Quantitative magnetic resonance imaging analysis correlates with surgical outcome of cervical spondylotic myelopathy

Study design: Prospective study. Objectives: To investigate whether preoperative and postoperative changes of signal intensity (SI) and transverse area (TA) of the spinal cord reflect the surgical outcome in patients with cervical spondylotic myelopathy (CSM). Setting: The Second Hospital of Tangshan, Tangshan, Hebei, China. Methods: In 45 consecutive prospective patients, magnetic resonance imaging (MRI) was performed preoperatively and 3 months postoperatively. The Japanese Orthopedic Association (JOA) scale was used to quantify the neurological status at admission and of at least 12-month follow-up. Preoperative and postoperative TA of the spinal cord at the site of maximal compression and grayscale of signal intensity (GSI) were measured using the image analysis software. Ratio of transverse area (RTA) and ratio of grayscale of signal intensity (RGSI) were used to assess the extent of spinal cord re-expansion and extent of SI regression. Preoperative status and postoperative recovery were assessed in relation to MRI parameters preoperatively and postoperatively using univariate and multivariate analysis. Results: Higher baseline JOA scores were associated with larger TA. Greater recovery rate was associated with larger preoperative and postoperative TA, along with greater RTA. Recovery rate negatively correlated with RGSI and age. Higher baseline JOA score was associated with greater recovery rate. RGSI negatively correlated with RTA. Multivariate stepwise regression analysis showed that the optimal combination of surgical outcome predictors included age, postoperative TA and RGSI. Conclusion: Quantitative MRI analysis in CSM may provide reliable information for the prediction of the postoperative outcome of CSM patients. MRI indicators of good outcome include the larger postoperative TA and greater RGSI.