title: Prediction of transitional lumbosacral anatomy on magnetic resonance imaging of the lumbar spine.
abstract: OBJECTIVE
  To evaluate two simple angle measurements for predicting lumbosacral transitional vertebra (LSTV) in magnetic resonance imaging (MRI) studies of the spine.
  
  
  METHODS
  The lumbar spine MRI studies of 50 subjects with LSTV and 50 subjects with normal lumbosacral anatomy were retrospectively evaluated. In each study, the mid-sagittal T2-weighted image was used to measure the angle formed by a line parallel to the superior surface of the sacrum and a line perpendicular to the axis of the scan table (A-angle), as well as the angle formed by a line parallel to the superior endplate of the L3 vertebra and a line parallel to the superior surface of the sacrum (B-angle).
  
  
  RESULTS
  The total study population consisted of 100 subjects (46 males, 54 females, 51 ± 16 years old). There were no differences in age and sex between the two groups. Both A-angle and B-angle were significantly increased in subjects with LSTV compared to controls (P < 0.05). The optimal cut-off values of A-angle and B-angle for the prediction of LSTV were 39.8° (sensitivity = 80%, specificity = 80%, accuracy = 83%; 95% confidence interval = 74%-89%, P = 0.0001) and 35.9° (sensitivity = 80%, specificity = 54%, accuracy = 69%; 95% confidence interval = 59%-78%, P = 0.0005), respectively.
  
  
  CONCLUSIONS
  On sagittal MR images of the lumbar spine, an increased A-angle and/or B-angle should alert the radiologist to the presence of LSTV.
authors.affiliation: Majid Chalian, Theodoros Soldatos, John A Carrino, Avneesh Chhabra, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Hospital, Baltimore, MD 21287, United States.
authors.forename: Majid
authors.initials: M
authors.lastname: Chalian
authors.forename: Theodoros
authors.initials: T
authors.lastname: Soldatos
authors.forename: John A
authors.initials: JA
authors.lastname: Carrino
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Belzberg
authors.forename: Jay
authors.initials: J
authors.lastname: Khanna
authors.forename: Avneesh
authors.initials: A
authors.lastname: Chhabra