One-Stop 68 Ga-FAPI/ 18 F-FDG Total-Body PET/CT Scan : More Theranostics Information Available
Huaping Gao, Han Tang, Zhe Zheng
1Division of Nuclear Medicine and Molecular Imaging, Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, VA.
Purpose:
This prospective study aims to assess the feasibility of a one-stop imaging protocol using 68 Ga-FAPI-04/ 18 F-FDG dual-radiotracer with dual-low-activity for tumor imaging.
Patients And Methods:
Forty patients underwent one-stop 68 Ga-FAPI-04 PET (PET FAPI ) and dual-radiotracer PET (PET DUAL ) using a total-body PET/CT scanner with a 194-cm axial field of view. After a half-dose (0.925 MBq/kg) 68 Ga-FAPI-04 PET/CT, an additional half-dose (1.85 MBq/kg) of 18 F-FDG was administered for a 60-minute dynamic acquisition. PET DUAL was reconstructed at 10-minute intervals (PET D0-10 , PET D10-20 , PET D20-30 , PET D30-40 , PET D40-50 , and PET D50-60 ). Data of lesion detectability, target-to-background ratios, tumor staging, and total radiation dose were analyzed. A target-to-liver ratio (TLR) ≥ 3 on PET FAPI was considered indicative of sufficient fibroblast activation protein expression.
Results:
PET D50-60 and PET FAPI showed similar performance in detecting primary tumors (42 vs 41, P > 0.999). However, significantly more metastatic lesions were identified on PET D50-60 compared with PET FAPI (102 vs 60, P < 0.001). PET FAPI demonstrated significantly higher TLR, target-to-blood-pool ratio, and target-to-normal-tissue ratio than PET DUAL ( P < 0.05). Lesion detectability was similar across PET D10-20 , PET D20-30 , PET D30-40 , PET D40-50 , and PET D50-60 (all P 's > 0.05). Notably, PET D30-40 and PET D40-50 detected all lesions identified by PET D50-60 . PET D40-50 showed no significant differences in TLR, target-to-blood-pool ratio, and target-to-normal-tissue ratio compared with PET D50-60 ( P > 0.05). Up to 94.9% of malignant primary lesions exhibited a TLR ≥ 3 on PET FAPI . The average effective dose was 9.85 ± 2.19 mSv, similar to that of a whole-body 18 F-FDG PET/CT.
Conclusions:
This one-stop, dual-radiotracer, dual-low-activity imaging protocol combines the strengths of 68 Ga-FAPI-04 and 18 F-FDG, offering a shorter imaging duration and reduced radiation exposure.
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