Dynamic PET/CT imaging of ¹⁸F-(2S, 4R)4-fluoroglutamine in healthy volunteers and oncological patients

The purpose of this study was to compare dynamic ¹⁸F-FGln PET/CT images of healthy subjects and cancer patients and explore the best imaging phase for different cancers.

Thirteen healthy volunteers and 31 cancer patients separately underwent ¹⁸F-FGln and ¹⁸F-FDG PET/CT scans within 1 week. The distributions of ¹⁸F-FGln and ¹⁸F-FDG in the whole body and the tumor avidity were analyzed and compared. The tumor maximum standardized uptake values (SUVmax) and tumor-to-nontumor SUV ratio (SUR) of ¹⁸F-FGln/PET at different scan phases were compared.

Compared to the healthy subjects, the cancer patients had lower ¹⁸F-FGln activity (SUVmean) in most normal organs, especially in the lung, muscle, spleen, and heart (p < 0.05). Additionally, the FGln-avid tumors did not necessarily manifest as FDG-avid and vice versa. Overall, among the 31 primary malignant lesions confirmed by biopsy or postoperative pathological analysis, 29 showed increased radioactive uptake on all ¹⁸F-FGln PET/CT imaging phases. The peak of SUVmax in breast and thyroid cancers was within 10 min, while in lung cancers, the plateau of SUVmax was within 30 min to 60 min. The SURs of lung cancer (p = 0.046) and thyroid cancer (p = 0.794) increased from the early-phase to the late-phase acquisition; however, a significant decrease was observed in the breast lesions (p = 0.022).

¹⁸F-FGln images may further supplement the diagnostic ability of ¹⁸F-FDG in cancer patients and detect metabolic changes in different tumors. Furthermore, the imaging time for ¹⁸F-FGln PET/CT needs to be optimized for different cancer types to improve the contrast resolution of tumors.