Abstract Background: Lumbar spinal stenosis (LSS) is a dynamic condition whose severity can be underestimated on conventional supine magnetic resonance imaging (cMRI), especially in patients with a clinico-radiological mismatch between symptoms and imaging findings. Axial loaded MRI (al-MRI) has been proposed to simulate the spine conditions under physiological load, potentially improving the diagnostic accuracy. Materials and Methods: In this retrospective observational study, patients with clinically suspected LSS, whose cMRI findings did not fully explain their symptoms, underwent additional al-MRI between L3 and S1. Disk levels were assessed for changes in the grade of central canal stenosis, lateral recess stenosis, foraminal stenosis, and dural sac cross-sectional area (DSA). Results: Out of 237 patients (711-disk levels), significant changes were observed on al-MRI compared to cMRI. Central canal stenosis grade increased from A/B to C/D in 87-disk levels in 73 patients (30.8%). Lateral recess stenosis changed in 33 patients (13.9%) with clear nerve root compression on al-MRI. DSA decreased from >75 mm² to <75 mm² in 93-disk levels (18.1%) in 80 patients (33.8%). Foraminal stenosis grade changed in 178 of 1422 foramina examined, with definite nerve root compression identified in 13 foramina across 11 patients (4.6%). Additionally, occult facet synovial cysts were detected in three patients on al-MRI but not on cMRI. Conclusion: Axial-loaded MRI provides valuable additional diagnostic information in patients with suspected LSS and a clinico-radiological mismatch on conventional MRI. Its routine use in carefully selected cases may enhance diagnostic accuracy and guide appropriate management.
Agrawal et al. (Thu,) studied this question.