Abstract: Objective:To research the MRI examination and diagnostic value of intervertebral space infection after nucleus pulposus extraction in patients with lumbar disc herniation.Methods:86 cases of intervertebral space infection after lumbar disc herniation in our hospital were selected as the research objects.All patients were given MRI examination，and gave positive treatment after diagnosis.Analyzed the MRI diagnostic results，and observed the changes of WBC count，ESR and C reactive protein levels before and after treatment.Result:The location of infection in 86 cases of intervertebral disc infection was mostly located in L4～L5 or L5～S1 intervertebral space.The intervertebral disc showed varying degrees of intervertebral disc fragmentation，smaller，disappeared，and uneven edge.MRI examination showed that the intervertebral disc space of lesion lost normal shape and signal，a 77 cases with long and low T1 signal，9 cases with equal T1 signal，82 cases with long and high T2 signal，4 cases with short and short T2 signal.The lesions in 86 cases of intervertebral disc infection showed different degrees of damage to the vertebral endplate and the adjacent vertebral spongy bone around the intervertebral disc.The surrounding part of adjacent vertebral bodies had abnormal signal appears（75 cases），the whole vertebral body signal was abnormal（11 cases）.Most of them were characterized by long T1 signal and long T2 signal，while a few of the lesions showed mixed signals dominated T2 signal.The soft tissue adjacent to the vertebral body showed swelling and thickening，and T1 showed equal signal，slightly higher signal or mixed signal，and T2 showed high signal.MRI enhanced scan was performed in 21 cases，the pathological changes of intervertebral disc，adjacent vertebral body and paravertebral soft tissue were obviously enhanced.After 6 months of followup，A total of 63 patients with complete disappearance of clinical symptoms，accounting for 73.26%.All the patients had significantly lower WBC counts，ESR and C reactive protein levels than before treatment（P<0.05）.Conclusion:In the diagnosis of lumbar disc herniation discectomy intervertebral space infection after MRI，check to fully display the lesion site of infection，it is important for early diagnosis and treatment of intervertebral space infection.

Key words: MRI examination, lumbar disc herniation, nucleus pulposus extraction, intervertebral space infection