Ultra-high field (7T) MRI allows scans at sub-millimetre resolution with exquisite signal-to-noise ratio (SNR). As 7T MRI becomes more widely used clinically, the challenge of patient motion must be overcome. Retrospective motion correction is used successfully for some protocols, but for acquisitions such as slice-by-slice scans only prospective motion correction can deliver the full potential of 7T MRI. We report the first implementation of prospective 3D Fat Navigator ("FatNav") motion correction for the Siemens 7T Terra MRI. We implemented a modular Sequence Building Block for FatNav and embedded it into the vendor's gradient-recalled echo (GRE) sequence. We modified the reconstruction pipeline to reconstruct FatNav images online, coregistering them and sending motion updates to the host sequence online. We tested five registration algorithms for performance and accuracy on synthetic FatNav data. We implemented the best three of these in our sequence and tested them online. We acquired T and T* weighted brain images of healthy volunteers correcting every other image for motion to visualise the effectiveness of online motion correction. Data were acquired with and without head immobilisation. We also tested performance while correcting every measurement for motion. Our implementation uses a 1.23 s 3D FatNav acquisition module and delivers motion updates in less than 3 s, which is sufficient for motion updates every few k-space lines in typical scans. Corrected images are crisper with fewer visible motion artefacts. This improved sharpness is reflected quantitatively by an increase in the variance of the image Laplacian which is 1.59 x better for corrected vs uncorrected images. Profiles across the cerebral falx are 33% steeper for corrected vs uncorrected images. Prospective FatNav improves GRE image quality in the brain. Our modular Sequence Building Block provides a simple method to integrate motion correction in 7T MRI pulse sequences.
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http://dx.doi.org/10.1002/nbm.5283 | DOI Listing |
Pediatr Radiol
January 2025
Research Department of Early Life Imaging, School of Biomedical Engineering and Imaging Sciences, King's College London, St Thomas' Hospital, London, SE1 7EH, UK.
Background: Motion correction methods based on slice-to-volume registration (SVR) for fetal magnetic resonance imaging (MRI) allow reconstruction of three-dimensional (3-D) isotropic images of the fetal brain and body. However, all existing SVR methods are confined to research settings, which limits clinical integration. Furthermore, there have been no reported SVR solutions for low-field 0.
View Article and Find Full Text PDFGels
December 2024
Department of Mechanics and Engineering Science, School of Physics, Nanjing University of Science and Technology, Nanjing 210094, China.
Magnetic hydrogel soft robots have shown great potential in various fields. However, their contact dynamic behaviors are complex, considering stick-slip motion at the contact interface, and lack accurate computational models to analyze them. This paper improves the numerical computational method for hydrogel materials with magneto-mechanical coupling effect, analyses the inchworm-like contact motion of the biomimetic bipedal magnetic hydrogel soft robot, and designs and optimizes the robot's structure.
View Article and Find Full Text PDFArch Orthop Trauma Surg
January 2025
UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
Introduction: Manipulation under anesthesia (MUA) is a standard and effective treatment to correct stiffness and improve range of motion (ROM) following total knee arthroplasty (TKA). Delayed MUA has been associated with increased rates of revision surgeries and infections. Early MUA has been shown to double the mean gain in flexion compared to delayed interventions.
View Article and Find Full Text PDFArthroscopy
February 2025
The Steadman Clinic, Vail, Colorado, U.S.A.; The Steadman Philippon Research Institute, Vail, Colorado, U.S.A.. Electronic address:
Revision hip arthroscopy is increasingly common and most often performed to treat residual femoroacetabular impingement caused by cam under-resection. Unfortunately, other pathologies encountered during revision hip arthroscopy are more difficult to treat, including capsular deficiency, labral deficiency, adhesion formation, and/or cam over-resection. When encountered, these various pathologies should be comprehensibly corrected with the goals of restoring anatomy, re-establishing the hip fluid seal, and ensuring impingement-free motion.
View Article and Find Full Text PDFOptom Vis Sci
January 2025
Indiana University School of Optometry, Bloomington, Indiana.
Purpose: This study investigated how obstacle contrast altered gait behavior of healthy younger and older adults.
Methods: Twenty normally sighted adults, 11 older (mean [standard deviation] age, 68.1 [5.
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