Trans -1-amino-3-18 F-fluorocyclobutanecarboxylic acid ( anti -18 F-FACBC) is a feasible alternative to11 C-methyl- L -methionine and magnetic resonance imaging for monitoring treatment response in gliomas

• Published in: Nuclear medicine and biology 2013, Vol.40 (6), p.808-815
• Main Authors: Sasajima, Toshio, Ono, Takahiro, Shimada, Naoya, Doi, Yoshihiro, Oka, Shuntaro, Kanagawa, Masaru, Baden, Atsumi, Mizoi, Kazuo
• Format: Article
• Language: English
• Subjects: Radiology
• ISSN: 0969-8051
• DOI: 10.1016/j.nucmedbio.2013.04.007

Abstract Introduction Amino acid PET tracers are promising for visualizing gliomas and evaluating radiochemotherapeutic effects. We compared the glioma detection and early response assessment utility between trans -1-amino-3-fluoro-1-14 C-cyclobutanecarboxylic acid ( anti -14 C-FACBC) and3 H-methyl- l -methionine (3 H-Met) by simultaneously analyzing their uptake by rat gliomas treated with and without temozolomide (TMZ) in vitro and in vivo. Methods C6 rat gliomas were incubated with low-dose TMZ to induce chemoresistance. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated a significantly greater surviving fraction in the TMZ-resistant subline (C6R) than in drug-naive cells (C6). The anti -14 C-FACBC and3 H-Met uptakes were quantified using a triple-label accumulation assay to examine the relationship between tracer uptake and proliferation (3 H-thymidine (TdR) accumulation rate) in tumor cells. C6 and C6R cells were inoculated into the right and left basal ganglia, respectively, of rats. Efficacy of TMZ against the orthotopic gliomas was analyzed by MRI, Evans blue extravasation, anti -14 C-FACBC and3 H-Met autoradiography, and MIB-5 proliferation index. Results The3 H-TdR accumulation rate and amino acid tracer ( anti -14 C-FACBC and3 H-Met) uptake significantly decreased 48 and 72 h, respectively, after TMZ treatment in C6 but not C6R cells. Anti -14 C-FACBC uptake correlated significantly with3 H-Met uptake and the3 H-TdR accumulation rate. In the intracerebral glioma model, anti -14 C-FACBC and3 H-Met autoradiography clearly delineated the tumor extent, which spread well beyond the high-T2-intensity and enhancing lesions visible on MRI and Evans blue extravasation. TMZ significantly decreased anti -14 C-FACBC and3 H-Met uptake and the MIB-5 index of C6 but not C6R tumors. TMZ inhibited tracer uptake and tumor proliferation before morphological changes on MRI. Conclusions Anti -14 C-FACBC, like3 H-Met, was more sensitive than post-contrast T1-weighted MRI for detecting tumor extent and early tumor response to TMZ treatment. Anti -18 F-FACBC should be a sensitive and precise imaging biomarker for tumor extent visualization and response assessment in glioma patients.