title: Lumbar spine: quantitative and qualitative assessment of positional (upright flexion and extension) MR imaging and myelography.
abstract: OBJECTIVE
  To compare measurements of the sagittal diameter of the lumbar dural sac obtained at positional magnetic resonance (MR) imaging and at functional myelography and to assess the influence of various body positions on the dural sac and the intervertebral foramina.
  
  
  METHODS
  Thirty consecutive patients referred for lumbar myelography were examined with an open 0.5-T MR imager, Sagittal T2-weighted fast spin-echo images were acquired with patients in the supine, upright flexion, and upright extension positions. The midsagittal diameter of the dural sac was measured at the level of the disks on MR images and myelograms. Foraminal sizes on the MR images were scored independently by two observers.
  
  
  RESULTS
  Correlation between MR imaging and myelographic measurements was high (r = .81-.97). A small but statistically significant positional dependence of the dural sac diameter was found in the lower lumbar spine. Position-dependent differences in foraminal scores were uncommon.
  
  
  CONCLUSIONS
  Quantitative assessment of sagittal dural sac diameters is comparable between lumbar myelography and positional MR imaging. In a selected patient population, only small changes in the sagittal diameter of the dural sac and foraminal size can be expected between various body positions, and the information gained in addition to that from  standard MR imaging is limited [corrected].
authors.affiliation: Department of Radiology, University Hospital, Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Wildermuth
authors.forename: M
authors.initials: M
authors.lastname: Zanetti
authors.forename: S
authors.initials: S
authors.lastname: Duewell
authors.forename: M R
authors.initials: MR
authors.lastname: Schmid
authors.forename: B
authors.initials: B
authors.lastname: Romanowski
authors.forename: A
authors.initials: A
authors.lastname: Benini
authors.forename: T
authors.initials: T
authors.lastname: Böni
authors.forename: J
authors.initials: J
authors.lastname: Hodler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004388:Dura Mater / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology; D007593:Joint Instability / Q000175:diagnosis / Q000000981:diagnostic imaging; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology* / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009192:Myelography; D015588:Observer Variation; D010347:Patient Care Planning; D011183:Postoperative Complications; D011187:Posture / Q000502:physiology; D012008:Recurrence; D013122:Spinal Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging; D013130:Spinal Stenosis / Q000175:diagnosis / Q000000981:diagnostic imaging; D013168:Spondylolisthesis / Q000175:diagnosis / Q000000981:diagnostic imaging; D013169:Spondylolysis / Q000175:diagnosis / Q000000981:diagnostic imaging; D016683:Supine Position / Q000502:physiology