What distinguishes areas of restricted diffusion on DWI and ADC maps?

Restricted diffusion on Diffusion Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) maps is an important concept in MRI, particularly in the evaluation of conditions like stroke, tumors, and certain types of infections.

In DWI, areas of restricted diffusion will appear bright. This brightness is due to the high signal resulting from the limited movement of water molecules in those areas. In contrast, ADC maps quantify the degree of diffusion and represent this as a numerical value, indicating how freely water molecules can move. In regions of restricted diffusion, the ADC values are typically lower, leading to a darker appearance on the ADC map.

Thus, the correct statement encapsulates the principle that restricted areas show a bright signal on DWI while appearing dark on ADC maps. This contrast helps radiologists distinguish between healthy and pathological tissue, as normal tissue would have higher diffusion and therefore show a dark signal on DWI and a bright signal on ADC maps.