Evaluation of Water Content in Lumbar Intervertebral Discs and Facet Joints Before and After Physiological Loading Using T2 Mapping MRI.

STUDY DESIGN: T2 mapping was used to quantify the water content of lumbar spine intervertebral discs (IVDs) and facet joints before and after physiological loading. OBJECTIVE: The aim of this study was to clarify the interaction between lumbar spine IVD and facet joints as load-bearing structures by measuring the water content of their matrix after physiological loading using T2 mapping magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA: To date, few reports have functionally evaluated lumbar spine IVD and facet joints, and their interaction in vivo. T2 mapping may help detect changes in the water content of IVD and articular cartilage of facet joints before and after physiological loading, thereby enabling the evaluation of changes in interacted water retention between IVD and facet joints. METHODS: Twenty asymptomatic volunteers (10 female and 10 male volunteers; mean age, 19.3 years; age range, 19-20 years) underwent MRI before and after physiological loading such as lumbar flexion, extension, and rotation. Each IVD from L1/2 to L5/S1 was sliced at center of the disc space, and the T2 value was measured at the nucleus pulposus (NP), anterior annulus fibrosus (AF), posterior AF, and bilateral facet joints. RESULTS: In the NP, T2 values significantly decreased after exercise at every lumbar spinal level. In the anterior AF, there were no significant differences in T2 values at any level. In the posterior AF, T2 values significantly increased only at L4/5. In the bilateral facet joints, T2 values significantly decreased after exercise at every level. CONCLUSION: There was a significant decrease in the water content of facet joints and the NP at every lumbar spinal level after dynamic loading by physical lumbar exercise. These changes appear to play an important and interactional role in the maintenance of the interstitial matrix in the IVD NP and cartilage in the facet joint. LEVEL OF EVIDENCE: 3.

Evaluation of Water Retention in Lumbar Intervertebral Disks Before and After Exercise Stress With T2 Mapping.

STUDY DESIGN: T2 mapping was used to quantify moisture content of the lumbar spinal disk nucleus pulposus (NP) and annulus fibrosus before and after exercise stress, and after rest, to evaluate the intervertebral disk function. OBJECTIVE: To clarify water retention in intervertebral disks of the lumbar vertebrae by performing magnetic resonance imaging before and after exercise stress and quantitatively measuring changes in moisture content of intervertebral disks with T2 mapping. SUMMARY OF BACKGROUND DATA: To date, a few case studies describe functional evaluation of articular cartilage with T2 mapping; however, T2 mapping to the functional evaluation of intervertebral disks has rarely been applied. Using T2 mapping might help detect changes in the moisture content of intervertebral disks, including articular cartilage, before and after exercise stress, thus enabling the evaluation of changes in water retention shock absorber function. METHODS: Subjects, comprising 40 healthy individuals (males: 26, females: 14), underwent magnetic resonance imaging T2 mapping before and after exercise stress and after rest. Image J image analysis software was then used to set regions of interest in the obtained images of the anterior annulus fibrosus, posterior annulus fibrosus, and NP. T2 values were measured and compared according to upper vertebrae position and degeneration grade. RESULTS: T2 values significantly decreased in the NP after exercise stress and significantly increased after rest. According to upper vertebrae position, in all of the upper vertebrae positions, T2 values for the NP significantly decreased after exercise stress and significantly increased after rest. According to the degeneration grade, in the NP of grade 1 and 2 cases, T2 values significantly decreased after exercise stress and significantly increased after rest. CONCLUSION: T2 mapping could be used to not only diagnose the degree of degeneration but also evaluate intervertebral disk function. LEVEL OF EVIDENCE: 3.