Combined 18F-naf and fluciclovine administration for PET imaging of prostate cancer.

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e17533 Background: 18F-fluciclovine is FDA approved for the detection of recurrent and metastatic prostate cancer. At our institution, 18F-fluciclovine PET had replaced 18F-NaF PET, but fluciclovine has mild to no uptake in dense sclerotic bony lesions. F18-NaF offers increased sensitivity and specificity in detection of osseous metastases and therefore we converted to using a combination of 18F-NaF and 18F-fluciclovine in patients with biochemical recurrence. In this study, we assessed the feasibility of performing a combined F18- fluciclovine and F18-NaF study, and evaluated the biodistribution of the combined radiotracers in patients with prostate cancer. Methods: We retrospectively reviewed 16 consecutive patients over a period of 3 months. 5 mCi of F18-NaF was injected, followed 45 minutes later by a 10 mCi injection of F18-fluciclovine. Patients were asked to hydrate after NaF injection and empty their bladder immediately prior to scanning. A non-diagnostic CT for attenuation correction and an emission PET scan were acquired on a time of flight Discovery 690 PET/CT (GE Healthcare) within 5 minutes of fluciclovine injection. We characterized the extent of soft tissue and osseous disease, as well as assessed the image quality, taking note for F18-NaF excretion in the bladder and the potential scatter artifact limiting evaluation of the prostate bed. Results: On average patients received 5.5 +/- 0.5 mCi of F18-NaF and 10.4 +/- 0.8 mCi of F18-fluciclovine. All 16 patients had diagnostic quality scans. None had limited evaluation of the prostate bed secondary to artifacts from bladder scatter. 10 patients (62.5%) had residual or recurrent prostate cancer within the prostate bed, of which 3 (18.8%) had distant nodal disease in the perirectal, pelvis, retroperitoneal, or periaortic lymph node regions. 7 patients (43.8%) demonstrated osseous metastatic lesions within the clavicle, sternum, iliac wing, vertebra, coccyx, or sacrum. Conclusions: Combined 18F-NaF and 18F-fluciclovine scans in patients with prostate cancer is a feasible method for detecting soft tissue recurrence and osseous disease. Bladder excretion from F18-NaF does not obscure the prostate bed nor degrades the diagnostic quality of the exam. The combined use of 18F-fluciclovine and F18-NaF in one PET/CT acquisition has the potential to increase the sensitivity for detecting prostate cancer and limit the time and radiation dose delivered compared to the conventional, separate acquisitions of the two radiotracers.