18 F-PSMA-1007 PET/CT at 60 and 120 minutes in patients with prostate cancer: biodistribution, tumour detection and activity kinetics

PSMA-targeted PET in patients with prostate cancer (PCa) has a significant impact on treatment decisions. By far the most frequently used PSMA ligand is68Ga-labelled PSMA-11. However, due to the availability of larger amounts of activity,18F-labelled PSMA ligands are of major interest. The aim of the present study was to evaluate the biodistribution and performance of the novel18F-labelled ligand PSMA-1007 at two different time points.

This retrospective analysis included 40 consecutive patients (mean age 68.7 ± 8.1 years) referred for PSMA PET/CT.18F-PSMA-1007 PET/CT was performed for localization of biochemical relapse, primary staging or therapy follow-up. Circular regions of interest were placed on representative slices of the liver, spleen, kidney, abdominal aortic blood pool, bone marrow (fourth lumbar vertebral body), urinary bladder and gluteus muscle at 60 and 120 min after injection. In malignant lesions the maximum standardized uptake (SUVmax) was measured within volumes of interest at both time points. All SUVs at 60 min were compared with those at 120 min after injection.

The activity in the blood pool, urinary bladder and gluteus muscle was very low and decreased significantly over time (P < 0.001). Uptake in the liver, spleen and kidney showed a significant increase over time and uptake in the bone marrow remained stable. Overall, 135 PCa lesions were detected at 60 min and 136 lesions at 120 min after injection. The median SUVmaxincreased significantly (P < 0.001) from 10.98 to 15.51 between 60 and 120 min.

PCa lesions show a significant increase in18F-PSMA-1007 uptake at 120 min compared with 60 min after injection. In addition, accumulation of the tracer in the urinary bladder was very low leading to improved contrast of adjacent PCa lesions. Increasing accumulation in the liver may limit the sensitivity of the tracer in detecting liver metastases.

European journal of nuclear medicine and molecular imaging. 2018 Mar 14 [Epub ahead of print]

Kambiz Rahbar, Ali Afshar-Oromieh, Martin Bögemann, Stefan Wagner, Michael Schäfers, Lars Stegger, Matthias Weckesser

Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany. ., Department of Nuclear Medicine, Inselspital, University Hospital Bern, Bern, Switzerland., Department of Urology, University Hospital Münster, Münster, Germany., Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.