The role of fluorodeoxyglucose, 18F-dihydroxyphenylalanine, 18F-choline, and 18F-fluoride in bone imaging with emphasis on prostate and breast

Diagnostic imaging has played a major role in the evaluation of patients with bone metastases. The imaging modalities have included bone scintigraphy, computed tomography, magnetic resonance imaging, and most recently PET/CT, which can be performed with different tracers, including fluorodeoxyglucose (FDG), F-18-fluoride, F-18-choline (FCH), and F-18-DOPA (dihydroxyphenylalanine). For most tumors the sensitivity of FDG in detecting bone metastases is similar to bone scintigraphy; additionally it can be used to monitor the response to chemotherapy and hormonal therapy. F-18-Fluoride may provide a more sensitive "conventional" bone scan and is superior for FDG nonavid tumors, but, nevertheless, FDG in "early disease" often has clear advantages over F-18-fluoride. Although more data need to be obtained, it appears that FCH is highly efficient in preoperative management regarding N and M staging of prostate cancer once metastatic disease is strongly suspected or documented. For neuroendocrine tumors and in particular in medullary thyroid cancer, DOPA is similar to F-18-fluoride in providing high quality information regarding the skeleton. Nevertheless, prospective studies with large patient groups will be essential to define the exact diagnostic role of FCH and DOPA PET in different clinical settings.