Myocardial extracellular volume quantification with computed tomography—current status and future outlook

Non-invasive quantification of the extracellular volume (ECV) is a method for the evaluation of focal and diffuse myocardial fibrosis, potentially obviating the need for invasive endomyocardial biopsy. While ECV quantification with cardiac magnetic resonance imaging (ECV(MRI)) is already an established method, ECV quantification with CT (ECV(CT)) is an attractive alternative to ECV(MRI), similarly using the properties of extracellular contrast media for ECV calculation. In contrast to ECV(MRI), ECV(CT) provides a more widely available, cheaper and faster tool for ECV quantification and allows for ECV calculation also in patients with contraindications for MRI. Many studies have already shown a high correlation between ECV(CT) and ECV(MRI) and accumulating evidence suggests a prognostic value of ECV(CT) quantification in various cardiovascular diseases. Adding a late enhancement scan (for dual energy acquisitions) or a non-enhanced and late enhancement scan (for single-energy acquisitions) to a conventional coronary CT angiography scan improves risk stratification, requiring only minor adaptations of the contrast media and data acquisition protocols and adding only little radiation dose to the entire scan. Critical relevance statement This article summarizes the technical principles of myocardial extracellular volume (ECV) quantification with CT, reviews the literature comparing ECV(CT) with ECV(MRI) and histopathology, and reviews the prognostic value of myocardial ECV quantification for various cardiovascular disease. Key points • Non-invasive quantification of myocardial fibrosis can be performed with CT. • Myocardial ECV quantification with CT is an alternative in patients non-eligible for MRI. • Myocardial ECV quantification with CT strongly correlates with ECV quantification using MRI. • Myocardial ECV quantification provides incremental prognostic information for various pathologies affecting the heart (e.g., cardiac amyloidosis). GRAPHICAL ABSTRACT: [Image: see text]