First in-vivo magic angle directional imaging using dedicated low-field MRI
Author(s)
Type
Journal Article
Abstract
Purpose: To report the first in-vivo results from exploiting the magic angle effect, using a dedicated
low-field MRI scanner that can be rotated about two axes. The Magic Angle Directional Imaging
(MADI) method is used to depict collagen microstructures with 3D collagen tractography of knee
ligaments and the meniscus.
Methods: A novel low-field MRI system was developed, based on a transverse field open magnet,
where the magnet can be rotated about two orthogonal. Sets of volume scans at various orientations
were obtained in healthy volunteers. The experiments focused on the anterior cruciate ligament (ACL)
and the meniscus of the knee. The images were co-registered, anatomical regions of interest (RoI)
were selected and the collagen fiber orientations in each voxel were estimated from the observed image
intensity variations. The 3D collagen tractography was superimposed on conventional volume images.
Results: The MADI method was successfully employed for the first time producing in-vivo results
comparable to those previously reported for excised animal specimens using conventional MRI.
Tractography plots were generated for the ACL and the menisci. These results are consistent with the
known microstructure of collagen fibers in these tissues.
Conclusion: Images obtained using low-field MRI with 1 mm3
resolution were of sufficient quality
for the MADI method, which was shown to produce high quality in-vivo information of collagen
microstructures. This was achieved using a cost effective and sustainable low-field magnet making
the technique potentially accessible and scalable, potentially changing the way we image injuries or
disease in joints.
low-field MRI scanner that can be rotated about two axes. The Magic Angle Directional Imaging
(MADI) method is used to depict collagen microstructures with 3D collagen tractography of knee
ligaments and the meniscus.
Methods: A novel low-field MRI system was developed, based on a transverse field open magnet,
where the magnet can be rotated about two orthogonal. Sets of volume scans at various orientations
were obtained in healthy volunteers. The experiments focused on the anterior cruciate ligament (ACL)
and the meniscus of the knee. The images were co-registered, anatomical regions of interest (RoI)
were selected and the collagen fiber orientations in each voxel were estimated from the observed image
intensity variations. The 3D collagen tractography was superimposed on conventional volume images.
Results: The MADI method was successfully employed for the first time producing in-vivo results
comparable to those previously reported for excised animal specimens using conventional MRI.
Tractography plots were generated for the ACL and the menisci. These results are consistent with the
known microstructure of collagen fibers in these tissues.
Conclusion: Images obtained using low-field MRI with 1 mm3
resolution were of sufficient quality
for the MADI method, which was shown to produce high quality in-vivo information of collagen
microstructures. This was achieved using a cost effective and sustainable low-field magnet making
the technique potentially accessible and scalable, potentially changing the way we image injuries or
disease in joints.
Date Issued
2025-03
Date Acceptance
2024-09-22
Citation
Magnetic Resonance in Medicine, 2025, 93 (3), pp.1077-1089
ISSN
0740-3194
Publisher
Wiley
Start Page
1077
End Page
1089
Journal / Book Title
Magnetic Resonance in Medicine
Volume
93
Issue
3
Copyright Statement
© 2024 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Identifier
https://onlinelibrary.wiley.com/doi/10.1002/mrm.30332
Publication Status
Published
Date Publish Online
2024-10-20