Correlation of listhesis on upright radiographs and central lumbar spinal canal stenosis on supine MRI: is it possible to predict lumbar spinal canal stenosis?
To investigate whether upright radiographs can predict lumbar spinal canal stenosis using supine lumbar magnetic resonance imaging (MRI) and to investigate the detection performance for spondylolisthesis on upright radiographs compared with supine MRI in patients with suspected lumbar spinal canal stenosis (LSS).
Materials and Methods
In this retrospective study, conventional radiographs and MR images of 143 consecutive patients with suspected LSS (75 female, mean age 72 years) were evaluated. The presence and extent of listhesis (median ± interquartile range) were assessed on upright radiographs and supine MRI of L4/5. In addition, the grade of central spinal stenosis of the same level was evaluated on MRI according to the classification of Schizas and correlated with the severity/grading of anterolisthesis on radiographs.
Anterolisthesis was detected in significantly more patients on radiographs (n = 54; 38%) compared with MRI (n = 28; 20%), p < 0.001. Pairwise comparison demonstrated a significantly larger extent of anterolisthesis on radiographs (9 ± 5 mm) compared with MRI (5 ± 3 mm), p < 0.001. A positive correlation was found regarding the extent of anterolisthesis measured on radiographs and the grade of stenosis on MRI (r = 0.563, p < 0.001). Applying a cutoff value of ≥5 mm anterolisthesis on radiographs results in a specificity of 90% and a positive predictive value of 78% for the detection of patients with LSS, as defined by the Schizas classification.
Upright radiographs demonstrated more and larger extents of anterolisthesis compared with supine MRI. In addition, in patients with suspected LSS, the extent of anterolisthesis on radiographs (particularly ≥5 mm) is indicative of LSS and warrants lumbar spine MRI.
KeywordsMagnetic resonance imaging Radiography Spine Lumbar spine Spinal canal stenosis Degenerative spinal changes Lower back pain Claudication Listhesis Anterolisthesis Spondylolisthesis
Compliance with ethical standards
Conflicts of interest
This study was supported by the Helmut Horten Foundation, Baugarten Foundation, Pfizer-Foundation for geriatrics and research into geriatrics, Symphasis Charitable Foundation and OPO-Foundation. We disclose any financial support or author involvement with organization(s) with a financial interest in the subject matter.
This study was approved by the local ethical committee of the University of Zurich, Switzerland. All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
All patients received written and oral information about the study and gave their written informed consent for participation. The project was registered at http://www.research-projects.uzh.ch/p16804.htm.
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