POCS‐based reconstruction of multiplexed sensitivity encoded MRI (POCSMUSE): A general algorithm for reducing motion‐related artifacts

Abstract

Purpose A projection onto convex sets reconstruction of multiplexed sensitivity encoded MRI (POCSMUSE) is developed to reduce motion-related artifacts, including respiration artifacts in abdominal imaging and aliasing artifacts in interleaved diffusion weighted imaging (DWI). Theory Images with reduced artifacts are reconstructed with an iterative POCS procedure that uses the coil sensitivity profile as a constraint. This method can be applied to data obtained with different pulse sequences and k-space trajectories. In addition, various constraints can be incorporated to stabilize the reconstruction of ill-conditioned matrices. Methods The POCSMUSE technique was applied to abdominal fast spin-echo imaging data, and its effectiveness in respiratory-triggered scans was evaluated. The POCSMUSE method was also applied to reduce aliasing artifacts due to shot-to-shot phase variations in interleaved DWI data corresponding to different k-space trajectories and matrix condition numbers. Results Experimental results show that the POCSMUSE technique can effectively reduce motion-related artifacts in data obtained with different pulse sequences, k-space trajectories and contrasts. Conclusion POCSMUSE is a general post-processing algorithm for reduction of motion-related artifacts. It is compatible with different pulse sequences, and can also be used to further reduce residual artifacts in data produced by existing motion artifact reduction methods.

Human brain diffusion tensor imaging at submillimeter isotropic resolution on a 3 Tesla clinical MRI scanner

“…As shown in recent papers, 2D MUSE was designed to estimate shot-to-shot phase variations directly from interleaved EPI data without relying on navigator echoes (Chang et al, 2014; Chen et al, 2013; Chu et al, 2014). However, for 3D interleaved EPI, navigator signals with zero k z encoding are needed (Figure 1), because the shot-to-shot phase variations cannot be inherently estimated from weak DWI signals at high k z planes.…”

Joint correction of Nyquist artifact and minuscule motion-induced aliasing artifact in interleaved diffusion weighted EPI data using a composite two-dimensional phase correction procedure

“…It has been shown in recent studies that high-resolution DWI can also be achieved with interleaved spiral imaging [23, 27, 32–35], PROPELLER [36, 37], PROPELLER-EPI [14, 15], readout-segmented EPI [17, 38, 39], steady-state free precession (SSFP) imaging [40], and radial fast spin-echo imaging [41]. …”

“…4) All the subsets of interleaved EPI data (step 3), the known coil sensitivity profiles, shot-to-shot phase variation information (step 2), and 2D Nyquist correction parameters are all incorporated into a mathematical framework that jointly solves the unknown magnitude source signals (based on Equation 2) to produce a set of images without Nyquist ghost and motion-induced aliasing artifacts. Note that the magnitude source images reconstructed in step 4 are free from undesirable noise amplification associated with SENSE reconstruction, as described previously [19, 27]. $$true[\begin{array}{c}centeru{\mid }_1^w\\ centeru{\mid }_2^w\\ center⋮\\ centeru{\mid }_N^w\\ centeru{\mid }_{N+1}^w\\ centeru{\mid }_{N+2}^w\\ center⋮\\ centeru{\mid }_{2N}^w\end{array}true]=\frac{1}{2N}true[\begin{array}{cccc}centerS{\mid }_1^w{e}^{i\frac{2\pi }{2N}\cdot 0\cdot 0}& centerS{\mid }_2^w{e}^{i\frac{2\pi }{2N}\cdot 0\cdot 1}& center\cdots & centerS{\mid }_{2N}^w{e}^{i\frac{2\pi }{2N}\cdot 0\cdot (2N-1)}\\ centerS{\mid }_1^w{e}^{i\frac{2\pi }{2N}\cdot 1\cdot 0}{e}^{i\Theta {\mid }_1^2}& centerS{\mid }_2^w{e}^{i\frac{2\pi }{2N}\cdot 1\cdot 1}{e}^{i\Theta {\mid }_2^2}& center\cdots & centerS{\mid }_{2N}^w{e}^{i\frac{2\pi }{2N}\cdot 1\cdot (2N-1)}{e}^{i\Theta {\mid }_{2N}^2}\\ cen...\end{array}$$…”

Reduced acoustic noise in diffusion tensor imaging on a compact MRI system

“…An iterative image reconstruction scheme was developed on MATLAB (Mathworks, Natick MA, USA), similar to [41] to account for phase inconsistencies [42] that typically occur with multi-shot DTI in vivo . Standard images reconstructed on the scanner were also used for the phantom multi-shot EPI.…”