Clinical correlation of a new practical MRI method for assessing cervical spinal canal compression.

Objective: The purpose of this study was to evaluate interobserver agreement and whether or not a new MRI grading system correlates with symptoms and neurologic signs for assessing spinal canal compression.

Materials And Methods: One hundred patients (52 men and 48 women; mean age, 50 years) underwent MRI of the cervical spine at our institution and were evaluated by two musculoskeletal radiologists. The presence and grade of cervical canal stenosis at the maximal narrowing point was assessed according to the new grading system suggested by Kang et al. (Kang system). The results correlated with the clinical manifestations and neurologic examination. Statistical analysis was performed using kappa statistics, categoric regression analysis, and nonparametric correlation analysis (Spearman correlation).

Results: Interobserver agreement in the grading of spinal stenosis between the two readers was almost perfect (κ = 0.925). Most of the patients with grade 0 cervical canal stenosis showed no neurologic manifestation, and patients with grades 2 and 3 cervical canal stenosis had positive neurologic manifestations. The correlation coefficient (R) of reader 1 between MRI grade (0, 1, 2, and 3) and neurologic manifestations (positive or negative) was 0.846. The R of reader 2 was 0.808. In the younger age group (< 50 years old), the R of reader 1 was 0.834 and the R of reader 2 was 0.745. In the older age group (≥ 50 years old), the R of reader 1 was 0.839 and the R of reader 2 was 0.839.

Conclusion: The interobserver agreement of the Kang system was almost perfect and was higher than in the study by Kang et al. Grade 0 cervical canal stenosis represents negative neurologic manifestations and grades 2 and 3 cervical canal stenosis represent positive neurologic manifestations. The Kang system and clinical manifestations are significantly correlated, especially in the older age group (≥ 50 years).