Quantitative Assessment Of Normal Intervertebral Disc Glycosaminoglycan Content By Delayed Gadolinium-Enhanced MRI Of Cartilage

Object:Nowadays,low back pain is more common than before,and most are results from intervertebral disc degeneration.MRI could show some inhomogeneous signal in IVD,but not early change in intervertebral disc degeneration.In earl stage,one of the most important composition,glycosaminoglycan?GAG?,decreased obviously,comparing with normal intervertebral disc.Delayed Gadolinium-Enhanced MRI of Cartilage?dGEMRIC?was considered as a technique to quantitative assessment of glycosaminoglycan content in early stage of degeneration.We could find if there is a pattern in distribution of GAG in one normal intervertebral disc through dGEMRIC,and there is a pattern in content of GAG from L1 to S1.On the basis of finding in our experiment,we will get more and more information about dGEMRIC in lumbar intervertebral disc GAG content in early stage of degeneration.Materials and Methods:There were 8 volunteers?5 male,3 female?in our experiment who had no complaint of low back pain.The average age was 24.1years old?the min was 23,the max was 25?,Injure,Ankylosing Spondylitis and rheumatoid arthritis were expected.Because of inhomogeneous signal in L4-5 and L5-S1,we got eight L1-2 IVDs,eight L2-3 IVDs,eight L3-4IVDs,seven L4-5 IVDs,seven L1-2 IVDs.Volunteers underwent two MRI scans using T1 mapping from L1 to S1,before and 3.5 hours after injection,and marked T1_PRE?T1_POST.We divided the IVD into 12 parts,the minor axis of IVD was subdivided into 5 parts,and the center of the nucleus was positioned in correspondence to the 3/5 of the minor axis,with a radius equal to 1/5 of the same axis.Then distributed into 2 concentric annular rings,each with a local thickness equal to 1/2 of the total annulus thickness,and in twelve 60°-wide angular sectors.We analyzed ROI of each part in IVD using Matlab.T1PRE?T1POST parametric images were obtained in pre and after injection,and the new index?T??T=T1PRE-T1POST?was computed.The SPSS 20.0 statistical software for statistical analysis in average value and standard deviation.Results:Compared with annulus fibrous?AF?in normal IVD,T1PRE?T1POST in nucleus pulposus?NP?were higher and?T value was lower.T1PRE?T1POST value in internal annulus were higher than those in external annulus.Besides,?T value in posterior AF was higher than in anterior parts.We could not find the tendency in?T value in each part in normal intervertebral discs in line from L1 to S1.Conclusion:The GAG content in NP and internal annulus were more than in external annulus.Besides,they were less in posterior AF,comparing in anterior parts.We found that there was no correlation between GAG content and the location of the IVDs.