Noncontrast Myocardial Characterization in Acute Myocardial Infarction Using Electron Density Imaging

Abstract

Purpose: Spectral computed tomography (CT) enables improvedtissue characterization, although virtually all research has focusedon contrast-enhanced examinations. We hypothesized that changesin myocardial tissue related to acute myocardial infarction (AMI)might potentially be identified without the need for contrastadministration using electron density (ED) imaging.Patients and Methods: This retrospective observational studyinvolved a small series (n = 15) of patients admitted to our institutionwith a first AMI without signs of hemodynamic instability andidentification of a culprit vessel with invasive coronary angiographyduring the same admission, who also underwent a noncontrast, lowdosechest CT using a dual-layer spectral CT scanner. Images wereassessed in search of dark areas with low density on ED imaging, andthe mean percentage ED relative to water (%EDW) was calculated.Results: Using a qualitative approach, ED assessment enabled theidentification of 11/15 (73%) affected coronary territories, with asensitivity of 73% (95% CI: 45; 92%) and a specificity of 87% (95%CI: 69; 96%). AMI segments showed significantly lower ED valuesthan the remote myocardium (103.8 ± 0.8 vs 104.3 ± 0.6 %EDW,P < 0.0001), and a threshold below 103.9 %EDW had a sensitivityof 66% and specificity of 79% for the identification of AMI. In acontrol group of patients without a history of cardiovascular disease,none had areas with focal reduction of ED following the shapeof the myocardial wall.Conclusions: In our preliminary series, ED imaging showed thepotential to enable the identification of myocardial tissue changesrelated to AMI without iodinated contrast requirement.