4DFlowNet: Super-Resolution 4D Flow MRI using Deep Learning and Computational Fluid Dynamics
This work addresses the need for higher resolution in 4D flow MRI for better assessment of blood flow in patients, particularly those with abnormal flows, by reducing imaging time constraints, but it is incremental as it applies existing super-resolution deep learning methods to a specific medical imaging domain.
The paper tackles the problem of low resolution in 4D flow MRI, which limits accuracy in blood flow analysis, by proposing 4DFlowNet, a deep learning model that generates super-resolution images with an upsample factor of 2, achieving absolute relative errors of 0.6-5.8% in phantom data and 1.1-3.8% in volunteer data compared to actual flow measurements.
4D-flow magnetic resonance imaging (MRI) is an emerging imaging technique where spatiotemporal 3D blood velocity can be captured with full volumetric coverage in a single non-invasive examination. This enables qualitative and quantitative analysis of hemodynamic flow parameters of the heart and great vessels. An increase in the image resolution would provide more accuracy and allow better assessment of the blood flow, especially for patients with abnormal flows. However, this must be balanced with increasing imaging time. The recent success of deep learning in generating super resolution images shows promise for implementation in medical images. We utilized computational fluid dynamics simulations to generate fluid flow simulations and represent them as synthetic 4D flow MRI data. We built our training dataset to mimic actual 4D flow MRI data with its corresponding noise distribution. Our novel 4DFlowNet network was trained on this synthetic 4D flow data and was capable in producing noise-free super resolution 4D flow phase images with upsample factor of 2. We also tested the 4DFlowNet in actual 4D flow MR images of a phantom and normal volunteer data, and demonstrated comparable results with the actual flow rate measurements giving an absolute relative error of 0.6 to 5.8% and 1.1 to 3.8% in the phantom data and normal volunteer data, respectively.