Utility of [F]FSPG PET to Image Hepatocellular Carcinoma: First Clinical Evaluation in a US Population.

Purpose: Non-invasive imaging is central to hepatocellular carcinoma (HCC) diagnosis; however, conventional modalities are limited by smaller tumors and other chronic diseases that are often present in patients with HCC, such as cirrhosis. This pilot study evaluated the feasibility of (4 S)-4-(3-[F]fluoropropyl)-L-glutamic acid ([F]FSPG) positron emission tomography (PET)/X-ray computed tomography (CT) to image HCC. [F]FSPG PET/CT was compared to standard-of-care (SOC) magnetic resonance imaging (MRI) and CT, and [C]acetate PET/CT, commonly used in this setting. We report the largest cohort of HCC patients imaged to date with [F]FSPG PET/CT and present the first comparison to [C]acetate PET/CT and SOC imaging. This study represents the first in a US HCC population, which is distinguished by different underlying comorbidities than non-US populations. Procedures: x transporter RNA and protein levels were evaluated in HCC and matched liver samples from The Cancer Genome Atlas ( n = 16) and a tissue microarray ( n = 83). Eleven HCC patients who underwent prior MRI or CT scans were imaged by [F]FSPG PET/CT, with seven patients also imaged with [C]acetate PET/CT. Results: x transporter RNA and protein levels were elevated in HCC samples compared to background liver. Over 50 % of low-grade HCCs and ~70 % of high-grade tumors exceeded background liver protein expression. [F]FSPG PET/CT demonstrated a detection rate of 75 %. [F]FSPG PET/CT also identified an HCC devoid of typical MRI enhancement pattern. Patients scanned with [F]FSPG and [C]acetate PET/CT exhibited a 90 and 70 % detection rate, respectively. In dually positive tumors, [F]FSPG accumulation consistently resulted in significantly greater tumor-to-liver background ratios compared with [C]acetate PET/CT. Conclusions: [F]FSPG PET/CT is a promising modality for HCC imaging, and larger studies are warranted to examine [F]FSPG PET/CT impact on diagnosis and management of HCC. [F]FSPG PET/CT may also be useful for phenotyping HCC tumor metabolism as part of precision cancer medicine. [ABSTRACT FROM AUTHOR]