ROLE OF DIFFUSION WEIGHTED MAGNETIC RESONANCE IMAGING IN ASSESSMENT OF THE GRADING OF URINARY BLADDER CARCINOMA

Abstract

Bladder cancer is the most common malignant tumor in the urinary tract among both men and women.The diagnosis of bladder cancers is often delayed due to the similarity of their symptoms to those of benign disorders that can lead to a worsened prognosis.Diffusion weighted imaging (DWI) is a form of magnetic resonance imaging (MRI). It is highly sensitive in the detection of the random motion (Brownian motion) of water molecules. Thus, in cases of cellular overcrowding such as in malignancies, this motion will be restricted. DWI visualizes this motion; the more restricted the molecular motion inside the tissue, the higher the signal intensity on imaging will appear.A value can be obtained for the degree of diffusivity of the displayed tissue, which is called apparent diffusion coefficient (ADC). It provides a quantitative parameter derived from DWI. As for any other malignant tissue, bladder cancers also present high signal intensity on DWI, as well as low ADC value, which reflects restriction to motion inside the tissue.ADC value is a noninvasive reliable modality for predicting histopathological grading and the aggressiveness of cancer. ADC can play an important role for guiding therapeutic decisions.