Initial evaluation of 18F-fluciclovine in prostate cancer using dynamic EXPLORER total-body PET/CT

1244 Purpose: 18F-fluciclovine is a radiotracer recommended for prostate cancer biochemical recurrence assessment by the NCCN and EAU. The tracer has rapid kinetics and tumor conspicuity changes over time. The current recommendation is to begin imaging at 3-5 min post-injection starting at the pelvis, but the recommendation is based on data acquired either only over the pelvic region or across the torso but with limited temporal sampling due to the limited axial field of view and sensitivity provided by conventional PET. Thus, tumor and normal tissue kinetics outside of the pelvic region are not fully understood. The EXPLORER total-body PET/CT scanner images the whole body simultaneously and captures the rapid kinetics of the tracer across the entire body with high fidelity. The aim of the study is 1) to qualitatively and 2) quantitatively evaluate 18F-fluciclovine using total-body PET/CT in patients with prostate cancer biochemical recurrence. Methods: Two patients with prostate cancer biochemical recurrence underwent standard-of-care 18F-fluciclovine total-body PET/CT scans. Imaging began at 4-5 min post-injection for 20 min. List-mode data were acquired to enable offline dynamic reconstructions. Image sequences with 1- and 5-min frame lengths were reconstructed using OSEM with 4 iterations and 20 subsets on a 2.344 mm isotropic matrix. ROIs were drawn on the target lesions (malignant and benign), using a 40% threshold of the maximum voxel SUV, as well as on 3 background tissues (L3 bone marrow (BM), blood pool (BP) in the ascending aorta, BP in the infra-renal aorta) for tumor-to-background calculations (respectively, TBR1, 2 and 3). Tracer kinetics for liver, skeletal muscles (SMs), BM and pancreas were also examined. Results: Two malignant lesions (lesion 1; ~3 cm, biopsy-proven metastatic prostate cancer in the scrotum, and lesion 2; ~1 cm, suspicious but not biopsy-proven, posterior bladder wall) were encountered in one patient (aged 75, Gleason score 7, on androgen deprivation therapy). Patient 2 (aged 64) did not show significant suspicious lesions. Both patients showed small