The clinical utility of hybrid imaging for the identification of vulnerable plaque and vulnerable patients

Abstract

A R T I C L E I N F O Keywords: Vulnerable plaque Atherosclerosis Computed tomography coronary angiography Myocardial perfusion Positron emission tomography Fractional flow reserve Coronary physiology A B S T R A C TDespite decades of research and major innovations in technology, cardiovascular disease remains the leading cause of death globally. Our understanding of major cardiovascular events and their prevention is centred around the atherosclerotic plaque and the processes that ultimately lead to acute plaque rupture. Recent advances in hybrid imaging technology allow the combination of high spatial resolution and anatomical detail with molecular assessments of disease activity. This provides the ability to identify vulnerable plaque characteristics and differentiate active and quiescent disease, with the potential to improve patient risk stratification. Combined positron emission tomography and computed tomography is the prototypical non-invasive hybrid imaging technique for coronary artery plaque assessment. In this review we discuss the current state of play in the field of hybrid coronary atherosclerosis imaging.

Positron emission tomography and its role in the assessment of vulnerable plaques in comparison to other imaging modalities

“…Non-invasive imaging modalities are used by physicians to evaluate asymptomatic patients and estimate their risk of cardiovascular events, allowing healthcare professionals to intervene in high-risk patients before major cardiovascular events ensue ( 12 ). Many pathological hallmarks of vulnerable plaques can be assessed through these methods, which also have the advantage of establishing risk predictions for major cardiovascular events ( 5 , 13 ).…”

“…MRI is another useful imaging technique that does not require ionizing radiation and provides excellent soft-tissue contrast, particularly using non-contrast T1-weighted imaging (black blood imaging) ( 5 , 17 ). Regarding tissue differentiation, calcification areas can be identified by a loss in signal intensity in every sequence; fibrous tissue by a hypointense signal in all sequences, fibrocellular areas as intermediate to hyperintense areas in all sequences and fatty tissue by a hyperintense signal in T1 with a hypointense signal in T2 ( 4 , 18 ).…”

Detection of Vulnerable Coronary Plaques Using Invasive and Non-Invasive Imaging Modalities

“…Hybrid imaging combines information from multiple imaging modalities, resulting in a visual representation of both anatomical as well as functional characteristics such as disease activity or hemodynamics [ 141 ]. The most typical form of hybrid non-invasive imaging for coronary plaque assessment is the combination of CTCA (or less commonly CMR) with molecular imaging such as PET or single positron emission computed tomography.…”

“…The left coronary artery demonstrates no uptake of the radioactive tracer. Reprinted from Bing et al [ 141 ], with permission from Elsevier.…”

“…Additionally, combining non-invasive functional imaging with coronary angiography and intracoronary imaging could have potential benefit in providing details about the type of plaque and state of disease activity. Bing et al [141] present a case where 18 F-NaF PET-CT was performed in a patient with recurrent non-ST-segment elevation ACS based on in-stent restenosis of the 6-month old stent; Figure 8. OCT during the procedure demonstrated aggressive in-stent neointimal hyperplasia in the culprit lesion, as well as plaque rupture distally from the culprit.…”