[O-1-076] Endorectal multiparametric 3T-MR detects local recurrent prostate cancer after radical prostatectomy
Purpose: Define the utility of diffusion-weighted imaging(DWI) and dynamic contrast-enhanced imaging(DCEI) at 3-T endorectal-coil MRI in identifying local prostate cancer recurrence after radical prostatectomy(RP).Materials and Methods: This retrospective study was HIPAA-compliant and approved by the IRB. 80 men underwent MRI for suspected local recurrence. The reference standard included histopathology, decline of PSA values after salvage radiotherapy, and follow-up. Two reviewers independently reviewed T2WI alone(protocol A), a combination of T2WI and DWI(protocol B), a combination of T2WI and DCEI(protocol C), and a combination of T2WI, DWI and DCEI(protocol D), using a five-point scoring system. Receiver operating characteristic(ROC) analysis was used to compare the four protocols. Results: 57 (71.3%) of the 80 patients were found to have local recurrence. Area under the ROC curves (AUC) of protocol A, B, C, and D were 0.71, 0.72, 0.90, and 0.89 for reader 1 and 0.65, 0.62, 0.84, and 0.83 for reader 2. Protocols C and D had statistically better performance than protocols A and B for both readers. When 53 MRI-identified recurrent lesions in 47 patients were stratified by long-axis diameter of less than 10 mm and more than 10 mm, DWI had detection rates of 29.2%(7/24) and 72.4%(21/29), respectively. The detection rate of local recurrent tumor by protocol C or D was 76.5-82.4% for PSA of less than 0.4 ng/mL, 60-73.3% for between 0.4 to 1.0 ng/mL, and 80-88.0% for more than 1.0 ng/mL.Conclusions: The addition of DCEI to T2WI at 3-T endorectal MRI improves detection accuracy for local recurrence after RP. The addition of DWI is of limited incremental value for detection, especially for small lesions.