Pilot Study of the Utility of the Synthetic PET Amino-Acid Radiotracer Anti-1-Amino-3-[18F]Fluorocyclobutane-1-Carboxylic Acid for the Noninvasive Imaging of Pulmonary Lesions

Purpose

Anti-1-amino-3-[¹⁸F]fluorocyclobutane-1-carboxylic acid (anti-3-[¹⁸F]FACBC) is a synthetic amino acid positron emission tomography (PET) radiotracer with utility in detection of prostate carcinoma and brain tumors and has also been shown to have uptake in lung tumor cell lines. The purpose of this study is to determine the uptake characteristics of anti-3-[¹⁸F]FACBC in lung carcinoma and if this radiotracer may help characterize pulmonary lesions.

Procedures

Ten patients with pulmonary lesions scheduled for surgical resection or biopsy underwent 45-min dynamic PET-CT imaging of the thorax after IV injection of 214.6–384.8MBq of anti-3-[¹⁸F]FACBC. Anti-3-[¹⁸F]FACBC uptake was compared with that of routine 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) PET-CT scans of the same patient and validated with a combination of pathology, imaging and clinical follow-up. Immunohistochemistry for Ki-67 was performed on tissue samples.

Results

There were nine malignant (seven lung nodules and two mediastinal nodes), two inflammatory, and one carcinoid lesion ranging from 1 to 3.75 cm. Mean(±SD) SUV_max of malignant lesions was 6.2(±2.6), 5.9(±2.7), 5.9(±3.4), and 5.7(±3.3), at 8, 16, 28, and 40 min, respectively; while for inflammatory lesions at the same time points, 4.1(±0.6), 3.3(±0.9), 2.2(±0.03), and 2.3(±0.03), respectively. The carcinoid tumor had SUV_max of 2.8, 2.6, 1.5, and 0.9 at similar time points. Mean SUV_max of all malignant lesions was higher than that of inflammatory lesions for anti-3-[¹⁸F]FACBC, and was statistically significant at greater than 28 min post-radiotracer infusion (p?<?0.05). There was no significant correlation of anti-3-[¹⁸F]FACBC activity with Ki67, though there was a positive trend. There was a strong correlation between anti-3-[¹⁸F]FACBC and [¹⁸F]FDG uptake.

Conclusions

Anti-3-[¹⁸F]FACBC uptake in malignant lesions is greater than in inflammatory lesions with a higher degree of separation of uptake on delayed imaging. More comprehensive study is required to determine the diagnostic performance of anti-3-[¹⁸F]FACBC in the characterization of pulmonary lesions.