ObjectiveTo determine if the three-dimensional proton magnetic resonance spectroscopic(MRS) imaging helps in diagnosing metastasis ofprostate cancer(Pca).MethodsSixty-five patients with biopsy proven Pca were recruited and divided into two groups:group 1 with metastasis(bone and/or lymph node metastasis)(n=34)and Group 2 without metastasis(n=31).Voxels were placed on cancerous area in peripheral zone and the ratios of(Cho+Cre)/Cit were measured.The mean ratio in each patient was calculated and ROC curve was drawn to determine the optimal operating point(OOP)for the prediction of Pca metastasis by the metabolite ratio.ResultsThe mean ratio of(Cho+Cre)/Cit in cancerous area of Pca without metastasis was 1.3 ±0.5,whereas that of Pca with metastasis was 2.2±0.6.Statistically significant difference existed between the two groups(t=6.38,P＜0.05).According to the ROC analysis,the OOP was determined and interpreted at 1.53 with higher sensitivity and specificity.If Pca with metastasis was predicted as whose the mean ratio of(Cho+Cre)/Cit in cancerous area larger than 1.53,the sensitivity,specificity and accuracy for metastasis determination were 94.12%(32/34),67.74%(21/31),and 81.54%(53/65)respectively.Conclusion MRS may be a useful noninvasive method to predict the metastasis of Pca.