Comparative effectiveness of [(18) F]-fluorocholine PET-CT and pelvic MRI with diffusion-weighted imaging for staging in patients with high-risk prostate cancer.

Background: Accurate staging is important before surgical decision in patients with high-risk prostate cancer (PCa). The purpose of this study was to prospectively compare the diagnostic performance of (18) F-FCholine and MRI with diffusion weighted imaging (DWIMRI) for local and regional lymph node (LN) staging before radical prostatectomy (RP) with extended pelvic lymphadenectomy (PLND).

Methods: We identified 47 patients who underwent (18) F-FCholine and DWIMRI followed by surgical treatment (either prostatectomy or LN dissection or an association of prostatectomy and LN dissection) between May 2010 and December 2012 at Bordeaux University Hospital. These patients were part of a prospective study (EudraCT number 2009-014839-21) evaluating the interest of (18) F-FCholine in staging of high-risk PCa. Diagnostic performances were retrospectively determined for each of (18) F-FCholine and DWIMRI considering LN invasion, each of prostate sextants, capsular invasion and extension to seminal vesicles. (18) F-FCholine and MR findings were correlated with histological findings.

Results: In a region-based LN analysis, the sensitivity and positive predictive value specificity were respectively, 56% and 98% for (18) F-Choline, and 17% and 97% for DWIMRI. In a patient-based analysis the sensitivity and positive predictive value were respectively 78% and 94% for (18) F-Choline and 33% and 84% for DWIMRI (P = 0.015). For tumor staging, DWIMRI showed better performances with a better specificity (69%) for sextants analysis and sensitivity to detect seminal vesicle invasion (73% vs. 36%).

Conclusions: (18) F-FCholine imaging appears to provide helpful additional information in the staging of high-risk PCa. It appears essential for predicting LN status due to its higher sensitivity and specificity for LN involvement. However, despite excellent performance, it cannot replace MRI that remains better for tumoral localization and local evaluation, especially for seminal vesicle invasion.

Patient Summary: This study highlights the interest of (18) F-Choline in the staging of high risk prostate cancer in addition with DWI MRI, especially so in the evaluation of lymph node involvement due to its high sensitivity and excellent specificity.