Dynamic PET/CT scan of ⁶⁸Ga-FAPI-04 for the optimal acquisition time in suspected malignant hepatic cancer patients

Purpose: Dynamic PET/CT scan of ⁶⁸Ga-FAPI-04 in patients with suspected malignant hepatic lesions were retrospectively analyzed to find the optimal acquisition time with better lesion detection rate.

Methods: Twenty-two patients with lesions confirmed by CT or MRI were performed with dynamic ⁶⁸Ga-FAPI-04 PET/CT scan. Tracer uptake of lesions and normal organs at different time points were analyzed. Standardized uptake value (SUV) and tumor-to-background (TBR) were calculated based on the quantification of images.

Results: SUV of normal organs decreased rapidly from 10 to 30 min and decreased gradually from 30 to 60 min. Besides, the uterus showed a particularly high uptake in all patients (12.62 ± 4.58 at 10 min p.i., 12.04 ± 3.99 at 30 min p.i., 10.92 ± 2.38 at 60 min p.i.). SUV of lesions decreased gradually, while TBR increased from 10- to 60-min post-injection. Visual analysis verified a comparable lesion detectability of 30 min and 60 min with images of 10 min showing a decreased lesion detection number.

Conclusion: This study revealed that similar detection rates were achieved at both 30 and 60 min, suggesting a static scan at 30 min to be appropriate in the clinic. Besides, although with high lesion uptake, early ⁶⁸Ga-FAPI-04 PET imaging at 10 min after tracer injection could cause missed lesion detection.