MR perfusion and diffusion imaging for the diagnosis of benign and malignant bone tumors

Objective： MR-PWI and MR-DWI were supplementary functional methods to differentiate benign from malignant bone tumors. The aim of this study was to assess the diagnostic potential of MR-PWI conjunction with MR-DWI in differentiating benign from malignant bone tumors. Methods： MR-PWI and MR-DWI were performed on 39 patients by using a 1.5 T MR imager. Perfusion imaging was started with GRE-EPI sequence as soon as the bolus administration commenced. With b value as 300 s/mm^2, diffusion imaging was performed with SE-EPI sequence. Type of TIC, peak enhancement, steepest slope, signal difference between 2 baselines and ADC were compared between benign and malignant bone tumors. The data were analyzed with soft-ware （SPSS, version 13.0）. Subjective overall performance of two techniques was evaluated with Receiver Operating Characteristic （ROC） analysis. Results： 1. MR-PWI： （1） The Patterns of TIC of most benign bone tumors （17/21） were type Ⅰ and Ⅱ, and all malignant bone tumors were type Ⅲ and Ⅳ. （2） There were significant differences in peak enhancement （17.52 ± 2.37 vs. 52.42 ± 5.74） %, steepest slope （4.69 ± 2.84 vs. 9.63 ± 4.05）%/s and signal difference between 2 baselines （6.87 ±3.34 vs. 31.75 ± 11.09） % between benign and malignant groups. And their diagnosis accuracy was 82.1%, 79.5% and 87.2%, respectively. （3）. 4 highly vascularized benign bone tumors were mistaken in diagnosis as malignant ones according to their perfusion characteristics. 2. MR-DWI： There was significant difference between ADC of benign and malignant groups [（1.86 ± 0.38） vs. （1.44± 0.26）] ×10^-3 mm^2/s when b value was 300 s/mm^2. The diagnosis accuracy was 79.5% when ADC value less than 1.63 × 10^-3 mm^2/s was considered as malignant ones. 3. The diagnosis accuracy of M R-PWI and MR-DWI were 89.7% and 79.5%, respectively. Conclusion： MR-PWI is the better valuable technique than MR-DWI in differentiation benign from malignant bone tumors. To suspicious highly vascularized bone tumors, MR-PWI combining with MR-DWI lead to higher diagnosis accuracy.