Brain tumours, brain metastases, and neuroinflammation: Insights from
neuroimaging studies.
Abstract
Brain tumors and brain metastases induce changes in brain tissue
remodelling that lead to immunosuppression and trigger an inflammatory
response within the tumor microenvironment. These immune and
inflammatory changes can influence invasion and metastasis. Other
neuroinflammatory and necrotic lesions may occur in patients with brain
cancer or brain metastases as sequelae from treatment with radiotherapy.
Glioblastoma (GBM) is the most aggressive primary malignant brain cancer
in adults. Imaging methods such as positron-emission tomography (PET)
and different magnetic resonance imaging (MRI) techniques are highly
valuable for the diagnosis and therapeutic evaluation of GBM and other
malignant brain tumors. However, differentiating between tumor tissue
and inflamed brain tissue with imaging protocols remains a challenge.
Here, we review recent advances in imaging methods that have helped to
improve the specificity of primary tumor diagnosis versus evaluation of
inflamed and necrotic brain lesions. We also comment on advances in
differentiating metastasis from neuroinflammation processes. Recent
advances include the radiosynthesis of 18F-FIMP, an L-type amino acid
transporter 1 (LAT1)-specific PET probe that allows better
differentiation between tumor tissue and inflammation compared to
previous probes; and the combination different advanced imaging
protocols with the inclusion of radiomics and machine learning
algorithms.