Beyond Conventional MRI: Molecular PET, Multiparametric MRI, and PET/MRI in Glioma Management

Despite its central clinical role, conventional magnetic resonance imaging (MRI) provides an incomplete picture of the tumor biology of gliomas, which are biologically heterogeneous tumors. Molecular positron emission tomography (PET) with amino acid tracers, multiparametric MRI techniques (perfusion-, diffusion-, and spectroscopy-based sequences), and hybrid PET/MRI have each been proposed to overcome specific limitations of anatomic imaging in diagnosis, treatment planning, and posttreatment assessment. This narrative review examined the current evidence for molecular PET, multiparametric MRI, and integrated PET/MRI across the glioma care pathway. Rather than framing these modalities as competing alternatives, we argue that amino acid transport, vascularity, water diffusion, and metabolite composition capture distinct and often spatially incongruent facets of tumor biology, such that discordance between modalities may reflect the underlying tumor heterogeneity. We also summarized the guideline recommendations (RANO/EANO, EANM/SNMMI, etc.), outlined current evidence gaps, and discussed emerging directions in novel PET tracers, artificial intelligence, radiomics, and theranostics. Molecular PET and multiparametric MRI should be used as modalities complementary to conventional MRI within multidisciplinary glioma care, while the choice and sequence of examinations should be guided by the clinical question.