Characterization of breast tissues by diffusion weighted MR imaging

Diffusion weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique that provides information on in vivo diffusion of water molecules in tissues which is referred as apparent diffusion coefficient (ADC). The advantage of DWI is the intrinsic tissue contrast it provides because of its sensitivity to the changes in cellular environment. Malignant breast tissues are characterized by low ADC while benign breast tissues and normal breast tissues of volunteers show high ADC values. Addition of DWI as an adjunct to the contrast-enhanced MRI of breast lesions has been shown to improve the specificity and the diagnostic accuracy. Despite significant technical improvements in DWI, small lesions are sometimes difficult to visualize on ADC maps due to low spatial resolution and it is often difficult to differentiate non-mass like lesions using ADC values. Further, ADC values have the potential to delineate necrotic portions of the tumor from the viable tumor regions. Studies have shown that DWI has the potential to predict early response of tumors to therapeutic intervention in breast tumors. In recent years, numerous applications of DWI in breast tissue evaluation have been documented; however, there is a need for standardized methods for acquisition and processing of diffusion data for effective clinical applications.