Non-Invasive Quantitation of Myocardial Fibrosis Using Combined Tissue Harmonic Imaging and Integrated Backscatter Analysis in Dilated Cardiomyopathy

Abstract

Background: Echocardiographic modalities have challenged the myocardial tissue characterization, but this reliability has not reached to the clinical use. This study investigated whether combined tissue harmonic imaging (THI) and integrated backscatter analysis (IB) provide the reliable and quantitative information about myocardial fibrosis in idiopathic dilated cardiomyopathy (DCM) in comparison with myocardial biopsy findings. Methods: We studied 56 patients with DCM. All patients underwent left ventricular endomyocardial biopsy and IB with fundamental imaging (FI) and THI. Results: In patients with good echocardiographic image quality, excellent correlations between the percentage of area occupied by myocardial fibrosis (% fibrosis) and the mean of integrated backscatter during a cardiac cycle (m-IB) measured with FI or THI were seen, and the correlation was closer with THI compared with FI. While in patients with poor image quality the correlation between m-IB and % fibrosis was only modest with FI, but the correlation was excellent with THI. Four cut-off values of m-IB with THI obtained from receiver operating characteristic curve discriminated between % fibrosis of more and less than 25, 30, 35, and 40% with high sensitivity and specificity. Multivariate analysis revealed that m-IB with THI was an independent predictor for discrimination of the severity of myocardial fibrosis. Conclusion: Combined IB and THI are a clinically applicable method and may be an alternative to myocardial biopsy in evaluating quantitatively myocardial fibrosis in DCM.