Combining variational mode decomposition with regularisation techniques to denoise MRI data.

In this paper, we propose a novel method for removing noise from MRI data by exploiting regularisation techniques combined with variational mode decomposition. Variational mode decomposition is a new decomposition technique for sparse decomposition of a 1D or 2D signal into a set of modes. In turn, regularisation is a method that can translate the ill-posed problem (e.g., image denoising) into a well-posed problem. The proposed method aims to remove the noise from the image in two steps. In the first step, the MR imaging data are decomposed by the 2D variational mode decomposition algorithm. In the second step, for effective suppression of Rician noise from MRI data, we used the fused lasso signal approximator with all modes acquired from the medical scan. The performance of the proposed approach was compared with state-of-the-art reference methods based on different metrics, that is, the peak signal-to-noise ratio, the structural similarity index metrics, the high-frequency error norm, the quality index based on local variance, and the sharpness index. The experiments were performed on the basis of both simulated and real images. The presented results prove the high denoising performance of the proposed algorithm; particularly under heavy noise conditions.

Asymmetry of electromechanical delay (EMD) and torque in the muscles stabilizing spinal column.

Stabilization of the spinal column is ensured by the activity of trunk flexor and erector muscles, including rectus abdominis (RA) and erector spinae (ES). The goal of this study was to evaluate the symmetry of action potential and electromechanical delay (EMD) in RA and ES during generation of maximal muscle torque. In the present study, the symmetry of EMG activity in the right and left parts of RA and ES was tested under isometric conditions. The subjects (N = 13) were selected from the university population. Electromyographic signals and muscles torques were recorded with the sampling frequency of 1000 Hz. Lack of significant differences in EMD between left and right sides in both muscles studied and lack of correlation between EMD and maximal muscle torque were observed. Analysis aimed at assessing the symmetry of EMG signals amplitude revealed crossed laterality characterized by increased activity in the right side of RA muscle and left side of ES. The proportion of maximal muscle torque in ES to RA in the women examined amounted to 1.7:1.