Clinical application of intervertebral disc to spinal cord signal ratio based on T2-weighted imaging in assessing disc degeneration.

The severity of intervertebral disc degeneration can be evaluated using scanning sequences, such as T1 mapping, T2 mapping, and T2* mapping. However, owing to objective constraints, including the time required for scanning and the limitations of magnetic resonance imaging (MRI) hardware, these methods are not readily applicable in clinical settings. By conducting a series of measurements and calculations on T2-weighted images obtained from routine cervical MRI scans, it is possible to derive the signal intensity ratio between the nucleus pulposus of the intervertebral disc and the spinal cord, which is relatively simple and feasible. This study investigated the utility of the signal intensity ratio (SR) as a quantitative measure for assessing intervertebral disc degeneration. MRI scans of the cervical spine of 126 patients were retrospectively analyzed. Regions of interest for the nucleus pulposus and spinal cord were delineated on sagittal T2-weighted images, and the corresponding average signal intensities were measured. SR was defined as the ratio of the mean signal intensity of the nucleus pulposus to that of the spinal cord. One-way analysis of variance was used to assess the correlations between the disc SR, Pfirrmann score, and patient demographic data (age and sex). Receiver operating characteristic curve analysis was conducted to evaluate the diagnostic efficacy of the SR in distinguishing adjacent intervertebral discs based on their Pfirrmann grades. The SR of the intervertebral disc was negatively correlated with both age (R range: -0.33 to -0.58, P < .01) and Pfirrmann grade, while demonstrating only a weak correlation with sex. Furthermore, the SR of the intervertebral disc was more sensitive in differentiating between the early and late stages of intervertebral disc degeneration, exhibiting superior diagnostic efficiency for distinguishing between Pfirrmann grades I, II, IV, and V (AUC: 0.873 for I vs. II; 0.837 for IV vs V). As a quantitative imaging index, SR can reduce the subjectivity inherent in qualitative grading systems such as the Pfirrmann classification. In the future, SR may serve as a complementary tool to the Pfirrmann classification, especially in distinguishing between the early and late stages of degeneration.