DIFFERENTIATION BETWEEN BENIGN PROSTATIC HYPERPLASIA AND PROSTATE CANCER IN THE TRANSITIONAL ZONE EVALUATED BY ~1H MAGNETIC RESONANCE SPECTROSCOPIC IMAGING

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.

Multimodality imaging using proton magnetic resonance spectroscopic imaging and ^(18)F-fluorodeoxyglucose-positron emission tomography in local prostate cancer

AIM To assess the relationship using multimodality imaging between intermediary citrate/choline metabolism as seen on proton magnetic resonance spectroscopic imaging(1H-MRSI) and glycolysis as observed on ^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography(^(18)F-FDG-PET/CT) in prostate cancer(PCa) patients. METHODS The study included 22 patients with local PCa who were referred for endorectal magnetic resonance imaging/1HMRSI(April 2002 to July 2007) and ^(18)F-FDG-PET/CT and then underwent prostatectomy as primary or salvage treatment. Whole-mount step-section pathology was used as the standard of reference. We assessed the relationships between PET parameters [standardized uptake value(SUVmax and SUVmean)] and MRSI parameters [choline + creatine/citrate(CC/Cmax and CC/Cmean) and total number of suspicious voxels] using spearman's rank correlation, and the relationships of PET and 1H-MRSI index lesion parameters to surgical Gleason score.RESULTS Abnormal intermediary metabolism on 1H-MRSI was present in 21/22 patients, while abnormal glycolysis on ^(18)F-FDG-PET/CT was detected in only 3/22 patients. Specifically, index tumor localization rates were 0.95(95%CI: 0.77-1.00) for 1H-MRSI and 0.14(95%CI: 0.03-0.35) for ^(18)F-FDG-PET/CT. Spearman rank correlations indicated little relationship(ρ =-0.36-0.28) between 1H-MRSI parameters and ^(18)F-FDG-PET/CT parameters. Both the total number of suspicious voxels(ρ = 0.55, P = 0.0099) and the SUVmax(ρ = 0.46, P = 0.0366) correlated weakly with the Gleason score. No significant relationship was found between the CC/Cmax, CC/Cmean or SUVmean and the Gleason score(P = 0.15-0.79). CONCLUSION The concentration of intermediary metabolites detected by 1H MRSI and glycolytic flux measured ^(18)F-FDG PET show little correlation. Furthermore, only few tumors were FDG avid on PET, possibly because increased glycolysis represents a late and rather ominous event in the progression of PCa.