能谱纯化技术在泌尿系虚拟平扫成像中的应用价值

目的:探讨双源CT能谱纯化技术在CT泌尿系虚拟平扫成像中的应用价值。方法:80例患者随机均分为两组行泌尿系CT扫描,A组采用一代双源CT扫描(140kV/80kV组),B组采用二代双源CT扫描(80kV/Sn 140kV组),两组间在增强扫描动脉期采用双能量扫描的方式,其余期相均采用单源扫描。将两组双能量扫描图像通过软件处理获得虚拟平扫图像。比较两组虚拟平扫图像的CT值、信噪比及噪声,并与常规平扫图像比较病灶的检出情况。结果:B组的图像噪声低于A组,信噪比高于A组;与140kV/80kV组比较,80kV/Sn 140kV组虚拟平扫提高了对小结石(直径<4mm)的显示能力;双能量扫描辐射剂量,80kV/Sn 140kV组比140kV/80kV组低约10%。结论:能谱纯化技术可明显提高对物质的识别能力,提高虚拟平扫的图像质量,真正达到减少扫描次数、降低患者辐射剂量的目的。     

双源能谱CT虚拟平扫替代常规平扫评估食管癌的可行性研究

目的探讨双源能谱CT虚拟平扫(VNC)替代常规平扫(TNC)评估食管癌的可行性。方法回顾性收集经胃镜或手术病理证实的食管癌病人46例,所有病人均行TNC及双能量动、静脉双期增强扫描,经双能后处理软件获得动脉期VNC影像。由2名观察者分析TNC和VNC影像上病灶形态学特征(管壁是否增厚、肿瘤与周围组织关系、淋巴结肿大等),并对影像质量进行评分;2组间比较采用卡方检验或Wilcoxon秩和检验,观察者间一致性采用Kappa检验分析。采用配对t检验比较TNC与VNC影像的辐射剂量及其他定量评价参数。结果TNC和VNC影像上显示病灶形态学特征差异均无统计学意义(均P>0.05)。2名观察者对TNC和VNC影像质量主观评分的一致性均较好(均κ>0.75),且对2种影像的主观评分的差异无统计学意义(P>0.05)。2种影像上测得的食管癌病灶处管壁厚度的差异无统计学意义(P>0.05),VNC影像上降主动脉、皮下脂肪CT值高于TNC(P<0.05),但食管癌病灶、椎体后肌肉和空气的CT值差异无统计学意义(P>0.05)。与TNC相比,VNC影像具有较高的SNR和较低的噪声(均P<0.05)。双能量动、静脉期扫描有效辐射剂量小于常规三期扫描(P<0.05),其有效辐射剂量降低了(3.46±0.87)mSv。结论双源能谱CT可为食管癌病人提供与TNC影像质量相似的VNC影像,并降低了辐射剂量。     

Effect of calcium scoring scan in reducing scan range and radiation dose in retrospectively ECG-gated CT coronary angiography

目的:探讨使用钙化积分扫描缩短增强扫描范围以降低后门控冠状动脉CTA检查辐射量的临床应用价值.方法:40例患者行冠脉钙化积分及冠脉CTA检查,其增强扫描的实际扫描范围根据钙化积分扫描图像来决定,即冠状动脉树上缘1 cm至心尖部心包影即将消失的层面.并按常规方法在定位像上测量增强扫描的预计扫描范围,即气管隆突下1 cm至心脏下缘2 cm.比较两种扫描范围及相应的辐射剂量的差异.结果:实际扫描范围比预计扫描范围平均缩短(2.09±0.76) cm(t=17.31,P＜0.01),冠状动脉CTA各序列总剂量较常规方法平均减少(1.51±0.87)mSv,差异有极显著性意义(t=10.92,P＜0.01),相当于各序列平均剂量总和的9.20％.结论:使用钙化积分扫描图像能有效缩短增强扫描的范围,从而明显降低冠状动脉CT血管成像的辐射量.     

钙化积分扫描缩短冠脉CTA扫描范围及降低辐射量的作用

目的:探讨使用钙化积分扫描缩短增强扫描范围以降低后门控冠状动脉CTA检查辐射量的临床应用价值。方法:40例患者行冠脉钙化积分及冠脉CTA检查,其增强扫描的实际扫描范围根据钙化积分扫描图像来决定,即冠状动脉树上缘1cm至心尖部心包影即将消失的层面。并按常规方法在定位像上测量增强扫描的预计扫描范围,即气管隆突下1cm至心脏下缘2cm。比较两种扫描范围及相应的辐射剂量的差异。结果:实际扫描范围比预计扫描范围平均缩短(2.09±0.76)cm(t=17.31,P<0.01),冠状动脉CTA各序列总剂量较常规方法平均减少(1.51±0.87)mSv,差异有极显著性意义(t=10.92,P<0.01),相当于各序列平均剂量总和的9.20%。结论:使用钙化积分扫描图像能有效缩短增强扫描的范围,从而明显降低冠状动脉CT血管成像的辐射量。     

A novel density-volume calcium score by non-contrast CT predicts coronary plaque burden on coronary CT angiography: Results from the MACS (Multicenter AIDS cohort study)

BackgroundThe purpose of this study is to determine if a new score calculated with coronary artery calcium (CAC) density and volume is associated with total coronary artery plaque burden and composition on coronary CT angiography (CCTA) compared to the Agatston score (AS).MethodsWe identified 347 men enrolled in the Multicenter AIDS cohort study who underwent contrast and non-contrast CCTs, and had CAC>0. CAC densities (mean Hounsfield Units [HU]) per plaque) and volumes on non-contrast CCT were measured. A Density-Volume Calcium score was calculated by multiplying the plaque volume by a factor based on the mean HU of the plaque (4, 3, 2 and 1 for 130–199, 200–299, 300–399, and ≥400HU). Total Density-Volume Calcium score was determined by the sum of these individual scores. The semi-quantitative partially calcified and total plaque scores (PCPS and TPS) on CCTA were calculated. The associations between Density-Volume Calcium score, PCPS and TPS were examined.ResultsOverall, 2879 CAC plaques were assessed. Multivariable linear regression models demonstrated a stronger association between the log Density-Volume Calcium score and both the PCPS (β 0.99, 95%CI 0.80–1.19) and TPS (β 2.15, 95%CI 1.88–2.42) compared to the log of AS (PCPS: β 0.77, 95%CI 0.61–0.94; TPS: β 1.70, 95%CI 1.48–1.94). Similar results were observed for numbers of PC or TP segments.ConclusionThe new CAC score weighted towards lower density demonstrated improved correlation with semi-quantitative PC and TP burden on CCTA compared to the traditional AS, which suggests it has utility as an alternative measure of atherosclerotic burden.     

Cardiac CT: coronary arteries and beyond

Multi-detector-row computed tomography (MDCT) has emerged as a rapidly developing method for non-invasive imaging of the heart. An understanding of ECG synchronization, contrast material administration, patient preparation and image post-processing is needed to optimize image quality. The basic technical principles and essentials of these technical basics are described here. Correctly applied cardiac MDCT allows imaging of the coronary arteries including coronary anatomy and stenosis detection. The same is true for evaluation of coronary artery bypass grafts and, to some extent, coronary artery stents. While quantification of total calcified plaque burden has been long established, coronary MDCT allows assessing plaque morphology and constitution. Recent approaches go beyond the coronaries and include evaluation of left ventricular function at rest and myocardial viability. In combination with experimental approaches for assessing aortic valve function and myocardial perfusion imaging, cardiac MDCT offers the potential for a comprehensive examination of the heart using a single breath-hold examination.     

老年人多排螺旋CT冠状动脉钙化扫描临床应用初探

目的：评估不同扫描层厚对冠状动脉钙化积分和冠状动脉显示的影响。方法：98例70岁以上疑为冠心病的病人进行不同层厚的多排螺旋CT冠状动脉钙化积分扫描，36例扫描层厚为1mm，其中28例病人同次先后进行层厚为1mm和2mm的扫描，62例层厚为2mm；对每次扫描进行钙化分析。结果：在层厚为1mm的扫描，78％的病人不能一次闭气完成扫描，出现呼吸伪影。在同次先后进行层厚为1mm和2mm扫描的28例病人，扫描层厚为1mm的钙化积分明显高于扫描层厚为2mm的扫描的钙化积分。结论：对于4层多排螺旋CT而言，使用2mm的扫描层厚进行冠状动脉钙化扫描较为合适。     

冠状动脉CT血管成像对非心脏手术术前风险评估的价值

术前心脏风险分层有利用改善手术的临床预后、缩短住院时间、减少医疗费用。冠状动脉CT血管成像(CCTA)作为诊断冠状动脉疾病最常应用的无创影像技术在非心脏手术病人的应用中有重要价值。就CCTA在非心脏手术术前风险分层中的潜在适用人群、研究进展和应用前景进行综述,以利于认识其临床价值、解释结果和探讨未来研究方向。     

利用虚拟平扫降低冠状动脉CT血管造影辐射剂量的可行性研究

目的探讨利用双层探测器光谱CT冠状动脉CT血管造影(CCTA)钙化积分的虚拟平扫成像(VNC)降低扫描辐射剂量的可行性。方法回顾性分析2019年3月至2020年8月在南京大学医学院附属鼓楼医院双层探测器光谱CT行CCTA扫描的122例患者资料。记录每位患者的CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)及有效剂量(E)。记录检查时间。在后处理工作站中, 基于CCTA的光谱基数据(SBI)生成VNC图像。2名医师分别独立评价左前降支(LAD)、左回旋支(LCx)、右冠状动脉(RCA)真实平扫(TNC)及VNC的钙化积分(CS_TNC, CS_VNC)并做Pearson相关性分析, 得到校正系数λ, 各分支校正系数分别记为λLAD、λLCx、λRCA, 总体冠状动脉(Total)的平均校正系数记为λAVG。校正后VNC的CS(CCS_VNC)=λ× CS_VNC。采用重复测量单因素方差分析比较CS_TNC、CCS_VNC的差异;采用Bland-Altman法分...     

双能量冠状动脉CT成像定量评估冠状动脉钙化

摘要目的评价双能量CT成像应用虚拟非对比增强(VNC)CT序列量化冠状动脉钙化的可行性。材料与方法本研究获得伦理审查委员会的批准,并符合HIPAA规定。所有病人均签署书面知情同意书。对36例病人进行非对比增强CT钙化评分,随后行双能量冠状动脉CT成像。     

CT冠状动脉钙化评分软件工作平台间重复性研究

摘要目的研究3个不同工作站生成的冠状动脉钙化(CAC)评分是否具有可比性,从而得到独立于厂商的结果。材料与方法本研究获得伦理审查委员会和放射防护联盟的批准,每例病人均签署了知情同意书。     

神经母细胞瘤双源CT增强扫描虚拟平扫与常规平扫的影像比较

目的：探讨双源CT虚拟平扫替代常规平扫在神经母细胞瘤应用的可行性。方法：16例神经母细胞瘤采用双源CT行常规平扫与140kV和80kV双能量增强扫描,将双能量增强扫描数据通过Liver VNC软件得到虚拟平扫图像。比较虚拟平扫与常规平扫的图像质量及钙化类型。比较肿瘤组织虚拟平扫与常规平扫的CT值,进行信度分析与Bland-Altman分析。结果：虚拟平扫图像质量略低于常规平扫,但差异无统计学意义。虚拟平扫显示团块钙化、颗粒钙化与常规平扫相同,显示细沙样钙化不如常规平扫。肿瘤组织的虚拟平扫CT值与常规平扫CT值内在一致性良好,两者平均差值为-2．8 H U。结论：双源CT虚拟平扫能替代常规平扫诊断钙化性神经母细胞瘤。     

Cardiac CT angiography after coronary artery surgery in children using 64-slice CT scan

Objective

The purpose of this study was to compare the diagnostic accuracy of 64-slice CT with that of invasive angiography in the detection of graft and/or coronary angioplasty stenosis in children who had undergone coronary artery surgery.

Population and methods

Fifteen consecutive children (8 male and 7 female; age 9.2 ± 6.1 years) underwent 64-slice CT because of chest pain or ECG changes mean 4.8 ± 3.7 years after surgical coronary artery surgery; 10 patients had coronary angioplasty using a patch from the saphenous vein, four had mammary artery bypass, and one had saphenous vein bypass. Six main segments of the coronary arteries and all the bypass graft considered as a single segment were analyzed and compared with invasive angiography used as the reference standard.

Results

CT correctly identified the four children with coronary angioplasty and mammary graft lesions that were confirmed by conventional angiography: one patient had a significant stenosis (>50% stenosis) at the mammary bypass graft anastomosis site; three other had non-significant stenosis (<50% stenosis) including a mild lesion of the saphenous vein patch in two patients and a mild lesion at the anastomosis site of the mammary bypass in one. All segments identified as normal by CT in the other 11 children were also found to be normal by conventional angiography.

Conclusion

In centers expert in this technique, 64-slice CT scanning is a promising, rapid, and useful diagnostic technique for evaluating both coronary angioplasty and bypass graft lesions in children who had undergone coronary artery surgery.     

The utility of cardiac CT beyond the assessment of suspected coronary artery disease

Extensive work has been done over recent years to improve the spatial and temporal resolution of electrocardiogram (ECG)-gated cardiac computed tomography (CT). Advances in both hardware and software analysis have enabled the development of non-invasive coronary angiography. However, these high-quality examinations lend themselves to multiple additional applications beyond coronary angiography. In this review, we illustrate and discuss some established and some emerging applications of ECG-gated cardiac CT beyond the assessment of suspected coronary disease, particularly in light of recent recommendations on the appropriate use of this technology.     

Incremental value of the CT coronary calcium score for the prediction of coronary artery disease

Objectives:

To validate published prediction models for the presence of obstructive coronary artery disease (CAD) in patients with new onset stable typical or atypical angina pectoris and to assess the incremental value of the CT coronary calcium score (CTCS).

Methods:

We searched the literature for clinical prediction rules for the diagnosis of obstructive CAD, defined as ≥50% stenosis in at least one vessel on conventional coronary angiography. Significant variables were re-analysed in our dataset of 254 patients with logistic regression. CTCS was subsequently included in the models. The area under the receiver operating characteristic curve (AUC) was calculated to assess diagnostic performance.

Results:

Re-analysing the variables used by Diamond & Forrester yielded an AUC of 0.798, which increased to 0.890 by adding CTCS. For Pryor, Morise 1994, Morise 1997 and Shaw the AUC increased from 0.838 to 0.901, 0.831 to 0.899, 0.840 to 0.898 and 0.833 to 0.899. CTCS significantly improved model performance in each model.

Conclusions:

Validation demonstrated good diagnostic performance across all models. CTCS improves the prediction of the presence of obstructive CAD, independent of clinical predictors, and should be considered in its diagnostic work-up.     

双源CT虚拟平扫在头部检查的初步应用

目的 探讨双源CT双能量头部虚拟平扫(VNC)的图像质量和临床应用价值.方法 对62例临床怀疑脑血管病变的患者,使用双源CT进行头部常规平扫(CNC)和双能量CTA检查,利用双能量软件得到VNC图像.比较CNC和VNC图像灰质、白质、脑脊液、高密度出血性和低密度缺血性病变的CT值,使用4分法对图像质量进行主观评价,比较两组图像的噪声、辐射剂量和病变检出率,使用配对t检验、Wilcoxon符号秩检验和χ2检验(McNemar检验和Kappa检验)进行统计分析.结果 CNC与VNC图像灰质、白质、脑脊液、高密度病变及低密度病变的CT值分别为[(43.3±1.5)和(33.2±1.3)HU,t=46.98]、[(32.9±1.3)和(28.8±1.6)HU,t=16.28]、[(9.0±1.4)和(5.3±1.9)HU,t=12.41]、[(62.8±10.0)和(51.3±11.5)HU,Z=-4.37]、[(20.7±4.7)和(18.0±6.9)HU,t=3.84],差异均有统计学意义(P值均＜0.01).VNC图像噪声[(1.63±0.34)HU]大于CNC图像[(0.99±0.18)HU](Z=-6.41,P＜0.01).VNC图像有效剂量[(0.53±0.08)mSv]低于CNC[(1.37±0.23)mSv](Z=-6.45,P＜0.01).CNC和VNC图像噪声、颅底伪影、灰白质对比、高密度和低密度病变显示的主观评分分别为(3.9±0.3)和(2.7±0.5)分、(3.7±0.5)和(2.4±0.9)分、(3.3±0.6)和(1.3±0.5)分、(4.0±0.0)和(3.0±0.4)分、(3.9±0.3)和(3.2±0.8)分,VNC图像噪声与颅底伪影的评分较CNC图像低(Z值分别为-6.84、-6.15,P值均＜0.01),灰白质对比、高密度和低密度病变显示低于CNC图像(Z值分别为-7.01、-4.52和-3.12,P值均＜0.01).在个体水平,VNC图像显示高密度出血性病变29例,无假阳性和假阴性病例,敏感性、特异性、阳性预测值和阴性预测值均为100.0%(29/29、33/33、29/29、33/33),与CNC一致(P＞0.05,Kappa值=1.000);VNC图像显示低密度缺血性病变22例,假阳性1例,假阴性2例,敏感性、特异性、阳性预测值和阴性预测值分别为91.3%(21/23)、97.4%(38/39)、95.5%(21/22)和95.0%(38/40),与CNC图像(23例)差异无统计学意义(χ2=0.00,P＞0.05,Kappa值=0.895).在病灶水平,VNC图像显示出血灶53个,假阴性4个,无假阳性,敏感性、特异性、阳性预测值和阴性预测值分别为93.0%(53/57)、100.0%(38/38)、100.0%(53/53)和90.5%(38/42),VNC图像对出血灶的显示率与CNC差异无统计学意义(χ2=2.25,P＞0.05,Kappa值=0.914);VNC图像显示低密度病灶38个,假阳性2个,假阴性13个,敏感性、特异性、阳性预测值和阴性预测值分别为73.5%(36/49)、96.4%(53/55)、94.7%(36/38)和80.3%(53/66),VNC图像对低密度病灶的显示率低于CNC(χ2=6.67,P＜0.01,Kappa值=0.707).结论 与CNC相比,头部VNC辐射剂量低,但图像质量下降,对出血性病变具有替代CNC的潜在使用价值,对缺血性病变也有一定的参考价值.

Abstract：

Objective To investigate image quality and clinical value of dual-source dual energy virtual non-contrast (VNC) CT of the head. Methods Sixty-two patients suspected of cerebrovascular diseases underwent conventional non-contrast (CNC) CT and dual energy CTA examination of the head with dual-source CT. Virtual non-contrast images were reconstructed using dual energy software. The CT values of gray matter, white matter, cerebrospinal fluid, hyperdense hemorrhagic lesion and hypodense ischemic lesion were compared between CNC and VNC images. A four-score scale was used to assess image quality subjectively. Image noise, radiation dosage and detection rate were compared between CNC and VNC images. Paired t test, Wilcoxon signed ranks test and Chi-square test (McNemar test and Kappa test) were used. Results The CT value on CNC and VNC images, were (43. 3 ± 1.5) and (33. 2 ± 1.3) HU for gray matter (t = 46.98, P ＜ 0. 01), (32. 9 ± 1.3) and (28.8 ± 1.6) HU for white matter(t = 16. 28, P ＜0.01), (9.0 ± 1.4) and (5.3 ± 1.9) HU for cerebrospinal fluid (t=12.41, P＜0.01),(62.8 ±10.0) and (51.3 ± 11.5) HU for hyperdense lesion (Z = -4.37, P ＜ 0.01), (20.7 ±4.7) and (18.0 ±6. 9) HU for hypodense lesion (t = 3. 84, P ＜ 0. 01), respectively. VNC images[(1.63 ±0.34) HU]had more noise than CNC images[(0.99±0.18) HU](Z= -6.41, P＜0.01). VNC [(0. 53 ± 0. 08) mSv]had less effective dose than CNC[(1.37 ± 0. 23) mSy](Z= - 6. 45, P ＜ 0. 01).In subjective assessment, VNC images had more noise (2. 7 ± 0. 5 for VNC and 3.9 ± 0. 3 for CNC,Z = -6. 84, P ＜ 0. 01) and skull base-related artifacts (2. 4 ± 0. 9 for VNC and 3.7 ± 0. 5 for CNC,Z = -6. 15, P ＜0. 01) than CNC images. The gray/white matter contrast (1.3 ± 0. 5 for VNC and 3.3 ±0. 6 for CNC, Z = - 7. 01, P ＜ 0. 01), hyperdense lesion display (3.0 ± 0. 4 for VNC and 4. 0 ± 0. 0 for CNC,Z = -4. 52, P ＜ 0. 01) and hypodense lesion display (3.2 ± 0. 8 for VNC and 3.9 ± 0. 3 for CNC,Z= -3. 12, P ＜0. 01) on VNC images were lower than those on CNC images. In per-patient analysis,29 cases of hyperdense lesion (hemorrhage) were found on VNC images without misdiagnosis. The sensitivity, specificity, positive predictive value and negative predictive value were all 100. 0% (29/29,33/33, 29/29, 33/33). VNC images had the same detection rate of hyperdense lesions as CNC images (P ＞0. 05, Kappa = 1. 000) at per-patient level. Twenty-two patients with hypodense ischemic lesions were found on VNC images with one false positive case and two false negative cases. The sensitivity,specificity, positive predictive value and negative predictive value were 91.3% (21/23), 97.4%(38/39), 95.5% (21/22) and 95.0% (38/40) respectively. No statistical difference was found in detecting hypodense lesions between VNC and CNC images (χ2 = 0. 00, P ＞ 0. 05, Kappa = 0. 895). In per-lesion analysis, 53 hemorrhage lesions were found on VNC images with false negative results of four lesions and no false positive result. The sensitivity, specificity, positive predictive value and negative predictive value were 93.0% (53/57), 100. 0% (38/38), 100. 0% (53/53) and 90. 5% (38/42)respectively. There was no significant difference in detection rate of hyperdense lesion between VNC and CNC images (χ2 =2. 25, P ＞0. 05, Kappa =0. 914). Thirty-eight hypodense lesions were found on VNC images with 2 false positive lesions and 13 false negative lesions. The sensitivity, specificity, positive predictive value and negative predictive value were 73.5% (36/49), 96.4% (53/55), 94. 7% (36/38)and 80. 3% (53/66) respectively. The detection rate of hypodense lesion on VNC images was lower than that on CNC images (χ2 = 6. 67 ,P ＜ 0.01, Kappa = 0. 707). Conclusion Compared with CNC images,head VNC images have reduced image quality and radiation dosage. VNC images can replace CNC images potentially in detecting intracranial hemorrhage and provide information for ischemic cerebrovascular diseases to some extent.