Abstract
18F-FDG PET has limited diagnostic applications in malignant melanoma (MM). 18F-PFPN is a novel PET probe with high affinity and selectivity for melanin. We conducted a clinical study with two aims, firstly to investigate the biodistribution and radiation dosimetry of 18F-PFPN in healthy volunteers, and secondly, to examine the diagnostic utility of 18F-PFPN PET imaging in patients with MM. Methods: 18F-PFPN was synthesized through a fluoro-for-tosyl exchange reaction. Five healthy volunteers were enrolled to investigate the biodistribution, pharmacokinetics, radiation dosimetry, and safety of the tracer. Subsequently, a total of 21 patients with clinically suspected or confirmed MM underwent both 18F-PFPN PET/MR and 18F-FDG PET/CT scans. Normalized maximum standardized uptake values of selected lesions were determined for both tracers and compared in patient- and lesion-based analyses. Results: 18F-PFPN has elevated radiochemical yield and was highly stable in vivo. In healthy volunteers, 18F-PFPN was safe and well-tolerated and its effective absorbed dose was comparable to that of 18F-FDG. In patient-based analysis, 18F-PFPN uptake was higher than 18F-FDG for both primary tumors and nodal metastases. In lesion-based analysis,18F-PFPN PET imaging could detect 365 metastases that were missed on 18F-FDG PET. Additionally, 18F-PFPN PET imaging had clinical value in distinguishing false-positive lesions on 18F-FDG PET. Conclusion: 18F-PFPN is a safe and well-tolerated melanin PET tracer. In a pilot clinical study, 18F-PFPN PET imaging outperformed traditional 18F-FDG PET in identifying both primary MM and its distant spread.
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