Reliability of Qualitative and Quantitative Imaging Findings on X-Ray and MRI in Patients with Lumbar Spinal Stenosis

Purpose: To evaluate the inter- and intraobserver reliability of imaging findings and measurements of lumbar spinal stenosis on X-ray and magnetic resonance imaging (MRI) using experienced musculoskeletal radiologists and spinal surgeons as raters.

Methods and Materials: A total of 108 patients diagnosed with lumbar spinal stenosis were included in the current study. The patients were selected consecutively from the Spinal Stenosis Trial of the Norwegian Degenerative Spondylolisthesis and Spinal Stenosis (NORDSTEN) study (ClinicalTrials.gov reference NCT02007083). There are 437 patients included in the trial. The patients in the current study had the same baseline demographic characteristics as well as the same inclusion and exclusion criteria as the main study. The Norwegian Committees for Medical and Health Research Ethics approved the study. Two musculoskeletal radiologists with > 10 years of experience each and two orthopaedic spinal surgeons with 6 and 10 years of experience, respectively, blinded to each other and the clinical data, rated 15 qualitative and quantitative parameters on X-ray and MRI. The nomenclature and measurement methods were discussed between the raters before the study began. The measured parameters are commonly used to diagnose and grade the severity of central canal and foraminal stenosis, spondylolisthesis, lumbar curves, degenerative changes in the intervertebral disks and the facet joints, and fatty degeneration of the paraspinal muscles. The measurements were repeated after 6 weeks by all raters to assess the intraobserver reliability. Gwet’s agreement coefficient (AC1) and intraclass correlation coefficient (ICC) were used to calculate the inter- and intraobserver agreement for the categorical and continuous parameters, respectively.

Results: Six patients were excluded because of exclusion from the main study or lacking radiologic examinations. All raters measured and scored quantitative and qualitative parameters of 102 patients (94%) on X-ray and MRI. Forty-nine (48%) of the included patients were women. The mean age was 66.1 ± 8.8 years for women and 66.2 ± 8.1 years for men.

The overall interobserver agreement for the quantitative parameters was good (ICC, 0.78–0.90; confidence interval [CI], 0.67–0.93), except for the facet joint angle that showed moderate agreement (ICC, 0.73; CI, 0.70–0.76). For the qualitative parameters, the interobserver agreement was substantial or almost perfect (AC1, 0.68–0.98; CI, 0.61–0.99), except for facet joint osteoarthritis, which showed fair agreement (AC1, 0.39; CI, 0.34–0.45). The intraobserver agreement was substantial or good for all raters and parameters (ICC, 0.80–1.0; CI, 0.78–1.0, and AC1, 0.63–1.0; CI, 0.56–1.0).

Conclusion: Given enough education and experience of radiologists and spinal surgeons, the inter- and intraobserver agreement for the commonly used quantitative and most of the qualitative radiologic measurements for lumbar spinal stenosis is good or excellent.

Publication History

Article published online:
17 December 2020