The purpose of this study is to analyze the most discriminative MR findings for making the differential diagnosis of tuberculous and pyogenic spondylitis.

Sixty MR scans of 18 pyogenic spondylitis patients and 42 tuberculous spondylitis patients were retrospectively reviewed. The statistical analysis was performed using stepwise discriminant analysis and Student's T-test.

The patients with tuberculous spondylitis had a significantly higher incidence of MRI findings as follows (p <0.05): smooth margin of a paraspinal mass/abscess in 67% [28/42] of the tuberculous spondylitis patients vs 6% [1/18] in the pyogenic spondylitis patients, mild endplate erosion in 52% [22/42] vs 38% [7/18], respectively, the presence of paraspinal mass/abscess in 100% [42/42] vs 6% [1/18], respectively, central dark signal intensity of the abscess in 86% [36/42] vs 39% [7/18]), respectively, subligamentous spread in 81% [34/42] vs 50% [9/18]), respectively, severe vertebral collapse in 20% [8/42] vs 11% [2/18]), respectively, and posterior extension in 62% [26/42] vs 33% [6/18]), respectively. Among of them, the significant discriminative MR findings were the margin of a paraspinal mass, the grade of endplate erosion and the presence or absence of a paraspinal mass in that order.

In the differentiation of tuberculous and pyogenic spondylitis, the margin of the paraspinal mass, the grade of endplate erosion and the presence or absence of a paraspinal mass are the most three discriminating MR findings in that order.