Diagnostic importance of axial loaded magnetic resonance imaging in patients with suspected lumbar spinal canal stenosis

Abstract Objective To study the efficacy of lumbar axial loading (AL) MRI in the suspected patients with lumbar spinal stenosis (LSS), with and without AL compression. Summary of Background Data Supine MRI is used in the assessment of patients with lumbar spinal stenosis (LSS). However, MRI findings may poorly correlate with neurological findings due to the morphological changes of the lumbar spinal canal between upright standing and supine positions. In patients without significant stenosis in routine lumbar MRI, by applying AL, MRI can show significant LSS. Methods This study included 103 consecutive patients (188 disc levels), presented with neurogenic claudication with and without low back pain. AL was performed using a non-magnetic compression device for five minutes. T1 and T2-weighted axial and sagittal sequences were obtained during AL applied to the spine. The dural sac cross sectional area (DSCA) appeared to be narrow at each disc level of L4-5 to L5-S1 in all patients and was measured using T2-weighted images in routine supine and AL images. Results The groups, included patients with a reduction in the DSCA (>15 mm 2 ) according to patient age and DSCA in routine spine MRI. The mean DSCA of the disc levels without and with AL were 138mm 2 and 123mm 2 , with a mean difference of 15mm 2 at L4-5, 134mm 2 and 125mm 2 and a mean difference of 9 mm 2 at L5-S1, respectively. Conclusion The use of AL MRI in patients with clinically suspected LSS could reduce the risk of misdiagnosis of stenosis, leading to inappropriate treatment.