[Zr]Zr-PSMA-617 PET/CT in a Patient with Biochemical Recurrence of Prostate Cancer and Prior Indetermined Findings on [F]PSMA-1007 Imaging.

We report a case of a 79-year-old male patient with a history of radical prostatectomy for prostate cancer. The patient presented with biochemical reoccurrence; however, previous conventional PSMA PET/CT using [F]PSMA-1007 showed two indetermined findings with low uptake in the right iliac lymph nodes. Further MRI evaluation provided no additional information. A recently introduced PSMA tracer, [Zr]Zr-PSMA-617 (half-life: 3.3 days), was administered in an attempt to confirm the diagnosis and aid in potential radiation planning. [Zr]Zr-PSMA-617 PET/CT clearly revealed the previously indetermined right iliac lymph nodes as definitely metastatic and also identified additional lymph node metastases that were undetected in prior scans. This case highlights the potential superior sensitivity of [Zr]Zr-PSMA-617 PET/CT in detecting recurrent disease, especially in unclear settings of [F]PSMA-1007 PET/CT and demonstrates its potential for guiding targeted radiation therapy with curative intent.