F-18 fluoro-deoxy-glucose and F-18 sodium fluoride cocktail PET/CT scan in patients with breast cancer having equivocal bone SPECT/CT

INTRODUCTION: Although single-photon emission computed tomography (SPECT)/computed tomography (CT) plays a major role in the characterization of equivocal lesions on bone scintigraphy, it remains equivocal in a fraction of these patients. We evaluated the additional value of cocktail F-18 sodium fluoride (18F-NaF) and F-18 fluorodeoxyglucose (18F-FDG) co-injection positron emission tomography (PET) (cocktail PET) in these patients. MATERIALS AND METHODS: Fifteen breast cancer patients, who had equivocal findings on the whole body bone scan (WBS) and SPECT/CT, were subjected to a cocktail PET/CT scan. The cocktail PET/CT was performed by co-administration of 18F-FDG and 18F-NaF in a ratio of about 2.4, with the total administered activity kept at approximately 10 mCi. RESULTS: Of the 15 patients, seven were with locally advanced breast cancer (LABC) and the other eight were referred because of suspicion of recurrent disease on follow-up. Of the seven patients with LABC, the cocktail PET scan was positive for all the lesions suspicious on WBS and SPECT/CT. Additionally, it showed uptake in the primary tumor and ipsilateral axillary lymph nodes as well as identified additional osseous, lymph nodal, and solid organ metastases in these patients. Similarly, of the eight patients studied for suspicion of recurrence, the cocktail PET scan was found to be positive in seven patients. In three patients, additional osseous lesions were noted. CONCLUSION: The cocktail PET/CT scan can characterize almost all the suspicious equivocal lesions on the bone scan and SPECT/CT. The distinct advantage of identifying lymph nodal and solid organ metastases allows it to be considered as a useful imaging modality in patients with equivocal bone SPECT/CT.