STUDY DESIGN: Cross-sectional study.

OBJECTIVE: To investigate if adding a lumbar pillow in supine position during magnetic resonance imaging (MRI) is superior to standing positional MRI for diagnosing lumbar spinal stenosis (LSS).

SUMMARY OF BACKGROUND DATA: The upright standing position and especially extension of the lumbar spine seem to worsening symptoms of LSS. However, it is unclear whether a forced lumbar extension by a pillow in the lower back during conventional supine MRI may improve the diagnostics of LSS compared with standing MRI.

METHODS: Patients suspected for LSS and referred to conventional MRI were included to an additional positional MRI scan (0.25T G-Scan) performed in: (1) conventional supine, (2) standing, (3) supine with a lumbar pillow in the lower back. LSS was evaluated for each position in consensus on a 0 to 3 semi-quantitative grading scale. Independently, L2-S1 lordosis angle, spinal cross-sectional diameter (SCSD), dural cross-sectional diameter (DCSD), and dural cross-sectional diameter (DCSA) were measured. The smallest dural diameter was defined as stenosis level and the largest control level for comparison.

RESULTS: Twenty-seven patients (60.6 years; ±9.4) were included. The lordosis angle increased significantly from supine to standing (3.2° CI: 1.2-5.2) and with the lumbar pillow (12.8° CI: 10.3-15.3). One-way analysis of variance (ANOVA) showed significant differences between positions (P < 0.001). When compared with the supine position, pairwise comparisons showed decreased SCSD, DCSD, DCSA, and increasing semi-quantitative grading, during both standing and supine with the lumbar pillow. A difference in the semi-quantitative grades was only found between standing and supine with a lumbar pillow, and the scan with a lumbar pillow was significantly more painful.

CONCLUSION: Standing MRI and supine MRI with a lumbar pillow resulted in equal changes in the lumbar spine, although standing MRI may be more sensitive in the assessment of patients suspected for LSS.

LEVEL OF EVIDENCE: 2.