Monoenergetic Dual-energy Computed Tomographic Imaging

Abstract

Monoenergetic imaging is an increasingly used reconstruction technique in postprocessing of dual-energy computed tomography (DECT). The main advantage of this technique is the ability to substantially increase image contrast of structures with uptake of iodinated contrast material. Although monoenergetic imaging was mainly used in oncological DECT applications, recent research has further demonstrated its role in vascular imaging. Using this dedicated postprocessing algorithm, image contrast of vascular structures in the thorax can be increased, a drastic reduction of contrast material is feasible, and even beam-hardening artifacts can be reduced. The aim of this review article is to explain the technical background of this technique, showcase its relevance in cardiothoracic DECT, and provide an outlook on the clinical impact of this technique beyond solely improvements in image quality.

Improved coronary artery contrast enhancement using noise-optimised virtual monoenergetic imaging from dual-source dual-energy computed tomography

“…CCTA in single-energy mode has been established as a robust technique to accurately and non-invasively grade and quantify coronary stenosis. DECT with the use of various post-processing algorithms has been shown to further improve various cardiothoracic applications [5]. To overcome unfavorable image noise at lower keV using traditional VMI algorithms, a noise-optimizing algorithm was developed, which was predominantly investigated for CT angiography other than cardiac in previous research [19].…”

“…Post-processing of DE-CCTA angiography datasets using VMI/ VMI + algorithms has been evaluated by several prior studies as optimal display of the coronary arteries requires maximization of vascular contrast and minimization of artifacts [5]. Martin et al reported substantially improved cardiac contrast in patients undergoing pre-TAVR imaging using DECT [25].…”

“…characterize more accurately the various types of atherosclerotic coronary plaques [4]. Linear blending is commonly used for the standard reconstruction of the DECT datasets; however, voltage settings are fixed and thus do not allow to separately alter image impressions at different hypothetical energy levels [5]. Post-processing of dataset information at various kiloelecton volt (keV) settings can be achieved by virtual monoenergetic imaging (VMI).…”

Society of cardiovascular computed tomography expert consensus document on myocardial computed tomography perfusion imaging

“…While low energy levels depict higher contrast enhancement in the myocardium, they are associated with increased noise, and are subject to increased beam hardening artifacts that can mimic perfusion abnormalties and increase false positive readings unless dedicated algorithms are used. 70 Conversely, higher energy levels yield lower myocardial and intravascular contrast but lower image noise, and decreased beam hardening artifacts. Thus, DECT may reduce or even eliminate beam hardening by generating monochromatic images.…”

Update on Cardiovascular Applications of Multienergy CT

“…Furthermore, multienergy CT data can also be manipulated to reconstruct VM images in which attenuation data approximate data that would be obtained with a monoenergy x-ray beam at a specified tube voltage setting (10). These images are termed virtual to highlight that they only simulate the monoenergy beam spectrum and that attenuation coefficients (in Hounsfield units) are only correct for the two base materials that were used to generate the monoenergy images (typically water and iodine, or water and calcium) (11). Furthermore, the terms virtual monochromatic and virtual monoenergetic images are used interchangeably in the literature (12,13).…”