Diagnostic value of increased diffusion weighting of a steady-state free precession sequence for differentiating acute benign osteoporotic fractures from pathologic vertebral compression fractures

BACKGROUND AND PURPOSE: Differentiating acute benign from neoplastic verteb ral compression fractures can pose a problem in differential diagnosis on r outine MR sequences, as signal changes can be quite similar. Our purpose wa s to assess the value of increasing the diffusion weighting of a diffusion- weighted steady-state free precession (SSFP) sequence for differentiating t hese two types of vertebral compression fractures. METHODS: Twenty-nine patients with 32 acute vertebral compression fractures caused by osteoporosis (n = 15) or malignancy (n = 17) were examined with a diffusion-weighted SSFP sequence, a T1-weighted spin-echo sequence, and a short-inversion-time inversion recovery sequence. The SSFP sequence was pe rformed with increased diffusion weighting (delta = 0.6, 3.0, 6.0, and 9.0 ms). The signal intensities of the fractured vertebral bodies were rated on a five-point scale from markedly hypointense to markedly hyperintense rela tive to normal adjacent vertebral bodies. Quantitative analysis was perform ed by region-of-interest measurements and by calculating the bone marrow co ntrast ratio. Statistical analysis was performed with the Mann Whitney U te st and Student's t test. RESULTS: At delta = 3 ms, the osteoporotic fractures yielded hypointense si gnal in seven cases, isointense signal in six, and hyperintense signal in t wo. The fractures showed a progressive signal loss with increased diffusion weighting, so that hypointensity was reached in all but one case. All meta static fractures had hyperintense signal with delta = 3 and 6.0 ms, With de lta = 9.0 ms, four fractures became isointense. CONCLUSION: Increasing diffusion weighting can reduce false-positive hyperi ntense osteoporotic fractures or make hypointensity more obvious in cases o f osteoporotic fractures.