Quantitative Study Of Lumbar Cartilaginous Endplates With MRI

Objective: By measuring T2 values of the lumbar cartilaginous endplates using IDEAL-SPGR sequence and T2 mapping technique, we discuss the changes of CEPs in the process of development and the relationship among age, lumbar level, intervertebral disk degeneration and cartilaginous endplates degeneration.Subjects and Methods: There were two parts. For the first part, twenty infants between 1 and 3 years old and twenty young people between 19 and 20 years old underwent examinations of lumbar MR. We judged the degree of CEPs’ clarity, measured and recorded the distance between superior and inferior endplates of each vertebra in midsagittal plane of IDEAL-SPGR sequence.We can acquire the exact location of superior and inferior endplates on midsaggital T2 mapping utilizing this distance and T2 relaxation times were calculated. For the infant and the young people, we compared T2 values of each vertebra between superior endplates and inferior endplates and compared T2 values of endplates among different vertebra. Finally, we can compare T2 of each endplate between the infant and the young people. For the second part, we enrolled 130 patients to be examined lumbar MR, including 71 men and 59 women. The age ranged 21-63 years old. Different signal characteristics of Modic changes and Schmorl’s node were observed on conventional T1 WI, T2 WI and IDEAL-SPGR images.Choosing cases with no Modic changes and Schmorl’s node, we classified disks based on the Pfirrmann grading system in midsagittal plane of T2 WI sequence. Utilizing IDEAL-SPGR images and T2 mapping images, a ROI was plotted on each superior and inferior endplate, and T2 relaxation times were calculated. To compare T2 value of each endplate among people of different ages; compare T2 value of each endplate corresponding different Pfirrmann grades of disks. The correlativity was analyzed between the T2 values of CEPs and age and Pfirrmann grade of intervertebral disks.Results: ①CEPs were visible on IDEAL-SPGR images and show high signal intensity at the interface between intervertebral disk and bony plates, while they were invisible on T1 WI and T2 WI sequence. When Modic changes and Schmorl’s nodes occurred, the erosion and rupture of CEPs were visible on IDEAL-SPGR images. ②For the infants, the difference of T2 values was not statistically significant. ③ For the young people, L4 superior and inferior endplates were statistically different(P<0.05). ④For the L4 inferior endplate and L5 superior endplate, the difference of T2 values between the infant and the young people were significant(P<0.05). ⑤The difference of T2 value was statistically significant among people of different ages(P<0.05); T2 values of CEPs correlated moderately with age; T2 decreased with aging. ⑥T2 value of each endplate was statistically different among the corresponding different Pfirrmann grades of disks(P<0.05), I-II level>III level >IV-V level. T2 value between the cranial and caudal endplates near degenerate disks were not statistically different. T2 values of CEPs were relevant with Pfirrmann grades of disks. T2 values of CEPs at a higher level correlated moderately with Pfirrmann grades of disks,but T2 values of CEPs at a lower level correlated highly with Pfirrmann grades of disks.Conclusion: ①On IDEAL-SPGR images, CEPs show a high signal intensity at the interface between intervertebral disk and bony plates and their thickness are homogeneous relatively. When Modic changes and Schmorl’s nodes occurred, the erosion and rupture of CEPs were visible. ②For the infants, the difference of T2 values was not statistically significant,which indicates that the structure and biochemical composition of the human CEPs are consistent during the infants. ③For the young people, T2 values of the L4 inferior endplate and L5 superior endplate decrease which indicates the earliest degeneration. ④T2 values of CEPs correlated with age. The degeneration aggravates with aging.The CEPs of different levels degenerate in different age. ⑤T2 values of CEPs were different among the corresponding different Pfirrmann grades of disks. The lower values correspond with the more serious degeneration. The cranial and caudal endplates near degenerate disks were not statistically different. CEPs degeneration may result in intervertebral disk degeneration. ⑥Biomechanics factors may have some effect on T2 values of CEPs.