Background: Gliomas are brain tumours arising from the glia, the supportive tissue
of the central nervous system (CNS), and constitute the commonest primary malignant
brain tumours. Gliomas are graded from grade I to IV according to their appearance under
the microscope. One of the most significant adverse features of high-grade gliomas is hypoxia,
a biological phenomenon that develops when the oxygen concentration becomes insufficient
to guarantee the normal tissue functions. Since tumour hypoxia influences negatively
patient outcome and targeting hypoxia has potential therapeutic implications, there is
currently great interest in imaging techniques measuring hypoxia.
Objectives: The aim of this review is to provide up to date evidence on the radiotracers
available for measuring hypoxia in brain tumours by means of positron emission tomography
(PET), the most extensively investigated imaging approach to quantify hypoxia.
Methods: The review is based on preclinical and clinical papers and describes the validation
status of the different available radiotracers.
Results: To date, [F-18] fluoromisonidazole ([18F]FMISO) remains the most widely used
radiotracer for imaging hypoxia in patients with brain tumours, but experience with other
radiotracers has expanded in the last two decades. Validation of hypoxia radiotracers is still
on-going and essential before these radiopharmaceuticals can become widely used in the
Conclusion: Availability of a non-invasive imaging method capable of reliably measuring
and mapping different levels of oxygen in brain tumours would provide the critical means of
selecting patients that may benefit from tailored treatment strategies targeting hypoxia.