Tissue and Organ-specific Tumor Heterogeneity on dual tracer PET-CT ([⁶⁸Ga] Ga-PSMA-11 and [¹⁸F] FDG) and Dural-based...

The present report describes a patient of metastatic castration-resistant prostate cancer (mCRPC) with dural-based brain metastasis, discordant and variable [⁶⁸Ga] Ga-prostate specific membrane antigen (PSMA)-11 and [¹⁸F] fluorodeoxyglucose ([¹⁸F] FDG) uptake in metastases on dual-tracer positron emission tomography computed tomography (PET/CT), illustrating three important teaching points: (a) Dual-tracer PET/CT demonstrating discordant tumor biology pattern between soft tissue and skeletal metastatic lesions in mCRPC even within the same individual, thereby provides a more comprehensive overview of whole-body tumor status, with implications for personalized patient profiling and treatment selection (b) valuable role of [¹⁸F] FDG-PET/CT in identifying PSMA-negative lesions (neuroendocrine transformation) in mCRPC patients, including the possibility of detecting second primary cancer, (c) high metabolic tumor volume on [¹⁸F] FDG-PET/CT associated with aggressive biology and adverse prognosis.