Using the directional information, underlying tissue structure can be further interrogated. This is particularly helpful when assessing lesions of decreased diffusivity to determine if they are more likely to be metabolic compromise or myelin vacuolization as opposed to irreversible metabolic failure. In addition tractography can be used in preoperative planning, however, appreciation for limitations in regions of edema need to be understood to avoid underestimating the presence of axonal bundles.