title: Juxtafacet cysts of the lumbar spine: a positional MRI study.
abstract: OBJECTIVE
  Juxtafacet cysts (JFC) are related to facet joint degeneration. Supine MRI is routinely used to evaluate JFC. However, some JFC are missed and found only intraoperatively. The present study addresses positional MRI features and factors leading to variation in the size of JFC.
  
  
  METHODS
  Fifty patients in whom positional MRI had been performed were investigated retrospectively and 67 distinct intraspinal or intraneuroforaminal were JFC found. Signal intensity, size of the JFC, the presence and variance of a vertebral slip and the angular movement of affected segments were assessed in supine, neutral sitting, flexion (sitting) and extension (standing). The overall movement of the spine and the lordosis angle in different positions were measured.
  
  
  RESULTS
  JFC varied in size in segments with unstable slip and increased angular movement (variation of the angle in the affected segment in function: 13.3 degrees compared to 8.7 degrees). JFC with bright signals tended to vary in size compared to JFC with intermediate or low signal intensity (all: p < 0.001). Joint effusion and displacement of effusion lead to formation and variations in the size of JFC. JFC were most prominent in extension: 6.7 mm, less prominent in supine: 5.5 mm and in neutral sitting position: 4.6 mm (all p < 0.05). The detection rate for JFC was 97% for extension, 89% for supine and 78% for neutral sitting.
  
  
  CONCLUSIONS
  The detection rate of JFC improves with increasing lordosis of the spine and under weight-bearing conditions, particularly when standing. Unstable slipping or increased angular movement affects the size of JFC.
authors.affiliation: Department of Radiology, University Hospital Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. Pascal.Niggemann@ukb.uni-bonn.de
authors.forename: Pascal
authors.initials: P
authors.lastname: Niggemann
authors.forename: Johannes
authors.initials: J
authors.lastname: Kuchta
authors.forename: Janine
authors.initials: J
authors.lastname: Hoeffer
authors.forename: Dieter
authors.initials: D
authors.lastname: Grosskurth
authors.forename: Hans-Konrad
authors.initials: HK
authors.lastname: Beyer
authors.forename: Karl-Stefan
authors.initials: KS
authors.lastname: Delank
mesh_terms: D003560:Cysts / Q000150:complications* / Q000473:pathology*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013122:Spinal Diseases / Q000150:complications* / Q000473:pathology*; D021801:Zygapophyseal Joint / Q000473:pathology*