CCTA技术对冠状动脉狭窄及其钙化斑块的评估

冠状动脉CT血管成像（CCTA）是一种可无创检测冠状动脉粥样硬化性疾病的成像手段,已成为临床筛查及诊断冠心病的首要检查方法。但对于钙化严重的冠状动脉节段,CCTA的特异性及阳性预测值偏低,可导致病人过度治疗,因此限制了CCTA的临床应用。综述钙化斑块伪影对CCTA的影响,并就CCTA对冠状动脉狭窄准确评估的相关技术进展进行分析,以利于临床诊断中提高CCTA对冠状动脉狭窄率的评估。     

Coronary CT angiography after stress testing: An efficient use of resources? Implications of the Advanced Cardiovascular Imaging Consortium (ACIC) results

Coronary CT angiography (CCTA) has matured to be a fast noninvasive imaging test in the evaluation of coronary artery disease (CAD). It has demonstrated excellent accuracy for defining the presence and the severity of luminal coronary artery stenoses and is probably the best noninvasive test to reliably exclude atherosclerotic coronary disease. Furthermore, accumulating CCTA data indicate that it can identify individuals at risk for all-cause mortality. It is also well known that despite the wealth of data regarding diagnostic and prognostic values of stress testing in CAD, up to 10% of stress imaging studies are considered inconclusive, leading to subsequent invasive coronary angiography for definitive diagnosis often with negative results. Moreover, recent data indicate that up to 30 % of patients undergoing angiography have no significant CAD despite a majority of them having had a prior stress test. Whether CCTA can serve as a cost-effective methodology to invasive angiography has been a source of active research. In this context, we will discuss the implications of the recently published data from the Advanced Cardiovascular Imaging Consortium registry looking at the use of CCTA after stress testing in Michigan.     

64层CT评价冠脉粥样斑块性质与狭窄程度的相关性

目的：探讨64层CT评价冠状动脉粥样硬化斑块性质与冠脉狭窄程度之间的相关性。方法：36例疑诊为冠心病患者行64层冠状动脉CT血管成像（CCTA）及冠状动脉血管造影（CAG）检查,以CAG为标准评价CCTA诊断冠脉狭窄程度的准确性,并诊断冠状动脉粥样硬化斑块性质,分析其与经CAG确诊的冠脉狭窄程度之间有无统计学意义。结果：36例患者中共检出105个斑块。冠脉轻度狭窄以钙化斑块引起为主,冠脉中度狭窄和重度狭窄以混合斑块引起为主。CCTA诊断冠状动脉钙化斑块与管腔轻度狭窄、混合斑块与中重度管腔狭窄存在相关性。结论：64层CCTA可在诊断冠脉狭窄的同时无创性评价斑块性质,可及时发现冠脉中脂质成分丰富的斑块,以便尽早及时给予临床干预,可降低急性冠脉综合征发生率。     

Coronary CT angiography.

Advances in multidetector CT (MDCT) technology with submillimeter slice collimation and high temporal resolution permit contrast-enhanced imaging of coronary arteries and coronary plaque during a single breath hold. Appropriate patient preparation, detailed technical and technological knowledge with regard to recognition of typical imaging artifacts (such as beam hardening or motion artifacts), and the adequate choice of postprocessing techniques to detect stenosis and plaque are prerequisites to achieving diagnostic image quality. A growing number of studies have suggested that 64-slice coronary CT angiography is highly accurate for the exclusion of significant coronary artery stenosis (>50% luminal narrowing), with negative predictive values of 97%-100%, in comparison with invasive selective coronary angiography. In addition, several studies have indicated that MDCT also can detect calcified and noncalcified coronary atherosclerotic plaques, especially in proximal vessel segments, showing a good correlation with intracoronary ultrasound. Studies on clinical utility, cost, and cost-effectiveness are now warranted to demonstrate whether and how this technique can change and improve the current management of patients with suspected or confirmed coronary artery disease.     

Coronary atherosclerosis imaging by CT to improve clinical outcomes

Coronary artery disease remains an important cause of morbidity and mortality world-wide. Coronary Computed Tomography Angiography (CCTA) has excellent diagnostic accuracy and the identification and stratification of coronary artery disease is associated with improved prognosis in multiple studies. Recent randomized controlled trials have shown that in patients with stable coronary artery disease, CCTA is associated with improved diagnosis, changes in investigations, changes in medical treatment and appropriate selection for revascularization. Importantly this diagnostic approach reduces the long-term risk of fatal and non-fatal myocardial infarction. The identification of adverse plaques on CCTA is known to be associated with an increased risk of acute coronary syndrome, but does not appear to be predictive of long-term outcomes independent of coronary artery calcium burden. Future research will involve the assessment of outcomes after CCTA in patients with acute chest pain and asymptomatic patients. In addition, more advanced quantification of plaque subtypes, vascular inflammation and coronary flow dynamics may identify further patients at increased risk.     

64层MDCT评价冠脉粥样硬化斑块的准确性:与IVUS对照研究

目的:评价64层MDCT在判断冠脉粥样硬化斑块性质及测量血管大小、斑块负担的应用价值。方法:14例患者经MDCT显示的位于冠脉近、中段的粥样硬化斑块作为研究对象,在斑块的最大层面测量斑块的CT值,根据CT值将斑块分类。并测量、计算最小管腔面积、血管外膜面积,斑块面积、斑块负荷。以IVUS为金标准,分别计算MDCT判断斑块性质的敏感性、特异性及各类斑块的平均CT值,并对血管测量进行统计学分析。结果:14例患者粥样硬化斑块25个,软斑块11个,纤维斑块7个,钙化斑块7个,平均CT值分别为49±32HU,93±23HU,1138±350HU。MDCT对脂质、纤维和钙化斑块诊断的敏感性和特异性分别为90.9%和92.9%;85.7%和94.4%;100%和100%。MDCT测量的管腔面积、血管面积、斑块面积、斑块负荷高于IVUS测量的结果,但两者之间没有统计学差异。结论:64层MDCT是一种准确无创的诊断和测量冠脉粥样硬化斑块的工具。     

Implications of computed tomography reconstruction algorithms on coronary atheroma quantification: Comparison with intravascular ultrasound

BackgroundAdvances in coronary computed tomography angiography (CCTA) reconstruction algorithms are expected to enhance the accuracy of CCTA plaque quantification. We aim to evaluate different CCTA reconstruction approaches in assessing vessel characteristics in coronary atheroma using intravascular ultrasound (IVUS) as the reference standard.MethodsMatched cross-sections (n ?= ?7241) from 50 vessels in 15 participants with chronic coronary syndrome who prospectively underwent CCTA and 3-vessel near-infrared spectroscopy-IVUS were included. Twelve CCTA datasets per patient were reconstructed using two different kernels, two slice thicknesses (0.75 ?mm and 0.50 ?mm) and three different strengths of advanced model-based iterative reconstruction (IR) algorithms. Lumen and vessel wall borders were manually annotated in every IVUS and CCTA cross-section which were co-registered using dedicated software. Image quality was sub-optimal in the reconstructions with a sharper kernel, so these were excluded. Intraclass correlation coefficient (ICC) and repeatability coefficient (RC) were used to compare the estimations of the 6 CT reconstruction approaches with those derived by IVUS.ResultsSegment-level analysis showed good agreement between CCTA and IVUS for assessing atheroma volume with approach 0.50/5 (slice thickness 0.50 ?mm and highest strength 5 ADMIRE IR) being the best (total atheroma volume ICC: 0.91, RC: 0.67, p ?< ?0.001 and percentage atheroma volume ICC: 0.64, RC: 14.06, p ?< ?0.001). At lesion-level, there was no difference between the CCTA reconstructions for detecting plaques (accuracy range: 0.64–0.67; p ?= ?0.23); however, approach 0.50/5 was superior in assessing IVUS-derived lesion characteristics associated with plaque vulnerability (minimum lumen area ICC: 0.64, RC: 1.31, p ?< ?0.001 and plaque burden ICC: 0.45, RC: 32.0, p ?< ?0.001).ConclusionCCTA reconstruction with thinner slice thickness, smooth kernel and highest strength advanced IR enabled more accurate quantification of the lumen and plaque at a segment-, and lesion-level analysis in coronary atheroma when validated against intravascular ultrasound. Clinicaltrials.gov (NCT03556644)     

Hunting for necrosis in the shadows of intravascular ultrasound

Coronary artery disease leads to failure of coronary circulation secondary to accumulation of atherosclerotic plaques. In adjunction to primary imaging of such vascular plaques using coronary angiography or alternatively magnetic resonance imaging, intravascular ultrasound (IVUS) is used predominantly for diagnosis and reporting of their vulnerability. In addition to plaque burden estimation, necrosis detection is an important aspect in reporting of IVUS. Since necrotic regions generally appear as hypoechic, with speckle appearance in these regions resembling true shadows or severe signal dropout regions, it contributes to variability in diagnosis. This dilemma in clinical assessment of necrosis imaged with IVUS is addressed in this work. In our approach, fidelity of the backscattered ultrasonic signal received by the imaging transducer is initially estimated. This is followed by identification of true necrosis using statistical physics of ultrasonic backscattering. A random forest machine learning framework is used for the purpose of learning the parameter space defining ultrasonic backscattering distributions related to necrotic regions and discriminating it from non-necrotic shadows. Evidence of hunting down true necrosis in shadows of intravascular ultrasound is presented with ex vivo experiments along with cross-validation using ground truth obtained from histology. Nevertheless, in some rare cases necrosis is marginally over-estimated, primarily on account of non-reliable statistics estimation. This limitation is due to sparse spatial sampling between neighboring scan-lines at location far from the transducer. We suggest considering the geometrical location of detected necrosis together with estimated signal confidence during clinical decision making in view of such limitation.     

In vivo coronary lesion differentiation with computed tomography angiography and intravascular ultrasound as compared to optical coherence tomography

Background

In vitro studies have shown the feasibility of coronary lesion grading with computed tomography angiography (CTA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) as compared to histology, whereas OCT had the highest discriminatory capacity.

Coronary plaque imaging by coronary computed tomography angiography

Coronary computed tomography angiography (CTA) has become the useful noninvasive imaging modality alternative to the invasive coronary angiography for detecting coronary artery stenoses in patients with suspected coronary artery disease (CAD). With the development of technical aspects of coronary CTA, clinical practice and research are increasingly shifting toward defining the clinical implication of plaque morphology and patients outcomes by coronary CTA. In this review we discuss the coronary plaque morphology estimated by CTA beyond coronary angiography including the comparison to the currently available other imaging modalities used to examine morphological characteristics of the atherosclerotic plaque. Furthermore, this review underlies the value of a combined assessment of coronary anatomy and myocardial perfusion in patients with CAD, and adds to an increasing body of evidence suggesting an added diagnostic value when combining both modalities. We hope that an integrated, multi-modality imaging approach will become the gold standard for noninvasive evaluation of coronary plaque morphology and outcome data in clinical practice.     

冠状动脉粥样硬化斑块的影像学评价

冠状动脉硬化斑块易发和腐蚀和破裂,导致急性冠状动脉综合征,引起急性心肌梗塞.有效的评价斑块的结构及成分特点,监测其演变过程,对选择治疗时机和治疗方案有重要意义.本文综述了冠状动脉粥样硬化斑块的病理特点和演变规律,评价了各种影像技术包括血管内超声,多层螺旋CT和磁共振,冠状动脉造影对其诊断的价值以及应用的限度.     

动脉粥样硬化斑块显像研究进展

现有的一些用于动脉粥样硬化斑块诊断的检测方法如X线血管造影、血管内超声、光学相干体层扫描、B-型超声、电子束CT、核磁共振、拉曼光谱学检查和温度测量法等,在显示血管腔狭窄、管壁增厚、斑块体积以及斑块成分等方面各有其独特价值。但是,它们或因是创伤性检查、或因为检查本身的局限性(如只能显示钙化)、或不能早期发现以代谢紊乱为特征的病变,因而限制了它们在临床上的广泛应用。利用核素标记参与动脉粥样硬化的中间物质进行显像,可以精确、定量反映斑块成分和代谢情况,为无创伤性显示动脉粥样硬化斑块带来了希望,在疾病筛选、治疗决策、疗效观察以及随访研究上具有广阔的应用前景。     

Quantitative assessment of atherosclerotic plaque,recent progress and current limitations

An important advantage of computed tomography coronary angiography (CCTA) is its ability to visualize the presence and severity of atherosclerotic plaque, rather than just assessing coronary artery stenoses. Until recently, assessment of plaque subtypes on CCTA relied on visual assessment of the extent of calcified/non-calcified plaque, or visually identifying high-risk plaque characteristics. Recent software developments facilitate the quantitative assessment of plaque volume or burden on CCTA, and the identification of subtypes of plaque based on their attenuation density. These techniques have shown promise in single and multicenter studies, demonstrating that the amount and type of plaque are associated with subsequent cardiac events. However, there are a number of limitations to the application of these techniques, including the limitations imposed by the spatial resolution of current CT scanners, challenges from variations between reconstruction algorithms, and the additional time to perform these assessments. At present, these are a valuable research technique, but not yet part of routine clinical practice. Future advances that improve CT resolution, standardize acquisition techniques and reconstruction algorithms and automate image analysis will improve the clinical utility of these techniques. This review will discuss the technical aspects of quantitative plaque analysis and present pro and con arguments for the routine use of quantitative plaque analysis on CCTA.     

基于CCTA对胸痛病人高危斑块成分及血流动力学特征的研究

目的 基于冠状动脉CT血管成像（CCTA）研究伴高危斑块的胸痛病人其斑块成分特征及血流动力学特征。方法 回顾性纳入行CCTA且于2个月内行有创冠状动脉造影检查的43例冠心病病人,男30例,女13例,平均年龄（60.8±8.7）岁。依据病人是否存在高危斑块及胸痛将病人分为2组,组1同时存在胸痛和至少1个高危斑块特征（23例）,组2仅有胸痛或高危斑块特征任意一项（20例）。测量斑块成分特征参数[斑块总体积、钙化斑块体积、纤维斑块体积、脂质斑块体积占比（脂质斑块%）、脂质斑块面积、最小管腔面积、偏心指数]和血流动力学特征参数[基于CCTA的血流储备分数（FFR_CT）,斑块近、远端FFR_CT差值（△FFR_CT）]。采用Mann-Whitney U检验或独立样本t检验比较2组间参数的差异。利用约登指数计算斑块成分特征及血流动力学特征判断高危斑块合并胸痛的临界值,采用受试者操作特征（ROC）曲线分析计算其临界值的敏感度、特异度以及曲线下面积（AUC）。结果 组1的脂质斑块%、脂质斑块面积均高于组2（均P<0.05）,FFR_CT值低于组2（P<0.05）,2组间其他斑块成分特征参数及△FFR_CT差异均无统计学意义（均P>0.05）。分析脂质斑块%、脂质斑块面积及FFR_CT 特征参数的诊断能力,FFR_CT的临界值为0.82时的敏感度最高（61%）、特异度最低（85%）,AUC最高（0.80）。结论 采用CCTA分析高危斑块中脂质斑块成分特征并进行FFR_CT测量,可作为评估高危斑块合并胸痛病人的有效辅助手段,为临床治疗决策提供依据。     

Endothelial shear stress computed from coronary computed tomography angiography: A direct comparison to intravascular ultrasound

IntroductionIntravascular ultrasound (IVUS) studies have shown that biomechanical variables, particularly endothelial shear stress (ESS), add synergistic prognostic insight when combined with anatomic high-risk plaque features. Non-invasive risk assessment of coronary plaques with coronary computed tomography angiography (CCTA) would be helpful to enable broad population risk-screening.AimTo compare the accuracy of ESS computation of local ESS metrics by CCTA vs IVUS imaging.MethodsWe analyzed 59 patients from a registry of patients who underwent both IVUS and CCTA for suspected CAD. CCTA images were acquired using either a 64- or 256-slice scanner. Lumen, vessel, and plaque areas were segmented from both IVUS and CCTA (59 arteries, 686 3-mm segments). Images were co-registered and used to generate a 3-D arterial reconstruction, and local ESS distribution was assessed by computational fluid dynamics (CFD) and reported in consecutive 3-mm segments.ResultsAnatomical plaque characteristics (vessel, lumen, plaque area and minimal luminal area [MLA] per artery) were correlated when measured with IVUS and CCTA: 12.7 ​± ​4.3 vs 10.7 ​± ​4.5 ​mm², r ​= ​0.63; 6.8 ​± ​2.7 vs 5.6 ​± ​2.7 ​mm², r ​= ​0.43; 5.9 ​± ​2.9 vs 5.1 ​± ​3.2 ​mm², r ​= ​0.52; 4.5 ​± ​1.3 vs 4.1 ​± ​1.5 ​mm², r ​= ​0.67 respectively. ESS metrics of local minimal, maximal, and average ESS were also moderately correlated when measured with IVUS and CCTA (2.0 ​± ​1.4 vs 2.5 ​± ​2.6 ​Pa^, r ​= ​0.28; 3.3 ​± ​1.6 vs 4.2 ​± ​3.6 ​Pa, r ​= ​0.42; 2.6 ​± ​1.5 vs 3.3 ​± ​3.0 ​Pa, r ​= ​0.35, respectively). CCTA-based computation accurately identified the spatial localization of local ESS heterogeneity compared to IVUS, with Bland-Altman analyses indicating that the absolute ESS differences between the two CCTA methods were pathobiologically minor.ConclusionLocal ESS evaluation by CCTA is possible and similar to IVUS; and is useful for identifying local flow patterns that are relevant to plaque development, progression, and destabilization.     

ISCHEMIA trial – Failed intervention or failed stratification?

Treatment of stable ischemic heart disease remains controversial due to lack of proper measures to identify the vulnerable patient who will suffer acute coronary events. Imaging modalities can identify rupture-prone coronary plaques but studies have found that most plaque ruptures without causing clinical events (1). High risk plaques identified by CT Angiogram (CTA) was found to be predictive of acute coronary events (ACS) in a large cohort study but the extent of atherosclerotic burden was a confounder (2). As such, numerous studies have suggested total atherosclerotic plaque burden as the main determinant of adverse patient outcomes (3,4). Coronary artery calcium (CAC) is a highly specific surrogate for coronary atherosclerosis burden and is the most predictive single cardiovascular risk marker in asymptomatic persons (5). The greater the atherosclerotic plaque burden, the more likely plaque ruptures will occur and the greater the probability that one of them triggers vascular thrombosis and a clinical event (6).     

Future of cardiac computed tomography

Coronary computed tomography angiography (CCTA) has become an integral tool in the noninvasive diagnostic workup of patients with suspected coronary artery disease in both elective and emergency settings. Today, it represents a mature technique providing accurate, non-invasive morphological assessment of the coronary arteries and atherosclerotic plaque burden. Iterative reconstruction algorithms, low kV imaging, and single-heart beat acquisitions hold promise to further reduce dose requirements and improve the safety and robustness of the technique in several circumstances including imaging of heavily calcified vessels, patients with morbid obesity or irregular heart rates, and assessment in the emergency setting. However, it has become clear over recent years that cardiac radiologists need to take further steps towards the development and integration of functional imaging with morphological CCTA assessment to truly provide a comprehensive evaluation of the heart. Computed tomography myocardial perfusion imaging, including both dynamic and static dual-energy approaches, has demonstrated the ability to directly assess and quantify myocardial ischemia with simultaneous CCTA acquisition with a reasonable contrast medium volume and radiation dose delivered to the patient. In order to promote CCTA in the clinical and research environments, radiologists should prepare to embrace the change from morphological to functional imaging, furnishing all the necessary resources and information to referring clinicians.     

Downstream resource utilization following hybrid cardiac imaging with an integrated cadmium-zinc-telluride/64-slice CT device

Purpose

Low yield of invasive coronary angiography and unnecessary coronary interventions have been identified as key cost drivers in cardiology for evaluation of coronary artery disease (CAD). This has fuelled the search for noninvasive techniques providing comprehensive functional and anatomical information on coronary lesions. We have evaluated the impact of implementation of a novel hybrid cadmium-zinc-telluride (CZT)/64-slice CT camera into the daily clinical routine on downstream resource utilization.

Methods

Sixty-two patients with known or suspected CAD were referred for same-day single-session hybrid evaluation with CZT myocardial perfusion imaging (MPI) and coronary CT angiography (CCTA). Hybrid MPI/CCTA images from the integrated CZT/CT camera served for decision-making towards conservative versus invasive management. Based on the hybrid images patients were classified into those with and those without matched findings. Matched findings were defined as the combination of MPI defect with a stenosis by CCTA in the coronary artery subtending the respective territory. All patients with normal MPI and CCTA as well as those with isolated MPI or CCTA finding or combined but unmatched findings were categorized as ??no match??.

Results

All 23 patients with a matched finding underwent invasive coronary angiography and 21 (91%) were revascularized. Of the 39 patients with no match, 5 (13%, p?p?Conclusion Cardiac hybrid imaging in CAD evaluation has a profound impact on patient management and may contribute to optimal downstream resource utilization.     

Coronary plaque characteristics in computed tomography and 2-year outcomes: The PREDICT study

BackgroundCoronary computed tomography angiography (CCTA) not only provides information regarding luminal stenoses but also allows for visualization of mural atheromatous changes (coronary plaques).ObjectiveWe sought to elucidate whether plaques seen on CCTA enable prediction of 2-year outcomes in patients with suspected and known coronary artery disease (CAD).MethodsOf 3015 patients who underwent CCTA, the images and 2-year clinical courses of 2802 patients were independently analyzed. The primary endpoint was the composite of all-cause death and acute coronary syndrome.ResultsDuring the 2-year observation period, 49 (1.7%) patients developed the primary outcome. The 2-year rates of the primary outcome in the normal (n = 515, no mural lesions), calcium (n = 654, calcified lesion alone), and plaque groups (n = 1633, presence of noncalcified or partially calcified plaques) were 0.2%, 2.0%, and 2.1%, respectively (P = 0.0028). Adverse plaque features such as low attenuation, positive remodeling, spotty calcification, and the napkin-ring sign (low-attenuation core with a higher-attenuation rim) were assessed by an independent core laboratory. Stepwise multivariate Cox proportional hazard analysis showed that a plaque with two or more characteristics (adjusted hazard ratio, 1.98; 95% confidence interval, 1.09–3.60; P = 0.0254), age of ≥67 years (mean), statin treatment after CCTA, and obstructive stenosis remained independent predictors of the primary outcome.ConclusionsPlaque imaging in CCTA has predictive value for the 2-year outcome and is a useful identifier for high-risk patients among those with known and suspected CAD.