographyObjective To evaluate the clinical application of 16-slice CT coronary angiography (CTCA) and the impact of plaques differently characterized on assessing coronary artery stenosis.Material and methods 53 patients underwent both 16-slice MSCT and invasive coronary angiography (CAG). CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. CTCA was evaluated by consensus of two independent experienced radiologists unknowing CAG findings. Two methods were used to evaluate the stenosis of coronary artery: stenosis was analyzed on a patient basis, and stenosis was analyzed on coronary segment basis. For a determined plaque an attenuation value <60HU was considered as soft plaque; an attenuation value between 60 and129HU was considered medium plaque, and≥130Hu noncalcified. The plaques were then classified into calcified plaque, mixed plaque and non-calcified plaque. The diagnostic accuracy of 16-slice CTCA findings as well as detect≥50% stenoses caused by plaques was evaluated respectively regarding CAG as the standard of reference.Results The sensitivity, specificity, positive and negative predictive value to identity significant obstructed coronary artery was 93.5%、71.4%、82.9%、88.2% respectively on a patient basis, and that on coronary segment basis was 88.4%、94.3%、73.1%、97.9% respectively. The sensitivity, specificity, positive and negative predictive value to identity≥50% stenoses caused by calcification plaque, mixes plaque and non-calcified plaque was 80%, 64.4%, 43.5%, 90.4%; 96.7%, 82.4%, 90.6%, 93.3%; 95.5%, 80.0%, 91.3%, 88.9% respectively. MSCT had limitation in the evaluation of coronary artery stenoses caused by calcification.Conclusion 16-slice CT coronary angiography is a simple, reliable and noninvasive method. MSCT can identify the stenoses, especially to the significant stenoses (≥50%) and non-calcified and mixed plaque. it can be the choice for the ruling out coronary heart disease, evaluation of pre -operation of coronary artery. ChapterⅢEvaluation of Coronary Artery Plaque and Modeling by MSCT in Patients with Stable Angina and Unstable AnginaObjective Using 16-slice computed tomography to evaluate the attenuation of plaques and coronary artery remodeling in patients with stable angina (SA) and unstable angina (UA).Material and methods 16-slice CT coronary angiography were underwent in 11 patients of SA and 10 patients of UA. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. The presence of noncalcified plaques were inspected on the axial and MPR images. In patients with multiple plaques, CT attenuation was measured on the plaque at the lesion of maximum stenosis. The remodeling index (RI) was calculated by the cross-sectional vessel area at the region of maximum luminal narrowing by the mean of the 2 reference areas (the proximal and distant area of lesion).Result The attenuation of plaque was significantly higher in patients of SA ( 69.7±17.3HU) than in those of UA (36.0±9.6HU). There was significant difference between remodeling index of patients of SA and those of UA. Positive coronary artery remodeling (PCAR) was present in 7 of 10 (70%), and negative coronary artery remodeling (NCAR) was present in 2 of 10 (20%) in UA. PCAR was present in 2 of 11 (18.2%), and NCAR was present in 7 of 11 (63.6%) in SA. There were significant difference between PCAR and NCAR.Conclusion MSCT can differentiate plaque texture and measure modeling index in patients with SA and UA. It is helpful to diagnose and treat acute coronary event. ChapterⅣ16-slice Computed Tomography Diagnosing Congenital Coronary Artery AnomaliesObjective To investigate the clinical application value of 16-slice CT in diagnosing congenital coronary artery anomalies.Materials and methods 538 patients performed 16-slice CT coronary artery angiography were analyzed retrospectively to find the coronary artery anomalies. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. For evaluation of coronary anomalies, axial and MPR images were used. The origins and course of coronary branches were assessed. If coronary anomaly was found, then the anomalous type was defined.Results 23 coronary artery anomalies were found, including high take-off position of left main coronary artery (11 cases), ectopic origin of right coronary artery from the left sinus of Valsalva (5 cases), separate origins of LAD and LCX from left sinus of Valsalva (3 cases), absence of left circumflex coronary artery (2 case), single coronary artery (1 case), ectopic origin of left circumflex artery from right sinus of Valsalva (1 case), and myocardial bridge (116 cases).Conclusion MSCT is a noninvasive, accurate, repeated method for diagnosis of congenital coronary artery anomalies.更多还原