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

Abstract

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 (ECVMRI) is already an established method, ECV quantification with CT (ECVCT) is an attractive alternative to ECVMRI, similarly using the properties of extracellular contrast media for ECV calculation. In contrast to ECVMRI, ECVCT 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 ECVCT and ECVMRI and accumulating evidence suggests a prognostic value of ECVCT 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 statementThis article summarizes the technical principles of myocardial extracellular volume (ECV) quantification with CT, reviews the literature comparing ECVCT with ECVMRI 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

Imaging biomarkers in cardiac CT: moving beyond simple coronary anatomical assessment

“…The role of CCTA has progressively grown from the mere detection of obstructive CAD, by the anatomical assessment of coronary stenosis, to an examination that enables the extrapolation of multiple parameters, useful for a more accurate evaluation of cardiovascular risk and the hemodynamic effect of stenosis. In addition, new applications of CT (e.g.,, LIE, ECV CT ) are expanding its domain to the characterization of myocardial damage [ 152 ] and improving prognostic stratification, moving toward an increasingly comprehensive examination.…”

CT Images in Follicular Lymphoma: Changes after Treatment Are Predictive of Cardiac Toxicity in Patients Treated with Anthracycline-Based or R-B Regimens

“…Therefore, the assessment of ECV at baseline could in future make it possible to identify patients with a higher risk of developing cardiac damage after therapy at an early stage and thus to identify in patients who already have, for example, an increased fibrosis index (i.e., a higher ECV) those who could benefit from treatment without anthracyclines. In this way, it might be possible to identify a group of patients misdiagnosed on echocardiographic examination [60].…”

Are Endomyocardial Ventricular Biopsies Useful for Assessing Myocardial Fibrosis?

“…Beyond its diagnostic value, virus detection through immunohistochemistry, PCR, reverse transcription PCR (RT-PCR), and the direct sequencing of heart samples have therapeutic implications, such as evaluating potential candidates for immunosuppressive therapy. Moreover, traditionally, a EMB has been the only method to visualize and measure the collagen volume fraction in the myocardium [ 8 , 9 ]. The aim of the study was to determine the significance of ventricular endomyocardial biopsies for the assessment of myocardial fibrosis and to identify the severity of myocardial fibrosis in different cardiovascular diseases.…”