Observer variability in assessing lumbar spinal stenosis severity on magnetic resonance imaging and its relation to cross-sectional spinal canal area.
METHODS
Magnetic resonance image grading of lumbar spinal stenosis severity was analyzed retrospectively using a common clinical format.


OBJECTIVE
To assess the interobserver and intraobserver reliability of magnetic resonance image used to grade patients with lumbar spinal stenosis, as compared with cross-sectional spinal canal area.


BACKGROUND
Physicians currently classify the degree of lumbar spinal stenosis on magnetic resonance imaging as mild, moderate, or severe. Unfortunately, there is no consensus on criteria for these definitions.


METHODS
The magnetic resonance image scans of 15 patients with lumbar stenosis were blindly rated by seven observers for the degree of central, lateral recess, and foraminal stenosis between L1-L2 and L5-S1. Weighted kappa statistics were performed to analyze the inter- and intraobserver agreement. Digitized spinal canal area measurements were calculated. Linear regression models were used to assess the reliability of the grading system in predicting the cross-sectional area.


RESULTS
The average interobserver kappa score was 0.26. Within different specialties, the interobserver reliability was higher among radiologists (0.40), followed by neurosurgeons (0.21) and orthopedic surgeons (0.15). The average intraobserver kappa score was 0.11, rising to 0.43 after categories were combined (P = 0.001). The classification of central stenosis highly predicted spinal canal area (P < 0.001).


CONCLUSIONS
The findings indicate only a fair level of agreement among all observers. However, the ability of the various readers to predict the degree of central stenosis was high. Further studies should evaluate a consensus-based, standardized magnetic resonance image classification aimed at improved agreement among observers.
Speciale
Alex C
AC
Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
Pietrobon
Ricardo
R
Urban
Chris W
CW
Richardson
William J
WJ
Helms
Clyde A
CA
Major
Nancy
N
Enterline
David
D
Hey
Lloyd
L
Haglund
Michael
M
Turner
Dennis A
DA
D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D015588:Observer Variation; D012720:Severity of Illness Index; D013115:Spinal Canal / Q000473:pathology; D013130:Spinal Stenosis / Q000473:pathology*