Advanced Imaging Techniques for the Detection and Follow-up of Brain Metastases

Optimal management of patients with brain metastases relies on both accurate detection on initial imaging and accurate differentiation between treatment-related effects from progression on follow-up imaging. Contrast-enhanced MRI remains the standard technique for initial and follow-up imaging, though advanced MRI techniques, such as perfusion MRI, diffusion-weighted MRI, MR spectroscopy, and chemical exchange saturation transfer (CEST), have also emerged as complementary examinations, particularly in distinguishing TRE from true progression. Molecular imaging with PET, especially using amino acid tracers, also demonstrates high diagnostic accuracy in discriminating between treatment-related effects and tumour progression. Artificial intelligence models, including those using radiomics and deep learning approaches, have been developed to enhance diagnostic performance and to streamline workflow. However, their clinical utility is limited by significant inter-study heterogeneity, lack of standardization, and lack of large-scale external validation. This review summarizes the current literature on advanced imaging techniques in BM diagnosis and response assessment.