Abstract
1097
Objectives: To evaluate the feasibility of fluciclovine, also known as anti-3-[18F]FACBC (Anti-1-amino-3-[18F]-fluorocyclobutane-1-carboxylic acid), PET imaging to identify recurrent brain metastatic disease in patients who are status post brain radiation for known metastatic brain disease.
Methods: The study was approved by Emory University Institutional Review Board and Radioactive Drug Research Council. 12 patients (5 M, 7 F, mean age 51, range 30-86) with previous brain radiation therapy for metastatic cerebral disease underwent fluciclovine PET imaging for evaluation of new or recurrent cerebral metastatic lesions identified on recent brain MR imaging. Fluciclovine PET analysis comprised semiquantitative PET parameters maximum and mean, and as a ratio to contralateral normal maximum and mean to determine metabolic tumor volume (MTV). MTV was compared to with post-gadolinium contrast enhanced T1-MRI. Lesions were also correlated with either subsequent histopathological confirmation or clinical imaging.
Results: A total of 17 intracranial lesions in 12 patients were identified with fluciclovine PET imaging. Primary site of disease included 6 (50%) lung cancer patients, 3 (25%) breast cancer patients and 1 (8.3%) patient each with colon cancer, renal cancer and melanoma. Of the 17 lesions, 15 were found to have significantly increased fluciclvoine uptake compared to the contralateral area of normal brain parenchyma. Two of the fluciclovine avid lesions were biopsied and were consistent with metastasis (1 adenocarcinoma of lung and 1 renal adenocarcinoma). Remaining 13 lesions with increased fluciclovine uptake had features consistent with metastasis on follow up imaging (increasing size and/or enhancement). Two of the 17 lesions with only mild fluciclovine uptake decreased in size on subsequent clinical imaging and were likely consistent with radiation necrosis.
Conclusions: PET imaging with radiolabeled amino acids has been shown be effective for brain tumor imaging, providing high contrast between tumor and normal brain parenchyma. The synthetic leucine amino acid analogue, fluciclovine has been recently FDA approved for evaluation of biochemical recurrent prostate cancer. Recent studies have been published demonstrating the utility of fluciclovine for glioma evaluation. Our findings suggest that fluciclovine can similarly be used for evaluation of new or recurrent brain metastasis in patients who previously have undergone brain radiotherapy where MRI is often limited due to background post-treatment changes.