The feasibility of ultra-early and fast total‑body [ Ga]Ga-FAPI-04 PET/CT scan.

Purpose: [ Ga]Ga-FAPI-04 PET/CT has been widely used in oncology patients. The patients need to lie still for 20-30 min during scan after waiting for 60 min post-tracer injection in traditional [ Ga]Ga-FAPI-04 PET/CT scan. This is difficult for some patients who are intolerant to prolonged horizontal positioning and waiting time. Therefore, we evaluated the diagnostic value of the images obtained in ultra-early and fast scan (5-min p.i., 30-s acquisition time) by the total-body [ Ga]Ga-FAPI-04 PET/CT and to investigate whether they could meet the requirements of clinical diagnosis.

Methods: Total-body [ Ga]Ga-FAPI-04 PET/CT was conducted in 12 patients at the Renji Hospital. Patients underwent PET with two acquisitions: 5-min p.i. and 30-s acquisition time (ultra-early and fast imaging) and 60-min p.i. and 300-s acquisition time (traditional imaging). Mean [ Ga]Ga-FAPI-04 injection dose was 1.85 MBq/kg.

Results: Forty-four lesions were detected in 12 patients on traditional imaging. All the 44 lesions on conventional imaging could also detected by ultra-early and fast imaging. For all the 12 patients, the tumor stage did not change, as same lesions were visible for every case in both images. There was no statistically significant difference in SUVmax of lesions between ultra-early and fast imaging and traditional imaging (12.5 ± 8.7 vs 13.7 ± 8.5, P = 0.528). Background bloodpool (4.0 ± 0.6 vs 0.9 ± 0.2, P < 0.001)and liver (2.5 ± 0.7 vs 1.0 ± 0.5, P < 0.001)at traditional imaging showed a significant decrease in SUVmean compared to ultra-early and fast imaging.

Conclusions: Ultra-early and fast imaging versus traditional [ Ga]Ga-FAPI-04 imaging resulted in equivalent tumor detection and lesion uptake. Ultra-early and fast total-body [ Ga]Ga-FAPI-04 PET/CT scan could meet clinical diagnostic requirements for patients with poor tolerant to prolonged horizontal positioning and waiting time.