| Background and Objective:1.As the growth of the age,lumbar intervertebral disc degeneration is often concomitant with osteoporosis,vertebral bone marrow fat deposition is positively associated with osteoporosis,the quantitative evaluation of lumbar vertebral bone marrow fat can indirectly reflect the osteoporosis,but its relationship with lumbar disc degeneration is unclear.One of the purposes of this study is to investigate the correlation between lumbar vertebrae bone marrow fat deposition and intervertebral disc degeneration by quantitative MRI.2.The nutrient supply of intervertebral disc is mainly obtained by the microvessels in adjacent vertebral bodies through the diffusion of cartilaginous endplate.The degree of intervertebral disc degeneration is often positively correlated with the defect of cartilaginous endplate.Currently,there are few systematic studies on cartilaginous endplate at different degeneration degrees and different lumbar segments at different ages.UTE T2* mapping is a novel quantitative magnetic resonance sequence that can be used to evaluate short T2 tissues.The second purpose of this study is to investigate the diagnostic value of novel UTE-T2* mapping for biochemical components changes in cartilaginous endplate,and to evaluate changes in different ages,different lumbar segment and different degrees of disc degeneration of cartilaginous endplate biochemical components.3.Pathologically,when the cartilaginous endplate ruptured,the number of bone marrow adipocytes adjacent to the broken part of the vertebral body often increased.But has not yet occurred early cartilage endplate morphological changes,the change of adjacent vertebral bone marrow fat content and the correlation of biochemical components of cartilaginous endplate changes has not yet been confirmed by imaging in vivo studies,whether the early changes of vertebral bone marrow fat content will cause cartilage endplate nutrition transportation reduce raising intervertebral disc degeneration is unclear.The third purpose of this study was to investigate the correlation between lumbar bone marrow fat deposition and the changes of intervertebral disc degeneration cartilage endplate,so as provide imaging basis for the above pathophysiological pathways.Materials and Methods1.Intervertebral disc degeneration associated with vertebral marrow fat: assessed by quantitative magnetic resonance imagingA total of 104 chronic lower-back pain volunteers underwent 3.0T MRI with T2 WI imaging,T2 mapping,and interactive decomposition of water and fat with echo asymmetry and least squares estimation(IDEAL IQ)between August 2018 and June 2019.Each disc was assessed with T2 value by T2 mapping,and the L1-S1 vertebral bone marrow fat fraction was assessed by IDEAL IQ.The differences and relationship between T2 value and the adjacent vertebral bone marrow fat fraction values within the five age groups,five lumbar levels,and four Pfirrmann groups,were statistically analyzed,and analyzed its correlation with gender and BMI.2.Cartilaginous endplate changes in degenerative intervertebral discs associated with vertebral marrow fat: assessed by quantitative magnetic resonance imagingA total of 80 chronic lower-back pain volunteers underwent 3.0 T MRI with T2 WI,T2 mapping,UTE T2* mapping and IDEAL IQ between August 2018 and October 2019.Each disc was assessed with T2 value by T2 mapping,T2* value by UTE T2* mapping and the L1-S1 vertebral bone marrow fat fraction was assessed by IDEAL IQ.The differences and relationship between T2* value and the adjacent vertebral bone marrow fat fraction values within the five age groups,and five lumbar levels,four Pfirrmann groups,were statistically analyzed,and analyzed its correlation with gender and BMI.Results.1.The vertebral bone marrow fat fraction had a significant negative correlation with T2 values of nucleus pulposus’ T2 values(p < 0.001).However,the significant negative correlation was only found between T2 values of nucleus pulposus and adjacent vertebral bone marrow fat in 40～49 years,L1/2-L5/S1 level,and Pfirrmann II-III groups.Pfirrmann grades of the intervertebral disc were positively correlated with adjacent vertebrae bone marrow fat fraction(p < 0.05).2.The T2* values of the cartilaginous endplate were significantly different in 20～29 to 60～70 age groups,L1/2-L5/S1 segment and Pfirrmann I-IV groups(P < 0.05).As the degree of disc degeneration increased and the lumbar segment moved toward the caudal side,the T2* value of the superior cartilaginous endplate generally decreased,while the T2* value of the inferior cartilaginous endplate gradually increased.3.In the 20～29 years to 60～70 years groups/ L1/2-L5/S1 segment/ Pfirrmann I-III groups,the T2* value in the middle part of the superior cartilaginous endplate was negatively correlated with the adjacent lumbar bone marrow fat content(P<0.01).In the early stage degeneration group(Pfirrmann II-III),the cartilaginous endplate T2* value was more correlated with the bone marrow FF value of adjacent vertebral bodies than in the advanced stage degeneration group(Pfirrmann IV)(P<0.05).With the increase of age,the correlation between T2* value and FF value of cartilaginous endplate increased.Conclusion1.Lumbar bone marrow fat deposition significantly increases during the early stages of intervertebral disc degeneration.Quantitative measurements of bone marrow fat deposition and water content of intervertebral discs have a predictive value and are an important supplement to the qualitative traditional classification strategies for the early stages of intervertebral disc degeneration.2.UTE T2* mapping sequence has certain feasibility and potential predictive value for quantitative measurement of early changes of collagen fibers and glycosaminoglycan in cartilaginous endplate,which provides an important supplementary basis for early diagnosis of lumbar disc degeneration.3.There is a correlation between vertebral bone marrow fat content and early biochemical changes of cartilaginous endplate and early degeneration of lumbar intervertebral disc.Increased bone marrow fat in the vertebral body may cause damage to the cartilaginous endplate and thus decrease the nutritional supply to the intervertebral disc.Increased bone marrow fat in the vertebral body may cause damage to the cartilaginous endplate and thus reduce the nutritional supply to the intervertebral disc,finally promoting the development of intervertebral disc degeneration. |
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