Imaging the carotid atherosclerotic plaque

Abstract

This mini review provides a concise overview of imaging techniques that are currently used to image the atheroscletoric plaque in the carotid artery in vivo. The main techniques include ultrasound imaging, X-ray imaging, magnetic resonance imaging and positron emission tomography imaging. Each technique has advantages and limitations and may be chosen depending on the availability, cost and clinical justification for its use. Common to all the imaging techniques presented here is the need for a skilled imaging professional to allow for high reliability and repeatability. While ultrasound-based imaging currently is regarded as a first line technique in clinical practice, the use of other techniques such as computed tomography angiography or magnetic resonance angiography need to be considered in the presence of significant stenosis with or without symptoms. Advancements in these two modalities, as well as in positron emission tomography imaging, are increasingly moving toward a better understanding of the risk-stratification and pre-interventional monitoring of patients at risk of plaque rupture as well as early identification of plaque development and better understanding of plaque composition (e.g. metabolic imaging).

Keywords: cardiology; imaging; vascular disease.

Figure 1

Summary of imaging techniques and relative advantages. MRI, magnetic resonance imaging; PET, positron emission tomography.

Figure 2

(A) Example of ultrasound-acquired images of the common carotid with B-mode non-contrast-enhanced ultrasonography and visualization of intima-media thickness in the near wall (NW) and far wall (FW); (B) example of near wall and far wall visualization using contrast‐enhanced ultrasound imaging. Reproduced from Shah BN, Chahal NS, Kooner JS & Senior R; Contrast‐enhanced ultrasonography vs B‐mode ultrasound for visualization of intima‐media thickness and detection of plaques in human carotid arteries; Echocardiography 2017, volume 34, pages 723–730 (33). Copyright 2017 John Wiley and Sons.

Figure 3

Example of plaque imaging by computed tomography angiogram in the common carotid artery with classification overlay to show non-calcified plaque (red) and calcified plaque (yellow). Reproduced from Ramanathan R, Dey D, Nørgaard BL, et al.; Carotid plaque composition by CT angiography in asymptomatic subjects: a head-to-head comparison to ultrasound; European Radiology, 2019 (34). Copyright 2019 John Wiley and Sons.

Figure 4

Example of segmentation of magnetic resonance angiography (MRA) data of the internal carotid artery (different views, A and B), including 3D reconstruction to reveal carotid anatomy (C and D). Example of black blood imaging in the internal carotid, the red arrow indicating a region of intraplaque hemorrhage (E) (reproduced from Yu et al. under the terms of the original Creative Commons CCBY Attribution License (35)). Example of T2 mapping of atherosclerotic carotid plaque, the red arrow indicating a region of intraplaque hemorrhage (F) (reproduced from Qi H, Sun J, Qiao H, et al.; Simultaneous T1 and T2 mapping of the carotid plaque (SIMPLE) with T2 and inversion recovery prepared 3D radial imaging; Magnetic Resonance in Medicine, 2018 volume 80, pages 2598–2608 (36); copyright 2018 John Wiley and Sons), which is shown mapped in (G).