A practical MRI grading system for cervical foraminal stenosis based on oblique sagittal images.

Objective: To propose a new and practical MRI grading method for cervical neural foraminal stenosis and to evaluate its reproducibility. Methods: We evaluated 50 patients (37 males and 13 females, mean age 49 years) who visited our institution and underwent oblique sagittal MRI of the cervical spine. A total of 300 foramina and corresponding nerve roots in 50 patients were qualitatively analysed from C4-5 to C6-7. We assessed the grade of cervical foraminal stenosis at the maximal narrowing point according to the new grading system based on T2 weighted oblique sagittal images. The incidence of each of the neural foraminal stenosis grades according to the cervical level was analysed by χ² tests. Intra- and interobserver agreements between two radiologists were analysed using kappa statistics. Kappa value interpretations were poor (κ<0.1), slight (0.1⩽κ⩽0.2), fair (0.2<κ⩽0.4), moderate (0.4<κ⩽0.6), substantial (0.6<κ⩽0.8) and almost perfect (0.8<κ⩽1.0). Results: Significant stenoses (Grades 2 and 3) were rarely found at the C4-5 level. The incidence of Grade 3 at the C5-6 level was higher than that at other levels, a difference that was statistically significant. The overall intra-observer agreement according to the cervical level was almost perfect. The agreement at each level was almost perfect, except for only substantial agreement at the right C6-7 by Reader 2. No statistically significant differences were seen according to the cervical level. Overall kappa values of interobserver agreement according to the cervical level were almost perfect. In addition, the agreement of each level was almost perfect. Overall intra- and interobserver agreement for the presence of foraminal stenosis (Grade 0 vs Grades 1, 2 and 3) and for significant stenosis (Grades 0 and 1 vs Grades 2 and 3) showed similar results and were almost perfect. However, only substantial agreement was seen in the right C6-7. Conclusion: A new grading system for cervical foraminal stenosis based on oblique sagittal MRI provides reliable assessment and good reproducibility. This new grading system is a useful and easy method for the objective evaluation of cervical neural foraminal stenosis by radiologists and clinicians. Advances in knowledge: The use of the new grading system for cervical foraminal stenosis based on oblique sagittal MRI can be a useful method for evaluating cervical neural foraminal stenosis. [ABSTRACT FROM AUTHOR]