Diffusion-weighted MR Imaging of Bone Marrow in the Spine: Differentiations of Metastatic Compression Fracture,Benign Compression Fracture, & Spondylitis

ABSTRACT

PURPOSE: To determine the findings of diffusion-weighted magnetic resonance (MR) imaging of acute and chronic benign compression fracture, metastatic compression fracture, and spondylitis, and to differentiate between them. MATERIALS AND METHODS: Forty-nine cases with vertebral compression fractures (17 metastatic, 16 acute osteo-porotic, 11 old osteoporotic, 5 acute traumatic) and seven with spondylitis (4 tuberculous, 3 pyogenic) underwent MR imaging. All cases were classified as belonging to one of four groups: A: acute osteoporotic and traumatic, B: metastatic, C: old osteoporotic, or D: spondylitic. For MR imaging, a 1.5-T scanner (Magnetom Vision, Siemens, Erlangen, Germany) was used, and the diffusion-weighted imaging sequence was based on reversed fast imaging with steady-state precession (PSIF) and a relatively low b value of about 150 sec/mm 2. Signal intensity characteristics were evaluated in terms of the contrast ratio (CR) and signal-to-noise ratio (SNR) of bone marrow. RESULTS: Diffusion-weighted MR imaging showed that signal intensity in group A was hypointense to adjacent normal vertebral bodies, but in group B, hyperintensity was noted. In group C, signal intensity was variable, while in group D, hyperintensity was again noted. Diffusion-weighted imaging revealed that in group A, bone marrow CR had a negative value, while in groups B and D, this value was positive (p .01). CONCLUSION: Diffusion-weighted MR imaging revealed that the signal intensity of metastatic compression fracture and spondylitis was hyperintense to adjacent normal vertebral bodies, that of acute benign compression fracture was hypointense, and that of chronic benign compression fracture was variable. This modality is therefore useful for differentiating between metastatic compression fracture, spondylitis and acute benign compression fracture.