The Classification And Quantitative Analysis Of Lumbar Intervertebral Disc With Mri Sagittal T₂ Mapping

Purpose:1. To investigate the lumbar intervertebral discs(IVDs) by MRI sagittal T₂ mapping through experimental research.A new classification system of IVDs was established by comparing other commonly used systems of classification,which can be a kind of early diagnosis of degeneration on IVDs.2. To investigate the mean value of T₂ in the nucleus pulposus and fibrosus annulus at all grades of degeneration of the IVDs at sagittal T₂ mapping.Then to establish a T₂ value standard on the assessment of IVDs.Materials and Methods:thirty volunteers (18 men, 12 women; age range: 21-49 years old; average age: 34.1 years)with no symptoms related to lumbar disease were imaged.The sagittal T₂W imaging and the sagittal 12-echo SE sequence were obtained.And sagittal T₂ mapping was performed for the L3/4,L4/5andL5/S1 IVDs. We used sagittal T₂ mapping and the other two classification systems to grade all the IVDs.The other commonly used systems of classification main focus on the signal of disc or the structural morphology in sagittal T₂W images,and sagittal T₂ mapping classification is based on the relationship between T₂,which is known to correlate with change in composition of intervertebral, and degenerative grade. Therefore, the classification syatems we have analyzed and compared help us to asses the differences between sagittal T₂ mapping classification and two other conventional classification syatems.The T₂ values of the nucleus pulposus(NP) and annulus fibrosus(AF) were measured.The data were analyzed by software of Statistics(SPSS17.0).Results:Under the premise of both intraobserver and interobserver agreenments,kappa value for three classification systems were moderate to almost perfect agreenment.The ratio of IVDs classified as grade I was higher with the commonly used classification systems than that with sagittal T₂ mapping.In contrast,the ratio of IVDs classified as grade II or III was higher with sagittal T₂ mapping than that with commonly used classification systems. In sagittal T₂ mapping degenerative grade increased with increasing age,and degenerative grade increased with reducing position.The T₂ value of NP decreased significantly with increasing age(p<0.05);the difference between the mean value of T₂ of NP between degenerative grades classified with sagittal T₂ mapping are significantly(p<0.05).Conclusion:Sagittal T₂ mapping provides a new idea and method which is more T₂-based classification for IVDs.Through the assessment on T₂ map and the measurement of T₂ value in NP and AF,the new system may be able to detect early degenerative changes before the conventional classification systems can.