RT Journal Article SR Electronic T1 Initial Results of a Prospective Clinical Trial of 18F-Fluciclovine PET/CT in Newly Diagnosed Invasive Ductal and Invasive Lobular Breast Cancers JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1350 OP 1356 DO 10.2967/jnumed.115.170456 VO 57 IS 9 A1 Gary A. Ulaner A1 Debra A. Goldman A1 Mithat Gönen A1 Hanh Pham A1 Raychel Castillo A1 Serge K. Lyashchenko A1 Jason S. Lewis A1 Chau Dang YR 2016 UL http://jnm.snmjournals.org/content/57/9/1350.abstract AB 18F-labeled 1-amino-3-fluorocyclobutane-1-carboxylic acid (18F-fluciclovine) is a leucine analog PET/CT radiotracer that depicts amino acid transport into cells. Amino acid transport proteins have been shown to be upregulated in breast malignancies by microarray and immunohistochemical analysis, so we hypothesized that 18F-fluciclovine may provide a novel method of visualizing breast cancer and now report a prospective clinical trial of 18F-fluciclovine PET/CT in newly diagnosed advanced local invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC). Methods: Twenty-seven women with a new diagnosis of locally advanced IDC (n = 19) or ILC (n = 8) underwent PET/CT of the chest after intravenous administration of 370 MBq of 18F-fluciclovine. The SUVmax, SUVmean, metabolic tumor volume, and total lesion avidity were obtained for the primary breast tumor, axillary lymph nodes, and extraaxillary lymph nodes. Sites of previously unsuspected malignancy were recorded and confirmed by pathology. Results of 18F-fluciclovine PET/CT were compared with those of 18F-FDG PET/CT, when available, using the concordance correlation coefficient. Results: All locally advanced breast cancers were 18F-fluciclovine–avid. Of 21 patients with pathologically proven axillary nodal metastases, 18F-fluciclovine–avid axillary nodes were seen in 20. 18F-fluciclovine detected pathologically proven extraaxillary nodal metastases in 3 patients, including 2 previously unsuspected internal mammary nodes. Fourteen patients underwent 18F-FDG PET/CT for comparison with 18F-fluciclovine. Concordance for metabolic tumor volume between 18F-fluciclovine and 18F-FDG was strong (concordance correlation coefficient, 0.89; 95% confidence interval, 0.73–0.96), but concordance for SUVmax was weak (concordance correlation coefficient, 0.04; 95% confidence interval, −0.16–0.24). In patients with both modalities available (n = 14), primary ILCs (n = 4) demonstrated 18F-fluciclovine avidity (median SUVmax, 6.1; range, 4.5–10.9) greater than 18F-FDG avidity (median SUVmax, 3.7; range, 1.8–6.0). Primary IDCs (n = 10) had a lower 18F-fluciclovine avidity (median SUVmax, 6.8; range, 3.6–9.9) than 18F-FDG avidity (median SUVmax, 10; range, 3.3–43.5). Conclusion: 18F-fluciclovine PET/CT demonstrates potential for imaging of both IDC and ILC, including the detection of unsuspected extraaxillary nodal metastases. The low concordance for SUVmax between 18F-fluciclovine and 18F-FDG suggests that these tracers measure different biologic phenomena within the tumor. The apparently higher uptake of 18F-fluciclovine in ILC requires confirmation in a larger cohort.