PT  - JOURNAL ARTICLE
AU  - Naeimi, Mahnoosh
AU  - Choyke, Peter L.
AU  - Dendl, Katharina
AU  - Mori, Yuriko
AU  - Staudinger, Fabian
AU  - Watabe, Tadashi
AU  - Koerber, Stefan A.
AU  - Röhrich, Manuel
AU  - Debus, Jürgen
AU  - Kratochwil, Clemens
AU  - Haberkorn, Uwe
AU  - Giesel, Frederik L.
TI  - Three-Time-Point PET Analysis of <sup>68</sup>Ga-FAPI-46 in a Variety of Cancers
AID  - 10.2967/jnumed.122.264941
DP  - 2023 Apr 01
TA  - Journal of Nuclear Medicine
PG  - 618--622
VI  - 64
IP  - 4
4099  - http://jnm.snmjournals.org/content/64/4/618.short
4100  - http://jnm.snmjournals.org/content/64/4/618.full
SO  - J Nucl Med2023 Apr 01; 64
AB  - A growing family of 68Ga-fibroblast activation protein inhibitor (FAPI) PET probes has shown promise in imaging a variety of medical conditions. 68Ga-FAPI-46, in particular, has emerged as unique for both its diagnostic and its theranostic applications; however, the optimal timing of PET remains unclear. Therefore, we evaluated uptake at 3 time points after 68Ga-FAPI-46 administration in a spectrum of tumor types. Methods: The cohort consisted of 43 patients with diverse cancer diagnoses undergoing 68Ga-FAPI-46 PET/CT at 3 time points (10 min, 1 h, and 3 h). We determined the tracer uptake based on SUVmean and SUVmax and on tumor-to-background-ratios (TBRs) (SUVmax/SUVmean). Results: There were 171 lesions in the 43 patients. Comparing all lesions at different time points, the mean SUVmax was maximal at 10 min (8.2) and declined slightly at 1 h (8.15) and 3 h (7.6) after tracer administration. Similarly, the mean SUVmax log still had a similar pattern in primary lesions at 10 min, 1 h, and 3 h (n = 30; 0.98, 1.01, and 0.98, respectively), lymph node metastases (n = 37; 0.82, 0.84, and 0.81, respectively), and distant metastases (n = 104; 0.81, 0.79, and 0.74, respectively). TBR also showed nonsignificant differences at the 3 times. Conclusion: 68Ga-FAPI-46 PET/CT imaging revealed remarkably stable tumor and background uptake as determined by SUV metrics and maintained high TBRs within 3 h of injection. Thus, it may be possible to scan with 68Ga-FAPI-46 within 10–20 min of injection, improving workflow and decreasing patient wait times. Confirmation of these findings in a larger cohort is under way.