Prostate cancer: 1HMRS-DCEMR at 3T versus [(18)F]choline PET/CT in the detection of local prostate cancer recurrence in men with biochemical progression after radical retropubic prostatectomy (RRP).

OBJECTIVES: This study compares proton magnetic resonancespectroscopic imaging (1H-MRSI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) combined techniques at 3T magnet versus [(18)F]choline PET/computed tomography (CT) in the detection of local prostate cancer recurrence in patients with biochemical progression after radical retropubic prostatectomy (RRP).

MATERIALS AND METHODS: 84 consecutive patients at high risk of local recurrence underwent combined 1HMRSI-DCEMR and 18-Fcholine- PET/CT. MR scan protocol included turbo spin echo (TSE) T2-weighted sequences in the axial, sagittal and coronal planes; three-dimensional (3D) chemical shift imaging (CSI) sequences with spectral/spatial pulses optimized for quantitative detection of choline and citrate; dynamic contrast enhanced gradient-echo (GRE) T1-weighted sequence. The population was divided into two groups. Group A included 28 patients with a lesion size ranging between 5.00mm and 7.2mm and PSA reduction following radiation therapy. Group B included 56 patients with a lesion size between 7.6mm and 19.4mm. Sensitivity, specificity, positive predictive value (PPV) and accuracy were evaluated and receiver operating characteristic (ROC) curves were performed.

RESULTS: In Group A combined 1H-MRSI and DCE-MRI showed a sensitivity of 92%, a specificity of 75% (PPV 96%) while PET-CT examination showed a sensitivity of 62% and a specificity of 50% (PPV 88%) in identifying local recurrence. The accuracy of MRI was 89% while PET-CT showed an accuracy of 60%. Areas under the ROC curve (AUC) values for MR and PET-CT were 0.833 and 0.562, respectively. In Group B combined 1H-MRSI and DCEMR showed a sensitivity of 94% and a specificity of 100% (PPV 100%) with accuracy of 94%. PET-CT had a sensitivity of 92% and a specificity of 33% (PPV 98%) with accuracy of 91%. The AUCs for MR and PET-CT values were 0.971 and 0.837, respectively.

CONCLUSION: The diagnostic accuracy of combined 1HMRSI-DCEMR was higher than PET/CT to identify local prostate cancer recurrence, mostly in patients with low biochemical progression after RRP (0.2-2ng/mL).