The diagnostic value of axial loading imaging of the lumbar spine during CT and MR examination in patients with degeneration disorders

Objective: To estimate the diagnostic value of axial loading imaging of the lumbar spine during CT and MRI examination in patients with degenerative disorders. Methods: One hundred patients were examined in psoas-relaxed position (PRP) and axially compressed in extension (ACE) supine position of the lumbar spine. Forty patients were examined with CT and 60 patients were with MRI. If a significant decrease (>15 mm²) of dural sac cross-sectional area to values smaller than 75 mm² was found during examination in axial loading, or if a suspected disc herniation, narrow lateral recess, narrow intervertebral foramen, or intraspinal synovial cyst changed to being obvious at the axial loading examination, they were regarded as additional information. Results: After axial loading CT examination, AVI was found in 16 of 40 patients. A significant decrease of dural sac area was found in 13 patients. Intervertebral disc herniation was more severe in 7 patients, lateral recess or intervertebral foramen narrowed in 4 patients, no intraspinal synovial cyst was found. After axial loading MRI examination, AVI was found in 19 of 60 patients. A significant decrease of dural sac area was found in 13 patients. Intervertebral disc herniation became severe in 10 patients, lateral recess or intervertebral foramen narrowed in 8 patients, no intraspinal synovial cyst was found. AVI was found in 32 of 79(40.5%) patients with sciatica and 2 of 20(10.0%) patients with low back pain (χ²=7.45 P<0.05). Conclusion: Compared with PRP examination, the ACE of CT or MRI can reflect the status of disc, dural sac and lateral recess or intervertebral foramen of the lumbar spine in the erect position. (authors)