Comparison between Ga-68-FAP PET/CT and post-therapy Lu-177-FAP SPET/CT in patients with pancreatic ductal adenocarcinoma (PDAC) undergoing Peptide Targeted Radioligand Therapy (PTRT) using Lu-177-, Ac-225- and Y-90-labeled 3BP-3940

Ziel/Aim: The purpose of our study was to compare Ga-68-FAP PET/CT and post-therapy Lu-177-FAP SPET/CT in patients with pancreatic ductal adenocarcinoma (PDAC) during their first PTRT cycle.

Methodik/Methods: A total of 10 patients (3 males, 7 females, mean age 59 years) with biopsy-proven PDAC underwent Ga-68-FAP-3940 and Lu-177-FAP-3940 SPECT/CT within 1- 6 days (mean 2 d) between the two examinations. SPECT/CTs were acquired at 16-24 h post-injection; lesions were given a score from 0 to 4 depending on the uptake of the radiopharmaceutical (0 being lowest and 4 highest). The number of tumor lesions which were identified on Lu-177-FAP-3940 scans was compared to those detected on Ga-68-FAP-3940 PET/CT studies obtained before the first PTRT.

Ergebnisse/Results: A total of 148 lesions were detected; 61 (46%) lesions were seen on both modalities (concordant). Among the remaining discordant lesions, all were positive on Ga-68-FAP-3940 and not detected by Lu-177-FAP-3940 SPECT/CT. No new lesions were detected on SPECT/CT alone. The sensitivity, for Lu-177-FAP-3940 as compared to Ga-68-FAP-3940 were as follows: primary pancreas 75%, lymph nodes 64%, bones 26%, liver 36%, peritoneum 36% and muscle/connective tissue 100%. Concordant lesions (n=57; largest size 12 cm, smallest size 2 cm) were significantly larger than discordant lesions (n=66; largest size 8 mm, smallest size 2 mm).

Schlussfolgerungen/Conclusions: Lu-177-FAP-3940 SPECT/CT posttherapy scans exhibited a good sensitivity for detecting metastases. 46% lesions were detected in SPECT/CT as compared to Ga-68-FAP-3940 PET/CT. Hence, SPECT/CT was extremely useful for evaluation of therapy response and planning further therapies.

Publikationsverlauf

Artikel online veröffentlicht:
25. März 2024