[Diffusion-weighted imaging of acute vertebral compression: Differential diagnosis of benign versus malignant pathologic fractures].

PURPOSE: Our purpose was to assess the value of diffusion-weighted steady-state free precession (SSFP) sequence for differentiating between benign and pathologic compression fractures.

MATERIALS AND

METHODS

Forty-nine patients with 63 acute vertebral compression fractures caused by osteoporosis (n = 23), trauma (n = 7), malignancy (n = 30), infection (n = 3) were examined with a diffusion-weighted SSFP sequence (diffusion gradient strength; 23 mT/m, diffusion pulse length 5 ms), T1-weighted turbo spin-echo sequence, and short-inversion-time (TI 150 ms) T2-weighted turbo inversion recovery sequence. The signal intensity characteristics were analyzed qualitatively and quantitatively for all sequences. Statistical analysis was performed with the Student's t test.

RESULTS

In diffusion-weighted MR imaging, benign osteoporotic and traumatic fractures were hypo- to isointense to adjacent normal vertebral bodies. Pathologic and infectious compression fractures were hyperintense to normal vertebral bodies. Pathologic vertebral fractures had positive bone marrow contrast ratios at diffusion-weighted imaging, whereas non infectious benign vertebral fractures had negative values (p < 0.001). The difference in bone marrow contrast ratios for benign and pathologic compression fractures at T1-weighted TSE and T2-weighted turbo IR was not significant (p > 0.01).

CONCLUSION

Diffusion-weighted SSFP sequence provides unique information that significantly impacts the accuracy of radiologic diagnosis. Diffusion-weighted SSFP sequence may allow the differentiation of acute benign osteoporotic fractures from malignant compression fractures. Acute benign osteoporotic or traumatic fractures show hypointense or isointense signal on diffusion-weighted sequences that reflects persistent free water proton mobility. Malignant compression fractures show hyperintensity compared with normal surrounding bone marrow probably due to altered water proton mobility within the neoplasm.