TY - JOUR T1 - F18-PSMA PET/CT in prostate cancer patients: frequency and distribution of benign findings and comparison to Ga68-PSMA imaging<strong/> JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1262 LP - 1262 VL - 61 IS - supplement 1 AU - Olga Kagna AU - Maria Khairulin AU - Zohar Keidar Y1 - 2020/05/01 UR - http://jnm.snmjournals.org/content/61/supplement_1/1262.abstract N2 - 1262Background: Prostate-specific membrane antigen (PSMA)-targeted PET imaging has changed the management of patients with prostate cancer (PCa). F18-PSMA is a novel PSMA ligand which progressively replaces the previously introduced Ga68-PSMA. The purpose of this study was to assess the frequency of benign F18-PSMA avid PET/CT findings and their distribution compared to the incidence of non-tumor related uptake of Ga68-PSMA. Metastatic patterns of prostate cancer detected by F18-PSMA were also investigated. Materials and Methods: 101 consecutive F18-PSMA -1007 PET/CT studies performed over a period of 12 months were retrospectively reviewed by a nuclear medicine physician. All PET positive lesions were recorded. Differentiation between malignant and benign findings was based on information provided by the CT component of the PET/CT, previous clinical and imaging data, and the pattern of known pitfalls of PSMA imaging already presented in the literature. The incidence of F18-PSMA uptake considered to be related to benign processes was compared to the frequency of Ga68 -PSMA uptake in non-tumor findings already described in another patient population in our department (1). Results: 101 prostate cancer patients (mean age 73, range 48-93 years) underwent F18-PSMA PET/CT for various indications including staging (n=41), restaging (n=14), biochemical failure (n=27), response assessment (n=5), and follow up (n=14). In total, 154 F18-PSMA avid foci were found in 101 PET/CT studies. There were 31 non-malignant F18-PSMA avid foci in 30 studies (30%), most common in non-specific lymph nodes (n=10, 32%), followed by bone (n=8, 26%), thyroid gland (n=6, 19%), lungs (n=5, 32%), spleen and celiac ganglion one of each (3%). In comparison with a different cohort of 445 Ga68 -PSMA PET/CT studies presented previously (1) that demonstrated an incidence of non-tumor findings in 21% of the studies, F18-PSMA demonstrated more benign foci of uptake (30% of the studies). However, this difference in benign foci incidence was found to be statistically non-significant. 123 F18-PSMA avid malignant sites were demonstrated in 79 studies (78%), most commonly observed in the prostate gland (n=68, 55%), loco-regional (n=15, 12 %) or abdominal lymph nodes (n=5, 4 %), and distant metastases (n=35, 28%), including bone metastases (n=28), lymphadenopathy beyond abdomino-pelvic region (n=5), liver and adrenal one of each. Conclusion: F18-PSMA-1007 PET/CT demonstrated a slightly higher incidence of PSMA-ligand uptake related to benign findings compared to non-tumor foci detected by Ga68 -PSMA. Our results are discordant with recently published data showing a significantly bigger difference between the two tracers (2). Nevertheless, knowledge of increased PSMA-ligand uptake in non-prostate cancer related sites is important for accurate interpretation and for avoiding potential pitfalls. ER -