Magic angle effect in normal collateral ligaments of the distal interphalangeal joint in horses imaged with a high-field magnetic resonance imaging system.
Abstract: Distal forelimb specimens of eight skeletally mature horses were imaged using proton density turbo spin echo, T1-weighted spoiled gradient echo, T2*-weighted gradient echo, short tau inversion recovery and T2-weighted fast spin echo sequences with the limb parallel to the main magnetic field, and with angulation of the limb relative to the main magnetic field. The magic angle effect can be identified in the collateral ligaments of the distal interphalangeal joint when imaged in a high-field magnetic resonance (MR) imaging system with a horizontally oriented main magnetic field. This effect has previously been described in the collateral ligaments of the distal interphalangeal joint in a low-field system with a vertically oriented main magnetic field. The curvature of the ligaments places the fibers at the magic angle in both horizontally and vertically orientated main magnetic fields. This effect can be identified on short time of echo sequences and impacts the signal pattern of the ligaments at the level of the middle phalanx with the limb in a neutral position and with angulation of the limb. Magic angle effect should be considered as a possible cause of an asymmetrical signal pattern, depending on the positioning of the limb and the sequences used for imaging, when evaluating the collateral ligaments of the distal interphalangeal joint on images acquired with a high-field MR imaging system that has a horizontally oriented main magnetic field.
Publication Date: 2010-02-20 PubMed ID: 20166386DOI: 10.1111/j.1740-8261.2009.01613.xGoogle Scholar: Lookup
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- Journal Article
Summary
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This research investigates how the ‘magic angle effect’ can impact the imaging of collateral ligaments in horse’s distal interphalangeal joints when using a high-field magnetic resonance imaging (MRI) system. The study finds that this effect, previously only described in low-field systems, can cause asymmetrical signal patterns and could interfere with an accurate assessment of ligament structure and health.
Methodology
- The study used distal forelimb samples from eight adult horses.
- Various MRI sequences, including proton density turbo spin echo, T1-weighted spoiled gradient echo, T2*-weighted gradient echo, short tau inversion recovery, and T2-weighted fast spin echo, were used to image the specimens.
- The sample positioning relative to the main magnetic field was adjusted, with positions being both parallel and angled.
Magic Angle Effect
- The magic angle effect was found in the collateral ligaments of the distal interphalangeal joints when imaged using a high-field MR imaging system with a horizontally oriented main magnetic field.
- This effect has previously been described in systems with a vertically oriented main magnetic field.
- The curvature of the ligaments contributes to this effect as it places the fibers at the magic angle in both field orientations.
Impact of the Magic Angle Effect
- This effect was found to impact the signal pattern of the ligaments at the level of the middle phalanx. This occurred whether the limb was in a neutral position or angled.
- The magic angle effect might cause an asymmetrical signal pattern in certain imaging sequences.
- When evaluating the collateral ligaments of the distal interphalangeal joint using a high-field MR imaging system with a horizontally oriented main magnetic field, the magic angle being a potential source of asymmetrical signal patterns must be considered.
Relevance of the Findings
- This discovery has implications for accurate MRI imaging of horse’s collateral ligaments – particularly in high-field systems.
- Veterinary practitioners using MRI should be aware of this potential anomaly in image interpretation.
Cite This Article
APA
Werpy NM, Ho CP, Kawcak CE.
(2010).
Magic angle effect in normal collateral ligaments of the distal interphalangeal joint in horses imaged with a high-field magnetic resonance imaging system.
Vet Radiol Ultrasound, 51(1), 2-10.
https://doi.org/10.1111/j.1740-8261.2009.01613.x Publication
Researcher Affiliations
- Equine Orthopaedic Research Center, Colorado State University Veterinary Teaching Hospital, 300 West Drake Road, Fort Collins, CO 80523, USA. nmwerpy@colostate.edu
MeSH Terms
- Animals
- Collateral Ligaments / diagnostic imaging
- Echo-Planar Imaging / veterinary
- Forelimb / diagnostic imaging
- Horses / anatomy & histology
- Image Processing, Computer-Assisted
- Radiography
- Regression Analysis
- Toe Joint / anatomy & histology
- Toe Joint / diagnostic imaging
Citations
This article has been cited 4 times.- Wilson KJ, Surowiec RK, Ho CP, Devitt BM, Fripp J, Smith WS, Spiegl UJ, Dornan GJ, LaPrade RF. Quantifiable Imaging Biomarkers for Evaluation of the Posterior Cruciate Ligament Using 3-T Magnetic Resonance Imaging: A Feasibility Study. Orthop J Sports Med 2016 Apr;4(4):2325967116639044.
- Ho LC, Sigal IA, Jan NJ, Squires A, Tse Z, Wu EX, Kim SG, Schuman JS, Chan KC. Magic angle-enhanced MRI of fibrous microstructures in sclera and cornea with and without intraocular pressure loading. Invest Ophthalmol Vis Sci 2014 Aug 7;55(9):5662-72.
- Scharf A, Acutt E, Bills K, Werpy N. Magnetic resonance imaging for diagnosing and managing deep digital flexor tendinopathy in equine athletes: Insights, advances and future directions. Equine Vet J 2025 Sep;57(5):1183-1203.
- De Moura HL, Monga A, Zhang X, Zibetti MVW, Keerthivasan MB, Regatte RR. Feasibility of 3D MRI fingerprinting for rapid knee cartilage T(1), T(2,) and T(1ρ) mapping at 0.55T: Comparison with 3T. NMR Biomed 2024 Dec;37(12):e5250.
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