Assessment of local prostate cancer recurrence after prostatectomy using multi-parametric Magnetic Resonance without endorectal coil: preliminary experience
Introduction: Clinical suspicion of prostate cancer (PC) recurrence after radical prostatectomy (RP) is based on biochemical relapse. An imaging modality is strongly desirable to identify and correctly localize local PC recurrence, also in order to guide possible target loco-regional therapy and to reduce procedure related complications and toxicity. Aim of this preliminary study is to evaluate clinical practice value of multiparametric Magnetic Resonance Imaging (Mp-MRI) in the detection of local recurrence after RP.
Materials & methods: 32 consecutive patients with biochemical failure after RP underwent mp-MRI. PSA levels ranged from 0.15 to 5.86 ng/mL. Two radiologists blinded to clinical data reviewed MRI scans together and quantified likelihood of tumor recurrence on a 1 to 5 confidence scale, considering each MRI parameter (T2-w, DWI and DCE). A MRI cutoff threshold (at least grade 3) was adopted to define positive MRI results. Standard of reference for MRI results were considered 11C-Cho PET positivity, positive biopsy findings in prostatectomy bed and reduction of PSA values after radiotherapy.
Results: 24 out of 32 patients presented nodules with highly suspicion of recurrence at MR images (3 with grade 5, 16 with grade 4 and 9 with grade 3 of confidence). Diameter of suspected local recurrences detected varied from 0.5 to 2 cm. In comparison to reference standards we obtained values of sensibility and specificity respectively of 85% and 90%. Positive and negative predictive values in detecting locoregional relapse were, respectively, 94.5% and 75%. Among different MRI parameters DCE appears to have higher specificity (95%) in detecting tumor recurrence.
Conclusion: Mp-MRI can be a promising tool in the management of suspected relapse in patients with biochemical failure after RP. Detection of and localization of local recurrence could also improve the targeting of salvage radiotherapy or other loco-regional ablative techniques, also reducing complications.