Comparison of bone scintigraphy with Tc-99m-DPD and PET/CT with C-11-choline for the detection of bone metastases in patients with prostate cancer

Objectives PET/CT with C-11-choline (choline-PET/CT) is a promising tool for imaging prostate carcinomas and its metastases. We compared the value of Choline-PET/CT for the detection of bone metastases with the standard imaging modality Tc-99m-bone-scintigraphy (scintigraphy).

Methods Retrospective analysis of scintigraphy and choline-PET/CT in 31 patients with histological proven prostate cancer and clinical suspicion of metastases, who were examined by both methods (mean time lapse of 13 days between the examinations). The examinations were evaluated lesion wise and region wise by a radiologist and a nuclear medicine physician. A consensus of all further examinations and a clinical follow-up of at least 6 months served as gold standard.

Results The mean PSA at the time of the examinations was 3,62 ng/ml (range: 0,97 to 26 ng/ml). In total 82 bone lesions were identified. In 11 of 31 patients (35%) neither cholin-PET/CT nor scintigraphy detected bone metastases. 20 of 31 patients (65%) had bone metastases and in 6 of these 20 patients the results of cholin-PET/CT and scintigraphy were identical. The accuracy for the detection of bone metastases was 92% for scintigraphy and 81% for choline-PET/CT. Scintigraphy showed a higher sensitivity whereas choline-PET/CT showed a superior specificity (82% vs. 36%). The lowest sensitivity of choline-PET/CT was found for metastases in ribs. In the examined patients there was no correlation between the choline-uptake of bone metastases and clinical parameters (grading, PSA).

Conclusions PET/CT with C-11-Choline is a method with a high specificity for the detection of bone metastases in whole body staging of patients with advanced prostate cancer. Nevertheless, due to its limited sensitivity it can not replace the widely available bone scintigraphy in many cases