T2 mapping of lumbar intervertebral disc: quantitative evaluation of degeneration in relation to Pfirrmann grading system and a template for intervertebral disc segmentation

Background: To assess the feasibility of using T2 relaxation time mapping at 3 Tesla (3T) magnetic resonance imaging (MRI) for detection and classification of lumbar intervertebral disc degeneration, introducing an objective model of disc segmentation for accurate disc assessment. Materials and Methods: The present study is a single-center prospective evaluation including 185 lumbar intervertebral discs from a cohort of 37 patients with chronic lower back pain. For the quantitative classification of disc degeneration, three regions of interest (ROIs) were drawn on T2 maps, and the Pfirrmann grading system was used for qualitative assessment. Intergroup evaluation was performed with paired t-tests. Analysis of variance (ANOVA) was used to compare the mean value of T2 mapping, and Tukey's multiple comparison test was applied to determine differences in mean values of T2 mapping among the Pfirrmann categories. Results: The ANOVA test analysis of ROIs showed that there is a statistically significant difference (p <0.001) among average T2 relaxation time mapping values in different Pfirrmann score groups, and Tukey's multiple comparison tests revealed that mean values of T2 map among the different grades of Pfirrmann differ from the rest (p <0.001) except grade V. Paired t-tests revealed significant differences in mean values of T2 map between different ROIs. Conclusion: This study showed that quantitative T2 mapping of the lumbar intervertebral discs at 3T MRI may overcome the subjective element of qualitative classification systems for degenerative intervertebral disc disease. Also, a new template of disc segmentation with more ROIs would be more sensitive for the assessment of disc degeneration.