Interpretable machine learning for automated left ventricular scar quantification in hypertrophic cardiomyopathy patients

PLOS Digit Health. 2023 Jan 4;2(1):e0000159. doi: 10.1371/journal.pdig.0000159. eCollection 2023 Jan.

Abstract

Scar quantification on cardiovascular magnetic resonance (CMR) late gadolinium enhancement (LGE) images is important in risk stratifying patients with hypertrophic cardiomyopathy (HCM) due to the importance of scar burden in predicting clinical outcomes. We aimed to develop a machine learning (ML) model that contours left ventricular (LV) endo- and epicardial borders and quantifies CMR LGE images from HCM patients.We retrospectively studied 2557 unprocessed images from 307 HCM patients followed at the University Health Network (Canada) and Tufts Medical Center (USA). LGE images were manually segmented by two experts using two different software packages. Using 6SD LGE intensity cutoff as the gold standard, a 2-dimensional convolutional neural network (CNN) was trained on 80% and tested on the remaining 20% of the data. Model performance was evaluated using the Dice Similarity Coefficient (DSC), Bland-Altman, and Pearson's correlation. The 6SD model DSC scores were good to excellent at 0.91 ± 0.04, 0.83 ± 0.03, and 0.64 ± 0.09 for the LV endocardium, epicardium, and scar segmentation, respectively. The bias and limits of agreement for the percentage of LGE to LV mass were low (-0.53 ± 2.71%), and correlation high (r = 0.92). This fully automated interpretable ML algorithm allows rapid and accurate scar quantification from CMR LGE images. This program does not require manual image pre-processing, and was trained with multiple experts and software, increasing its generalizability.

Grants and funding

Funding for this study was provided by the Peter Munk Cardiology Center Innovation Fund and the MSH-UHN AMO Innovation Fund. BW is partially supported by the CIFAR AI Chair Program. WT is supported by a Heart and Stroke Foundation of Canada National New Investigator Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.