Objective: To evaluate interobserver agreement and determine whether a new MRI grading system agrees with symptoms and neurological signs.
Methods: We examined 160 patients (72 males and 88 females; mean age 57 years) who underwent MRI of the lumbar spine at our institution and were evaluated by two musculoskeletal radiologists. The presence and grade of central lumbar spinal stenosis (CLSS) at L3-4, L4-5 and L5-S1 were assessed according to a new grading system, the Lee system. The results were correlated with clinical manifestations and neurological examinations [positive neurological manifestation (PNM) and negative neurological manifestation (NNM)]. Statistical analyses were performed using kappa statistics and non-parametric correlation analysis (Spearman's correlation).
Results: Interobserver agreement in the grading of CLSS between the two readers was substantial (κ=0.780). Interobserver agreement of the L4-5 level and older age group was high (0.789, 0.814). The correlation coefficient (R) of Reader 1 between MRI Grades 0, 1, 2 or 3 and neurological manifestations (negative or positive) was 0.654; the R of Reader 2 was 0.591. In the younger age group (<57 years), the R of Reader 1 was 0.634 and the R of Reader 2 was 0.500. In the older age group (≥57 years), the R of Reader 1 was 0.650 and the R of Reader 2 was 0.645. Correlation coefficients were higher at the L3-4 level (0.612-0.678) than at other levels but did not show statistical significance (p>0.05).
Conclusion: Interobserver agreement for the new CLSS grading system was substantial. Grade 0 was associated with NNMs and Grade 3 with PNMs in this cohort. Grade 2 demonstrates more cases of PNM than NNM but requires further evaluation. Correlations between MRI grades and clinical manifestations were moderate and slightly higher in older patients.
Advances in knowledge: The new practical MRI grading method can be useful in the categorisation of CLSS and shows strong clinical correlation.