Diagnostic Benefits of Axial-Loaded Magnetic Resonance Imaging Over Recumbent Magnetic Resonance Imaging in Obese Lower Back Pain Patients.

ABSTRACT

STUDY DESIGN: Single center before-after case series study. OBJECTIVE: To determine when and in which kind of lower back pathologies, axial-loaded magnetic resonance imaging (MRI) provides additional benefit over recumbent MRI. SUMMARY AND BACKGROUND DATA Systems simulating physiological axial loading of the spine in patients examined in the supine position have recently been introduced in clinical practice. However, indications for examinations with axial loading have yet to be clearly specified. METHODS: Ninety patients (46 men, 44 women, aged 20-90 yr) with lower back pain underwent lumbar spine MRI with and without axial loading. MRI was performed in a supine position on a 1.5 T system using a compression device. A high-resolution 3D T2-weighted sequence was used for image acquisition. Clinical characteristics of patients were established using questionnaire surveys and demographic data. MR images were assessed for the appearance of changes after axial loading. After determining which patients showed significant changes, logistic regression analysis was performed with 15 independent variables (clinical, demographic, and imaging-related). RESULTS: After axial loading, 48.9% of patients showed additional changes. Multivariate analysis revealed that only obesity was a statistically significant predictor of the occurrence of changes (P < 0.05). After axial loading, 11 potentially clinically relevant changes appeared in seven patients, the most common being absolute spinal stenosis (n = 7). CONCLUSION: Axial loading may increase the diagnostic value of lumbar spine MRI in patients with obesity and/or those with suspected spinal canal stenosis. LEVEL OF EVIDENCE 4.