Role of 11C-choline PET/CT in the restaging of prostate cancer patients showing a single lesion on bone scintigraphy

Aim To assess the utility of 11 C-choline PET/CT in the restaging of prostate cancer (PC) patients who showed a single finding on bone scintigraphy (BS) that was classified as equivocal or suspected for metastatic lesion. Materials and methods A total of 25 PC patients with biochemical failure (mean PSA value 11.1 ng/mL; median value 6.3 ng/mL; range 0.2–37.7 ng/mL) after primary treatment were included in this retrospective study. All of them showed a single lesion on BS reported as suspected for metastatic lesion or as equivocal finding. Patients underwent 11 C-choline PET/CT within 1–4 months from BS. Validation was established by follow-up for at least 6 months. Results On the basis of biopsy confirmation and/or 6-month follow-up, 22 of 25 patients were classified as positive for the presence of metastatic bone lesions: 13 with a single lesion and 9 with multiple lesions. 11 C-choline PET/CT was positive in 19/25 patients and, on a lesion basis, it showed 50 positive findings. BS results were confirmed in 8/25 (32%) patients. 11 C-choline PET/CT detected multiple sites of relapse in 11/25 (44%) patients: in 2/11, a single bone lesion associated with other extraosseous sites of relapse; in 6/11, multiple bone lesions; in 3/11, multiple bone lesions and other extraosseous localizations. Finally, 6/25 patients were negative on 11 C-choline PET/CT. In 3/6 patients, an osteoblastic lesion was seen on CT attenuation correction images (PET false negative; BS true positive), while in 3/6 patients only findings suggestive of the presence of degenerative disease were found (PET true negative; BS false positive). On a patient basis, 11 C-choline PET/CT showed a diagnostic sensitivity of 86% (19/22) and a specificity of 100% (19/19). Conclusions In our study, 11 C-choline PET/CT detected unknown lesions in 11/25 patients. Patients with a single equivocal finding on BS could have important additional information from 11 C-choline PET/CT study, especially in the detection of additional metastases, to choose an appropriate treatment.