Breast Tumor Microstructure Imaging with Diffusion MRI

Abstract

Despite the notable scientific progress in screening procedures and treatment strategies, breast cancer remains a significant cause of mortality, suffering and financial burden. Breast tumor detection, classification and treatment response monitoring currently rely on combinations of invasive biopsies and imaging procedures that use contrast agents, which increase the patient risks and discomfort. Diffusion MRI (dMRI), as a non-invasive and contrast agent-free imaging method, could be considered a viable alternative approach. Conventional dMRI methods already possess a role in breast cancer protocols, due to their contribution to the sensitivity and specificity of tumor diagnosis and assessment. This role however has remained purely a supplementary one, due to their low capability to resolve sub-voxel tissue heterogeneities that yield low specificity. Novel diffusion imaging techniques that claim microstructural imaging capabilities, could only recently be clinically investigated, after advancements in MRI software and hardware. By providing microstructural information and measuring biochemical properties on cellular scales, the hypothesized higher specificity of the obtained diffusion-based parameters could expand the clinical role of dMRI in breast cancer. This hypothesis is investigated in this review article, by presenting a compilation of findings from studies that report on breast tumor microstructure obtained by either conventional or microstructural dMRI methods. In an attempt to explore the feasibility of dMRI becoming a stand-alone breast cancer approach, the clinical value of the microstructural findings reported in each method is highlighted.