Motion‐corrected MRI with DISORDER: Distributed and incoherent sample orders for reconstruction deblurring using encoding redundancy

Abstract

Purpose: To enable rigid body motion-tolerant parallel volumetric magnetic resonance imaging by retrospective head motion correction on a variety of spatiotemporal scales and imaging sequences. Theory and methods: Tolerance against rigid body motion is based on distributed and incoherent sampling orders for boosting a joint retrospective motion estimation and reconstruction framework. Motion resilience stems from the encoding redundancy in the data, as generally provided by the coil array. Hence, it does not require external sensors, navigators or training data, so the methodology is readily applicable to sequences using 3D encodings. Results: Simulations are performed showing full inter-shot corrections for usual levels of in vivo motion, large number of shots, standard levels of noise and moderate acceleration factors. Feasibility of inter-and intra-shot corrections is shown under controlled motion in vivo. Practical efficacy is illustrated by high-quality results in most corrupted of 208 volumes from a series of 26 clinical pediatric examinations collected using standard protocols. Conclusions: The proposed framework addresses the rigid motion problem in volumetric anatomical brain scans with sufficient encoding redundancy which has enabled reliable pediatric examinations without sedation. K E Y W O R D S distributed and incoherent sampling, image reconstruction, magnetic resonance, motion correction, parallel imaging 714 | CORDERO-GRANDE Et Al.

Evaluation of DISORDER: retrospective image motion correction for volumetric brain MRI in a pediatric setting

“…In Figure 1, each shot is represented by a different color. As demonstrated in 14 , DISORDER aims to improve motion tolerance by guaranteeing that the acquisition of every shot contains a series of samples distributed incoherently throughout kspace. This is achieved with a modified phase encoding (PE) sampling order.…”

“…Motion and reconstruction were estimated jointly using a parallel k- space model in the presence of rigid motion 14 . Starting from a standard reconstruction assuming no motion, a first approximation of the motion parameters for each shot is obtained by maximizing the likelihood of the k- space measures for current reconstructed volume.…”

“…Then, a new volume is reconstructed with current motion parameters and the method alternates between motion estimation and reconstruction until convergence. An in-depth description of the reconstruction algorithm has been described previously 15,14 .…”

“…Here, we use a more general retrospective motion correction technique: Distributed and Incoherent Sample Orders for Reconstruction Deblurring using Encoding Redundancy (DISORDER). In this method, k-space samples are reordered to enable retrospective motion correction during image reconstruction 14 . Our hypothesis is that DISORDER improves clinical MRI quality and readability.…”

Evaluation of DISORDER: Retrospective Image Motion Correction for Volumetric Brain MRI in a Pediatric Setting

“…In this method, k-space samples are reordered to enable retrospective motion correction during image reconstruction. 14 Our hypothesis is that DISORDER improves clinical MR imaging quality and readability. To assess its use for clinical sequences, we acquired a dedicated epilepsy MR imaging protocol in 32 children across a wide age range.…”