Coronary CT angiography with prospective ECG-triggering: an effective alternative to invasive coronary angiography

Abstract

Despite the tremendous contributions of coronary CT angiography to coronary artery disease, radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing radiation-induced malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. Of these strategies, prospective ECG-triggering is one of the most effective techniques with resultant effective radiation dose similar to or even lower than that of invasive coronary angiography. Prospective ECG-triggered coronary CT angiography has been reported to have high diagnostic accuracy in the diagnosis of coronary artery disease with image quality comparable to that of retrospective ECG-gating, but with significantly reduced radiation dose. Successful performance of prospective ECG-triggering is determined by strict exclusion criteria and careful patient preparation. The aim of this article is to provide an overview of the diagnostic applications of coronary CT angiography with prospective ECG-triggering with focus on radiation dose reduction. Radiation dose measurements are discussed with aim of allowing accurate dose estimation. Diagnostic value of prospective ECG-triggered coronary CT angiography in patients with different heart rate is discussed. Finally, current status and future directions are highlighted.

Keywords: Coronary artery disease; coronary CT angiography; image quality; prospective ECG-triggering; radiation dose.

Figure 1

Conventional retrospective ECG-gated coronary CT angiography. X-ray beam is turned on during the entire cardiac cycle without adjusting the tube current, allowing for acquisition of volume data

Figure 2

Prospective ECG-triggering with X-ray beam on during a portion of cardiac cycle, while in the remaining cardiac phase, the X-ray beam is turned off

Figure 3

Prospective ECG-triggered coronary CT angiography curved planar reformatted image shows presence of misalignment, affecting visualization of the right coronary artery

Figure 4

Box plot shows the mean effective dose reported in the studies with use of retrospective ECG-gating and prospective ECG-triggering. It is obvious that the radiation dose of prospective ECG-triggered coronary CT angiography is significantly lower than that of retrospective gating protocol according to a systematic review (32). Horizontal line in each box shows median and top and bottom lines of boxes show interquartile range.

Figure 5

Prospective ECG-triggered coronary CT angiography curved planar reformatted images of the right coronary artery (A) and left coronary artery branches (B) with excellent vessel visualization and no artefacts

Figure 6

Prospective ECG-triggered coronary CT angiography curved planar reformatted images of the right (A) and left coronary arteries (B) with blurred borders due to moderate artefacts