Learning the Regularization in DCE-MR Image Reconstruction for Functional Imaging of Kidneys
This work addresses the challenge of balancing artifact reduction and functional accuracy in kidney DCE-MRI for medical imaging, representing an incremental improvement over compressed sensing methods.
The paper tackled the problem of under-sampling artifacts in accelerated kidney DCE-MRI, which reduce accuracy in functional imaging, by proposing a deep neural network that generates images from a lower-dimensional representation to reduce artifacts without compromising biomarker accuracy, resulting in high correlation with ground truth markers and reduced artifacts.
Kidney DCE-MRI aims at both qualitative assessment of kidney anatomy and quantitative assessment of kidney function by estimating the tracer kinetic (TK) model parameters. Accurate estimation of TK model parameters requires an accurate measurement of the arterial input function (AIF) with high temporal resolution. Accelerated imaging is used to achieve high temporal resolution, which yields under-sampling artifacts in the reconstructed images. Compressed sensing (CS) methods offer a variety of reconstruction options. Most commonly, sparsity of temporal differences is encouraged for regularization to reduce artifacts. Increasing regularization in CS methods removes the ambient artifacts but also over-smooths the signal temporally which reduces the parameter estimation accuracy. In this work, we propose a single image trained deep neural network to reduce MRI under-sampling artifacts without reducing the accuracy of functional imaging markers. Instead of regularizing with a penalty term in optimization, we promote regularization by generating images from a lower dimensional representation. In this manuscript we motivate and explain the lower dimensional input design. We compare our approach to CS reconstructions with multiple regularization weights. Proposed approach results in kidney biomarkers that are highly correlated with the ground truth markers estimated using the CS reconstruction which was optimized for functional analysis. At the same time, the proposed approach reduces the artifacts in the reconstructed images.