Comparison of FDG PET and SPECT for detection of bone metastases in breast cancer

OBJECTIVE. The purpose of our study was to evaluate the efficacy of FDG PET and bone SPECT for diagnosing bone metastases in breast cancer. SUBJECTS AND METHODS. The study was a prospective series of 15 patients with breast cancer who underwent both PET and bone scanning with SPECT. Comparison was performed on a lesion-by-lesion analysis. MDCT, MRI, and the patient's clinical course were used as references. RESULTS. In the lesion-by-lesion analysis (n = 900), the sensitivity for diagnosing bone metastases was 85% for SPECT and 17% for PET, specificity was 99% for SPECT and 100% for PET, and accuracy was 96% for SPECT and 85% for PET. In the statistical analysis, bone SPECT was significantly superior to FDG PET for its sensitivity (p < 0.0001) and accuracy (P < 0.0001). Nostatistically significant difference was seen with regard to specificity. When classifying the bone metastases as osteoblastic or osteolytic, bone scanning classified 92% of metastases as osteoblastic and 35% of metastases as osteolytic, whereas PET classified 6% of metastases as osteoblastic and 90% of metastases as osteolytic. CONCLUSION. Bone SPECT is superior to FDG PET in detecting bone metastases in breast cancer. The sensitivity of osteoblastic lesions is limited with FDG PET. Surveillance of metastatic spread to the skeleton in breast cancer patients based on FDG PET alone is not possible.