Abstract
BACKGROUND: There is a growing interest in cardiovascular magnetic resonance (CMR) radiomic signatures as novel imaging biomarkers of cardiac disease. However, very little is known about pathological correlates of the radiomics signature of myocardium on CMR sequences. In this study, we sought to investigate the association between CMR myocardial radiomic signatures and histological features in patients with non-ischemic dilated cardiomyopathy (DCM). METHODS: CMR images from DCM patients who underwent CMR followed by endomyocardial biopsy within 6 [2-15] days were used to investigate the association between myocardial radiomic signatures measured from native T(1), extra-cellular volume (ECV), late gadolinium enhancement (LGE) and histological features. Radiomic first-order and textural features were computed for each sequence from the mid-septal myocardium near the biopsy region. Hierarchical clustering was then applied to identify distinct radiomic clusters. A representative feature known as the "medoid" was identified within each cluster based on its minimal dissimilarity from other features. Logistic regression models were built using one medoid per model to evaluate the association between each medoid and histological feature. Association was determined using odds ratio (OR) with a 95% confidence interval. RESULTS: 132 DCM patients (71% male, 94/132; 54 ± 15 years) were included in the study. Clustering analysis unveiled two radiomic clusters for each sequence. For native T(1), the medoids were textural features. The first medoid was associated with fibrosis, inflammation, myocyte hypertrophy, vacuolization, and fat replacement (OR = 2.84 [1.62-5.46]; OR = 2.05 [1.15-4.03]; OR = 2.39 [1.01-6.62]; OR = 2.03 [1.22-3.60]; OR = 0.35 [0.12-0.86]; respectively). The second medoid was associated with nuclear generation (OR = 0.55 [0.31-0.91]). ECV medoids included first-order and textural features. The first-order medoid was associated with fibrosis (OR = 2.97 [1.75-5.46]), myocyte hypertrophy (OR = 3.20 [1.17-10.37]), and nuclear degeneration (OR = 1.66 [1.02-2.89]), while medoid 2 (texture) was associated with fibrosis (OR = 4.44 [2.26-10.00]). LGE medoid 1 (texture) was associated with myocyte hypertrophy (OR = 0.31 [0.10-0.77]), while medoid 2 (texture) was associated with fibrosis (OR = 2.40 [1.38-4.66]) and vacuolization (OR = 2.00 [1.16-3.72]). CONCLUSIONS: In DCM patients, CMR radiomic signatures were associated with myocardial tissue composition, as assessed by invasive biopsy.