Objective:

To explore the influence of different acquisition time

injection dose and reconstruction algorithm on the image quality of

64

Cu-FAPI-XT positron emission tomography (PET)/computed tomography (CT)

so as to provide empirical basis and reference for clinical practice.

Methods:

Eleven cancer patients from The First Affiliated Hospital of Guangzhou Medical University from June to September

2023 were retrospectively selected. Six patients were injected with high dose (2.22- 3.22 Mbq/kg) of

64

Cu-FAPI-XT

while other five patients were injected with low dose (1.59-2.18 Mbq/kg) of 64 Cu-FAPI-XT. Ordered subset expectation maximization (OSEM) and HYPER Iterative algorithms were used to reconstruct the 3.0 min/bed image respectively to simulate the image acquisition at 1.0 min/bed

1.5 min/bed

2.0 min/bed

2.5 min/bed and 3.0 min/bed. Two doctors scored all the images subjectively and compared the image quality

noise level and diagnostic value of different groups of images. Mean standard uptake value (SUV

mean

)

standard deviation (SD) and signal-to-noise ratio (SNR) of blood pools in liver and mediastinum were measured for semi-quantitative analysis.

Results:

Subjective evaluation: in the high-dose group (2.22-3.22 MBq/kg)

the images of 2.0 min/bed were reconstructed respectively by HYPER Iterative and OSEM

the image quality of which met the requirements of daily diagnosis (the scores were all ≥3 points). In the low-dose group (1.59-2.18 MBq/kg)

the image quality of 2.0 min/bed reconstructed by HYPER Iterative and 2.5 min/bed reconstructed by OSEM reached the requirements of daily diagnosis (scores≥3). Objective semi-quantitative analy

sis: at the same acquisition time

injecting different doses of

64

Cu-FAPI-XT to scan PET images

the image quality of HYPER Iterative reconstruction was significantly better than that of OSEM reconstruction (

P

＜0.05). In the high dose group (2.22-3.22 MBq/kg)

the image quality of 1.5 min/bed was obviously better than that of 1.0 min/bed (

P

＜0.05)

but there was no statistical difference between 1.5 min/bed image and 2.5 min/bed image (

P

＞0.05). There was no statistical difference in image quality between low dose recombinant (1.59-2.18 Mbq/kg) for 2.0 min/bed and 3.0 min/bed (

P

＞0.05).

Conclusion:

The PET/CT images of UMI Panorama were reconstructed by HYPER Iterative method

and high dose (2.22-3.22 Mbq/kg) of

64

Cu-FAPI-XT was injected

and the quality of PET images collected for 1.5 min/ bed met the requirements of daily diagnosis. Low dose (1.59-2.18 Mbq/kg) of

64

Cu-FAPI-XT was injected and collected for 2.0 min/bed

which can meet the daily diagnosis requirements.