Table 3.
Comparison of normalised quantitative MRI metrics
| Region | MRI metric | Uncompressed (n=20) |
Compressed (n=20) |
P values | Direction matches DCM |
| Rostral (C1–C3) | CSA | 75.4±4.7 | 81.7±9.6 | 0.02* | N |
| FA | 0.731±0.031 | 0.720±0.037 | 0.48 | Y | |
| MTR | 53.6±3.0 | 51.9±1.8 | 0.046* | Y | |
| T2*WI WM/GM | 0.838±0.029 | 0.863±0.031 | 0.03* | Y | |
| Mid (MCL or C4–5) | CSA | 79.2±7.7 | 81.9±12.8 | 0.34 | N |
| FA | 0.670±0.044 | 0.631±0.043 | 0.04* | Y | |
| MTR | 51.1±3.3 | 49.8±2.4 | 0.35 | Y | |
| T2*WI WM/GM | 0.842±0.019 | 0.864±0.026 | 0.005* | Y | |
| Caudal (C6–C7) | FA | 0.616±0.046 | 0.595±0.051 | 0.24 | Y |
| T2*WI WM/GM | 0.845±0.037 | 0.881±0.050 | 0.01* | Y | |
| Composite Score | 0±1 | −0.984±1.259 | 0.002* | Y | |
Normalised MRI metrics were compared between subjects with and without cord compression. A composite z score was used as an overall measure of tissue injury. Data extracted at the MCL were converted to z scores to normalise for rostrocaudal variations prior to comparison and then converted back to values at C4–5 for convenience of interpretation. The direction of differences (increases/decreases) in compressed versus uncompressed subjects was compared with previous findings in DCM versus healthy patients. Caudal CSA and MTR were not analysed because they did not show significant results in our prior DCM study.15
*Denotes significance (p<0.05).
CSA, cross-sectional area; DCM, degenerative cervical myelopathy; FA, fractional anisotropy; MCL, maximally compressed level; MTR, magnetisation transfer ratio; T2*WI WM/GM, T2*-weighted imaging white to grey matter.