Quantification of Infarct Size in Acute and Chronic Ischaemic and Non-Ischaemic Heart Diseases: Reproducibility of Different Techniques

Abstract

Background: Several techniques have been proposed for the quantification of late gadolinium enhancement (LGE), including manual planimetry, manual thresholding, the signal threshold versus reference myocardium technique (STRM) and the full width at half maximum (FWHM) technique. However, none of these approaches is considered as the optimal method for quantitative assessment of left ventricular (LV) scar. This study compares the intra- and inter-observer reproducibility of the aforementioned quantification techniques across different disease processes that give rise to LV scar, i.e. acute myocardial infarct (AMI), acute myocarditis (AMy), chronic ischaemic heart disease (CIHD), hypertrophic cardiomyopathy (HCM) and non-ischaemic cardiomyopathy (NICM). Methods: 100 patients (20 AMI patients, 20 AMy patients, 20 CIHD patients, 20 HCM patients and 20 NICM patients) who had cardiac magnetic resonance imaging and visually detectable LGE were included in the study. LGE images were analysed by two independent observers and intra- and inter-observer agreement of each technique was reported using the intraclass correlation coefficient (ICC). Results: All quantitative techniques had excellent intra- and inter-observer agreement (ICC values ≥0.95) in AMI patients, while only FWHM performed well in AMy and CIHD patients (intra- and inter-observer ICC were 0.96 and 0.92 among AMy patients and 0.95 and 0.93 among the CIHD patients). Among HCM and NICM patients, all quantitative techniques had good intra- and inter-observer agreement (ICC values ≥0.90), except manual thresholding, which had ICC values <0.90; FWHM presented the highest intra- and inter-observer ICC (0.97 and 0.94, respectively). Conclusions: FWHM technique performs well in all cardiac conditions; STRM techniques represent a valid alternative in AMI, HCM and NICM.