Prospective evaluation of 11C-choline positron emission tomography/computed tomography and diffusion-weighted magnetic resonance imaging for the nodal staging of prostate cancer with a high risk of lymph node metastases.
Contrast-enhanced computed tomography (CT) and magnetic resonance (MR) imaging for lymph node (LN) staging of prostate cancer (PCa) are largely inadequate. Our aim was to assess prospectively the sensitivity, specificity, and positive and negative predictive values for the LN staging by (11)C-choline positron emission tomography (PET)-CT and MR diffusion-weighted imaging (DWI) of the pelvis before retropubic radical prostatectomy (RRP) with extended pelvic LN dissection (PLND). From February 2008 to August 2009, 36 patients with histologically proven PCa and no pelvic LN involvement on contrast-enhanced CT with a risk ≥ 10% but ≤ 35% at LN metastasis according to the Partin tables were enrolled in this study. Patients preoperatively underwent (11)C-choline PET-CT and DWI. Subsequently all patients underwent a wide RRP and an extended PLND. Sensitivity, specificity, and positive and negative predictive values (PPV and NPV) for LN status of (11)C-choline PET-CT and DWI were calculated with the final histopathology of the LNs as comparator. Seventeen patients (47%) had a pN1 stage, and 38 positive LNs were identified. On a LN region-based analysis, sensitivity, specificity, PPV, NPV, and the number of correctly recognised cases at (11)C-choline PET-CT were 9.4%, 99.7%, 75.0%, 91.0%, and 7.9%, respectively, and at DWI these numbers were 18.8%, 97.6%, 46.2%, 91.7%, and 15.8%, respectively. Twelve LN regions containing macrometastases, of which 2 had capsular penetration, were not detected by (11)C-choline PET-CT; 11 LNs, of which 2 had capsular penetration, were not detected by DWI. This is a small study with 36 patients, but we intend to recruit more patients. From this prospective histopathology-based evaluation of (11)C-choline PET-CT and DWI for LN staging in high-risk PCa patients, it is concluded that these techniques cannot be recommended at present to detect occult LN metastases before initial treatment.