QUALITATIVE ASSESSMENT OF CEREBRAL ATROPHY ON MRI - INTEROBSERVER ANDINTRAOBSERVER REPRODUCIBILITY IN DEMENTIA AND NORMAL AGING

To assess the reproducibility of a qualitative rating scale of cerebra l atrophy on MRI in an aged population of demented and non-demented in dividuals, 4 raters independently judged cerebral atrophy (CA) in 13 r egions on a 0-3 scale on 75 MRI scans, on two occasions. The level of agreement was expressed by kappa statistics as well as by analysis of variance for interexaminer reproducibility studies. The mean CA scores ranged from 13.3 to 21.2, indicating moderately high prevalence of ce rebral atrophy in this sample. Complete agreement among observers was reached in 49.7% of the ratings during the first assessment and in 44. 1% in the second assessment. The inter-observer agreement was poor in both sessions (mean overall kappas 0.34 and 0.24). The intra-observer agreement was moderate to good for all raters (mean overall kappa: 0.5 8). The average standard deviation of the differences between CA score s of the 4 raters was 5.12 in the first and 5.13 in the second session . The average standard deviation for the differences within raters was 2.4. We conclude that the assessment of cerebral atrophy using this r ating scale on MRI in an aged population has a poor reproducibility am ong raters, However, it provides regional atrophy measurements and is quite reliable when performed by a single rater.