Evaluation of lumbar intervertebral disc degeneration with synthetic MRI / 中华放射学杂志

ABSTRACT

Objective:To investigate the value of synthetic MRI for evaluating lumbar intervertebral disc degeneration.Methods:A total of 414 lumbar intervertebral discs from 85 patients were included prospectively from September 2018 to February 2019 in First Affiliated Hospital of China Medical University. The T 1, T 2 and proton density (PD) mapping were generated from synthetic MRI. Two doctors measured the T 1, T 2 and PD values to evaluate intraobserver agreement by using ICC. For Pfirrmann grade comparisons, the variables with normal distribution were analyzed with the one-way analysis of variance, whereas those with skewed distribution were analyzed with the Kruskal-Wallis H test. Furthermore, the ROC curves were used on significant parameters to evaluate their diagnostic efficacy. The Z test was used to compare the differences of area under the ROC curves (AUC). Results:The color of the quantitative mapping changed along with the increase of the Pfirrmann grade of the intervertebral discs, which corresponded to the decrease of the T 2WI signal intensity. The ICC values of the quantitative values of nucleus pulposus indicated excellent agreement (ICC>0.900), followed by anterior annulus fibrosus (ICC>0.700) and then the posterior annulus fibrosus (ICC>0.600). The results of the adjacent Pfirrmann grade comparisons were as follows between Pfirrmann grade Ⅰ and Ⅱ, the differences of T 2 and PD values of nucleus pulposus were statistically significant ( P=0.004 and P<0.001, respectively); between Pfirrmann grade Ⅱ and Ⅲ, the differences of T 1, T 2 and PD values of nucleus pulposus were statistically significant (all P<0.001); between Pfirrmann grade Ⅲ to Ⅳ, the T 1, T 2 and PD values of nucleus pulposus (all P<0.001) and the T 1 and PD values of posterior annulus fibrosus ( P=0.025, P<0.001, respectively) had statistically significant differences; between Pfirrmann grade Ⅳ to Ⅴ, the difference of T 2 values of nucleus pulposus were statistically significant ( P=0.031). The AUC of T 2 values of nucleus pulposus between Pfirrmann grade Ⅱ to Ⅲ and grade Ⅳ to V were higher than those of the PD values ( Z=2.443, 3.591 and P=0.015,<0.001). Conclusions:Synthetic MRI can quantitatively evaluate lumbar disc degeneration, in which the T 2 value of nucleus pulposus may be the most effective parameter with high repeatability.