COMPREHENSIVE ASSESSMENT OF VIRTUAL MONOENERGETIC IMAGING FOR CORONARY COMPUTED TOMOGRAPHY ANGIOGRAPHY

Coronary computed tomography angiography (CCTA) is a technique that allows for a non-invasive evaluation of anatomy, structure and function of the heart, as well and of coronary arterial patency. It consists of a contrast-enhanced computed tomography of the thorax, which is synchronized with the patient's electrocardiographic activity that permits to acquire high-resolution images of the heart and coronary arteries. Each vessel can be assessed with specific reconstructions in order to better assess the presence of stenoses. Conversely to coronary angiograms, CCTA images also allow for extraluminal evaluation of coronary vessels, as well as for plaque and perivascular space analysis, providing a complete morphological picture of coronary atherosclerosis. Currently, this technique is considered the first-line non-invasive test for the diagnostic workup of patients with low or intermediate risk of coronary artery disease (CAD) and chest pain, according to the guidelines of the European Society of Cardiology of 2019.1 Thanks to the speed and ease of execution and the increasing availability, CCTA has rapidly become a widespread examination in radiologists’ clinical routine. During the last two decades, CCTA has also benefited of the technological advances in computed tomography imaging. In particular, its diagnostic value has been further expanded by the application of dual-energy computed tomography (DECT) techniques.2 DECT is based on the simultaneous acquisition of X-ray beams with two different energy levels. Since each tissue shows a different attenuation profile when exposed to different energy levels, DECT can provide quantitative information about material composition. This may allow to differentiate structures with similar attenuation in conventional CT.3 There are different technical approaches to obtain DECT images, which can be easily differentiated in single-source, dual-source, and dual-layer systems.2 One of the unique features of DECT is the possibility to obtain virtual monoenergetic images at different keV levels.4 This algorithm has demonstrated to provide clear advantages in DE-CCTA. Previous studies have shown that low-keV monoenergetic reconstructions increase iodine attenuation and contrast, whereas high-keV monoenergetic reconstructions can reduce beam-hardening artefacts.4 The purpose of our research is to prove that CCTA monoenergetic reconstructions obtained from dual-source (DSCT) and dual-layer (DLCT) platforms show improved objective and subjective image quality compared to conventional images.