5 0 1What ' s known on the subject? and What does the study add? Positron emission tomography/computed tomography (PET/CT) with choline and fl uoride for the detection of metastases in patients with prostate cancer have each been evaluated, with mixed results. Choline PET/CT has been evaluated against pelvic lymphadenectomy, generally with a low sensitivity but a high specifi city; however, the study populations have been heterogenous. Fluoride PET/CT has been evaluated against other imaging methods, such as bone scan, single photon emission CT and MRI, and has been shown to have high specifi city as well as sensitivity for bone metastases, but there are no studies with biopsy verifi cation. This is the fi rst study that evaluates the clinical use of both choline and fl uoride PET/CT on the same patients in a well-defi ned population of patients with high-risk prostate cancer. OBJECTIVE• To investigate how often positron emission tomography/computed tomography (PET/CT) scans, with both 18 F-fl uorocholine and 18 F-fl uoride as markers, add clinically relevant information for patients with prostate cancer who have high-risk tumours and a normal or inconclusive planar bone scan. PATIENTS AND METHODS• Patients with prostate cancer with prostate specifi c antigen (PSA) levels between 20 and 99 ng/mL and/or Gleason score 8 -10 tumours, planned for treatment with curative intent based on routine staging with a negative or inconclusive bone scan, were further investigated with a 18 F-fl uorocholine and a 18 F-fl uoride PET/CT.• None of the patients received hormonal therapy before the staging procedures were completed. RESULTS• For 50 of the 90 included patients (56%) one or both PET/CT scans indicated metastases.• 18 F-fl uorocholine PET/CT indicated lymph node metastases and/or bone metastases in 35 patients (39%).• 18 F-fl uoride PET/CT was suggestive for bone metastases in 37 patients (41%).• In 18 patients (20%) the PET/CT scans indicated widespread metastases, leading to a change in therapy intent from curative to non-curative.• Of the patients with positive scans, 74% had Gleason score 8 -10 tumours. Of the patients with Gleason score 8 -10 tumours, 64% had positive scans. CONCLUSIONS• PET/CT scans with 18 F-fl uorocholine and 18 F-fl uoride commonly detect metastases in patients with high-risk prostate cancer and a negative or inconclusive bone scan.• For 20% of the patients the results of the PET/CT scans changed the treatment plan. KEYWORDS INTRODUCTIONThe most common sites for metastases from prostate cancer are the pelvic and retroperitoneal lymph nodes and the axial skeleton. Radical local therapy is usually not considered for patients with skeletal metastases, widespread or large lymph node metastases. The standard of reference for detection of lymph node metastases is an extended pelvic lymph node dissection (ePLND) [ 1,2 ] . However, this procedure is invasive and associated with complications and morbidity [ 3 ] . Positron emission tomography (PET) with 11 C-or 18 F-labelledAccepted for publication 20...

Repeated FDG-PET/CT seems to predict histological response. However, with the histological response criteria used in this study, five non-responders were not identified by the second FDG-PET/CT investigation.

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