Quantitative signal intensity of the spinal cord: predictors of suboptimal outcome of degenerative cervical myelopathy
Description
This study involved 108 patients with DCM， we used signal change ratio (SCR) and the area ratio of ISI to quantitatively assess the changes of ISI on T2WI MRI. We aimed to identify the risk factors for suboptimal recovery after cervical decompression surgery for DCM and discuss whether quantitative measurements of ISI on both sagittal and axial T2-weighted MRI can predict surgical outcomes in patients with DCM.All the quantitative measurements of ISI were repeated three times by a signle observer, and the final data were expressed as average values.To assess the reliability of measurements, the intraclass correlation coefficient (ICC) two-way mixed model was used. An ICC greater than or equal to 0.75 was considered excellent. Area under the curve (AUC) is calculated using receiver operating characteristic curve analyses (ROC) to estimate the cut-off value of the pre-operative SCR and ISI area proportion as predictors of suboptimal surgical results. An AUC of >0.9 and 0.7–0.9 was considered to demonstrate excellent and good discriminatory performance, respectively. All tests were two-sided, and p-values of <0.05 were considered statistically significant. The statistical analyses were conducted with IBM SPSS Statistics (version 25.0, IBM Corp., Armonk, NY, USA).Sheet 1 is the 108 patient characteristics and operative datas and sheet 2 is the three times quantitative measurements of ISI by a signle observer.
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The increased signal intensity values were quantified using ImageJ software (National Institutes of Health, Bethesda, MD, USA), and the normal signal intensity values of the cord were obtained at C7–T1 disc level. The regions of interest （ROI）were set at 0.3 cm2. The signal change ratio (SCR) was defined as the signal intensity of ISI divided by the signal intensity in ROI . Using ImageJ tools, we were able to define the maximum borders of the ISI on axial T2WI and calculate the areas within. In the same manner, we measured the cross sectional area of the spinal cord at the same level. The proportion of the ISI area on axial T2WI was calculated as the ratio between the ISI area and the cross-sectional area of the cord . For patients with two nearly symmetrical ISI spots depicted on axial T2WI (“snake-eyes” sign), the maximal area of the ISI was measured as the sum of the two individual signal areas .