Visual rating of age-related white matter changes on magnetic resonance imaging: scale comparison, interrater agreement, and correlations with quantitative measurements

BACKGROUND AND PURPOSE

To provide further insight into the MRI assessment of age-related white matter changes (ARWMCs) with visual rating scales, 3 raters with different levels of experience tested the interrater agreement and comparability of 3 widely used rating scales in a cross-sectional and follow-up setting. Furthermore, the correlation between visual ratings and quantitative volumetric measurement was assessed.

METHODS

Three raters from different sites using 3 established rating scales (Manolio, Fazekas and Schmidt, Scheltens) evaluated 74 baseline and follow-up scans from 5 European centers. One investigator also rated baseline scans in a set of 255 participants of the Austrian Stroke Prevention Study (ASPS) and measured the volume of ARWMCs.

RESULTS

The interrater agreement for the baseline investigation was fair to good for all scales (kappa values, 0.59 to 0.78). On the follow-up scans, all 3 raters depicted significant ARWMC progression; however, the direct interrater agreement for this task was poor (kappa, 0.19 to 0.39). Comparison of the interrater reliability between the 3 scales revealed a statistical significant difference between the scale of Manolio and that of Fazekas and Schmidt for the baseline investigation (z value, -2.9676; P=0.003), demonstrating better interrater agreement for the Fazekas and Schmidt scale. The rating results obtained with all 3 scales were highly correlated with each other (Spearman rank correlation, 0.712 to 0.806; P< or =0.01), and there was significant agreement between all 3 visual rating scales and the quantitative volumetric measurement of ARWMC (Kendall W, 0.37, 0.48, and 0.57; P<0.001).

CONCLUSIONS

Our data demonstrate that the 3 rating scales studied reflect the actual volume of ARWMCs well. The 2 scales that provide more detailed information on ARWMCs seemed preferential compared with the 1 that yields more global information. The visual assessment of ARWMC progression remains problematic and may require modifications or extensions of existing rating scales.

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.