Objective To quantitatively evaluate the metabolic changes of benign prostatic hyperplasia（BPH） and prostate cancer in the transitional zone using magnetic resonance spectroscopic imaging（MRSI）

and to analyze the characteristics and differences of the spectra in this zonal area.Methods Eighteen patients with prostate cancer in the transitional zone underwent magnetic resonance imaging（MRI）/MRSI examinations.The（Choline+Creatine）/Citrate（CC/Ci） ratio and the Choline/Creatine（Cho/Cr） ratio were evaluated in each voxel with cancer or BPH confirmed by pathological results.Discriminant analysis was used to determine the power of the two ratios in differentiation between cancer and BPH.Results The CC/Ci ratio and Cho/Cr ratio for cancer voxels were significantly higher than those in the voxels with BPH in the transitional zone（CC/Ci:2.36±1.31 vs.0.85±0.29

P<0.01;Cho/Cr:4.14±1.79 vs.1.26±0.45

P<0.01）.As for the discriminant function with the CC/Ci ratio and the Cho/Cr ratio

the specificity

sensitivity

and accuracy were 98.6%

85.7%

92.9% respectively for the differentiation between cancer and BPH.Conclusions The prostate cancer is characterized by higher CC/Ci ratio and Cho/Cr ratio compared to BPH in the transitional zone.Both CC/Ci ratio and Cho/Cr ratio have high specificity

sensitivity

and accuracy in their discriminative power between cancer and BPH in this zonal area.