Oral Presentation Sydney Spinal Symposium 2018

Validity of Sagittal and Axial Plane Metrics in the Assessment of Cervical Canal Stenosis on Magnetic Resonance Imaging (#22)

Keerthana 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

Introduction

Magnetic resonance imaging (MRI) is the current imaging modality of choice for quantifying cord compression in cervical canal stenosis patients. The objective of this study was to assess the effectiveness of various, commonly-used axial and sagittal plane metrics in distinguishing stenotic from non-stenotic levels.

Methods

In a retrospective review of 85 consecutive patients for MRI of their cervical spine from Sept 2010 to Aug 2017, the following metrics determined at the level of stenosis and cephalad and caudal control levels; R1 (cord diameter to canal diameter), R2 (cord diameter to average of cephalad and caudal cord diameters), R3 (canal diameter to average of cephalad and caudal canal diameters), R4 (cord compression ratio) and R5 (absolute transverse cord area). Friedman’s test and post hoc analysis with Wilcoxin signed-rank tests was conducted with Bonferroni correction applied (p < 0.0167) to find significant differences between various groups.

Results

Figure 1: Magnitude of differences between stenotic and non-stenotic levels, and cephalad and caudal levels (‘*’ denotes significant differences, p<0.0167)

 

Stenotic and non-stenotic levels

Cephalad and caudal levels

R1

0.1005*

0.0292*

R2

0.2354*

0.0195

R3

0.3195*

0.0211*

R4

0.1093*

0.0248*

R5

4.0491*

3.6856*

For the mid-sagittal plane metrics (R1, R2, R3), significant differences were observed between stenotic and non-stenotic groups. Differences between cephalad and caudal levels were not significant for R2, but significant for R1 and R3. For axial plane metrics (R4, R5), significant differences were observed between stenotic and non-stenotic groups and cephalad and caudal levels.

Discussion

Significant differences between cephalad and caudal levels for R1, R3, R4 and R5 suggests that these ratios are sensitive to external, non-compressive factors, falsely magnifying their Type 2 error rate. Therefore, R2 is the metric of choice for the quantification of cord compression on MRI. Nonetheless, the magnitude of difference between control levels for R1, R3 and R4 is comparatively small. There remains a need for further studies to examine the clinical relevance of our results.