The purpose of this study was a phantom study to measure the diffusion properties of water molecules by steady-state free precession diffusion-weighted imaging (SSFP-DWI) with a low b-value and to determine if this sequence might be useful for application to the evaluation of bone marrow pathology.

1. The phantom study: A phantom study using two diffusion weighted sequences for the evaluation of the diffusion coefficient was performed. Three water-containing cylinders at different temperatures were designed: phantom A was 3℃, B was 23℃ and C was 63℃. Both SSFP and echo planar imaging (EPI) sequences (b-value: 1000 s/mm²) were performed for comparison of the diffusion properties. The Signal to noise ratios (SNR) and apparent diffusion coefficient (ADC) values of the three phantoms using each diffusion-weighted sequence were assessed. 2. The Clinical study: SSFP-DWI was performed in 28 patients [sacral insufficiency fractures (10), osteoporotic lumbar compression fractures (10), malignant compression fractures (8)]. To measure the ADC maps, a diffusion-weighted single shot stimulated echo-acquisition mode sequence (650s/ mm²) was obtained using the same 1.5-T MR imager

For the phantom study, the signal intensity on the SSFP as well as the classic EPI-based DWI was decreased as the temperature increased in phantom A to C. The ADC values of the phantoms on EPI-DWI were 0.13x10^-3 mm²/s in phantom A, 0.22x10^-3 mm²/s in B and 0.37x10^-3 mm²/s. in C. The SSFP can be regarded as a DWI sequence in view of the series of signal decreases.

Bone marrow pathologies with different diffusion coefficients were evaluated by SSFP-DWI. All benign fractures were hypointense compared to the adjacent normal bone marrow where as the malignant fractures were hyperintense compared to the adjacent normal bone marrow.