Multiparametric MRI for characterization of the tumour microenvironment

Our understanding of tumour biology has evolved over the past decades and cancer is now viewed as a complex ecosystem with interactions between various cellular and non-cellular components within the tumour microenvironment (TME) at multiple scales. However, morphological imaging remains the mainstay of tumour staging and assessment of response to therapy, and the characterization of the TME with non-invasive imaging has not yet entered routine clinical practice. By combining multiple MRI sequences, each providing different but complementary information about the TME, multiparametric MRI (mpMRI) enables non-invasive assessment of molecular and cellular features within the TME, including their spatial and temporal heterogeneity. With an increasing number of advanced MRI techniques bridging the gap between preclinical and clinical applications, mpMRI could ultimately guide the selection of treatment approaches, precisely tailored to each individual patient, tumour and therapeutic modality. In this Review, we describe the evolving role of mpMRI in the non-invasive characterization of the TME, outline its applications for cancer detection, staging and assessment of response to therapy, and discuss considerations and challenges for its use in future medical applications, including personalized integrated diagnostics. By combining multiple MRI sequences, each providing different but complementary information about the tumour microenvironment (TME), multiparametric MRI (mpMRI) enables non-invasive assessment of the heterogeneous features of the TME components. The authors of this Review describe the role of mpMRI in the non-invasive characterization of the TME, presenting examples of its utility in cancer detection, staging and assessment of response to therapy, and considering future applications for personalized integrated diagnostics. Imaging in clinical oncology currently relies predominantly on morphological assessments without exploiting the complexity of the tumour microenvironment (TME), which is increasingly becoming a therapeutic target.Multiparametric MRI (mpMRI) combines multiple MRI sequences, each providing different but complementary information. Therefore, mpMRI is well-suited to the examination of the TME.MpMRI enables assessment of cellular features of the TME, including vascularization, immune cell infiltration, metabolic alterations, cellularity, oedema and haemorrhage, and biomechanical properties.TME characterization using mpMRI provides deep insight into primary tumours and their metastatic sites, going beyond size and number, and adequately reflecting intratumoural and intertumoural heterogeneity.MpMRI enables early assessment of response to anticancer therapies, in particular, molecularly targeted therapies and immunotherapies, highlighting the important role of radiology in delivering treatment regimens that are tailored to each individual patient.