New Magnetic Resonance Imaging Features Predictive for Post-Treatment Ambulatory Function: Imaging Analysis of Metastatic Spinal Cord Compression.

STUDY DESIGN This is a retrospective, single-institute, radiographical study. OBJECTIVE The study aimed to determine the correlation of magnetic resonance imaging (MRI) findings observed in metastatic spinal cord compression (MSCC) with post-treatment ambulatory status. SUMMARY OF BACKGROUND DATA Previous studies have reported various predictors of ambulatory outcome in patients with MSCC, but the relationship between the MRI features and post-treatment ambulatory function remains to be elucidated. METHODS Fifty-six hospitalized patients with MSCC and risk of MSCC were examined using MRI before therapeutic intervention. Circumferential ratio of cord compression (CRCC), clock position of compression, cross-sectional area (CSA), and change in signal intensity of the spinal cord were recorded. Each imaging feature was analyzed statistically regarding unassisted ambulatory status at the time of hospital discharge as the endpoint. RESULTS CRCC showed a prognostic value for post-treatment ambulatory function. More than half of CRCC predicted poor functional prognosis with statistical significance. However, the site of cord compression expressed by clock position on axial plane showed no relationship with functional prognosis. CSA of the spinal cord was enlarged in 23% of patients at the level of MSCC, which indicated that cord compression could also be formed by a relative relationship between cord swelling and surrounding mass effect. The said patients showed a better functional outcome. High intensity of the spinal cord on T2-weighted sagittal image was not useful because of lack of inter-rater reliability. CONCLUSION CRCC on axial T2 image can guide clinicians to identify cancer patients at risk of paraplegia because of MSCC. More than half of CRCC entails urgent treatment despite preserved ambulatory function. Furthermore, some cases of MSCC accompany increased cord CSA. The measurement is also a useful guide to balance the risk and benefit of systemic steroid therapy. MRI is the key imaging modality in the risk assessment of MSCC. LEVEL OF EVIDENCE 4.