Coronary CT Angiography in the Quantitative Analysis of Coronary Plaques

Zhonghua Sun

• Publisher: WSPC
• Year: 2018
• ISBN:
  9789814725637
• Topic: Medicina
• Subtopic: Cardiología

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This book provides a comprehensive overview of the author's work which includes significant developments of coronary CT angiography in the diagnosis of coronary plaques. The main contributions of the book lie in the following areas: both 2D and 3D analysis of coronary plaques with coronary CT angiography, diagnostic value of coronary CT angiography with use of different multislice CT scanners, quantitative analysis of coronary plaques in terms of lumen assessment, and bifurcation angle analysis, in particular, the diagnostic performance of coronary CT angiography in calcified plaques, and finally, hemodynamic analysis of plaques with regard to the effects of plaques on coronary blood flow, and CT-derived fractional flow reserve (FFRCT).

Contents:

• Introduction
• Coronary CT Angiography Technological Developments
• Coronary CT Angiography: 2D and 3D Characterization of Coronary Plaques
• Coronary CT Angiography: Quantitative Assessment of Coronary Plaques
• Coronary CT Angiography-Derived Computational Fluid Dynamics
• Coronary CT Angiography-Derived Fractional Flow Reserve in Coronary Artery Disease
• Summary and Conclusions

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Readership: Postgraduate students, radiologists, cardiologists, radiographers, researchers in cardiac CT imaging.
-->Keywords:Coronary CT Angiography;Coronary Plaques;Coronary Artery Disease;DiagnosisReview: Key Features:

• Comprehensive overview of the diagnostic applications of coronary CT angiography with a focus on plaque analysis
• Quantitative analysis of coronary plaques based on author's research expertise in cardiac CT imaging, which is supported by many refereed publications
• Latest and novel research areas such as computational fluid dynamics in analysis of coronary plaques

1	Introduction

Coronary artery disease (CAD) is the leading cause of morbidity and mortality in developed countries and its prevalence is increasing in developing countries. Invasive coronary angiography (ICA) is the gold standard for accurate assessment of coronary anatomy changes and diagnosis of CAD due to its superior spatial and temporal resolution which allows for accurate identification and assessment of degree of lumen stenosis resulting from obstructive coronary lesions. However, a major limitation of ICA is that it is a “luminogram”, thus, providing little information about plaque morphological features/plaque components or coronary wall changes, both of which play an important role in determining plaque vulnerability.¹ This results in low sensitivity and specificity for the early detection of the vulnerable plaque by ICA.

The most important role of radiological imaging in the diagnostic assessment of CAD is to analyze imaging features of CAD with the aim of determining the risk of plaque rupture since there is a poor correlation between coronary lumen stenosis and functional/hemodynamic significance. In addition to the routine diagnosis of the degree of lumen stenosis,^2–5 quantitative assessment of the morphological characteristics including presence of calcification within plaque,^6–9 complex lesions with plaque disruption and thrombosis,^10,11 and coronary artery movement patterns has become part of coronary plaque imaging evaluation.^12,13

ICA is unable to provide information about the morphology or plaque composition such as non-calcified plaque, or large lipid-rich core indicating vulnerable plaque, or other histological characteristics including thin fibrous cap, plaque erosion, and neoangiogenesis.^14,15 Current evidence shows that although ICA is the standard reference for diagnostic assessment of coronary lumen irregularities, it has limited value for determining coronary plaque features.^1,10 Table 1.1 summarizes the advantages and limitations of ICA in the diagnosis of various plaque features.

Table 1.1. Advantages and limitations of ICA in coronary plaque assessment (modified from Chan and Ng¹).

Plaque characteristics	Ability to detect or diagnose (references)
Degree of stenosis	Yes with high precision^2–4
Vessel wall	No
Plaque composition	No
Plaque volume	No
Fibrous cap or lipid core thickness	No
Thrombus within plaque	Possibly^10,11
Calcium within plaque	Possibly^6–9
Ruptured plaque	Possibly^10,11
Coronary artery movement	Yes^2,12,13

The established role of ICA in the diagnosis of CAD is gradually losing when compared to other imaging modalities such as coronary computed tomography angiography (CCTA) or intravascular ultrasound which is able to look beyond the coronary lumen changes, thus allowing for both anatomic detection and hemodynamic evaluation of CAD.¹⁶ Rapid technological advancements in CT scanners have enabled the widespread use of CCTA for the non-invasive assessment of CAD with high accuracy because of excellent quality images, even in patients with high heart rates. CT scanners that are post-64 and have more detector rows are available worldwide, with studies reporting the superior diagnostic value of CCTA in the detection of significant CAD with ICA as the reference method.^17–23 In particular, the very high negative predictive value of CCTA (>95%) indicates that it can be used as a reliable imaging modality for exclusion of significant CAD, thus, avoiding unnecessary downstream imaging tests or invasive procedures in patients with low to intermediate risk of CAD.

CCTA allows evaluation of coronary plaque imaging features.^24,25 Classification of coronary plaque compositions by CCTA has demonstrated important clinical implications, because there is significant association of plaque components with myocardial ischemia and prevalence of adverse major cardiac events and prediction of CAD prognosis.^26–29 The recently introduced semi-quantitative and automatic quantitative plaques assessment tools further advance the diagnostic value of CCTA through characterizing and quantifying coronary plaques with high intra- and inter-observer reproducibility.^30,31 There is a growing body of evidence showing that CCTA has incremental prognostic value over traditional risk factors.^32,33 Furthermore, CCTA combined with computational fluid dynamics, or CCTA-derived fractional flow reserve (FFR_CT) has further advanced the diagnostic performance of CCTA to determine the physiological significance of coronary stenosis, therefore, improving clinical decision-making and clinical outcome through identification of coronary lesions that result in myocardial ischemia.^34–38 Analysis of coronary lesions by CCTA providing both anatomic and functional information represents the current research direction in quantitative assessment of coronary plaques, and this is the main focus of this book.

The following chapters will provide a comprehensive overview of CCTA with regard to its clinical applications in the quantitative assessment of coronary plaques. Chapter 2 focuses on technical developments in CCTA including recently introduced various dose-saving strategies, while Chapter 3 provides an overview of 2D and 3D characterization of coronary plaques by CCTA with a focus on quantitative assessment of plaque features with the aim of identifying vulnerable plaques. Chapter 4 focuses on CCTA quantitative analysis of various plaques. Chapters 5 and 6 discuss the functional assessment of coronary plaques including CCTA-derived computational fluid dynamics and FFR_CT. Chapter 6 provides an updated overview of the current evidence of FFR_CT in the detection of coronary plaques, especially lesion-specific ischemia based on multicenter, single-center studies as well as systematic reviews and meta-analyses. Chapter 7 is a summary and conclusion of the clinical value of CCTA in CAD.

References

1.Chan KH, Ng MKC. (2013) Is there a role for coronary angiography in the early detection of vulnerable plaque? Int J Cardiol 164: 262–266.

2.Chan K, Chawantanpipat C, Gattorna T et al. (2010) The relationship between coronary stenosis severity and compression type coronary artery movement in acute myocardial infarction. Am Heart J 159: 584–592.

3.Frøbert O, van’t Veer M, Aarnoudse W, Simonsen U, Koolen J, Pijls N. (2007) Acute myocardial infarction and underlying stenosis severity. Catheter Cardiovasc Interv 70: 958–965.

4.Manoharan G, Ntalianis A, Muller O et al. (2009) Severity of coronary arterial stenoses responsible for acute coronary syndromes. Am J Cardiol 103: 1183–1188.

5.Little W, Constantinescu M, Applegate R et al. (1988) Can coronary angiography predict the site of a subsequent myocardial infarction in patients with mild-to-moderate coronary artery disease? Circulation 78: 1157–1166.

6.Burke A, Taylor A, Farb A, Malcom G, Virmani R. (2000) Coronary calcification: insights fro...