Functional pituitary adenoma imaging

High-resolution pituitary MRI localises most pituitary neuroendocrine tumours (PitNETs), yet clinically important subgroups remain challenging: (i) very small functioning tumours, particularly corticotroph microadenomas, and (ii) post-operative remnants where scar, gland and tumour cannot be reliably separated. Functional imaging, specifically PET has matured into a problem-solving modality when conventional imaging is equivocal, provided it is used selectively and interpreted within a physiology-led framework. This review proposes an MRI-first, tiered imaging strategy and a pragmatic approach to tracer selection from the available armamentarium ([ 11 C]methionine, [ 68 Ga]SSTR ligands, [ 68 Ga]PentixaFor, [ 18 F]FET and [ 18 F]FDG). We emphasise how to optimise PET acquisition and reporting, and how to integrate imaging with endocrine phenotype, treatment history and surgical/radiosurgical planning to maximise clinical impact while safeguarding pituitary function.