Diagnostic Advancement of Axial Loaded Lumbar Spine MRI in Patients With Clinically Suspected Central Spinal Canal Stenosis

Abstract

Case series study. To define diagnostic advancement of L-spine magnetic resonance with axial loading device in patients with clinically suspected central spinal canal stenosis, and to show a relationship of facet joint instability with aggravated central spinal canal stenosis in axial loaded studies. Although the axial loading device has been used for several years, there have been few reports about the usefulness of the axial loading device in clinical settings. Also, there has been no report about the relationship between facet arthrosis and dynamic central spinal canal stenosis. Lumbar magnetic resonance image (MRI) with axial loading device was obtained in 54 patients. Axial images were evaluated with attention to (1) gross change of central spinal canal stenosis, (2) findings of facet joint, including arthrosis, effusion, effacement of effusion, and (3) formation of ventral synovial cyst after axial loading. In addition, dural sac cross-sectional area was measured in L3-L4, L4-L5, and L5-LS1 levels to quantify the change of stenosis. Changes of neural foraminal stenosis, curvature, and spondylolisthesis were evaluated with sagittal images. With a use of axial loading device, the additional diagnosis of severe central spinal canal stenosis was made in 13 patients (25%) in both gross interpretation and quantitative study (dural sac cross-sectional area <75 mm). The significant decrease of dural sac cross-sectional area was demonstrated in 22 patients (42%). The significant decrease was related to facet joint effusion and effacement of effusion. Measurable advancement in diagnosis of severe central spinal canal stenosis was possible with axial loaded MRI. Patients with facet joint instability had a tendency to show significant changes in the central spinal canal area. 4.