Sparse-view CT Reconstruction with 3D Gaussian Volumetric Representation

Sparse-view CT is a promising strategy for reducing the radiation dose of traditional CT scans, but reconstructing high-quality images from incomplete and noisy data is challenging. Recently, 3D Gaussian has been applied to model complex natural scenes, demonstrating fast convergence and better rendering of novel views compared to implicit neural representations (INRs). Taking inspiration from the successful application of 3D Gaussians in natural scene modeling and novel view synthesis, we investigate their potential for sparse-view CT reconstruction. We leverage prior information from the filtered-backprojection reconstructed image to initialize the Gaussians; and update their parameters via comparing difference in the projection space. Performance is further enhanced by adaptive density control. Compared to INRs, 3D Gaussians benefit more from prior information to explicitly bypass learning in void spaces and allocate the capacity efficiently, accelerating convergence. 3D Gaussians also efficiently learn high-frequency details. Trained in a self-supervised manner, 3D Gaussians avoid the need for large-scale paired data. Our experiments on the AAPM-Mayo dataset demonstrate that 3D Gaussians can provide superior performance compared to INR-based methods. This work is in progress, and the code will be publicly available.

Gait Cycle-Inspired Learning Strategy for Continuous Prediction of Knee Joint Trajectory from sEMG

Predicting lower limb motion intent is vital for controlling exoskeleton robots and prosthetic limbs. Surface electromyography (sEMG) attracts increasing attention in recent years as it enables ahead-of-time prediction of motion intentions before actual movement. However, the estimation performance of human joint trajectory remains a challenging problem due to the inter- and intra-subject variations. The former is related to physiological differences (such as height and weight) and preferred walking patterns of individuals, while the latter is mainly caused by irregular and gait-irrelevant muscle activity. This paper proposes a model integrating two gait cycle-inspired learning strategies to mitigate the challenge for predicting human knee joint trajectory. The first strategy is to decouple knee joint angles into motion patterns and amplitudes former exhibit low variability while latter show high variability among individuals. By learning through separate network entities, the model manages to capture both the common and personalized gait features. In the second, muscle principal activation masks are extracted from gait cycles in a prolonged walk. These masks are used to filter out components unrelated to walking from raw sEMG and provide auxiliary guidance to capture more gait-related features. Experimental results indicate that our model could predict knee angles with the average root mean square error (RMSE) of 3.03(0.49) degrees and 50ms ahead of time. To our knowledge this is the best performance in relevant literatures that has been reported, with reduced RMSE by at least 9.5%.