Diffuse Peritoneal Carcinomatosis of Prostate Cancer Unveiled by [89Zr]Zr-PSMA-617 PET/CT

We report an interesting case of a 64-year-old man with a history of radical prostatectomy for prostate cancer. The patient presented with steady increasing prostate-specific antigen levels, but with negative findings on previous multiple conventional prostate-specific membrane antigen (PSMA) PET/CT (with [68Ga]Ga-PSMA-11) and [18F]FDG PET/CT. A recently introduced PSMA tracer using long-lived 89Zr (half-life 3.3 days), [89Zr]Zr-PSMA-617, was administered in attempt to localize potential local recurrence or metastasis. [89Zr]Zr-PSMA-617 PET/CT clearly revealed diffuse peritoneal carcinomatosis and local recurrence of the prostate cancer, which were unidentified on previous conventional PET/CT scans. This case highly demonstrates the potential of PET imaging with the novel PSMA tracer [89Zr]Zr-PSMA-617.