Morphological and Functional Neuroradiology of Brain Metastases

Neuroimaging plays a key role in the diagnosis and differentiation of brain metastases (BM) in patients with known or unknown malignancies. Computed tomography and magnetic resonance imaging are the key imaging modalities used in the detection of BM. Advanced imaging techniques including proton magnetic resonance spectroscopy, magnetic resonance perfusion, diffusion weighted imaging, and diffusion tensor imaging may aid in arriving at the correct diagnosis, in particular cases, such as newly diagnosed solitary enhancing brain lesions in patients without known malignancy. Imaging is also performed to predict and/or assess the efficacy of treatment, and to differentiate residual or recurrent tumors from therapy-related complications. Furthermore, the recent advent of artificial intelligence is opening up a vast scenario for the analysis of quantitative information deriving from neuroimaging. In this image-rich review, we provide an up-to-date overview on the application of imaging in patients with BM. We describe typical and atypical imaging findings of parenchymal and extra-axial BM on Computed tomography, magnetic resonance imaging, and positron emission tomography, focusing on the role of advanced imaging techniques, that can serve as problem-solving tools in the management of patients with BM.