Reducing motion artefact in high resolution 7T MRI using the Magnetic Resonance Minimal Motion ('MR-MinMo') head stabilisation device

Purpose: To evaluate the effectiveness of the MR-MinMo head stabilisation device in mitigating motion artifacts during long-duration, high-resolution 7T MRI scans, with and without retrospective motion correction. Methods: The MR-MinMo was tested on 7 paediatric and 12 adult healthy volunteers using 0.6mm isotropic, 3D Multi-Echo Gradient Echo (ME-GRE) scans. A ~10-minute ME-GRE scan (linear sampling acceleration factor 2x2) and a ~20-minute scan (DISORDER sampling acceleration factor 1.4x1.4) were obtained. Both scans were acquired with and without the MR-MinMo in a 2x2 factorial study design. Qualitative and quantitative assessment of image quality of the first echo image was obtained via visual inspection and the normalized gradient squared (NGS) metric respectively. A repeated measures ANOVA was used to determine individual and combined effects of the device and DISORDER images with retrospective motion correction on NGS values, with age as a binary factor (paediatric/adult). T2* maps were generated and the standard deviation of white matter R2*(=1/T2*) values assessed across conditions. Results: The MR-MinMo significantly reduced motion artifacts both visually and in terms of NGS scores, particularly in paediatric volunteers. There was a significant interaction between MR-MinMo and DISORDER motion correction, suggesting that MR-MinMo improved retrospective motion correction. T2* maps demonstrated improved visual appearance and reduced WM variance with the MR-MinMo. Conclusion: The MR-MinMo can improve image quality via motion reduction in high-resolution 7T scans By keeping motion within a correctable regime, the device can also improve the performance of retrospective motion correction methods.