Diffusion-weighted magnetic resonance imaging of spinal infection and malignancy

Background and Purpose. Pyogenic and tuberculous spondylitis can mimic malignancy. The purpose of this study was to determine the efficacy of diffusion-weighted magnetic resonance imaging in differentiating spinal infection and malignancy. Methods. Fifty-one consecutive patients with suspected spinal infection or malignancy were enrolled in the study. Apparent diffusion coefficients (ADCs) of paraspinal soft tissue mass and normal and abnormal vertebral bone marrow were determined on the diffusion-weighted magnetic resonance images of the spine. The mean ADCs of normal and abnormal vertebral bodies in patients with confirmed infection or malignancy were compared using nonparametric tests. Results. ADCs of 69 tuberculous, 9 pyogenic, and 50 malignant vertebral marrow lesions were significantly higher than ADCs of normal marrow. ADCs of malignant bone marrow and 5 paraspinal soft tissue lesions were significantly lower than tuberculosis and pyogenic infection. There was no significant difference between the ADCs of 44 adult and 25 pediatric tuberculous bone lesions or between tuberculosis and pyogenic infection. Using the cutoff ADC of 1.02 x 10(-3)mm(2)/s for bone marrow, the sensitivity, specificity, and accuracy were 60.26%, 66.00%, and 62.50%, respectively, for distinguishing infection from malignancy. The sensitivity, specificity, and accuracy increased to 94.12%, 82.35%, and 90.20%, respectively, when the ADCs of associated soft tissue lesions were higher than 1.17 x 10(-3)mm(2)/s. Conclusions. Diffusion-weighted magnetic resonance imaging has limited usefulness for differentiating spinal infection and malignancy.