title: The influence of chemical shift artifact on magnetic resonance imaging of the ligamentum flavum at 0.5 tesla.
abstract: METHODS
  Retrospective clinical magnetic resonance imaging study and prospective magnetic resonance imaging volunteer study of the appearance of the ligamentum flavum.
  
  
  OBJECTIVE
  To demonstrate the effect of chemical shift artifact on the apparent thickness of the ligamentum flavum on axial magnetic resonance images.
  
  
  BACKGROUND
  The ligamentum flavum is a symmetric structure clearly seen on magnetic resonance images. Apparent unilateral thickening may be interpreted as indicating a pathologic process, and the influence of chemical shift artifact on the apparent thickness of the ligamentum flavum has not been emphasized.
  
  
  METHODS
  Ligamenta flava thicknesses were measured from axial T1-weighted gradient echo magnetic resonance scans of 12 consecutive patients and various axial sequences in seven volunteers.
  
  
  RESULTS
  The ligamentum flavum appeared consistently thicker on the lower side of the readout gradient field. This chemical shift effect could be manipulated by swapping phase and frequency or patient orientation in the magnet.
  
  
  CONCLUSIONS
  Caution should be applied in attributing apparent asymmetry of the ligamenta flava to disease; the influence of chemical shift artifact should be considered.
authors.affiliation: Department of Clinical Radiology, Manchester Royal Infirmary, United Kingdom.
authors.forename: R W
authors.initials: RW
authors.lastname: Whitehouse
authors.forename: C E
authors.initials: CE
authors.lastname: Hutchinson
authors.forename: R
authors.initials: R
authors.lastname: Laitt
authors.forename: J P
authors.initials: JP
authors.lastname: Jenkins
authors.forename: A
authors.initials: A
authors.lastname: Jackson
mesh_terms: D000293:Adolescent; D000328:Adult; D019412:Anatomy, Cross-Sectional; D016477:Artifacts; D005260:Female; D006801:Humans; D017843:Ligamentum Flavum / Q000473:pathology*; D017116:Low Back Pain / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000175:diagnosis