Imaging Discordance Between [⁶⁸Ga]-PSMA PET and [¹⁷⁷Lu]-PSMA SPECT in mCRPC.

Küçüker, Cansu; Kaya, Gürsan; Ergün, Eser Lay; Uğur, Ömer; Tuncel, Murat · Clin Nucl Med · 2026

case_report · Level V

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Abstract

PSMA PET/CT is commonly used for selecting candidates for [¹⁷⁷Lu]-PSMA radioligand therapy (LuPSMA RLT). However, discrepancies may occur due to pharmacokinetic and biodistribution differences between [⁶⁸Ga]-PSMA-11 and [¹⁷⁷Lu]-PSMA-617 ligands. Such discordance risks underestimating disease burden and excluding eligible patients. We present a case of metastatic castration-resistant prostate cancer (mCRPC) in whom a PSMA-negative adrenal lesion on PET exhibited significant LuPSMA uptake post-therapy and was subsequently confirmed as FDG-avid. Complementary stereotactic body radiotherapy (SBRT) achieved metabolic remission. This case highlights the clinical significance of integrating post-therapy LuPSMA imaging and FDG PET/CT with systemic treatment to ensure accurate disease characterization and personalized management of PSMA-/FDG+ lesions in advanced prostate cancer.

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