The Diagnostic Advancement of Axial Loaded Lumbar Spine MR in Patients with Clinically Suspected Central Canal Stenosis

Abstract

Objective: The purpose of this study was to define diagnostic advancement of L-spine MR with axial loading device in patients with clinically suspected central canal stenosis, and to show a relationship of facet joint instability with aggravated central canal stenosis in axial loaded studies. Materials and Methods: From April 2006 to May 2010, lumbar MRI with axial loading device (DynaWell, DynaWell Inc., Las Vegas) was taken in 54 patients. Axial and sagittal T2 weighted images were obtained in preloaded phase and axial loaded phase. Axial images were evaluated with concerns of 1) gross change of central canal stenosis, 2) findings of facet joint change, including arthrosis, effusion, effacement of effusion, and 3) formation of ventral synovial cyst after axial loading. In addition, dural sac cross sectional area (DSCSA) was measured in L3/4, L4/5 and L5/S1 levels to quantify the change of stenosis. The significant change in DSCSA was defined as 10% decrease. Changes of neural foraminal stenosis, curvature and spondylolisthesis were evaluated with sagittal images. Results: With a use of axial loading device, the additional diagnosis of severe central canal stenosis was made in 13 patients (25%) in both gross interpretation and quantitative study(DSCSA <75mm2). The significant decrease of DSCSA was demonstrated in 22 patients (42%). The significant decrease was related to facet joint effusion and effacement of effusion. Conclusions: Measurable advancement in diagnosis of severe central canal stenosis was possible with axial loaded MRI. Patients with facet joint instability had tendency to show significant changes in central canal area