Diagnostic capability of low- versus high-field magnetic resonance imaging for lumbar degenerative disease.

Study Design: Cohort study.

Objective: To investigate the diagnostic capability of low-field magnetic resonance imaging (MRI) compared with high-field MRI for degenerative disease of the lumbar spine.

Summary Of Background Data: Low-field MRI has several advantages over high-field magnetic resonance systems (easier installation, lower purchase, and maintenance cost). The diagnostic capability of low-field MRI for degenerative disease of the lumbar spine has not been compared with that of high-field MRI.

Methods: Hundred patients (mean age: 56.3 yr, range: 32-80; F:M = 59:41) with neurogenic claudication or sciatica were studied. All patients underwent MRI of the lumbar spine on both low-field (0.25T) and high-field (1.5T or 3.0T) magnetic resonance systems. Intervertebral disc herniation, central canal, lateral recess, and exit foraminal stenosis as well as nerve root compression at L3-L4, L4-L5, and L5-S1 were evaluated by 2 radiologists for both low- and high-field systems using established reliable grading systems.

Results: There was excellent agreement between low- and high- field MRI with regard to grading the presence and severity of disc herniation (r = 0.92-0.94; P < 0.05), central canal stenosis (r = 0.89-0.91; P < 0.05), lateral recess stenosis (r = 0.81-0.87; P < 0.05), and exit foramen stenosis (r = 0.81-0.89; P < 0.05). Descending or exiting nerve root compression occurred in 52% of patients at L3-L4, L4-L5, or L5-S1 levels, with good agreement between low-field and high-field MRI (r = 0.71-0.76; P < 0.05) for nerve root compression.

Conclusion: Excellent reliability between low- and high- field MRI was found for most features of lumbar disc degeneration, with good agreement for nerve root compression. 0.25T MRI was more susceptible to motion artifact, probably due to longer scanning time.

Level Of Evidence: 3.