Asymmetric signal intensity in normal collateral ligaments of the distal interphalangeal joint in horses with a low-field MRI system due to the magic angle effect

Mathieu Spriet, Wilfried Mai, Alexia McKnight

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo T1, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The signal intensity in a ligament was significantly increased when the ligament orientation relative to the magnetic field was 55±10°. The signal intensity was markedly increased in pulse sequences with short echo time (TE) 5.0, 4.9, and 3.9 times increased, respectively, for 3D gradient echo T1, spin echo T1, and turbo spin echo proton density) and to a lesser extent with pulse sequences with a longer TE (1.8 times increased for turbo spin echo T2). These changes are characteristic of the magic angle effect. Because of the anatomic orientation of the collateral ligaments of the DIP joint, a slight deviation of the long axis of the digit in the dorsal plane, from the ideal horizontal position, will induce an increased signal intensity that can be confused with desmitis. Careful positioning of the foot in magnetic resonance imaging systems where B0 is perpendicular to the long axis of the digit is critical to prevent the occurrence of the magic angle effect.

Original languageEnglish (US)
Pages (from-to)95-100
Number of pages6
JournalVeterinary Radiology and Ultrasound
Volume48
Issue number2
DOIs
StatePublished - Mar 2007
Externally publishedYes

Fingerprint

Collateral Ligaments
Magnetic Fields
ligaments
Horses
magnetic fields
Joints
Ligaments
horses
Protons
protons
Magnets
Foot
magnetic resonance imaging
Magnetic Resonance Imaging

Keywords

  • Artifact
  • Collateral ligaments of the distal interphalangeal joint
  • Equine
  • Foot
  • Magic angle effect
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • veterinary(all)

Cite this

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title = "Asymmetric signal intensity in normal collateral ligaments of the distal interphalangeal joint in horses with a low-field MRI system due to the magic angle effect",
abstract = "Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo T1, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The signal intensity in a ligament was significantly increased when the ligament orientation relative to the magnetic field was 55±10°. The signal intensity was markedly increased in pulse sequences with short echo time (TE) 5.0, 4.9, and 3.9 times increased, respectively, for 3D gradient echo T1, spin echo T1, and turbo spin echo proton density) and to a lesser extent with pulse sequences with a longer TE (1.8 times increased for turbo spin echo T2). These changes are characteristic of the magic angle effect. Because of the anatomic orientation of the collateral ligaments of the DIP joint, a slight deviation of the long axis of the digit in the dorsal plane, from the ideal horizontal position, will induce an increased signal intensity that can be confused with desmitis. Careful positioning of the foot in magnetic resonance imaging systems where B0 is perpendicular to the long axis of the digit is critical to prevent the occurrence of the magic angle effect.",
keywords = "Artifact, Collateral ligaments of the distal interphalangeal joint, Equine, Foot, Magic angle effect, Magnetic resonance imaging",
author = "Mathieu Spriet and Wilfried Mai and Alexia McKnight",
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AU - Mai, Wilfried

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N2 - Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo T1, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The signal intensity in a ligament was significantly increased when the ligament orientation relative to the magnetic field was 55±10°. The signal intensity was markedly increased in pulse sequences with short echo time (TE) 5.0, 4.9, and 3.9 times increased, respectively, for 3D gradient echo T1, spin echo T1, and turbo spin echo proton density) and to a lesser extent with pulse sequences with a longer TE (1.8 times increased for turbo spin echo T2). These changes are characteristic of the magic angle effect. Because of the anatomic orientation of the collateral ligaments of the DIP joint, a slight deviation of the long axis of the digit in the dorsal plane, from the ideal horizontal position, will induce an increased signal intensity that can be confused with desmitis. Careful positioning of the foot in magnetic resonance imaging systems where B0 is perpendicular to the long axis of the digit is critical to prevent the occurrence of the magic angle effect.

AB - Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo T1, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The signal intensity in a ligament was significantly increased when the ligament orientation relative to the magnetic field was 55±10°. The signal intensity was markedly increased in pulse sequences with short echo time (TE) 5.0, 4.9, and 3.9 times increased, respectively, for 3D gradient echo T1, spin echo T1, and turbo spin echo proton density) and to a lesser extent with pulse sequences with a longer TE (1.8 times increased for turbo spin echo T2). These changes are characteristic of the magic angle effect. Because of the anatomic orientation of the collateral ligaments of the DIP joint, a slight deviation of the long axis of the digit in the dorsal plane, from the ideal horizontal position, will induce an increased signal intensity that can be confused with desmitis. Careful positioning of the foot in magnetic resonance imaging systems where B0 is perpendicular to the long axis of the digit is critical to prevent the occurrence of the magic angle effect.

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