General Session: Cervical Degenerative - Hall F

Presented by: K. Sritharan

Author(s):

K. Sritharan(1), U. Chamoli(1), J. Kuan(2), A. Diwan(1)

(1) University of New South Wales, Spine Service, St. George & Sutherland Clinical School, Sydney, NSW, Australia
(2) St. George MRI, Sydney, NSW, Australia

Abstract

Introduction: Magnetic resonance (MR) is the current imaging modality of choice for visualizing and quantifying cord compression in cervical canal stenosis patients. Previous studies have described various measurement tools for quantitative assessment of cervical canal stenosis on MR imaging, but the validity of these metrics in distinguishing stenotic from non-stenotic levels has not been assessed.

Objective: To assess the validity of various sagittal and axial plane metrics used for quantifying cervical canal stenosis on MR imaging in distinguishing stenotic from non-stenotic levels.

Methods: A retrospective MR imaging review of 238 consecutive patients who presented for MR imaging of cervical spine from Sept 2010 to Aug 2017 was performed. The degree of cervical canal stenosis was measured using the following sagittal and axial plane measurement ratios. In the mid-sagittal plane R1: cord diameter to canal diameter R2: cord diameter to the average of cephalad and caudal cord diameters R3: canal diameter to the average of cephalad and caudal canal diameter In the axial plane R4: cord compression ratio (AP/LR width of the cord) R5: cord area to the average of cephalad and caudal cord areas An independent observer performed measurements on de-identified MR images using ImageJ software. The control was defined as the nearest, non-stenotic cephalad and/or caudal cervical levels on the same patient. Using SPSS software, statistical tests (Kruskal Wallis and post-hoc comparisons) were performed to detect significance in differences between various groups (α = 0.001).

Results: Figure 1 shows the mean ± standard deviation for the five ratios for stenotic and non-stenotic levels (cephalad and/or caudal). For the mid-sagittal plane metrics (R1, R2, and R3), significant differences were observed between stenotic and non-stenotic groups (p< 0.001). Differences between cephalad and caudal levels were not significant for R1 and R3; but significant for R2 (p< 0.001). For the axial plane metrics (R4 and R5), significant differences were observed between stenotic and non-stenotic groups (p< 0.001). Differences between cephalad and caudal levels were not significant for R4; but significant for R5 (p< 0.001). Discussion/

Conclusion: The above results show that Ratios 2 and 5 are sensitive to normal variation in cord morphology and therefore may not be able to distinguish between differences arising from stenosis and differences due to gradual variation in cord morphology. Based on the findings of this study, we recommend using sagittal plane metrics R1 (cord diameter to canal diameter) or R3 (canal diameter to the average of cephalad and caudal canal diameter), and axial plane metric R4 (cord compression ratio (AP/LR width of the cord)) for quantifying cord compression in cervical canal stenosis patients.

Figure 1