Breast Cancer Histopathological Features: Diffusion-Weighted Imaging and Apparent Diffusion Coefficient Correlation

Abstract

Breast cancer is the most common cancer in women, with a life-time risk of 12% (one in eight) for average-risk women, and is the second most common cause of death from cancer in women. The majority of cases are curable, and much of that curability depends on early detection. Recent magnetic resonance imaging (MRI) techniques are based on the evaluation of morphological and functional parameters that are influenced by tumour biology. As a consequence, there is a growing interest in their application in a disease like breast cancer, where biological hetero-geneity affects prognosis and therapeutic decisions. DWI is a specific modality to produce images of tissues weighted with the local microstructural characteristics of water diffusion. A significant advantage of diffusion-weighted MR imaging over conventional contrast material–enhanced MR imaging is its high sensitivity to change in the microscopic cellular environment without the need for intravenous contrast material injection. Diffusion-weighted (DW) MR imaging has been investigated as a means of overcoming the limitations of conventional MR imaging assessment, which is reliant on inherent unique tissue contrast mechanism. DW imaging makes use of the variability of Brownian motion of water molecules in tissue. DWI is a powerful imaging tool that provides unique information related to tumor cellularity and the integrity of the cellular membrane. With respect to breast DWI a potential role for the apparent diffusion coefficient (ADC), a quantitative measure that is directly proportional to the diffusion of water and inversely proportional to the tumor cellular density, has been reported to be useful for characterizing breast tumors and distinguishing malignant tissues from benign tissues. So use of DWI as a diagnostic tool can increase the specificity of breast MR imaging and can reduce the number of false-positive results and associated unnecessary biopsies. Apparent diffusion coefficient (ADC) values are quantified by measurement of mean diffusivity along three orthogonal directions, which are affected by cellularity of the tissue, fluid viscosity, membrane permeability and blood flow Because of the heterogeneity of breast cancer. The technique can be applied widely for tumor detection and tumor characterization and for the monitoring of response to treatment. In addition, DWI appears to have the ability to predict treatment response to chemotherapy and radiation treatment. The chemotherapy causes cell lysis that leads to increase in the extracellular water and so increase in the apparent diffusion coefficient (ADC).