Background: Gliomas are neuroepithelial tumours classified by cell type and grade. In adults, low-grade gliomas are comprised mainly of astrocytomas and oligodendrogliomas grade II. The aim was to non-invasively characterise suspected low-grade gliomas through use of ¹¹C-methionine-PET and physiological MRI in order to facilitate treatment decisions.

Materials and methods: Patients with suspected low-grade glioma were prospectively and consecutively included after referral to the Neurosurgical Department, Uppsala University Hospital, between February 2010 and February 2014. All patients underwent morphological MRI, perfusion MRI, diffusion MRI and ¹¹C-methionine PET. The institutional review board approved the study, and written informed consent was obtained prior to participation from each patient.

Results: ¹¹C-methionine PET hot spot regions corresponded spatially with regions of maximum relative cerebral blood volume in dynamic susceptibility contrast (DSC) perfusion MRI_. The skewness of the transfer constantin dynamic contrast-enhanced (DCE) perfusion MRI, and the standard deviation of relative cerebral blood flow in DSC perfusion MRI could most efficiently discriminate between glioma grades II and III. In diffusion MRI, tumour fractional anisotropy differed between suspected low-grade gliomas of different neuropathological types. Quantitative diffusion tensor tractography was applicable for the evaluation of tract segment infiltration.

Conclusion: PET and physiological MRI are able to characterise low-grade gliomas and are promising tools for guiding therapy and clinical decisions before neuropathological diagnosis has been obtained.