Pitfalls of PSMA PET-CT in Advanced Prostate Cancer Imaging
False negatives are not as much of an issue in the overt metastatic disease setting. However, there is a low sensitivity for nodal disease at <4mm, and nodes cannot be detected at <2mm.
Furthermore, and importantly, 5-10% of prostate cancers do not express PSMA, and thus one must be aware of PSMA-negative, but FDG-positive patients.
The pitfalls of false negatives include radical treatment of incurable patients and unnecessary multimodality treatment of “localized” prostate cancer that is actually metastatic.
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Prostate-Specific Membrane Antigen–Negative Metastases—A Potential Pitfall in Prostate-Specific Membrane Antigen PET
68Ga-PSMA-11 PET/CT was performed in a 74-year-old man because of biochemical recurrence of prostate cancer following radiation therapy of the prostate gland 24 months earlier. Besides focal nuclide accumulation in the prostate gland suggestive of local recurrence, PET scan revealed no further pathologic uptake.
However, CT showed multiple pulmonic nodules suggestive of metastases.
Thoracotomy and pathologic examination revealed the nodules to be prostate cancer metastasis. Furthermore, immunohistochemical staining with PSMA antibodies demonstrated a virtual lack of PSMA expression.
This case demonstrates the possibility of PSMA-negative metastases of prostate cancer an important pitfall that should be known to physicians interpreting PSMA PET.
https://journals.lww.com/nuclearmed/Abs ... ve.33.aspx