White matter changes on CT and MRI: an overview of visual rating scales. European Task Force on Age-Related White Matter Changes.

Since the recognition of white matter changes on CT (leukoaraiosis), rating scales for the location and severity of white matter changes have been developed, mainly for research purposes, to investigate factors such as the relation with cognition, risk factors, and pathology. The main purpose of rating scales is to provide scores that can be used in statistical analyses. The development of the NINDS-AIREN criteria for vascular dementia have introduced a new application for these rating scales in investigating and delineating the amount of white matter changes on CT/MRI sufficient to fulfill the criteria. Furthermore, in Alzheimer's disease, recognition of white matter changes may serve to delineate homogeneous groups and help to identify patients with different symptomatology. We reviewed the existing rating scales for CT and MRI and judged their properties and reliability. The ideal rating scale does not yet exist, but different rating scales may serve different purposes, for which some recommendations are made.