**1. Introduction**

Structural imaging using contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) is crucial for the initial detection and diagnosis of brain tumours. However, it has limitations in post-treatment surveillance where tumour- and therapy-related changes can appear similarly. Molecular imaging with positron emission tomography (PET) provides additional information that can better delineate tumour extent and burden, for example fluorodeoxyglucose (FDG) depicts the metabolic activity and fluroethyltyrosine (FET) and fluorodihydroxyphenylalanine (FDOPA) depict the amino acid turnover of otherwise nonspe‐ cific soft tissue changes on CT and MRI. This could ultimately improve clinical decision-making and anatomical targeting of tumour for biopsy, radiotherapy or surgery.

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