PT - JOURNAL ARTICLE AU - Nilsson, Ted AU - Rasinski, Pawel AU - Smedby, Örjan AU - af Burén, Siri AU - Sparrelid, Ernesto AU - Löhr, J. Matthias AU - Tran, Thuy A. AU - Blomgren, August AU - Tzortzakakis, Antonios AU - Axelsson, Rimma AU - Holstensson, Maria TI - Acquisition Duration Optimization Using Visual Grading Regression in [<sup>68</sup>Ga]FAPI-46 PET Imaging of Oncologic Patients AID - 10.2967/jnmt.123.267156 DP - 2024 Apr 16 TA - Journal of Nuclear Medicine Technology PG - jnmt.123.267156 4099 - http://tech.snmjournals.org/content/early/2024/04/16/jnmt.123.267156.short 4100 - http://tech.snmjournals.org/content/early/2024/04/16/jnmt.123.267156.full AB - Fibroblast activation protein is a promising target for oncologic molecular imaging with radiolabeled fibroblast activation protein inhibitors (FAPI) in a large variety of cancers. However, there are yet no published recommendations on how to set up an optimal imaging protocol for FAPI PET/CT. It is important to optimize the acquisition duration and strive toward an acquisition that is sufficiently short while simultaneously providing sufficient image quality to ensure a reliable diagnosis. The aim of this study was to evaluate the feasibility of reducing the acquisition duration of [68Ga]FAPI-46 imaging while maintaining satisfactory image quality, with certainty that the radiologist’s ability to make a clinical diagnosis would not be affected. Methods: [68Ga]FAPI-46 PET/CT imaging was performed on 10 patients scheduled for surgical resection of suspected pancreatic cancer, 60 min after administration of 3.6 ± 0.2 MBq/kg. The acquisition time was 4 min/bed position, and the raw PET data were statistically truncated and reconstructed to represent images with an acquisition duration of 1, 2, and 3 min/bed position, additional to the reference images of 4 min/bed position. Four image quality criteria that focused on the ability to distinguish specific anatomic details, as well as perceived image noise and overall image quality, were scored on a 4-point Likert scale and analyzed with mixed-effects ordinal logistic regression. Results: A trend toward increasing image quality scores with increasing acquisition duration was observed for all criteria. For the overall image quality, there was no significant difference between 3 and 4 min/bed position, whereas 1 and 2 min/bed position were rated significantly (P &lt; 0.05) lower than 4 min/bed position. For the other criteria, all images with a reduced acquisition duration were rated significantly inferior to images obtained at 4 min/bed position. Conclusion: The acquisition duration can be reduced from 4 to 3 min/bed position while maintaining satisfactory image quality. Reducing the acquisition duration to 2 min/bed position or lower is not recommended since it results in inferior-quality images so noisy that clinical interpretation is significantly disrupted.