ElastoNet: Neural network-based multicomponent MR elastography wave inversion with uncertainty quantification
Héloïse Bustin, Tom Meyer, Rolf Reiter, Jakob Jordan, Lars Walczak, Heiko Tzschätzsch, Ingolf Sack, Anja Hennemuth
Abstract
Magnetic Resonance Elastography (MRE) quantifies soft tissue stiffness by measuring induced shear waves. MRE inversion techniques for parameter reconstruction are often affected by noise and compression waves. Neural network-based inversions have emerged as a possible solution to address these challenges. However, current approaches lack generalizability and do not provide uncertainty estimates. Therefore, we propose ElastoNet, a novel neural network-based approach for MRE wave inversion that analyzes multiple wave components independently of resolution and vibration frequency and provides uncertainty quantification maps. ElastoNet was trained on synthetically generated wave patches of 5 × 5 pixels. Uncertainty quantification was implemented using evidential deep learning. ElastoNet was evaluated on synthetically generated plane waves, finite element simulations of abdominal MRE, phantom MRE data, and a prospective wideband multifrequency abdominal MRE study (excitation frequencies of 20 to 80 Hz) in 14 healthy volunteers. ElastoNet was compared with established inversion methods LFE and k-MDEV, as well as neural network-based TWENN. ElastoNet generated shear wave speed maps as a proxy of stiffness with comparable or better accuracy than established methods and did not require retraining for different resolutions and vibration frequencies. ElastoNet achieved a lower root mean square error relative to ground truth values in finite element simulations and phantom data than other inversion methods and provided uncertainty maps. ElastoNet is a promising method for universal neural network-based inversion in MRE, effectively overcoming current challenges and expanding the potential use of neural networks in diagnostic MRE applications.