Coronary CT angiography: current status and continuing challenges

Abstract

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted.

Figure 1

Coronary CT angiography of non-calcified plaque. A non-calcified plaque is found at the mid-segment of the left cunterior descending artery on a curved planar reformatted image. (Reproduced from [127].)

Figure 2

Coronary CT angiography of calcified plaques beyond luminography. CT maximum-intensity projection shows focally calcified plaques in the proximal segment of the right coronary artery (a). Corresponding coronary angiography shows mild coronary lumen stenosis [arrow in (b)]. Extensive calcified plaques are noticed in the proximal and middle segments of left anterior descending (LAD) on curved multiplanar reformatted (c) and volume rendering images (d). A significant stenosis of LAD is confirmed on coronary angiography [arrows in (e)].

Figure 3

Coronary CT angiography of mixed plaques. Mixed plaques are observed in the proximal segment of the left anterior descending (LAD) artery with >50% stenosis (a, arrow). Coronary angiography confirms the significant stenosis of the LAD (b, arrow).

Figure 4

Coronary CT angiography follow-up of a coronary bypass graft. Three-dimensional surfaced shaded display shows a patent saphenous vein graft (long arrows) in a patient treated with a coronary artery bypass graft because of significant stenosis in the left coronary artery. The short arrow indicates the left coronary artery while the arrowhead indicates the right coronary artery.

Figure 5

Coronary CT angiography of a patent stent. A patent coronary stent is noticed in the proximal left anterior descending (LAD) artery on a curved multiplana reformatted (MPR) image with clear demonstration of the intrastent lumen without in-stent restenosis.

Figure 6

Coronary CT angiography of in-stent restenosis. An in-stent restenosis is present at the distal part of the right coronary atery (RCA) stent which is demonstrated as the low-attenuating area on longitudinally straightened (a), curved multiplana reformatted (b) and cross-sectional images (c).